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Chemical properties of root mats in some south coastal British Columbia podzols : implications for classification… Martin, Dale Elizabeth 1986

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CHEMICAL PROPERTIES OF ROOT MATS IN SOME SOUTH COASTAL BRITISH COLUMBIA PODZOLS: IMPLICATIONS FOR CLASSIFICATION AND GENESIS by DALE ELIZABETH MARTIN B.Sc. Botany, University of B r i t i s h Columbia, 1980 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of S o i l Science) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA February, 19 86 7, © D a l e Elizabeth Martin In p resen t ing this thesis in partial fu l f i lment of the requ i rements for an a d v a n c e d d e g r e e at the Univers i ty of Brit ish C o l u m b i a , I agree that the Library shall make it f reely avai lable for re fe rence a n d study . I further agree that p e r m i s s i o n for extens ive c o p y i n g o f this thesis for scholar ly p u r p o s e s may be g ranted by the h e a d of m y d e p a r t m e n t o r by his o r her representat ives . It is u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f this thesis fo r f inancia l gain shall no t b e a l l o w e d w i t h o u t m y wr i t ten pe rm iss ion . D e p a r t m e n t T h e Un ivers i ty o f Brit ish C o l u m b i a 1956 M a i n M a l l V a n c o u v e r , C a n a d a V 6 T 1Y3 DE-6(3 /81) i i ABSTRACT P o d z o l s , s i t u a t e d a t h i g h e l e v a t i o n w i t h i n the Coast Mountains s u r r o u n d i n g Vancouver, o f t e n have a c c u m u l a t i o n s of o r g a n i c m a t e r i a l w i t h i n the m i n e r a l s o i l e i t h e r as mats above an impermeable l a y e r o r as c h a n n e l s r u n n i n g o b l i q u e l y and h o r i z o n t a l l y through the B h o r i z o n . T h i s o r g a n i c m a t e r i a l i s "greasy" t o the touch w i t h few d i s c e r n i b l e m i n e r a l g r a i n s on hand t e x t u r i n g . The mats range i n t h i c k n e s s from 1 cm t o g r e a t e r than 40 cm, are s i t u a t e d i n seepage zones and are o v e r l a i n by a w e l l d r a i n e d sandy loam, o f t e n of low o r g a n i c c o n t e n t . The c h a n n e l s have the g r o s s morphology of r o o t s and are up t o 5 cm wide. O c c a s i o n a l remnants of wood s t r u c t u r e are d i s c e r n a b l e in s i t u and the c e l l u l a r n a t u r e of the o r g a n i c m a t e r i a l can be seen under the compound m i c r o s c o p e . The m a j o r i t y of the mats c o u l d be c l a s s i f i e d as o r g a n i c (>17% C ) , e i t h e r as an H or an O h o r i z o n . I f they c o n t a i n e d l e s s than 17% C they met the c r i t e r i a of a Bhf h o r i z o n . C h e m i c a l l y the mats and c h a n n e l s have some u n u s u a l p r o p e r t i e s . They are s i m i l a r t o the s u r f i c i a l humus i n carbon t o n i t r o g e n r a t i o and n i t r o g e n t o s u l p h u r r a t i o but much c l o s e r t o a p o d z o l i c B h o r i z o n i n i r o n c o n t e n t . The r a t i o of carbon i n humic a c i d s t o f u l v i c a c i d s (Ch/Cf) and p o l y p h e n o l i c t o t o t a l f u l v i c a c i d s (Ca/Cf) was a l s o more c h a r a c t e r i s t i c of a p o d z o l . The o r g a n i c mats had an average Ch/Cf of 0.23 and a Ca/Cf of 0.73. T h i s i s i n comparison w i t h 2.44 and 0.44, r e s p e c t i v e l y , f o r the s u r f i c i a l humus and 0.34 and 0.72, r e s p e c t i v e l y , i n the o r g a n i c m a t e r i a l of the c o n v e n t i o n a l l y s i t u a t e d Bhf h o r i z o n s . Both mats and c h a n n e l s had very h i g h c o n c e n t r a t i o n s of aluminum, sometimes e x c e e d i n g 10%. From the o r g a n i c mats on Burke Mountain, aluminum e x t r a c t e d by a c i d ammonium o x a l a t e was j u s t s l i g h t l y h i g h e r than t h a t e x t r a c t e d w i t h sodium pyrophosphate and o x a l a t e s i l i c o n was low. T h i s i m p l i e d t h a t most of the aluminum was bound w i t h the o r g a n i c m a t e r i a l . In c o n t r a s t , the o x a l a t e aluminum of C y p r e s s Park mat samples was o f t e n more than double t h a t which was e x t r a c t e d w i t h pyrophosphate and o x a l a t e s i l i c o n v a l u e s were a l s o h i g h . The f i g u r e s i n d i c a t e d t h a t a l l o p h a n e , w i t h an approximate A l t S i r a t i o of 2, may make up a h i g h p r o p o r t i o n of t h i s h o r i z o n . M o r p h o l o g i c a l l y , the mats and c h a n n e l s seem t o have o r i g i n a t e d t h r ough r o o t d e c o m p o s i t i o n b u t c h e m i c a l l y , p o d z o l i c mechanisms seem t o have p l a y e d an i m p o r t a n t r o l e . Because of s i m i l a r i t i e s between s o i l s s t u d i e d i n t h i s t h e s i s and s o i l s of the l i t e r a t u r e found t o c o n t a i n i m o g o l i t e , a column study was und e r t a k e n t o t e s t a mechanism whereby decomposing r o o t s c o u l d be e n r i c h e d by the aluminum of p r o t o - i m o g o l i t e . I t was found t h a t the o r g a n i c m a t e r i a l of r o t t i n g wood c o u l d scavenge aluminum from t h i s p o s i t i v e l y charged a l u m i n o s i l i c a t e c o l l o i d and t h a t i n t h e p r o c e s s the f u l v i c a c i d s of the wood were a l s o i m m o b i l i z e d . I f a mechanism s i m i l a r t o t h i s was o p e r a t i n g w i t h i n a p o d z o l , i t c o u l d i v h e l p e x p l a i n b o t h the h i g h c o n c e n t r a t i o n of aluminum and of f u l v i c a c i d s i n the mats and c h a n n e l s . V TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS v LIST OF TABLES v i i i LIST OF FIGURES x ACKNOWLEDGEMENTS x i INTRODUCTION 1 CHAPTER 1: THE CHANGING CONCEPT OF THE PODZOL THROUGH TIME 4 I n t r o d u c t i o n 4 E a r l y R u s s i a n and European Views 5 R e c o g n i t i o n of the I l l u v i a l H o r i z o n 7 Western European Views of the E a r l y 1900's.... 10 Views of the Modern E r a 23 CHAPTER 2: MODERN MODELS. OF PODZOL GENESIS 3 6 The Movement of I r o n and Aluminum as an O r g a n i c Complex 3 6 Movement of Aluminum (and I r o n ) as I n o r g a n i c P r o t o - i m o g o l i t e 42 C o n c l u s i o n 55 v i Page CHAPTER 3: SOIL CLASSIFICATION IN CANADA 56 I n t r o d u c t i o n 56 E a r l y H i s t o r y of the C l a s s i f i c a t i o n System 57 Some M o d i f i c a t i o n s i n the C l a s s i f i c a t i o n of P o d z o l s . . . . 58 C h a r a c t e r i z a t i o n and C l a s s i f i c a t i o n of S o i l O r g a n i c M a t t e r 61 CHAPTER 4: DESCRIPTION OF THE STUDY AREA 66 G e n e r a l D e s c r i p t i o n of the S o i l s 66 L o c a t i o n s Where These S o i l s are Found 68 G e n e r a l environment of the Coast Mountains 69 A. V e g e t a t i o n 6 9 B. A i r and S o i l C l i m a t e 71 C. S u r f i c i a l Geology and Bedrock of the Sampling S i t e s 73 CHAPTER 5: MORPHOLOGY AND CHEMICAL CHARACTERIZATION OF THE SOILS 76 F i e l d Sampling 76 L a b o r a t o r y Methods on F i e l d C o l l e c t e d Samples 77 Column Study 80 R e s u l t s and D i s c u s s i o n 86 C l a s s i f i c a t i o n of the Root Mats 105 CHAPTER 6: POSSIBLE ORIGINS OF THE ANOMOLOUS ORGANIC MATERIAL 109 Proposed Models of Root Mat/Channel G e n e s i s . . . 109 How These Suggested Models F i t the P r o p e r t i e s Found....112 v i i page Column Study T e s t i n g the P r o t o - i m o g o l i t e Model 117 C o n c l u s i o n s 127 SUMMARY AND CONCLUSIONS 129 LITERATURE CITED 13 5 APPENDIX A 146 APPENDIX B 163 APPENDIX C 164 APPENDIX D 166 v i i i LIST OF TABLES page Table 4-1: Change i n P r e c i p i t a t i o n with. Change i n E l e v a t i o n i n N o r t h Vancouver 72 Table 4-2: C l i m a t i c Data O b t a i n e d from S t a t i o n s C l o s e t o the Burke Mountain and C y p r e s s Park Sampling S i t e s 74 Table 5-1: Average and Range of P e r c e n t Carbon, N i t r o g e n and S u l p h u r V a l u e s found i n the Root Mats, Root Channels and S u r f i c i a l Humus H o r i z o n s S t u d i e d . . . 87 Table 5-2: pH, C o n d u c t i v i t y and I o n i c C o n c e n t r a t i o n of R a i n f a l l i n the Lower M a i n l a n d 89 Table 5-3: E s t i m a t i o n s of the Forms of I r o n and Aluminum i n the S o i l U s i n g V a r i o u s E x t r a c t a n t s 94 Table 5-4: Average and Range of Pyrophosphate and O x a l a t e E x t r a c t a b l e Fe, A l and S i i n Root Mats and Root Channels 95 Table 5-5: The D i s t r i b u t i o n of Aluminum and S i l i c o n W i t h i n a B h f l H o r i z o n w i t h a High %C and the U n d e r l y i n g Bhf2 H o r i z o n w i t h a Lower %C 97 i x Page Table 5-6: Average and Range of Humic t o F u l v i c A c i d R a t i o s , P o l y p h e n o l i c F u l v i c t o T o t a l F u l v i c A c i d R a t i o s and P e r c e n t of T o t a l Carbon E x t r a c t e d 102 Table 5-7: Average P e r c e n t Carbon and P e r c e n t Pyrophosphate and O x a l a t e E x t r a c t a b l e Fe and A l i n the Root Mat Bhf Compared t o More C o n v e n t i o n a l Bhf H o r i z o n s Found Near the Top of the P r o f i l e 107 Table 6-1: P e r c e n t Aluminum and S i l i c o n Adsorbed From P r o t o - i m o g o l i t e by O r g a n i c Columns and ppm Carbon r e l e a s e d by the C o n t r o l Columns 122 Table 6-2: ppm C i n F u l v i c A c i d P r i o r t o and Subsequent t o T h e i r L e a c h i n g Through Two O r g a n i c Columns; The F i r s t P r e v i o u s l y T r e a t e d With P r o t o - i m o g o l i t e and the Second Not 124 X LIST OF FIGURES page F i g u r e 2-1: Proposed S t r u c t u r e of I m o g o l i t e 44 F i g u r e 2-2: The S m a l l e s t P o s s i b l e B u i l d i n g U n i t of the I m o g o l i t e S t r u c t u r e 46 F i g u r e 4-1: D i a g r a m a t i c R e p r e s e n t a t i o n of a Root Mat and Root Channel i n a P o d z o l i c S o i l 67 F i g u r e 5-1: S e t Up of Column Study 83 F i g u r e 6-1: P e r c e n t Aluminum, E x t r a c t e d from O r g a n i c M a t t e r and Sand, by A c i d Ammonium O x a l a t e and Na Pyrophosphate A f t e r 1 and 2 Months Treatment w i t h P r o t o - i m o g o l i t e 120 F i g u r e 6-2: D i a g r a m a t i c R e p r e s e n t a t i o n of I n o r g a n i c P r o t o - i m o g o l i t e Moving Through the S o i l and R e a c t i n g w i t h F u l v i c A c i d s R e l e a s e d by Decomposing Roots 125 ACKNOWLEDGEMENTS Dur i n g the c o u r s e of my s t u d i e s I have r e c e i v e d h e l p from many s o u r c e s . Thanks, f i r s t of a l l , t o Dr. L.E. Lowe bo t h f o r h i s academic s u p p o r t , and f o r h i s e n d l e s s p a t i e n c e d u r i n g the c o m p l e t i o n of t h i s t h e s i s . Thanks, a l s o t o Dr. L.M. L a v k u l i c h , who always f i n d s the time t o l i s t e n , and t o my committee members, Dr. T.M. B a l l a r d , Mr. H.A. L u t t m e r d i n g and Mr. T. L o r d . An a d d i t i o n a l thank you must go t o H. A. L u t t m e r d i n g , f o r s u g g e s t i n g the t h e s i s t o p i c and f o r showing us the Burke Mountain s i t e . A p p r e c i a t i o n i s extended t o E s t e r Y i p , P a t t i C a r b i s and B e r n i e von S p i n d l e r f o r t e c h n i c a l a s s i s t a n c e i n the l a b o r a t o r y and f o r h e l p i n g make the work e n j o y a b l e . A s p e c i a l thank you t o L a u r i e Donovan f o r h i s h e l p i n c o n s t r u c t i n g the columns and f o r h i s e n d l e s s s u p p o r t and encouragement thr o u g h o u t my U n i v e r s i t y e d u c a t i o n . T h i s r e s e a r c h was s u p p o r t e d i n p a r t by a g r a n t from the N a t i o n a l S c i e n c e and E n g i n e e r i n g Research C o u n c i l , No. A-4465. 1 INTRODUCTION Many p o d z o l i c s o i l s of south c o a s t a l B r i t i s h Columbia p o s s e s s m o r p h o l o g i c a l and c h e m i c a l i r r e g u l a r i t i e s which do not " f i t " the c o n v e n t i o n a l c o n c e p t of a p o d z o l ( L e w i s , 1976) (McKeague, 1979). One u n u s u a l f e a t u r e i s t y p i c a l of s o i l s i n very h i g h r a i n f a l l e n v i r o n m e n t s . These p o d z o l s are d i s t i n g u i s h e d by u n u s u a l o r g a n i c a c c u m u l a t i o n s w i t h i n the B h o r i z o n , most n o t a b l y i n l a y e r s above a d u r i c h o r i z o n o r bedrock c o n t a c t and i n ch a n n e l s r u n n i n g v e r t i c a l l y and o b l i q u e l y t h r o u g h o u t the e n t i r e depth of the m i n e r a l s o i l . The o r g a n i c m a t t e r found i n these l o c a t i o n s i s greasy t o the touch and m i n e r a l g r a i n s may or may not be d e t e c t a b l e . The h o r i z o n t a l l a y e r s have been c a l l e d " r o o t mats" i n s o i l s u r v e y r e p o r t s and as the m u l t i d i r e c t i o n a l c h a n n e l s o f t e n have the g r o s s morphology of r o o t s , they are r e f e r r e d t o as " r o o t c h a n n e l s " i n t h i s paper. In the Canadian system of s o i l c l a s s i f i c a t i o n (CSSC, 1978), the r o o t mats can be c l a s s i f i e d as " o r g a n i c " i f they c o n t a i n g r e a t e r than 17% o r g a n i c c a r b o n . With l e s s c a r b o n , they have o f t e n been found t o have enough N a - p y r o p h o s p h a t e - e x t r a c t a b l e i r o n and aluminum t o meet the d e f i n i t i o n of a p o d z o l i c Bhf h o r i z o n (H. A. L u t t m e r d i n g , p e r s . comm.). I f t h i s o r g a n i c - r i c h m i n e r a l h o r i z o n , s i t u a t e d a l o n g the c o n t a c t , i s g r e a t e r than 10 cm t h i c k i n an o t h e r w i s e o r g a n i c - p o o r s o i l , the s o i l w i l l be c l a s s i f i e d as a f e r r o - h u m i c p o d z o l , a l t h o u g h the Bhf w i l l not be i n the same 2 p o s i t i o n and may not have the same o r i g i n as i m p l i e d i n our p r e s e n t u n d e r s t a n d i n g of p o d z o l g e n e s i s . R e c e n t l y , however, the view t h a t i r o n and aluminum owe t h e i r s o l u b i l i t y w i t h i n a p o d z o l i c s o i l t o m e t a l - c o m p l e x i n g o r g a n i c a c i d s , has been c h a l l e n g e d . Anderson e t a_l. (1982) have found e v i d e n c e t h a t aluminum, a t l e a s t , may move i n an i n o r g a n i c form and t h a t c o m p l e x a t i o n w i t h o r g a n i c a c i d s o c c u r s some time a f t e r m o b i l i z a t i o n . T h e r e f o r e , a b e t t e r u n d e r s t a n d i n g of the p r o c e s s e s i n v o l v e d , both i n r o o t mat f o r m a t i o n and i n the g e n e s i s of p o d z o l i c s o i l s i n g e n e r a l , i s n e c e s s a r y b e f o r e d e c i d i n g i f the c l a s s i f i c a t i o n of the r o o t mat as a p o d z o l i c Bhf h o r i z o n i s j u s t i f i e d . The o b j e c t i v e s of t h i s study were: 1. To c h a r a c t e r i z e c h e m i c a l l y and m o r p h o l o g i c a l l y the o r g a n i c m a t e r i a l w i t h i n the r o o t mats and r o o t c h a n n e l s . 2. To determine i f the noted c h a r a c t e r i s t i c s were d i f f e r e n t from those of Bhf h o r i z o n s found d i r e c t l y beneath the Ae . 3. To study the mechanisms proposed i n the l i t e r a t u r e f o r p o d z o l g e n e s i s and how these have changed through t i m e , and 4. With the use of a column s t u d y , t o t e s t one of these mechanisms t o see i f i t may a p p l y t o the g e n e s i s of the r o o t mat h o r i z o n s . I t was hoped t h a t an h i s t o r i c a l p e r s p e c t i v e would serve t o show t h a t i d e a s c o n c e r n i n g p o d z o l g e n e s i s have always been i n a s t a t e of f l u x and t h a t new c o n c e p t s s h o u l d be met w i t h an open mind. I t was a l s o hoped t h a t the p r o p e r t i e s examined would g i v e some c l u e t o the g e n e s i s of the o r g a n i c a c c u m u l a t i o n s and, w i t h the l i t e r a t u r e r e v i e w , h e l p determine i f the c l a s s i f i c a t i o n of the r o o t mats as p o d z o l i c Bhf h o r i z o n s s h o u l d be changed. 4 CHAPTER 1 THE CHANGING CONCEPT OF THE PODZOL THROUGH TIME The Lack of a Concensus I n t r o d u c t i o n Two b a s i c q u e s t i o n s have c h a l l e n g e d p o d z o l r e s e a r c h s i n c e the s o i l was f i r s t d e s c r i b e d by Dokuchaiev i n 1879. 1. What i s a p o d z o l ? What c h a r a c t e r i s t i c s must a s o i l p o s s e s s t o be i n c l u d e d i n the p o d z o l i c c l a s s i f i c a t i o n ? 2. What unique e n v i r o n m e n t a l c o n d i t i o n s and c h e m i c a l p r o c e s s e s l e d t o the g e n e s i s of these s o i l s ? The answers t o the f i r s t q u e s t i o n have changed d r a m a t i c a l l y through the y e a r s . O p i n i o n s about which h o r i z o n i s d i a g n o s t i c , the i n c l u s i o n o r o m i s s i o n of c l a y - e n r i c h e d s o i l s , the degree t o which the p r o c e s s must o c c u r b e f o r e the s o i l meets p o d z o l i c c l a s s i f i c a t i o n , and what c h e m i c a l e x t r a c t a n t s are b e s t s u i t e d t o measuring t h i s p r o c e s s , have changed through time and from c o u n t r y t o c o u n t r y . Hypotheses on p o d z o l g e n e s i s have been c e n t e r e d around t h r e e main themes: 1. I r o n and aluminum move as i n o r g a n i c c a t i o n s . 2. S e s q u i o x i d e s move as humus-protected s o l s . 3. I r o n and aluminum are complexed by f u l v i c a c i d o r simple o r g a n i c a c i d s and l e a c h e d from the A h o r i z o n i n t h i s form. 5 A l t h o u g h volumes of work have been p u b l i s h e d on the s u b j e c t s of p o d z o l g e n e s i s and c l a s s i f i c a t i o n , no t r u e consensus has e v e r been a c h i e v e d on a l l a s p e c t s of t h i s p r o c e s s and the same q u e s t i o n s are s t i l l b e i n g asked today. As b o t h q u e s t i o n s are once a g a i n a d d r e s s e d i n t h i s t h e s i s , an attempt i s made t o put t h i s r e s e a r c h i n t o h i s t o r i c a l p e r s p e c t i v e . E a r l y R u s s i a n and European Views A c c o r d i n g t o J o f f e (1936), s o i l s s i m i l a r t o p o d z o l s were d e s c r i b e d by S p r e n g e l as e a r l y as 1837 and were a l s o noted by S c a n d i n a v i a n and German f o r e s t e r s and g e o l o g i s t s of t h a t t i m e . The ash-gray t o w h i t e m a t e r i a l (the Ae h o r i z o n i n CSSC, 1978) was b e l i e v e d by some t o have been c a r r i e d from s u r r o u n d i n g a r e a s by wind and water and d e p o s i t e d on top of the s o i l as an independant s t r a t u m . In " C a r t o g r a p h y of R u s s i a n S o i l s " (1879) Dokuchaev d e s c r i b e d a p o d z o l as a s h a l l o w s o i l of "6-12 i n c h e s , deepening o n l y i n p l a c e s as i t approaches bogs." The " e x t e r n a l c h a r a c t e r i s t i c s of the p o d z o l a r e : an ashy c o l o u r , g e n e r a l l y w i t h y e l l o w i s h , b l u i s h o r g r e e n i s h t o n e s , " "of a sandy-type and c o n t a i n [ i n g ] 83-84% s i l i c a . " " M i c r o s c o p i c a n a l y s i s shows t h a t samples examined so f a r c o n s i s t of p h y t o l i t h s , d i a t o m s , s o f t v e g e t a b l e r e s i d u e s , q u a r t z g r a i n s , s i l t y p a r t i c l e s , e t c . " (as quoted i n M u i r , 1961, p . 3 ) . The t o t a l p o d z o l i c p r o f i l e i n Dokuchaev's view c o n s i s t e d of what Canadians now c a l l the e l u v i a l Ae h o r i z o n l E a r l y R u s s i a n s d i d not r e c o g n i z e a zone of d e p o s i t i o n . Dokuchaev d e s c r i b e d the i l l u v i a l B h o r i z o n o n l y i n n o t i n g t h a t 6 " p o d z o l s are u n d e r l a i n by c l a y s , loams o r sands: i n a l l these c a s e s the p o d z o l appears t o pass g r a d u a l l y i n t o the u n d e r l y i n g r o c k " ( a f t e r M u i r , 1961, p . 3 ) . A l s o , they d i d not s e p a r a t e s o i l s l e a c h e d s i m p l y of c l a y i n the upper h o r i z o n s from s o i l s l e a c h e d a l s o of bases and s e s q u i o x i d e s . A l l p r o f i l e s w i t h an e l u v i a l A h o r i z o n were c l a s s i f i e d as p o d z o l s . Dokuchaev summed up the views of h i s day when he l i s t e d f o u r p o s s i b i l i t i e s t o a c c o u n t f o r the g e n e s i s of a p o d z o l . He saw the ashy l a y e r a r i s i n g : 1. "Due t o [ n a t u r a l ] f i r e s . 2. Due t o the b u r n i n g of p e a t . 3. From m i c r o s c o p i c e v i d e n c e i t might be c o n s i d e r e d [ t h a t p o d z o l s were] a s i m p l e a c c u m u l a t i o n of v e g e t a b l e r e s i d u e s , eg. p h y t o l i t h s " ( M u i r , 1961, pp.3-4). 4. That p o d z o l s were formed as a s o i l i n a r e a s where t h e r e was "more m o i s t u r e , l e s s l i g h t and l e s s a c c e s s of a i r t o the s o i l " ( M u i r , 1961, p . 4 ) . Dokuchaev seemed t o c o n c u r w i t h the l a t t e r mechanism, n o t i n g t h a t p o d z o l s were "formed m a i n l y i n f o r e s t s w i t h a s i g n i f i c a n t p a r t i c i p a t i o n of bog and f o r e s t v e g e t a t i o n " and t h a t these f a c t o r s worked t o g e t h e r t o produce a s o i l w i t h p r o p e r t i e s i n c o n t r a s t t o "the common n o r t h e r n d r y - l a n d v e g e t a b l e loamy and sandy s o i l s " which were "formed i n d r i e r p l a c e s w i t h f r e e a c c e s s of a i r and l i g h t and the predominance of a d r y l a n d herbaceous v e g e t a t i o n " ( a f t e r M u i r , 1961, p. 4 ) . In 1885, V.P. A m a l i t s k i i , a R u s s i a n s c i e n t i s t who worked i n c l o s e c o l l a b o r a t i o n w i t h Dokuchaev, d e s c r i b e d p o d z o l s as "a 7 p r o d u c t of the m o d i f i c a t i o n of l o c a l p a r e n t m a t e r i a l by the combined e f f e c t of e l u v i a l p r o c e s s e s , a t m o s p h e r i c phenomena and f o r e s t v e g e t a t i o n " (as quoted by Ponomareva, 1969, p . 5 ) . Another R u s s i a n , A.V. G e o r g i e v s k i i , a p p l i e d Dokuchaev 1s s o i l f o r m ing f a c t o r s i n a t t e m p t i n g t o u n d e r s t a n d the g e n e s i s of p o d z o l s . He c o n c l u d e d t h a t p o d z o l s were d i f f e r e n t i a t e d from the u n d e r l y i n g s u b s o i l m a i n l y by an abundance of S i C ^ and a low c o n t e n t of Ca, Mg, Fe and A l . He a t t r i b u t e d these m o d i f i c a t i o n s t o the a c t i o n of a c i d o r g a n i c s o l u t i o n s and c o n c l u d e d t h a t "humic a c i d s are among the most e n e r g e t i c f a c t o r s of w e a t h e r i n g found i n n a t u r e ' s l a b o r a t o r y : they are a b l e t o e x t r a c t not o n l y o x i d e s of a l k a l i n e and a l k a l i - e a r t h m e t a l s , but a l s o those of heavy m e t a l s . We may b e l i e v e t h a t the p o d z o l i c h o r i z o n which we are ex a m i n i n g and p o d z o l s i n g e n e r a l , arose through the i n f l u e n c e of these p a r t i c u l a r a c i d s " (1888, as quoted by Ponomareva, 1969, pp. 5-6). L i k e Dokuchaev, G e o r g i e v s k i i d i d not r e c o g n i z e the d e p o s i t i o n of these w e a t h e r i n g p r o d u c t s i n the u n d e r l y i n g s u b s o i l . R e c o g n i t i o n of the I l l u v i a l H o r i z o n V a r i o u s d e s c r i p t i o n s of s o i l s s i m i l a r t o the R u s s i a n " p o d z o l " were p u b l i s h e d by European a u t h o r s t h r o u g h o u t the 18th c e n t u r y . In t h e s e , the b l e a c h e d e l u v i a l h o r i z o n was o f t e n d e s i g n a t e d " B l e i c h e r d e " and was l i n k e d w i t h an u n d e r l y i n g h o r i z o n c a l l e d " O r t s t e i n " (Jenny, 1980). O r t s t e i n was a p p l i e d b o t h t o g r e y i s h h o r i z o n s h i g h i n c l a y and r e d f e r r u g i n o u s l a y e r s i n s a n d i e r s o i l s . M u i r (1961) quotes m i c r o s c o p i c e v i d e n c e p r e s e n t e d by P. E. M i i l l e r i n 1887 which showed t h a t the B l e i c h e r d e h o r i z o n was "composed m a i n l y of pure m i n e r a l fragments, e s p e c i a l l y q u a r t z , i n t e r m i x e d w i t h o t h e r components of g r a n i t e " (pp. 15-16). Whereas, o r t s t e i n p o s s e s s e d "a q u i t e d i f f e r e n t c o n s t i t u t i o n : each g r a i n , each s o l i d p a r t i c l e i s surrounded by an a p p a r e n t l y s t r u c t u r e l e s s s u b s t a n c e , each e n c r u s t e d w i t h the brown m a t e r i a l which c o n f e r s i t s c o l o u r t o the l a y e r " ( M u i r , 1961, p.16). M u l l e r a l s o found t h a t " o r t s t e i n " h o r i z o n s of loamy s o i l s were o f t e n e n r i c h e d i n c l a y compared t o the o v e r l y i n g and u n d e r l y i n g h o r i z o n s . T h i s , as w e l l as the work of o t h e r e a r l y Western European s o i l s c i e n t i s t s , p o i n t e d the way f o r the r e c o g n i t i o n of the i l l u v i a l a s p e c t of p o d z o l s . In 1888, P. A. K o s t y c h e v , who was p r o b a b l y f a m i l i a r w i t h the Western European l i t e r a t u r e , i n t r o d u c e d t o R u s s i a the c oncept of a three-membered p o d z o l i c p r o f i l e , i n c l u d i n g an o r t s t e i n h o r i z o n . In h i s view, the decay of o r g a n i c r e s i d u e s a t the s u r f a c e of p o d z o l i c s o i l s produced water s o l u b l e a c i d s . As the m a t e r i a l of the o r g a n i c r e s i d u e had i n s u f f i c i e n t bases t o n e u t r a l i z e these a c i d s , they were washed by r a i n w a t e r i n t o deeper l a y e r s , where they formed s a l t s w i t h m e t a l l i c bases. T h i s r e s u l t e d i n the l e a c h i n g of a l l r e a d i l y s o l u b l e s u b s t a n c e s from the p o d z o l i c h o r i z o n i n t o the u n d e r l y i n g hardpan (Ponomareva, 1969); however, by what s p e c i f i c c h e m i c a l p r o c e s s the l e a c h i n g o c c u r r e d i s not mentioned. The m o b i l e a c i d s were known as " c r e n i c a c i d s " and c o n s i d e r e d o x i d a t i o n p r o d u c t s of the i n s o l u b l e humic a c i d . F u r t h e r o x i d a t i o n of c r e n i c a c i d produced " a p o c r e n i c a c i d " . These a c i d s were b e l i e v e d t o be b i o c h e m i c a l l y produced by m i c r o o r g a n i s m s i n the s o i l , but t h e i r presence was n e v e r 9 c o n c l u s i v e l y e s t a b l i s h e d . The r o l e of f u n g i i n the p o d z o l i c p r o c e s s was p a r t i c u l a r l y s t r e s s e d . The f i r s t R u s s i a n s o i l t e x t b o o k was w r i t t e n by N. M. S i b i r t s e v i n 1909 (Ponomareva, 1969). In t h i s work he u n i f i e d much of the e a r l y R u s s i a n and Western European r e s e a r c h t o a r r i v e a t the f o l l o w i n g view on the f o r m a t i o n of p o d z o l s . An a c c u m u l a t i o n and t r a n s l o c a t i o n of c r e n i c and a p o c r e n i c a c i d s o c c u r r e d i n the s o i l under the c o n d i t i o n s of a moderately c o l d and humid c l i m a t e i n c o n i f e r o u s o r mixed f o r e s t s . With these a c i d s "many m i n e r a l s u b s t a n c e s [were] l e a c h e d out of the s o i l , p a r t l y as o r g a n o m i n e r a l compounds, i . e . , bound w i t h a c i d and p a r t l y as s a l t s of humus a c i d s - a p o c r e n a t e s (K, Na, Ca, Mg, A l , F e O ) . . . I n s o l u b l e s i l i c a [would] s e p a r a t e out of s i l i c a t e s and c h i e f l y from z e o l i t e s ; t h e i r p r o p o r t i o n [would] i n c r e a s e i n the s o i l " (1909, as quoted by Ponomareva, 1969, p . 7 ) . Some of the m i n e r a l and o r g a n i c s u b s t a n c e s l e a c h e d from the " p o d z o l " would e n t e r the groundwater but the r e s t , perhaps the m a j o r i t y , would be r e t a i n e d i n the u n d e r l y i n g s o i l by the f o l l o w i n g mechanisms: 1. A s i m p l e p r e c i p i t a t i o n of s a l t s would o c c u r as i n c r u s t a t i o n s on the s u r f a c e of sand g r a i n s , w i t h no change i n the c h e m i c a l c o n s t i t u t i o n of these s a l t s . 2. In some, a c h e m i c a l changeover from one c h e m i c a l compound t o a l e s s s o l u b l e form would r e s u l t i n p r e c i p i t a t i o n . T h i s c o u l d i n c l u d e the o x i d a t i o n of f e r r o u s o x i d e , the o x i d a t i o n of c r e n i c a c i d t o a p o c r e n i c a c i d o r the f o r m a t i o n of i r o n compounds w i t h p h o s p h o r i c a c i d , e t c . (Ponomareva, 1969). In t h i s way, these e a r l y R u s s i a n s c i e n t i s t s , u s i n g o b s e r v a t i o n and i n s t i n c t , a r r i v e d a t a t h e o r y of p o d z o l t h a t touches many of our c u r r e n t c o n c e p t s . Western European Views of the E a r l y 1900's The term " p o d z o l " was f i r s t i n t r o d u c e d i n t o the nomenclature of Western Europe by E. Ramann i n 1911, but i n a much narrower sense than was u n d e r s t o o d by the R u s s i a n s . I t was a p p l i e d o n l y t o sandy s o i l s t h a t e x h i b i t e d b o t h a b l e a c h e d h o r i z o n and an a c c u m u l a t i o n of c o l o u r e d s u b s t a n c e s such as humus and/or i r o n o x i d e s i n the o r t s t e i n . I t d i d not i n c l u d e s o i l s l e a c h e d s i m p l y of c l a y . These were t o be c l a s s i f i e d i n t o o t h e r c a t e g o r i e s , m a i n l y the "brown s o i l s " , (Braunerden i n German) ( P e t e r s o n , 1976). A second d i v e r g e n c e from R u s s i a n views o c c u r r e d i n the e a r l y 1900's w i t h the emergence i n Western Europe of an a l t e r n a t e t h e o r y f o r p o d z o l g e n e s i s (Ponomareva, 1969). The " c o l l o i d o c h e m i c a l " t h e o r y proposed the movement of i r o n and aluminum as c o l l o i d s of i n o r g a n i c h y d r o x i d e s r a t h e r than as complexes o r s a l t s of the " h y p o t h e t i c a l " c r e n i c a c i d s . As these h y d r o x i d e s were p o s i t i v e l y charged i n the pH range of a p o d z o l , to m i g r a t e from the n e g a t i v e l y charged humus i n the A h o r i z o n , e a r l y r e s e a r c h e r s suggested they were p r o t e c t e d by c o l l o i d a l humic a c i d s . As a complex s o l (a p o s i t i v e l y c h a r g e d h y d r o x i d e s o l s u r r o unded by n e g a t i v e l y charged humus s o l s ) , the two would m i g r a t e t o the B h o r i z o n where they would be p r e c i p i t a t e d by h i g h e r pH or d i v a l e n t c a t i o n s (Deb, 1949; Stobbe and W r i g h t , 10 p r i m a r i l y g e n e s i s 11 1959). Rode (1970) l i s t s a number of e a r l y workers who found e v i d e n c e t h a t these complex s o l s c o u l d e x i s t and so f o r the n e x t f o u r decades o p i n i o n f l u c t u a t e d between the e a r l y R u s s i a n t h e o r y and t h i s new European c o n c e p t . In 1913, u s i n g water e x t r a c t s of p e a t , B. A a r n i o e s t i m a t e d t h a t i t would take between 24 and 10 p a r t s of humus t o m a i n t a i n 1 p a r t of A^O-j a n c * between 2.8 t o 0.4 p a r t s of humus t o m a i n t a i n 1 p a r t of F©2°3 a s complex s o l s . T h i s , t o many, seemed t o o h i g h a r a t i o t o e x p l a i n the h i g h s e s q u i o x i d e , low o r g a n i c m a t t e r c o n t e n t of the B h o r i z o n (Deb, 1949). None the l e s s , M o r i s o n and S o t h e r s (1914) s t u d i e d the c o l l o i d o c h e m i c a l t h e o r y of p o d z o l g e n e s i s , t o u n d e r s t a n d the f o r m a t i o n of an i r o n pan and by e x t r a p o l a t i o n of l a b o r a t o r y e x p e r i m e n t s t o the r e a l s o i l , produced the f o l l o w i n g model. In the a c c u m u l a t i n g o r g a n i c m a t t e r a t the s o i l s u r f a c e , s u b s t a n c e s were produced t h a t e x h i b i t e d a c i d p r o p e r t i e s . These s u b s t a n c e s would f i r s t remove a l l r e a d i l y s o l u b l e m a t e r i a l , p r o b a b l y i n t r u e s o l u t i o n . At the same t i m e , c o l l o i d a l humates of i r o n , aluminum and c a l c i u m o x i d e s would form. These s o l s would move downwards i n the p r o f i l e d u r i n g the wet season, p r o d u c i n g a b l e a c h e d l a y e r a t the s o i l s u r f a c e . D u r i n g the dry season, d e s i c c a t i o n of the s o i l would o c c u r t o the p o i n t of the permanent water t a b l e , above which the b u l k of the c o l l o i d s would have accumulated. Upon r e w e t t i n g i n the r a i n y season, the c o a g u l a t e d and d e s i c c a t e d c o l l o i d s would not e n t i r e l y go back i n t o s u s p e n s i o n , as the c o l l o i d c h a r a c t e r would have changed d u r i n g the p r o c e s s of d e s i c c a t i o n . T h i s was s u p p o r t e d by the l a b o r a t o r y e x p e r i m e n t s of these a u t h o r s . O x i d a t i o n of the 12 humus d u r i n g the dry p e r i o d would r e s u l t i n most of the i r o n l e f t i n the form of f e r r i c h y d r o x i d e , which a f t e r many seasons, would form the i r o n pan ( M o r i s o n and S o t h e r s , 1914). In c o n t r a s t , J ones and W i l l c o x (1929) f e l t the R u s s i a n t h e o r y c o u l d e q u a l l y w e l l e x p l a i n the f o r m a t i o n of the pan and p r e s e n t e d t h e i r own l a b o r a t o r y r e s u l t s t o s u b s t a n t i a t e t h i s . They used the e a r l i e r work of P i c k e r i n g , 1913, which showed t h a t the i r o n of f e r r i c t a r t r a t e , malate and c i t r a t e was p r e s e n t i n the e l e c t r o n e g a t i v e p o r t i o n of the m o l e c u l e . Jones and W i l l c o x , t h e r e f o r e , assumed t h a t as s o i l o r g a n i c a c i d s c o n s i s t l a r g e l y of h y d r o x y a c i d s , compounds were formed on r e a c t i o n w i t h i r o n t h a t were s i m i l a r t o the f e r r i c t a r t r a t e , malate and c i t r a t e s t u d i e d by P i c k e r i n g . These compounds, c a r r y i n g i r o n i n the e l e c t r o n e g a t i v e p o r t i o n of the m o l e c u l e , were l e a c h e d t h rough the s o i l , d i s s o l v i n g i n c r e a s i n g q u a n t i t i e s of s e s q u i o x i d e s u n t i l a c o n c e n t r a t i o n was reached beyond which the o r g a n i c - i r o n compound formed a b a s i c s a l t and was p r e c i p i t a t e d . T h i s gave r i s e t o a zone of s e s q u i o x i d e a c c u m u l a t i o n and f i n a l l y a pan (Jones and W i l l c o x , 1929). I t seems t h a t a l a c k of good a n a l y t i c a l methods p r e v e n t e d these e a r l y workers from knowing e x a c t l y what they had produced i n t h e i r l a b o r a t o r y e x p e r i m e n t s and, t h e r e f o r e , the r e s u l t s c o u l d be argued as p r o o f f o r e i t h e r mechanism of p o d z o l i z a t i o n . The R u s s i a n community a l s o took up t h i s debate, w i t h K. D. G l i n k a and K. K. G e d r o i t s t a k i n g the s i d e of the c o l l o i d o c h e m i c a l h y p o t h e s i s and V. R. V i l ' y a m s and I . V. T y u r i n s u p p o r t i n g movement of Fe and A l t h r o u g h complex f o r m a t i o n w i t h o r g a n i c 13 a c i d s (Ponomareva, 1969). Meanwhile, i n Western Europe, the c o l l o i d o c h e m i c a l t h e o r y was s u p p o r t e d by a proced u r e d e s i g n e d t o measure the amorphous forms of i r o n and aluminum i n the B h o r i z o n assumed t o have been t r a n s l o c a t e d from above. T h i s was the a c i d ammonium o x a l a t e e x t r a c t i o n de v e l o p e d by 0. Tamm i n 1920 (Farmer, 1982). Perhaps because so l i t t l e of the e x t r a c t e d i r o n and aluminum o x i d e s were a s s o c i a t e d w i t h o r g a n i c m a t t e r and because the m o b i l i t y of the humus p r o t e c t e d o x i d e s o l had nev e r been proven i n the r e a l s o i l , Tamm proposed t h a t movement of i r o n and aluminum i n a p o d z o l o c c u r r e d as an e l e c t r o p o s i t i v e c o l l o i d . He a l s o proposed development of the Bh h o r i z o n by m i g r a t i o n of u n a s s o c i a t e d o r g a n i c c o l l o i d s t h r o u g h the Ae and t h e i r p r e c i p i t a t i o n on t o p r e v i o u s l y d e p o s i t e d i n o r g a n i c c o l l o i d s a t the top of the B h o r i z o n (Farmer, 1982). A s i m i l a r mechanism was e n v i s i o n e d by S. Ma t t s o n , i n p u b l i c a t i o n s of the 1930's. By a p p l y i n g the p r i n c i p l e s of i s o e l e c t r i c w e a t h e r i n g t o the m i g r a t i o n of i r o n and aluminum h y d r o x i d e s and o r g a n i c m a t t e r , he found these complex c o l l o i d s would be the l e a s t d i s p e r s e d and t h e r e f o r e , the l e a s t m o b i l e , a t a s o i l pH t h a t c o r r e s p o n d e d t o t h e i r i s o e l e c t r i c p o i n t . T h i s was the pH where the number of n e g a t i v e c h a r g e s e q u a l l e d the number of p o s i t i v e c h a r g e s and the c o l l o i d , as a whole, was n e u t r a l . S e s q u i o x i d e s a l o n e , had a h i g h i s o e l e c t r i c p o i n t and t h e r e f o r e , had a p o s i t i v e charge a t the pH of a p o d z o l . P e p t i z a t i o n by s i l i c a o r humus d e c r e a s e d the i s o e l e c t r i c p o i n t of the complex s o l . Below the i s o e l e c t r i c p o i n t , a complex c o l l o i d would have 14 more b a s i c groups ( p o s i t i v e c h a r g e s ) than a c i d i c groups ( n e g a t i v e c h a r g e s ) and would be h e l d i n s u s p e n s i o n as a c a t i o n i c c o l l o i d . Above the i s o e l e c t r i c p o i n t , the n e g a t i v e c h a r g e s would dominate and an a n i o n i c c o l l o i d would form. Whether the s o l moved as a p o s i t i v e o r n e g a t i v e c o l l o i d t h r ough a p o d z o l depended on the w e a t h e r i n g stage of the p r o f i l e and the p r o p o r t i o n of each component ( s e s q u i o x i d e s , humus and s i l i c a ) i n v o l v e d i n the complex. Mattson used i s o e l e c t r i c weathe°ring t o e x p l a i n the f o r m a t i o n of deep or s h a l l o w p o z o l s , t o show how p o d z o l p r o f i l e s d e v e l o p e d from the bottom up and t o e x p l a i n what d e t e r m i n e d the l o w e r l i m i t of the A h o r i z o n (Mattson and G u s t a f s s o n , 1937). F o r these i n t e r e s t i n g h y p o t h e s e s , p l e a s e r e f e r t o the o r i g i n a l work. Mattson was v i r t u a l l y i g n o r e d i n the l a t e r r e v i e w a r t i c l e s . Stobbe and W r i g h t (1959) c l a i m e d the pH g r a d i e n t was not g r e a t enough w i t h i n most p o d z o l s f o r the i s o e l e c t r i c p o i n t t o be reached and Deb (1949) c l a i m e d a p o s i t i v e c o l l o i d c o u l d not move through the n e g a t i v e l y c h a r g e d humus-rich A h o r i z o n . However, J o f f e (1936) was s u f f i c i e n t l y impressed t o w r i t e t h a t the "work of Mattson . . . p r o m i s e s t o uncover the fundamental p r i n c i p l e s of the [ p o d z o l i z a t i o n ] p r o c e s s " p. 293. Work by G a l l a g h e r (1942) may have f o r c e d some c o l l o i d o c h e m i c a l s u p p o r t e r s t o r e c o n s i d e r the e a r l y R u s s i a n v i e w s . G a l l a g h e r f e l t t h a t the p r o p e r t i e s of o r g a n i c c o l l o i d s , under the c o n d i t i o n s found i n a p o d z o l , would be such as t o promote the c o a g u l a t i o n of s e s q u i o x i d e s o l s , r a t h e r than t h e i r p e p t i z a t i o n . He a l s o c i t e d the l a c k of o r g a n i c a c c u m u l a t i o n i n 15 the B h o r i z o n of many p o d z o l s as e v i d e n c e a g a i n s t the movement of s e s q u i o x i d e s as humus p r o t e c t e d c o l l o i d s . I n s t e a d , he s u p p o r t e d the c o n c e p t s of Jones and W i l l c o x (1929) t h a t s i m p l e o r g a n i c a c i d s , such as o x a l i c a c i d , p l a y e d a major r o l e . He f e l t t h a t more a t t e n t i o n had not been g i v e n these s i m p l e m o l e c u l e s i n the p a s t because r e s e a r c h e r s of the time f e l t t h e i r p r e s e nce i n the s o i l t o o t r a n s i t o r y . However, G a l l a g h e r quoted work of French and German r e s e a r c h e r s t h a t showed o x a l i c and c i t r i c a c i d s t o be the most abundant e n d - p r o d u c t s produced by f u n g i under n u t r i e n t - p o o r c o n d i t i o n s . He f e l t t h a t because of the abundance of these a c i d s and because p o d z o l i z a t i o n was known t o o c c u r most r e a d i l y on sandy t e x t u r e d s o i l w i t h f r e e p e r c o l a t i o n , under l e a c h i n g c o n d i t i o n s , a c i d s of a t r a n s i t o r y c h a r a c t e r c o u l d w e l l complex Fe and A l and move them l o w e r i n the s o i l . G a l l a g h e r c o n ducted a column study t o determine the e f f e c t s of l e a c h i n g s i m p l e o r g a n i c a c i d s through a p o d z o l i c B s o i l . He found t h a t movement of o x a l i c a c i d through the column soon produced a s t r o n g l y l e a c h e d p r o f i l e w i t h the upper s o i l b l e a c h e d t o a depth of 3 cm, an o b v i o u s zone of d e p o s i t i o n below and c l e a r d r a i n a g e w a t e r . The hydroxy a c i d s of t a r t a r i c , c i t r i c and l a c t i c formed no such zone of d e p o s i t i o n but i n s t e a d , the d r a i n a g e soon became h i g h l y c o l o u r e d and c o n t a i n e d i r o n . The poor l e a c h i n g power of c o l l o i d a l humus on s e s q u i o x i d e s was demonstrated by the a d s o r p t i o n of humus on the s o i l s u r f a c e of a column c o n t a i n i n g C h o r i z o n m a t e r i a l . In the r e a l s o i l G a l l a g h e r saw the i r o n and aluminum p r e c i p i t a t i n g out i n the B h o r i z o n f i r s t as s a t u r a t e d s a l t s of o r g a n i c a c i d s but f i n a l l y , w i t h c o n t i n u e d f u n g a l d e c o m p o s i t i o n , as f r e e h y d r o x i d e s o r h y d r a t e d o x i d e s . C o l l o i d a l humus was e i t h e r s u b s e q u e n t l y o r s i m u l t a n e o u s l y l e a c h e d through the A h o r i z o n due t o a p r o t e c t i v e a c t i o n of c o l l o i d a l s i l i c a , and was c o a g u l a t e d i n the B h o r i z o n by the s e s q u i o x i d e g e l . T h e r e f o r e , the r o l e of c o l l o i d a l humus i n p o d z o l i z a t i o n was p a s s i v e r a t h e r than a c t i v e and t h i s a c c o u n t e d f o r the wide d i f f e r e n c e s i n humus to s e s q u i o x i d e r a t i o s found i n many B h o r i z o n s ( G a l l a g h e r , 1942). In 1946, Bremner e_t a_l. s t u d i e d the e x t r a c t i n g power of the n e u t r a l s a l t s of some i n o r g a n i c a c i d s , such as pyrophosphate, on s o i l o r g a n i c m a t t e r , i r o n , manganese and copper. R e s u l t s showed t h a t compounds which were good p o l y v a l e n t m e t a l e x t r a c t a n t s and t h a t i n f a c t , formed c o - o r d i n a t i o n complexes w i t h these m e t a l s , a l s o e x t r a c t e d l a r g e amounts of o r g a n i c m a t t e r from the s o i l . T h i s s u g g ested t h a t some of the o r g a n i c m a t t e r i n the s o i l was i n the form of c o - o r d i n a t i o n complexes w i t h the m e t a l s , and when these p o l y v a l e n t c a t i o n s were removed by the e x t r a c t i n g compounds, t h i s o r g a n i c m a t t e r a l s o became s o l u b l e . The f a c t t h a t these m e t a l s were i n complexed r a t h e r than exchangeable form was demonstrated when l i t t l e o r g a n i c m a t t e r was s o l u b l i z e d upon l e a c h i n g the s o i l w i t h d i l u t e HC1 t o remove exchangeable Fe, Mn and Cu. However, t h i s p r e t r e a t m e n t i n e v i t a b l y l e d t o an i n c r e a s e i n the amount of these m e t a l s and o r g a n i c m a t t e r i n the subsequent pyrophosphate e x t r a c t i o n . A l s o , when the pyr o p h o s p h a t e - m e t a l complexes were d i a l y s e d from the e x t r a c t i n g s o l u t i o n , the r e m a i n i n g o r g a n i c m a t t e r , r e p r e s e n t i n g what was o r i g i n a l l y bound w i t h the m e t a l s , was water s o l u b l e . A d d i t i o n of manganese, copper o r i r o n i m m e d i a t e l y p r e c i p i t a t e d t h i s o r g a n i c m a t t e r and the m e t a l - o r g a n i c complex formed, showed the same s o l u b i l i t y c h a r a c t e r i s t i c s as the o r i g i n a l compounds p r e s e n t i n the s o i l . T h e r e f o r e , the a u t h o r s proposed t h a t some of the O r g a n i c m a t t e r i n the s o i l formed c o - o r d i n a t i o n complexes w i t h some of the p o l y v a l e n t m e t a l s and t h a t the presence of these m e t a l s r e n d e r e d the o r g a n i c - m e t a l complex i n s o l u b l e . However, they d i d not a t t e m p t t o l i n k the presence of these c o o r d i n a t i o n complexes w i t h movement of the m e t a l s i n t h i s form. A l t h o u g h the work of Bremner e_t a_l. (1946) would s t e e r p o d z o l i c r e s e a r c h towards c h e l a t i o n c h e m i s t r y i n the 1950's and 1960*s, the case f o r c o l l o i d o c h e m i c a l movement of i r o n and aluminum was s t i l l the s t r o n g e r i n the 1940's and i t s s t r e n g t h was f u r t h e r i n c r e a s e d by the work of Deb (1949). Deb attempted to r e p e a t A a r n i o ' s work of 1913 but a l s o wanted t o i n c l u d e the e f f e c t of pH and c o n c e n t r a t i o n on the f o r m a t i o n of humus-protected i r o n o x i d e s o l s . Deb found: 1. The l o w e r the c o n c e n t r a t i o n of i r o n o x i d e s o l , the s m a l l e r was the amount, i n p r o p o r t i o n , of humus n e c e s s a r y f o r p e p t i z a t i o n . 2. The amount of humus n e c e s s a r y f o r p e p t i z a t i o n v a r i e d w i t h the source of the humus. 3. The l o w e r the pH, the h i g h e r was the amount of humus r e q u i r e d f o r p e p t i z a t i o n . In c o n t r a s t t o A a r n i o , Deb c o n c l u d e d t h a t humus was a b l e tc c a r r y many t i m e s i t s w e i g h t i n e x c e s s i r o n . He e s t i m a t e d t h a t f o r c o n c e n t r a t i o n s of 100 ppm i r o n a t pH 4.0, not more than 18 30-40% of the i r o n o x i d e (by we i g h t ) i n humus would be needed f o r f u l l p e p t i z a t i o n . T h e r e f o r e , t h e r e was ample humus i n the A h o r i z o n of p o d z o l p r o f i l e s t o f u l l y p e p t i z e any i r o n formed i n t h i s h o r i z o n by w e a t h e r i n g . A l t h o u g h Deb found t h a t complex s o l s c o u l d be f l o c c u l a t e d i n the l a b o r a t o r y by the a d d i t i o n of C a C ^ t o t h e i r s u s p e n s i o n s , no a d s o r p t i o n took p l a c e by these s o l s on c a l c i u m s a t u r a t e d s o i l . Deb, t h e r e f o r e c o n c l u d e d t h a t exchangeable c a l c i u m i n the B h o r i z o n of a p o d z o l i s not s u f f i c i e n t t o f l o c c u l a t e the humus-protected i r o n o x i d e s o l and he i m p l i c a t e d m i c r o b i a l decompositon of the humus as an a l t e r n a t i v e f o r t h e i r p r e c i p i t a t i o n . Deb (1949) d i d not r e p e a t these e x p e r i m e n t s u s i n g aluminum t o form the complex s o l , but i f the p r e v i o u s work of A a r n i o (1913) had any v a l i d i t y , i t would r e q u i r e an o r d e r of magnitude more humus t o p e p t i z e an e q u i v a l e n t amount of aluminum o x i d e o v e r t h a t r e q u i r e d f o r i r o n . T h i s mechanism may t h e r e f o r e not work as n e a t l y f o r t h i s e l e m e n t . In the 1950's, C. B l o o m f i e l d a g a i n t u r n e d the t i d e of t h i n k i n g towards o r g a n i c a c i d complexed movement of Fe and A l i n a p o d z o l . Most l a b o r a t o r y e x p e r i m e n t s p r e v i o u s t o t h i s time had used o r g a n i c m a t t e r e x t r a c t e d from peat t o model o r g a n i c i n t e r a c t i o n s w i t h s e s q u i o x i d e s . However, as B l o o m f i e l d (1951) p o i n t e d o u t , by the very f a c t of i t s p e r s i s t a n c e , peat must have r e p r e s e n t e d a r e l a t i v e l y i n e r t f r a c t i o n of the o r i g i n a l o r g a n i c d e b r i s , and the s o l u b l e m a t e r i a l , which arose e i t h e r through d e c o m p o s i t i o n o r was n a t u r a l l y p r e s e n t as s m a l l o r g a n i c m o l e c u l e s i n the l i v e p l a n t m a t e r i a l , may have been more a c t i v e i n m o b i l i z i n g i r o n and aluminum. B l o o m f i e l d (1951) showed t h a t the a b i l i t y of raw humus and peat e x t r a c t s t o cause the d i s s o l u t i o n of f e r r i c h y d r o x i d e was much l e s s than t h a t of the s o l u b l e compounds washed from autumn l e a v e s and g r a s s . He then began a 6-part s e r i e s on p o d z o l i z a t i o n u s i n g the s o l u b l e p r o d u c t s from v a r i o u s t r e e l i t t e r s . Aqueous e x t r a c t s of S c o t ' s p i n e , Norway s p r u c e , l a r c h , S i t k a s pruce and D o u g l a s - f i r n e e d l e s were t e s t e d f o r t h e i r a b i l i t y t o d i s s o l v e i r o n and aluminum from the c o - p r e c i p i t a t e d s e s q u i o x i d e s ( B l o o m f i e l d 1953a, 1953b, 1954a, 1954b). H i g h l i g h t s from t h i s work were: 1. The e x t r a c t s were a b l e t o reduce much of the f e r r i c o x i d e t o a f e r r o u s form complexed w i t h o r g a n i c m a t t e r . The e x i s t a n c e of a complex bond was shown by the a b i l i t y of the o r g a n i c m o l e c u l e t o r e t a i n much of the i r o n i n s o l u t i o n i n the f e r r o u s form, under a l k a l i n e o x i d i z i n g c o n d i t i o n s . 2. The o r g a n i c a c i d s p r o v i d e d much l e s s p r o t e c t i o n t o the aluminum i o n as seen by a l a r g e p r e c i p i t a t i o n of aluminum when the pH was r a i s e d from 3.94 t o 6.00. 3. The e x t e n t t o which the s e s q u i o x i d e s were d i s s o l v e d by the aqueous e x t r a c t was d e c r e a s e d as the pH of the e x t r a c t i n g s o l u t i o n was i n c r e a s e d . T h i s e f f e c t was most pronounced under a e r o b i c c o n d i t i o n s . 4. However, even, under the adver s e c o n d i t i o n s of h i g h pH and oxygen, the s o l u t i o n e f f e c t was s t i l l a p p r e c i a b l e . The r e l a t i v e l y s m a l l changes i n pH and degree of a e r a t i o n found i n a p o d z o l i c s o i l c o u l d not have caused the r e p r e c i p i t a t i o n of the o x i d e s i n the B h o r i z o n . B l o o m f i e l d (1953a) suggested m i c r o b i a l a s s i m i l a t i o n of the o r g a n i c l i g a n d s caused p r e c i p i t a t i o n , a l t h o u g h he found he c o u l d not e x p l a i n the s e g r e g a t i o n of p r e c i p i t a t e d i r o n , aluminum and o r g a n i c m a t t e r by t h i s mechanism, nor the c o n s i s t e n t o r d e r i n which they appeared. L a t e r , he found t h a t the a c i d s and i r o n seemed t o be removed from s o l u t i o n by a d s o r p t i o n on t o u n d i s s o l v e d f e r r i c h y d r o x i d e ( B l o o m f i e l d , 1955) . 5. The s o l u t i o n of the o x i d e s was n o n - b i o l o g i c a l as i t proceeded i n the presence of t o l u e n e and c h l o r o f o r m ( B l o o m f i e l d , 1953a). 6. The e x t r a c t was s e p a r a t e d i n t o a sim p l e o r g a n i c a c i d f r a c t i o n and a p o l y p h e n o l i c f r a c t i o n u s i n g an a n i o n exchange r e s i n . B l o o m f i e l d found e v i d e n c e t h a t the p o l y p h e n o l i c f r a c t i o n was r e s p o n s i b l e f o r the r e d u c t i o n of i r o n ( B l o o m f i e l d , 1957). A l t h o u g h aluminum was i n c l u d e d i n e a r l i e r work, B l o o m f i e l d found much l e s s e v i d e n c e f o r complex movement of t h i s i o n by o r g a n i c m a t t e r . He, t h e r e f o r e , c o n c e n t r a t e d h i s l a t e r r e s e a r c h on r e d u c t i o n and movement of i r o n , v i r t u a l l y i g n o r i n g aluminum. S i m i l a r work by DeLong and S c h n i t z e r (1955) and S c h n i t z e r and DeLong (1955) l e d these a u t h o r s t o very d i f f e r e n t c o n c l u s i o n s . Aqueous e x t r a c t i o n of the autumn l e a f f a l l of p o p l a r , beech, b i r c h , p i n e and sugar maple from t r e e s growing on p o d z o l i z e d s o i l s , as w e l l as e x t r a c t s from the f o r e s t canopy and 21 LFH h o r i z o n , were mixed w i t h f e r r i c h y d r o x i d e . In c o n t r a s t t o B l o o m f i e l d , these a u t h o r s found t h a t as the pH of the e x t r a c t was r a i s e d w i t h NaOH, more i r o n was h e l d i n s o l u t i o n up t o an Fe:OM mass r a t i o of u n i t y a t pH 8.5. DeLong and S c h n i t z e r (1955) c o n c l u d e d , l i k e Deb, t h a t a suspending c a p a c i t y of t h i s magnitude c o u l d o n l y be e x p l a i n e d i f the o r g a n i c m a t t e r was a c t i n g as a p r o t e c t i v e c o l l o i d t o c o l l o i d a l i r o n h y d r o x i d e . The a u t h o r s then s u p p o r t e d t h i s r e a s o n i n g by e l e c t r o d i a l y s i s a t pH 5.5 of a 50% s a t u r a t e d p o p l a r e x t r a c t ( S c h n i t z e r and DeLong, 1955). They found t h a t most of the i r o n moved towards the n e g a t i v e e l e c t r o d e and even the p o r t i o n which moved p o s i t i v e l y was e x p l a i n e d as be i n g due t o o r g a n i c m a t t e r p r o t e c t i o n . The a b s o r p t i o n s p e c t r a of the s o l u t i o n p r e s e n t a t the a n i o n i c c e l l s a f t e r e l e c t r o d i a l y s i s , showed no maxima i n d i c a t i v e of f e r r i c i o n s o r of s o l u b l e complexed i r o n . They a l s o found no s p e c t r o p h o t o m e t r i c e v i d e n c e f o r c h e l a t i o n ( S c h n i t z e r and DeLong, 1955). The s i m i l a r i t y of these a u t h o r s r e s u l t s t o those of Deb (1949) may i n d i c a t e t h a t t h e i r e x p e r i m e n t a l c o n d i t i o n s r e s u l t e d i n the p r o d u c t i o n of c o l l o i d s of i r o n o x i d e r a t h e r than i r o n - o r g a n i c complexe s. B l o o m f i e l d was s u p p o r t e d , however, by the work of Co u l s o n e_t a l . (1960a, 1960b). These a u t h o r s l e a c h e d columns of s o i l w i t h the p o l y p h e n o l i c m a t e r i a l s , D- and e p i - c a t e c h i n , two of the major e x t r a c t a b l e components of beech l e a v e s (Fagus s y l v a t i c a ) grown on mor s i t e s . They found t h a t these compounds c o u l d indeed reduce f e r r i c o x i d e and t h a t e i t h e r of the compounds l e a c h i n g a t pH 3.72 c o u l d remove lOx more i r o n than a s o l u t i o n b u f f e r e d t o 3.72 but w i t h o u t t h e p o l y p h e n o l , a n d 5 x m o r e i r o n t h a n t h e s a m e p o l y p h e n o l l e a c h i n g a t p H 5 . 8 9 . T h i s d e c r e a s e i n e f f i c i e n c y i n a l e s s a c i d e n v i r o n m e n t w a s e x p l a i n e d b y t h e l o w e r s t a b i l i t y o f p o l y p h e n o l i c c o m p o u n d s a t h i g h e r p H . E x p e r i m e n t s s h o w e d t h a t u n d e r s l i g h t l y a c i d o r n e a r l y n e u t r a l c o n d i t i o n s , t h e p o l y p h e n o l i c c o m p o u n d s w e r e d e g r a d e d t o a n u m b e r o f c o m p l e x p h e n o l i c p r o d u c t s , m a n y o f w h i c h d i d n o t c o m b i n e w i t h i r o n . T h e m o v e m e n t o f a l u m i n u m a p p e a r e d i n d e p e n d a n t o f t h e p o l y p h e n o l s b u t c o r r e l a t e d n e g a t i v e l y w i t h p H . A t h i r d m e c h a n i s m p r o p o s e d f o r s e s q u i o x i d e m o v e m e n t w a s t h e t r a n s l o c a t i o n o f i r o n a n d a l u m i n u m a s i n o r g a n i c c a t i o n s . A c c o r d i n g t o r e v i e w a r t i c l e s , t h i s w a s a t h e o r y p r e v a l e n t t h o u g h o u t t h e f i r s t h a l f o f t h e t w e n t i e t h c e n t u r y b u t o n w h i c h l i t t l e e x p e r i m e n t a l w o r k h a d a c t u a l l y b e e n d o n e . I t w a s b e l i e v e d t h a t o r g a n i c d e c o m p o s i t i o n i n t h e A h o r i z o n p r o d u c e d a c i d c o n d i t i o n s w h i c h b r o u g h t a b o u t t h e s o l u t i o n o f s e s q u i o x i d e s , a n d t h e h i g h e r r e a c t i o n i n t h e B h o r i z o n w a s r e s p o n s i b l e f o r t h e i r s u b s e q u e n t p r e c i p i t a t i o n ( S t o b b e a n d W r i g h t , 1 9 5 9 ) . H o w e v e r , V a n S c h u y l e n b o r g h a n d B r u g g e n w e r t ( 1 9 6 5 ) d e m o n s t r a t e d , w i t h v a r i o u s a s s u m p t i o n s , t h a t t h e s o l u b i l i t y o f f e r r i c i r o n w a s s o l o w a t p H 4 . 0 t h a t i t w o u l d r e q u i r e 4 3 0 , 0 0 0 y e a r s t o t r a n s l o c a t e , i n i o n i c f o r m , t h e a m o u n t o f i r o n t h a t h a d b e e n r e m o v e d f r o m t h e A h o r i z o n o f t h e p o d z o l i n q u e s t i o n . T h e s o i l s s t u d i e d w e r e a m a x i m u m o f 1 5 , 0 0 0 y e a r s o l d . I n c o n t r a s t , a l u m i n u m i o n s h a d a h i g h e r s o l u b i l i t y . I t w o u l d h a v e r e q u i r e d o n l y 2 0 4 y e a r s a t p H 4 . 0 a n d 6 7 , 2 0 0 y e a r s a t p H 5 t o e x p l a i n t h e l o s s o f 3% A ^ O ^ f r o m t h e A h o r i z o n ( V a n Schuylenborgh and Bruggenwert, 1965). Under r e d u c i n g c o n d i t i o n s , i r o n may be t r a n s l o c a t e d i n the f e r r o u s form, as the s o l u b i l i t y of t h i s i o n i s h i g h (Stobbe and W r i g h t , 1959). Views of The Modern E r a D e s p i t e c o n f l i c t i n g e v i d e n c e , complexed and c h e l a t e d movement of aluminum and e s p e c i a l l y i r o n became the f o c u s of p o d z o l i c r e s e a r c h t h r o u g h o u t the n e x t decade. A c h e l a t i n g agent i s an o r g a n i c l i g a n d which forms two o r more c o o r d i n a t e c o v a l e n t bonds w i t h a m e t a l i o n . Movement i n t h i s form had been suggested but n e v e r e s t a b l i s h e d by a number of e a r l y workers (Schatz e_t a l . , 1954; Barshad, 1955; S c h n i t z e r and DeLong, 1955). A t k i n s o n and W r i g h t (1957) a t t e m p t e d t o model p o d z o l f o r m a t i o n by l e a c h i n g a column of c a l c a r e o u s s o i l w i t h the known c h e l a t i n g agent, EDTA. These a u t h o r s found t h a t a f t e r seventeen months, a p r o f i l e had formed i n the column which resembled a p o d z o l i c s o i l . The r e d i s t r i b u t i o n of i r o n was i n d i c a t e d by the f o r m a t i o n of a b l e a c h e d Ae and dark brown B h o r i z o n s . In c o n t r a s t , a column l e a c h e d o n l y w i t h water showed no r e d i s t r i b u t i o n of i r o n . I n s t e a d , a dark s t a i n i n g a t the top of the column seemed i n d i c a t i v e of w e a t h e r i n g and the f o r m a t i o n , _in s i t u , of h y d r a t e d o x i d e s of i r o n . At t h i s t i m e , e x t e n s i v e work was u n d e r t a k e n t o e s t a b l i s h the c h e m i c a l n a t u r e of the o r g a n i c m a t e r i a l a c t u a l l y p r e s e n t i n the s o i l . As humus, b o t h a t the s o i l s u r f a c e and w i t h i n the m i n e r a l s o i l , c o n s i s t s of a m i x t u r e of o r g a n i c a c i d s , v a r y i n g i n s i z e and i n k i n d s and numbers of f u n c t i o n a l groups, i t i s very d i f f i c u l t 24 to c h a r a c t e r i z e p r e c i s e l y . T y p i c a l r e s e a r c h of the e a r l y 1960's i s e x e m p l i f i e d i n the f o l l o w i n g papers p r e s e n t e d by the S o i l R e s earch I n s t i t u t e , Ottawa. S c h n i t z e r and D e s j a r d i n s (1962) c a l c u l a t e d the number-average m o l e c u l a r w e i g h t s of o r g a n i c m a t t e r from a p o d z o l by f r e e z i n g - p o i n t d e p r e s s i o n i n s u l p h o l a n e and c y c l o h e x a n o l . A f t e r u l t i m a t e and f u n c t i o n a l group a n a l y s e s , m o l e c u l a r formulae were deve l o p e d t o r e p r e s e n t the l a r g e humic m o l e c u l e s of the Ao ( r o u g h l y e q u i v a l e n t t o the H h o r i z o n i n the CSSC, 1978) and the much s m a l l e r f u l v i c m o l e c u l e s of the i l l u v i a l h o r i z o n . These a u t h o r s r e p o r t e d t h a t 61% by w e i ght of e x t r a c t e d o r g a n i c m a t t e r from a Bh was composed of f u n c t i o n a l groups, and t h a t these c o n t a i n e d a l l of the oxygen of the m o l e c u l e . The number of c a r b o x y l s t o h y d r o x y l s was 1.0. In c o n t r a s t , o n l y 23% of the w e i ght of the Ao o r g a n i c s was i n f u n c t i o n a l groups and these c o n t a i n e d o n l y h a l f the oxygen of the m o l e c u l e . The number of c a r b o x y l t o h y d r o x y l groups was o n l y 0.25 ( S c h n i t z e r and D e s j a r d i n s , 1962). U s i n g methods of o x i d a t i v e d e g r a d a t i o n i n both a c i d i c and a l k a l i n e media, W r i g h t and S c h n i t z e r (1963) c o n c l u d e d t h a t the " n u c l e u s " of o r g a n i c a c i d s w i t h i n the Bh h o r i z o n c o n s i s t e d p r i m a r i l y of a r o m a t i c s t r u c t u r e s , whereas those of the Ao c o n t a i n e d a p p r e c i a b l e amounts of a l i p h a t i c and/or a l i c y c l i c s t r u c t u r e s i n a d d i t i o n t o the a r o m a t i c . U s i n g these c a l c u l a t e d m o l e c u l e s as model compounds, S c h n i t z e r and S k i n n e r (1963) began a s y s t e m a t i c i n v e s t i g a t i o n i n t o the r e a c t i o n s between the o r g a n i c m a t t e r and the m e t a l i o n s l i k e l y t o o c c u r i n p o d z o l i c s o i l s . P o t e n t i o m e t r i e and conductome t r i e t i t r a t i o n s , a b s o r p t i o n and IR s p e c t r o s c o p y and f l o c c u l a t i o n e x p e r i m e n t s r e v e a l e d t h a t o r g a n i c a c i d s formed +3 +3 +2 +2 +2 s t a b l e , w a t e r - s o l u b l e complexes w i t h Fe , A l , Ca , Mg , Cu +2 +3 +3 and N i . More Fe and A l c o u l d be complexed a t pH 5.0 t h a n pH 3.0. The molar r a t i o s of i r o n and aluminum t o the model o r g a n i c compounds of S c h n i t z e r and D e s j a r d i n s (1962) v a r i e d from 1:1 t o 6:1, becoming i n c r e a s i n g l y w a t e r - i n s o l u b l e as more metal was complexed. The r e a c t i o n i n v o l v e d a t l e a s t one c a r b o x y l group per atom of m e t a l and no e v i d e n c e was found f o r p h e n o l i c h y d r o x y l p a r t i c i p a t i o n i n complex f o r m a t i o n . S c h n i t z e r and S k i n n e r (1963) a l s o d i s c o v e r e d t h a t the power of o r g a n i c m a t t e r t o h o l d s e s q u i o x i d e s i n s o l u t i o n seemed much low e r f o r aluminum than f o r i r o n . T h i s was s u b s t a n t i a t e d by the r e a c t i o n s of m e t a l : o r g a n i c complexes p r e p a r e d i n the l a b o r a t o r y . S c h n i t z e r and S k i n n e r (1964) found t h a t i r o n complexes began t o p r e c i p i t a t e out a t a m e t a l : o r g a n i c r a t i o of 3 and complete p r e c i p i t a t i o n o c c u r r e d a t a r a t i o of 6. S l i g h t f l o c c u l a t i o n of aluminum complexes o c c u r r e d a t a molar r a t i o of u n i t y , a p p r e c i a b l e and complete f l o c c u l a t i o n of aluminum complexes o c c u r r e d a t the r a t i o s of 3 and 6, r e s p e c t i v e l y . By e x t r a p o l a t i o n of these r e s u l t s , one might e x p e c t i r o n t o move f u r t h e r i n t o the s o i l than aluminum, a c o n d i t i o n not g e n e r a l l y found i n a p o d z o l (McKeague e_t a _ l . , 19 83). However, Wr i g h t and S c h n i t z e r (1963) a l s o r e p o r t e d t h a t as l i t t l e as 0.13 ppm Ca as CaCl2 and 4.5 ppm Mg as MgC^ caused complete f l o c c u l a t i o n of i r o n - o r g a n i c m a t t e r complexes but i t r e q u i r e d 10 and 45 ppm Ca and Mg, r e s p e c t i v e l y , t o f l o c c u l a t e A l - o r g a n i c complexes. T h e r e f o r e , a l t h o u g h the Bh o r g a n i c m a t t e r had a g r e a t e r 26 complexing power f o r i r o n than aluminum, the F e - o r g a n i c m a t t e r was much more s u s c e p t i b l e t o f l o c c u l a t i o n by Ca and Mg. T h i s l e d the a u t h o r s t o suggest t h a t the A l - o r g a n i c complexes may move deeper i n t o the p r o f i l e than those of i r o n , as i n accordance w i t h f i e l d o b s e r v a t i o n s . However, i t i s i n t e r e s t i n g t o note t h a t a l t h o u g h Deb (1949) found i r o n - o r g a n i c c o l l o i d s p r e c i p i t a t e d w i t h ease upon a d d i t i o n of C a C ^ t o t h e i r s o l u t i o n s , a s o i l s a t u r a t e d w i t h c a l c i u m c o u l d not i m m o b i l i z e o r g a n i c m o l e c u l e s l e a c h e d through i t . A r e v i e w by Mortensen (1963) l i s t e d s i m i l a r r e s e a r c h from o t h e r l a b o r a t o r i e s a t t e m p t i n g t o c h a r a c t e r i z e m e t a l : o r g a n i c complexes. P e t e r s e n (1976) was very c r i t i c a l of the methods used and some of the c o n c l u s i o n s drawn i n much of t h i s work. He p o i n t e d out ranges i n m o l e c u l a r w e i g h t s , r e p o r t e d i n t h i s l i t e r a t u r e , t h a t v a r i e d by o r d e r s of magnitude, even f o r s i m i l a r f r a c t i o n s . For example, u s i n g d i f f e r e n t methods the above Ottawa l a b o r a t o r y r e p o r t e d hundred f o l d d i s c r e p a n c i e s i n the number average m o l e c u l a r w e i g h t v a l u e s of an o r g a n i c f r a c t i o n e x t r a c t e d from a s i n g l e h o r i z o n (Wright e_t a_l. , 1958; S c h n i t z e r and D e s j a r d i n s , 1962; Hansen and S c h n i t z e r , 1969). As a n o t h e r example, P e t e r s e n was c r i t i c a l of a s p e c t r o s c o p i c t e c h n i q u e o r i g i n a l l y d e s c r i b e d by Vosburgh and Cooper (1941) and used by S c h n i t z e r and S k i n n e r (1963). He c l a i m e d t h i s t e c h n i q u e was o n l y a p p l i c a b l e i f one complex was formed p e r m o l e c u l e . I f more than one complex was i n v o l v e d , a m o d i f i e d method not f o l l o w e d by S c h n i t z e r and S k i n n e r , s h o u l d have been employed. In f a c t , so many i n c o n s i s t e n c i e s and c o n t r a d i c t i o n s o c c u r r e d w i t h i n the 27 1960's r e s e a r c h on o r g a n i c m a t t e r c h a r a c t e r i z a t i o n t h a t o n l y g e n e r a l i t i e s c o u l d be drawn from the work. N o n e t h e l e s s , P e t e r s e n f e l t t h e r e was enough e v i d e n c e t o s u p p o r t a c o n s i d e r a b l e c o n t e n t of a c i d i c groups w i t h s t r u c t u r a l arrangements a b l e t o form complex and c h e l a t e compounds w i t h m e t a l i o n s . T h i s , however, was s t i l l o n l y c i r c u m s t a n t i a l e v i d e n c e f o r movement of the o r g a n i c m a t t e r and m e t a l s i n t o the B h o r i z o n t o g e t h e r as a complex. McKeague (1968) and McKeague e t a l . (1971) found t h a t the molar r a t i o of pyrophosphate e x t r a c t a b l e i r o n and aluminum t o f u l v i c a c i d w i t h i n a p o d z o l was i n the range of 3-10 f o r a l l of the B h o r i z o n s t e s t e d . I f f u l v i c a c i d began t o p r e c i p i t a t e a t a m e t a l : o r g a n i c r a t i o of 1-3 and complete p r e c i p i t a t i o n o c c u r r e d a t a r a t i o of 6 ( S h n i t z e r and S k i n n e r , 1964), how c o u l d complexes w i t h these h i g h r a t i o s form, e s p e c i a l l y as more f u l v i c a c i d would have s u b s e q u e n t l y l e a c h e d down and lowered the a p p a r e n t molar r a t i o of the complex? McKeague e_t a_l. (1971) f e l t t h a t t h i s r a i s e d some o l d q u e s t i o n s c o n c e r n i n g the g e n e s i s of these h o r i z o n s . To t h i s time most e v i d e n c e i n support of proposed p o d z o l i c models was g a i n e d t h r o u g h l a b o r a t o r y e x p e r i m e n t a t i o n . Few s t u d i e s a c t u a l l y l o o k e d a t what was happening i n the r e a l s o i l . However, by c e n t r i f u g a t i o n , B r u c k e r t (1970) was a b l e ' t o c o l l e c t the s o i l s o l u t i o n from a p o d z o l and show t h a t the dominant o r g a n i c c o n s t i t u e n t s moving t h r o u g h t h i s s o i l were the a l i p h a t i c a c i d s , c i t r i c and o x a l i c , and the s m a l l m o l e c u l a r weight a r o m a t i c a c i d s , v a n i l l i c and p - h y d r o x y b e n z o i c . A l l had the a b i l i t y t o 28 complex i r o n , a l t h o u g h the s i m p l e a l i p h a t i c compounds were a b l e to complex 3x more of t h i s element than the a r o m a t i c . The h i g h e s t c o n c e n t r a t i o n of these a c i d s was c o l l e c t e d from the l i t t e r and the c o n c e n t r a t i o n d e c r e a s e d r a p i d l y w i t h d e p t h . A l a t e r r e v i e w a r t i c l e by Vedy and B r u c k e r t (1979) r e p o r t e d t h a t the s m a l l a l i p h a t i c a c i d s were s p e c i f i c a l l y i n the "bound" water adsorbed on t o s o i l s u r f a c e s and h e l d w i t h i n s m a l l p o r e s . T h i s would be the f r a c t i o n B r u c k e r t (1970) had removed by c e n t r i f u g a t i o n and i t s presence was c o n s i s t e n t w i t h the p r o l i f e r a t i o n of m i c r o o r g a n i s m s i n t h i s e n v i r o n m e n t . In c o n t r a s t , the " g r a v i t a t i o n a l " w ater i n the l a r g e r p o r e s c o n t a i n e d p r e d o m i n a n t l y h i g h m o l e c u l a r w e i ght p o l y m e r i c m a t e r i a l s t h a t were b r o w n i s h y e l l o w i n c o l o u r and r e l a t e d t o f u l v i c a c i d s . These were much more s t a b l e t o b i o d e g r a d a t i o n than the low m o l e c u l a r w e i g h t compounds. Vedy and B r u c k e r t (19 79) suggested t h a t the s m a l l a l i p h a t i c a c i d s w i t h i n the "bound" water, a f f e c t e d the w e a t h e r i n g of c e r t a i n s o i l m i n e r a l s and formed s t a b l e and u n s t a b l e complexes w i t h the m e t a l s r e l e a s e d d u r i n g t h i s p r o c e s s . Upon s o i l d r a i n a g e , the s m a l l a l i p h a t i c a c i d complexes e n t e r e d the " g r a v i t a t i o n a l " water and were e i t h e r r a p i d l y b i o d e g r a d e d i n t h i s a e r a t e d medium o r i n t e g r a t e d i n t o the l a r g e r " f u l v i c a c i d s " . I t was i n the l a t t e r form t h a t i r o n and aluminum were t r a n s p o r t e d through the s o i l . Throughout the 1970's, the l y s i m e t e r became an i m p o r t a n t t o o l used t o m o n i t o r p o d z o l i z a t i o n p r o c e s s e s . S c h n i t z e r and D e s j a r d i n s (1969) found t h a t the l e a c h a t e moving through the Ae h o r i z o n of a humus p o d z o l had many c h e m i c a l and s p e c t r a l 29 p r o p e r t i e s s i m i l a r t o the f u l v i c a c i d s e x t r a c t e d from the s o i l b ut seemed t o have a l o w e r number average m o l e c u l a r w e i g h t . U g o l i n i e_t a_l. (1977) u s i n g l y s i m e t e r s , measured the c o n c e n t r a t i o n of c e r t a i n e l e m e n t s moving through the s o i l s o l u t i o n of a p o d z o l s i t u a t e d i n the c e n t r a l Cascade Mountains of Washington. T h e i r r e s u l t s d i v i d e d t h i s ecosystem i n t o two d i s t i n c t h o r i z o n t a l compartments, the f i r s t e x t e n d i n g from the f o r e s t canopy t o the bottom of the I I B 2 h i r ( a p p r o x i m a t e l y e q u i v a l e n t t o the Bhf, CSSC, 1978) and the second from t h i s h o r i z o n down through the IVB32 (Bf, CSSC, 1978). R a i n w a t e r p a s s i n g t h rough the canopy and f o r e s t f l o o r became e n r i c h e d i n b a s i c c a t i o n s , N, P, Fe, S i and A l and e x c e p t f o r s i l i c a t h e i r maximum c o n c e n t r a t i o n i n the the s o i l s o l u t i o n was reached a t the bottom of the 0 h o r i z o n (H, CSSC, 1978). The c o n c e n t r a t i o n of these elements dropped s l i g h t l y i n the A2 and reached a minimum a t the bottom of the I I B 2 h i r . The c o n c e n t r a t i o n of the mobile f u l v i c a c i d f r a c t i o n a l s o dropped 60-70% w i t h i n the I I B 2 h i r . Below t h i s h o r i z o n , the s o i l s o l u t i o n a g a i n became e n r i c h e d i n b a s i c c a t i o n s , A l and N. S i n g e r e_t a_l. (1978) a t t r i b u t e d the l a t t e r e n r i c h m e n t t o the renewed c a r r y i n g c a p a c i t y of s o i l water w i t h i n the I I B 2 i r h o r i z o n . T h i s was due t o the p r e c i p i t a t i o n of much of the w a t e r ' s i o n i c c o n t e n t i n the h o r i z o n above. U g o l i n i e t a l . (1977) c a l l e d the upper solum where f u l v i c a c i d s were a c t i v e , the b i o p e d o l o g i c a l compartment and the l o w e r solum, the g e o c h e m i c a l compartment. A l t h o u g h the c o n c e n t r a t i o n of aluminum i n the " g e o c h e m i c a l " compartment n e a r l y e q u a l l e d t h a t p a s s i n g through the A2, no a t t empt was made t o c h a r a c t e r i z e the form i n 30 which the aluminum o c c u r r e d . However, the a u t h o r s noted t h a t l i t t l e aluminum was c a r r i e d out of t h i s compartment i n t o the ground water. The m o l e c u l a r w e i g h t s of the s o l u b l e o r g a n i c compounds moving through t h i s s o i l were 837-845 by g e l f i l t r a t i o n and i n f r a r e d a n a l y s i s i n d i c a t e d the presence of a r o m a t i c hydroxy c a r b o x y l i c a c i d s . I n t e r a c t i o n of t h i s l e a c h a t e w i t h m a t e r i a l from the I I B 2 i r h o r i z o n demonstrated how e f f e c t i v e r e a c t i v e s e s q u i o x i d e s were i n a d s o r b i n g the s o l u b l e o r g a n i c compounds w i t h i n the s o i l s o l u t i o n (Dawson e_t a_l. , 1978). In 19 76, L. P e t e r s e n completed an e x h a u s t i v e work on p o d z o l s and p o d z o l i z a t i o n . In t h i s , i t i s i n t e r e s t i n g t o note how many a s p e c t s of p o d z o l g e n e s i s remain i n q u e s t i o n d e s p i t e a c e n t u r y of r e s e a r c h on the s u b j e c t . A l t h o u g h western c l a s s i f i c a t i o n schemes have removed s o i l s w i t h B h o r i z o n s e n r i c h e d i n l a y e r s i l i c a t e c l a y s from the p o d z o l g r e a t group, R u s s i a n s s t i l l c ontend t h a t the two s h o u l d be u n i t e d . They see the c l a y e n r i c h m e n t as due t o n e o s y n t h e s i s of l a y e r s i l i c a t e s w i t h i n the B h o r i z o n , from raw m a t e r i a l s t r a n s l o c a t e d from above (Ponomareva, 1969). However, Lowe (1980) showed t h a t o r g a n i c m a t t e r , as w e l l as c l a y e n r i c h m e n t , d i s t i n g u i s h e d a Bt h o r i z o n from a Bf h o r i z o n . He found t h a t the r a t i o of p o l y p h e n o l i c f u l v i c s t o t o t a l f u l v i c s (Ca/Cf) was c o n s i s t e n t l y much lo w e r i n l u v i s o l i c B h o r i z o n s . O r g a n i c m a t t e r e x t r a c t i o n from the l i t t e r and m i n e r a l s o i l i s s t i l l a c c o m p l i s h e d by methods used i n the e a r l y 1900's. The r e s u l t i n g o r g a n i c s must be c o n s i d e r e d a t l e a s t s l i g h t l y m o d i f i e d by the e x t r a c t i n g p r o c e d u r e s and a l t h o u g h we have o b t a i n e d a 31 g e n e r a l i d e a of the t y p e s of m o l e c u l e s p r e s e n t , the wide v a r i e t y of o r g a n i c compounds w i t h i n the s o i l humus make i t i m p o s s i b l e t o c h a r a c t e r i z e p r e c i s e l y . As a r e s u l t , P e t e r s e n (1976) s t i l l l i s t s c i r c u m s t a n t i a l e v i d e n c e f o r the f o r m a t i o n of complex bonds between o r g a n i c a c i d s and m e t a l s and he f i n d s i t i s a l s o d i f f i c u l t t o prove c h e l a t i n g compounds a c t u a l l y e x i s t i n the s o i l . Even the mechanisms of p o d z o l g e n e s i s are s t i l l i n q u e s t i o n . P e t e r s e n shows through thermodynamic c a l c u l a t i o n s , t h a t i t i s i m p o s s i b l e t o r u l e out the movement of aluminum as an i n o r g a n i c c a t i o n . He b e l i e v e s movement of c o l l o i d a l s e s q u i o x i d e s p r o t e c t e d by humus c o u l d a l s o be p o s s i b l e , a l t h o u g h P e t e r s e n can not v i s u a l i z e the means by which s o l u t i o n s of these c o l l o i d s would form i n the s o i l . Complex f o r m a t i o n between water s o l u b l e o r g a n i c compounds and metal c a t i o n s i s the most p o p u l a r c a n d i d a t e f o r t r a n s l o c a t i o n of i r o n and aluminum w i t h i n a p o d z o l , but arguments s t i l l e x i s t as t o whether the most a c t i v e compounds are the s i m p l e o r g a n i c a c i d s or the p o l y p h e n o l i c f u l v i c a c i d p r e c u r s o r s . P e t e r s e n f i n d s i t d i f f i c u l t t o e x p l a i n how simple a c i d s would p r e c i p i t a t e out i n the B h o r i z o n . D e c o m p o s i t i o n of the s m a l l o r g a n i c a c i d s i s most o f t e n i m p l i c a t e d b u t t h i s a u t h o r q u e s t i o n s why the organisms r e s p o n s i b l e would be p a r t i c u l a r l y abundant a t t h i s l e v e l i n the s o i l . P e t e r s e n , t h e r e f o r e , f a v o r s t r a n s p o r t of i r o n and aluminum by p o l y p h e n o l i c a c i d s and the d e p o s i t i o n of t h i s complex when the amount of i r o n and aluminum ta k e n up exceeds a c e r t a i n l i m i t . O r i g i n a l r e s e a r c h by P e t e r s e n a l s o added t o the b u l k of 32 knowledge. He found, by c e n t r i f u g a t i o n of m o i s t s o i l and from aqueous e x t r a c t i o n s , t h a t d i s s o l v e d o r g a n i c carbon was p r e s e n t i n the s o i l s o l u t i o n t h r o u g h o u t the p r o f i l e . A h i g h carbon c o n t e n t was found i n e x t r a c t s from the AO, A l and B l and, a l t h o u g h the amount d e c r e a s e d w i t h depth, a p p r e c i a b l e carbon was s t i l l found i n the c o l o u r l e s s s o i l s o l u t i o n of the C h o r i z o n . S o l u b l e i r o n and aluminum a l s o d e c r e a s e d w i t h depth but a l t h o u g h the C/Al va l u e i n s o l u t i o n dropped n o t i c e a b l y from the A2 t o the B l , v a r i a t i o n i n the C/Fe v a l u e was l e s s r e g u l a r . In l a b o r a t o r y r e a c t i o n s between m e t a l i o n s and a s o i l o r g a n i c e x t r a c t , P e t e r s e n found t h a t a c i d s and m e t a l s remained s o l u b l e u n t i l a c e r t a i n amount of m e t a l had been added and then complete p r e c i p i t a t i o n of both took p l a c e . L i k e S c h n i t z e r and S k i n n e r (1963, 1964), P e t e r s e n found t h a t t h i s p r e c i p i t a t i o n o c c u r r e d a t a l o w e r c o n c e n t r a t i o n of aluminum i o n s than f e r r i c i r o n . As w i t h the r e s t of the temperate w o r l d , r e s e a r c h e r s of so u t h w e s t e r n B r i t i s h Columbia have a l s o a t t e m p t e d t o a d d r e s s the q u e s t i o n of g e n e s i s and c l a s s i f i c a t i o n of p o d z o l i c s o i l s but u n l i k e many of the p a s t s i t u a t i o n s , s o i l s here are not the " c l a s s i c a l " p o d z o l of the l i t e r a t u r e . The c l a s s i c a l model c o n s i s t s of a t h i c k , l i g h t - c o l o u r e d e l u v i a t e d h o r i z o n o v e r a B h o r i z o n , a p p r o x i m a t e l y comparable i n t h i c k n e s s t o the Ae and e n r i c h e d w i t h t r a n s l o c a t e d s e s q u i o x i d e s and o r g a n i c m a t t e r . I n s t e a d L e w i s (1976) found t h a t the p o d z o l s of Vancouver I s l a n d o f t e n c o n t a i n e d no Ae o r a t h i n d i s c o n t i n u o u s h o r i z o n over a v e r y t h i c k , v e r y s e s q u i o x i d e - r i c h B h o r i z o n . The amount of s e s q u i o x i d e s e x t r a c t e d from t h i s h o r i z o n u s u a l l y d e c r e a s e d w i t h 33 depth e x c e p t f o r o x a l a t e aluminum, which f r e q u e n t l y a t t a i n e d i t s maximum im m e d i a t e l y o v e r l y i n g the C h o r i z o n . The s o i l s a l s o had l a r g e a c c u m u l a t i o n s of o r g a n i c m a t t e r b o t h a t the s o i l s u r f a c e and randomly d i s t r i b u t e d t hroughout the m i n e r a l s o i l . L e w i s suggested t h a t the d i s c r e p a n c i e s between the c l a s s i c a l model and these s o i l s were a f u n c t i o n of c l i m a t e and a b a s e - r i c h p a r e n t m a t e r i a l . Heavy r a i n f a l l e n s u r e d t h a t _in s i t u w e a t h e r i n g was a dominant f o r c e i n s o i l g e n e s i s and as a consequence, the t r a n s l o c a t i o n of s e s q u i o x i d e s was l i m i t e d when the ch a r g e s on complexing o r g a n i c a c i d s were n e u t r a l i z e d near the s u r f a c e by the abundant i r o n and aluminum o x i d e s . A l s o , the randomly d i s t r i b u t e d o r g a n i c m a t e r i a l w i t h i n the B h o r i z o n r e s u l t e d from the p e r i o d i c u p r o o t i n g of l a r g e t r e e s . These b u r i e d l a r g e amounts of o r g a n i c d e b r i s which s u b s e q u e n t l y decomposed. Lewis (1976) suggested t h a t the c u r r e n t c oncept of p o d z o l g e n e s i s , which c e n t e r e d on the t r a n s l o c a t i o n of s e s q u i o x i d e s as a complex w i t h o r g a n i c m a t t e r , s h o u l d be broadened t o i n c l u d e g e n e s i s by: 1. In s i t u w e a t h e r i n g and n e g a t i v e e n r i c h m e n t of i r o n and aluminum; and 2. A n t i - h o r i z o n a t i o n p r o c e s s e s such as p h y s i c a l t u r b a t i o n and the b i o c y c l i n g of e l e m e n t s . Lewis b e l i e v e d t h a t a l l t h r e e p r o c e s s e s were a c t i v e i n a l l p o d z o l s and t h a t the d i f f e r e n t p o d z o l m o r p h o l o g i e s found t h r o u g h o u t the w o r l d r e s u l t e d from the dominant e n v i r o n m e n t a l f o r c e s under which the s o i l s d e v e l o p e d . A l s o on Vancouver I s l a n d , p o d z o l - l i k e s o i l s were s t u d i e d by 34 Moon (1981). These s o i l s o c c u r r e d over a c l i m o s e q u e n c e , c r e a t e d by an i n c r e a s e i n e l e v a t i o n . With the a i d of l y s i m e t e r d a t a , s o i l morphology and c h e m i c a l e x t r a c t i o n s t h i s a u t h o r was a b l e t o d e r i v e a s i m p l e , l i n e a r model t o account f o r the g e n e s i s of these s o i l s and t o f i n d e v i d e n c e t h a t some of the mechanisms suggested by Lewis (1976) a c t u a l l y o c c u r r e d . One of the most i n t e r e s t i n g a s p e c t s of Moon's work was t h a t he was a b l e t o r e l a t e the g e n e r a l i z e d p r o c e s s e s of s o i l f o r m a t i o n - a d d i t i o n , l o s s , t r a n s f o r m a t i o n and t r a n s l o c a t i o n - t o r e a l s o i l s i n the f i e l d . He b e l i e v e d t h a t the ba l a n c e of these p r o c e s s e s r e s u l t e d i n the unique c h a r a c t e r of the s o i l a t each s i t e . A l t h o u g h a l l p r o c e s s e s p l a y e d a r o l e i n a l l s o i l s , under the l i g h t r a i n f a l l c o n d i t i o n s of lo w e r e l e v a t i o n s , w e a t h e r i n g and n e g a t i v e e n r i c h m e n t of i r o n and aluminum were the dominant p r o c e s s e s a c t i n g i n the f o r m a t i o n of the h o r i z o n . However, under the h i g h e r r a i n f a l l of mid- and h i g h e l e v a t i o n s i t e s , the i l l u v i a t i o n of i r o n and aluminum from the A h o r i z o n and f o r e s t f l o o r w i t h subsequent p r e c i p i t a t i o n i n the B, was the mechanism most r e s p o n s i b l e f o r the development of the s e s q u i o x i d e - r i c h h o r i z o n . The l a t t e r two s i t e s were s e p a r a b l e p r i m a r i l y on the r a t e of p r o f i l e development, w i t h the h i g h b i o l o g i c a l a c t i v i t y of the m i d - e l e v a t i o n s o i l s r e s u l t i n g i n the g r e a t e s t m o r p h o l o g i c a l e x p r e s s i o n of p o d z o l i c c h a r a c t e r i s t i c s and the h i g h e s t a c i d ammonium o x a l a t e i r o n and aluminum v a l u e . However, the sodium p y r o p h o s p h a t e - e x t r a c t e d s e s q u i o x i d e s of the s i t e were low, presumably because a h i g h d e c o m p o s i t i o n r a t e q u i c k l y r e l e a s e d the met a l s from the o r g a n i c complex and t h e r e f o r e , the s o i l c o u l d not be c l a s s i f i e d as a p o d z o l under the c r i t e r i a e s t a b l i s h e d by the CSSC, 1978. In s i t u a t i o n s such as t h e s e , methods of p o d z o l c l a s s i f i c a t i o n a re s t i l l i n q u e s t i o n t o d a y . In c o n c l u s i o n , a l l r e s e a r c h from the p a s t c e n t u r y has c o n t r i b u t e d t o our knowledge today and forms the b a s i s of the two models of p o d z o l g e n e s i s p r e s e n t e d i n C h a p t e r 2. The f i r s t of these i s the most w i d e l y a c c e p t e d " c l a s s i c a l " model and the second, a r e c e n t d i v e r g e n c e based most c l o s e l y t o the work of Tamm (1920, as r e a d i n Farmer, 1982) and Mattson and G u s t a f s s o n (1937). In b o t h models many q u e s t i o n s remain t o be answered b e f o r e the proposed mechanism of p o d z o l f o r m a t i o n can be a c c e p t e d . F u t u r e r e s e a r c h may prove the t r u t h l i e s somewhere between the two extremes or i n a n o t h e r d i r e c t i o n a l t o g e t h e r . 36 CHAPTER 2 MODERN MODELS OF PODZOL GENESIS The Movement of I r o n and Aluminum as an O r g a n i c Complex Concepts of p o d z o l f o r m a t i o n e v o l v e d w i t h the r e s e a r c h of the 1960's and 1970's i n t o an a c c e p t e d b i o c h e m i c a l mechanism, o u t l i n e d by b o t h DeConinck (1980) and Duchaufour (1982), as f o l l o w s . L e a c h i n g of s o l u b l e bases from the s o i l by r a i n w a t e r , and a c o n i f e r - d o m i n a t e d v e g e t a t i o n which by r o o t i n g h a b i t s r e t u r n s few of these bases t o the s o i l s u r f a c e , r e s u l t s i n the f o r m a t i o n of an a c i d "mor" humus (Duchaufour,1982). The low pH and n u t r i e n t c o n t e n t r e s t r i c t b a c t e r i a l a c t i v i t i e s . Simple o r g a n i c a c i d s , formed b o t h w i t h and w i t h o u t the a i d of f u n g a l d e c o m p o s i t i o n , a re l e a c h e d from the l i t t e r l a y e r . These by c o m p l e x o l y s i s , weather the m i n e r a l s of the A h o r i z o n , reduce any f r e e i r o n p r e s e n t and w i t h the a i d of l a r g e r f u l v i c a c i d p r e c u r s o r s , c a r r y t h i s i o n as w e l l as aluminum, i n complex form, i n t o the B h o r i z o n (Duchaufour, 1982). Through v a r i o u s mechanisms, the i r o n and aluminum are p r e c i p i t a t e d i n the B h o r i z o n as h y d r o x i d e s (DeConinck, 1980; Duchaufour, 1982). The amorphous s i l i c a , which has moved from the A h o r i z o n i n a s o l u b l e form, p r e c i p i t a t e s w i t h the Fe and A l h y d r o x i d e s , forming a mixed g e l s i m i l a r t o the a l l o p h a n e of a n d o s o l s . A l l t h a t remains i n the e l u v i a l h o r i z o n i s d e t r i t a l q u a r t z and a few c l a y m i n e r a l s r e s i s t a n t t o a c i d w e a t h e r i n g (Duchaufour, 1982). 37 DeConinck (1980) r e l i e s on two p r i n c i p l e s of c o l l o i d c h e m i s t r y t o g i v e a more complete account of t h i s p o d z o l i z a t i o n mechanism: 1. O r g a n i c s u b s t a n c e s may form h y d r o p h i l i c c o l l o i d s w i t h s u r f a c e c h a r g e s . 2. The h y d r o p h i l i c c h a r a c t e r and n e g a t i v e s u r f a c e c harges determine the d i s p e r s i b i l i t y of the c o l l o i d s . The o r g a n i c s u b s t a n c e s i n v o l v e d i n i r o n r e d u c t i o n and complex f o r m a t i o n are the s m a l l a l i p h a t i c and a r o m a t i c a c i d s of B r u c k e r t (1970) and a l s o l a r g e r f u l v i c a c i d p r e c u r s o r s w i t h m o l e c u l a r w e i g h t s of 2500-3000 (Duchaufour, 1982). These have s t r u c t u r e s of a l i p h a t i c c h a i n s and benzene r i n g s s u b s t i t u t e d w i t h d i f f e r e n t r a d i c a l s such as -COOH, pheno l i c - O H , a l c o h o l i c - O H , NH2 and q u i n o n e s . The p o l a r n a t u r e of these r a d i c a l s a t t r a c t s water m o l e c u l e s . A l s o , i f the c a r b o x y l groups form the s t r o n g e s t a c i d i n the s o i l e n vironment, they may d i s s o c i a t e r e l e a s i n g an H+ i o n and i m p a r t i n g a n e g a t i v e charge t o the m o l e c u l e . The charge and h y d r o p h i l i c n a t u r e of the p r i m a r y compounds cause them t o r e p e l each o t h e r and form d i s c r e t e p a r t i c l e s surrounded by water m o l e c u l e s (DeConinck, 1980). DeConinck (1980) l i s t s f o u r c h a r a c t e r i s t i c s of the o r g a n i c compounds t h a t determine t h e i r m o b i l i t y w i t h i n the s o i l : 1. The s i z e of the compounds. 2. The r a t i o of h y d r o p h i l i c t o h y d r o p h o b ic p a r t s , the l a t t e r b e i n g the benzene r i n g s and a l i p h a t i c c h a i n s w i t h o u t replacement r a d i c a l s . 3. The c h a r g e s p r e s e n t on the compounds. 3 8 4 . T h e w a y i n w h i c h t h e s e c h a r g e s a r e n e u t r a l i z e d . T h e n e g a t i v e s i t e s p r e s e n t o n t h e o r g a n i c m o l e c u l e s a t t r a c t c a t i o n s o f m o n o v a l e n t , d i v a l e n t a n d t r i v a l e n t c h a r a c t e r p r e s e n t i n t h e e n v i r o n m e n t . A s m o n o v a l e n t c a t i o n s a r e u n a b l e t o f o r m s t r o n g c o v a l e n t o r c o - o r d i n a t e c o v a l e n t b o n d s w i t h t h e o r g a n i c r a d i c a l s , t h e i r n e u t r a l i z a t i o n p o w e r s a r e e x c l u s i v e l y p h y s i c a l o r e l e c t r o s t a t i c . I f , a s f o u n d i n p o d z o l s , t h e m o n o v a l e n t c a t i o n c o n c e n t r a t i o n i s l o w , t h e c a t i o n s a d o p t a d i s t r i b u t i o n i n a t h i c k d o u b l e l a y e r a r o u n d t h e o r g a n i c a n i o n . T h i s l a y e r r e p e l s t h e o t h e r o r g a n i c a c i d s , a l s o s u r r o u n d e d b y a t h i c k d o u b l e l a y e r a n d t h e a c i d s r e m a i n d i s p e r s e d . D i v a l e n t a n d t r i v a l e n t c a t i o n s , o n t h e o t h e r h a n d , a r e a b l e t o f o r m c h e m i c a l b o n d s o f s t r o n g c o - o r d i n a t e c o v a l e n t c h a r a c t e r w i t h t h e o r g a n i c a n i o n . T h i s o r g a n o - m e t a l l i c b o n d i s i n t h e f o r m o f a c h e l a t e o r o t h e r t y p e o f c o m p l e x . I n t h i s w a y , t h e c a t i o n s a r e c h e m i a b s o r b e d w i t h o u t a w e l l - d e v e l o p e d d o u b l e l a y e r a n d n o r e p u l s i o n o c c u r s ( D e C o n i n c k , 1 9 8 0 ) . T h e s t a b i l i t y o f t h e o r g a n i c - p o l y v a l e n t b o n d i n c r e a s e s w i t h c h a r g e a n d w i t h d e c l i n i n g s i z e a s f o l l o w s : A l + 3 > F e + 3 > F e + 2 > M g + 2 > C a + 2 ( D e C o n i n c k , 1 9 8 0 ) D u c h a u f o u r ( 1 9 8 2 ) s e e s c o m p l e x f o r m a t i o n o c c u r r i n g a t l o w p H ( 4 ) , i n p e r i o d s o f h e a v y r a i n f a l l i n w h i c h t e m p o r a r y w a t e r l o g g i n g o c c u r s i n t h e s o i l . T h e E h a t t h i s t i m e i s a t a m i n i m u m a t t h e H / A e b o u n d a r y a n d s o t h e i r o n i s g e n e r a l l y c o m p l e x e d i n t h e f e r r o u s s t a t e . T h e s e c o m p l e x e s a r e v e r y s t a b l e , a b l e t o r e s i s t t h e r i s e i n p H a n d E h w h i c h c a n o c c u r a t t h e b o t t o m o f t h e A e . I n c o n t r a s t , t h e s a l t c o m p l e x e s f o r m e d u n d e r c o n d i t i o n s o f b e t t e r 39 a e r a t i o n , are not as mobile o r s t a b l e and p r e c i p i t a t i o n o c c u r s more r a p i d l y . A l s o , a c c o r d i n g t o Duchaufour (1982, p. 318, p. 77), the r e a s o n why aluminum moves f u r t h e r i n t o the B h o r i z o n than i r o n i s because aluminum-organic complexes are the more s o l u b l e . However, very l i t t l e e v i d e n c e i s g i v e n by Duchaufour t o support t h i s c l a i m and the r e s u l t s of p a s t r e s e a r c h , l i s t e d i n c h a p t e r 1, seem c o n t r a d i c t o r y t o t h i s . I r o n and aluminum i n complex form w i t h the o r g a n i c a c i d s , move downwards t h r o u g h the s o i l u n t i l the m o b i l i t y of the complex i s l o s t t h r o u g h t h r e e d i f f e r e n t p r o c e s s e s (DeConinck, 1980): 1. D u r i n g t h e i r m i g r a t i o n , a d d i t i o n a l c a t i o n s may be complexed by the o r g a n i c c o l l o i d s . The d i v a l e n t and t r i v a l e n t c a t i o n s may n e u t r a l i z e the n e g a t i v e charge t o the p o i n t where the o r g a n i c a c i d s can approach one a n o t h e r . A l s o , a p o l y v a l e n t c a t i o n may b i n d two p r i m a r y o r g a n i c m o l e c u l e s t o g e t h e r , b r i n g i n g about p o l y m e r i z a t i o n of the l i g a n d s . P r e c i p i t a t i o n o c c u r s through the l a c k of charge and i n c r e a s e d s i z e . 2. The o r g a n i c c o l l o i d s may p r e c i p i t a t e out of s o l u t i o n under c o n d i t i o n s of h i g h e r i o n i c c o n c e n t r a t i o n o r a s o i l r e a c t i o n t h a t i s d i f f e r e n t from where they were m o b i l i z e d . 3. D e s i c c a t i o n of the s o i l may i n c r e a s e i o n i c c o n c e n t r a t i o n , r e s u l t i n g i n c o n t r a c t i o n of the double l a y e r s u r r o u n d i n g the complex and e x p u l s i o n of water m o l e c u l e s from v o i d s . When i m m o b i l i z e d , the p r i m a r y compounds are s t i l l s urrounded 40 by w ater of h y d r a t i o n . A l s o , d u r i n g f o r m a t i o n of the l a r g e r p a r t i c l e s , many water m o l e c u l e s and c a t i o n s p r e s e n t i n the s u r r o u n d i n g s o l u t i o n are l o c k e d i n s i d e the v o i d s . As a r e s u l t , the complex i s i n a g e l s t a t e r a t h e r than a s o l i d s t a t e . The water i s l o s t t h r ough g r a d u a l d e h y d r a t i o n (DeConinck, 1980). V a r i o u s a u t h o r s , quoted by Duchaufour (1982), have demonstrated the ease w i t h which c l a y i s d e s t r o y e d i n the A h o r i z o n by the c o m p l e x i n g a b i l i t y of simple o r g a n i c a c i d s . However, owing t o the r a p i d m i n e r a l i z a t i o n of a l i p h a t i c a c i d s , t h e i r e f f e c t i v e n e s s as w e a t h e r i n g agents i s r e s t r i c t e d t o the s u r f a c e h o r i z o n s . At l o w e r l e v e l s the a l i p h a t i c a c i d s are r e p l a c e d by p h e n o l i c polymers which a c t m a i n l y as c a r r i e r s of i r o n and aluminum r a t h e r than as w e a t h e r i n g a g e n t s . B i o l o g i c a l a c t i v i t y a t the top of the B h o r i z o n may b iodegrade a p o r t i o n of these c o m p l e x i n g a n i o n s , r e d u c i n g the a n i o n r c a t i o n r a t i o and f r e e i n g p a r t of the i r o n and aluminum. The m e t a l s may then i n t u r n n e u t r a l i z e the charge on o t h e r o r g a n i c complexes and b r i n g about t h e i r i m m o b i l i z a t i o n . Duchaufour s p e c i f i c a l l y c i t e d the work of B r u c k e r t (1970) which i l l u s t r a t e d how b i o l o g i c a l d e c a r b o x y l a t i o n , o c c u r r i n g i n the B h o r i z o n , was one i n i t i a l cause of s o l u b l e complex p r e c i p i t a t i o n . D e s p i t e an abundance of o r g a n i c a c i d s , w e a t h e r i n g w i t h i n a w e l l - d e v e l o p e d p o d z o l i s o f t e n not as g r e a t as i s commonly b e l i e v e d . T h i s i s because of a l a c k of w e a t h e r a b l e m i n e r a l s w i t h i n the A h o r i z o n , and w i t h i n the B h o r i z o n , because of the p r o t e c t i o n a f f o r d e d m i n e r a l s by a c o v e r i n g of p r e c i p i t a t e d , s u r f a c e - d e r i v e d amorphous m a t e r i a l . The p r o d u c t i o n of t h i s 41 a m o r p h o u s m a t e r i a l b y p o l y m e r i z a t i o n o f t h e i r o n a n d a l u m i n u m c o m p l e x e s a n d / o r s i l i c a i s m u c h m o r e i m p o r t a n t t h a n c l a y f o r m a t i o n i n t h e B h o r i z o n o f a p o d z o l ( D u c h a u f o u r , 1 9 8 2 ) . A c c o r d i n g t o D u c h a u f o u r ( 1 9 8 2 ) , t h e f o r m a t i o n o f a B h h o r i z o n o c c u r s a t f i r s t s i m u l t a n e o u s l y w i t h t h e d e v e l o p m e n t o f t h e B s , a s s m a l l a r o m a t i c a c i d s m o v e t o a g r e a t e r d e p t h w i t h i n t h e p r o f i l e t h a n l a r g e r m o l e c u l e s . A f t e r p r e c i p i t a t i o n , t h e a c i d s g r a d u a l l y p o l y m e r i z e t o f o r m h u m i c a c i d s , d o m i n a n t i n t h e B h a n d f u l v i c a c i d s , d o m i n a n t i n t h e B s . A s t h e p o d z o l d e v e l o p s , t h e a m o u n t o f f r e e i r o n r e s p o n s i b l e f o r i n s o l u b i l i z a t i o n o f t h e o r g a n i c c o m p l e x e s i n c r e a s e s i n t h e s o i l , p a r t i c u l a r l y i n t h e B h h o r i z o n . A s a r e s u l t , e v e n t u a l l y a l l c o m p l e x e s , r e g a r d l e s s o f s i z e , a r e i n s o l u b i l i z e d i n t h e B h . T h i s f o r m s a n a b s o l u t e c h e m i c a l b a r r i e r t h a t c a n n o t b e c r o s s e d b y m o b i l e c o m p l e x e s . D u c h a u f o u r s u b s t a n t i a t e s t h i s w i t h t h e c a r b o n 1 4 d e t e r m i n a t i o n s o f G u i l l e t ( 1 9 7 2 ) w h i c h s h o w t h a t t h e m e a n a g e o f t h e B s i s a l w a y s g r e a t e r t h a n t h a t o f t h e B h . L a t e r r e m o b i l i z a t i o n o f o r g a n i c a c i d s a n d s e s q u i o x i d e s w i t h i n t h e e l u v i a l h o r i z o n may r e s u l t i n a t h i c k e n i n g o f t h e B h o r i z o n ( D u c h a u f o u r , 1 9 8 2 ) . I n g e n e r a l t e r m s r e g a r d i n g o r g a n i c m a t t e r , D u c h a u f o u r r e p o r t s t h a t t h e s t a b i l i z i n g e f f e c t o f i r o n o n o r g a n i c c o m p o u n d s i s m i n i m a l . A l l t h e h u m i c c o m p o u n d s p r e c i p i t a t e d b y i r o n r e m a i n s u s c e p t i b l e t o b i o d e g r a d a t i o n . T h e i r b i o l o g i c a l t u r n o v e r i s r a p i d a n d t h e y d o n o t a c c u m u l a t e i n a c i d f o r e s t m u l l s . I n c o n t r a s t , a m o r p h o u s a l u m i n a h a s a g r e a t s t a b i l i z i n g e f f e c t a g a i n s t m i c r o b i a l b i o d e g r a d a t i o n o f o r g a n i c m a t t e r . T h i s i s i l l u s t r a t e d e s p e c i a l l y w e l l i n a n d o s o l s w h e r e a m o r p h o u s a l u m i n a 42 i s the a c t i v e p a r t of the a l l o p h a n e s p r e v a l e n t i n these s o i l s . The aluminum bonds s t r o n g l y w i t h the o r g a n i c m o l e c u l e s , p a r t i c u l a r l y the p r e c u r s o r compounds and t h i s r e s u l t s i n an al m o s t immediate i n s o l u b i l i z a t i o n and s t a b i l i z a t i o n of the o r g a n i c m a t t e r . Duchaufour c i t e s work by H e t i e r (1975) which showed t h a t a c o n s i d e r a b l e p o r t i o n of the o r g a n i c m a t t e r i n the c e n t r a l p a r t of the allophane-humus a g g r e g a t e s a c c u m u l a t i n g i n an a n d o s o l , was of the same age as the s o i l , (up t o 4000 y e a r s o l d ) . T h i s i s one f a c t o r b e h i n d the second model of p o d z o l g e n e s i s now to be p r e s e n t e d . Movement of Aluminum (and I r o n ) as I n o r g a n i c P r o t o - i m o g o l i t e A reassessment of p o d z o l f o r m a t i o n was made by Anderson et. a l . (1982) based on work by V. C. Farmer and coworkers a t the Macauley I n s t i t u t e f o r S o i l Research i n S c o t l a n d . These r e s e a r c h e r s d i s c o v e r e d i n p o d z o l i c B h o r i z o n s , i m o g o l i t e , a m i n e r a l r e l a t e d t o a l l o p h a n e . A l l o p h a n e i s a s e r i e s name a p p l i e d t o n a t u r a l l y o c c u r r i n g hydrous a l u m i n o s i l i c a t e c l a y s c h a r a c t e r i z e d by a s h o r t - r a n g e o r d e r and by the predominance of S i - O - A l bonds (Wada, 1977). Because a l l o p h a n e i s a w e a t h e r i n g p r o d u c t of v o l c a n i c ash, many p a s t s t u d i e s have emphasized i t s importance i n a n d o s o l s , but a l l o p h a n e i s a l s o found i n a v a r i e t y of o t h e r s o i l s . I t i s formed from b a s i c igneous r o c k s by i n t e n s e t r o p i c a l w e a t h e r i n g , from a c i d r o c k s by p o d z o l i z a t i o n , by the p h y s i c a l p r o c e s s of g l a c i a l g r i n d i n g and from s o l u t i o n i n a r e a s w i t h ground waters h i g h i n d i s s o l v e d s i l i c a and alumina (Brown et. a_l. , 1978). 43 Yoshinaga and Aomine (1962a) found t h a t by d i s p e r s i n g a v o l c a n i c ash s o i l f i r s t a t the h i g h pH of 10.5-11.0 then s u b s e q u e n t l y , by d i s p e r s i n g the r e s i d u e a t the low pH of 3.5-4.0, they c o u l d s e p a r a t e two d i s t i n c t < 0.2 m i c r o n f r a c t i o n s . The f i r s t was x - r a y amorphous and d etermined t o be pure a l l o p h a n e ; O 0 the second had b r o ad, r e l a t i v e l y i n t e n s e 14.5 A and 7.6 A o d i f f r a c t i o n s and a weak peak a t 5.5 A. T h i s m i n e r a l had never b e f o r e been d e s c r i b e d . The a u t h o r s proposed the name " i m o g o l i t e " a f t e r imogo, a b r o w n i s h y e l l o w l a y e r i n v o l c a n i c ash s o i l s of the Kuma b a s i n i n Japan, i n which i m o g o l i t e was f i r s t found. U n t i l r e c e n t l y , t h i s c o l l o i d was c o n s i d e r e d e x c l u s i v e t o the w e a t h e r i n g of v o l c a n i c a s h . Under the e l e c t r o n m i c r o s c o p e , Yoshinaga and Aomine (1962b) found t h a t i m o g o l i t e appeared t o be of t h r e a d - l i k e shape w i t h a r e l a t i v e l y u n i f o r m s i z e . T h i s u n i f o r m i t y i n shape seemed t o suggest some r e g u l a r i t y of atomic arrangement w i t h i n the i m o g o l i t e p a r t i c l e s . F u r t h e r work determined the i m o g o l i t e o f i b e r s t o be 20 A i n o u t s i d e d i a m e t e r (Wada e_t a_l. , 1970) and e l e c t r o n d i f f r a c t i o n i n d i c a t e d a r e p e a t d i s t a n c e a l o n g the f i b e r o a x i s of 8.4 A and a r e p e a t d i s t a n c e p e r p e n d i c u l a r t o t h i s a x i s of 22-23 A. The 8.4 & r e p e a t d i s t a n c e was t e n t a t i v e l y a s s i g n e d t o a g i b b s i t e - l i k e c h a i n o r r i b b o n (Wada and Y o s h i n a g a , 1969; R u s s e l l e t a l . , 1969). As w e l l , Cradwick e_t a l . (1972) p r e s e n t e d s t r o n g e v i d e n c e f o r the presence of an o r t h o s i l i c a t e group i n i m o g o l i t e . These a u t h o r s then proposed t h a t i m o g o l i t e had a "tube" s t r u c t u r e , the o u t e r w a l l s l i k e a s i n g l e s h e e t of g i b b s i t e w i t h o r t h o s i l i c a t e groups r e p l a c i n g the i n n e r h y d r o x y l s u r f a c e of the 44 g i b b s i t e s h e e t . The b i n d i n g of s i l i c a t o t h i s f r e e h y d r o x y l s u r f a c e s h o r t e n s the 0-0 d i s t a n c e s between h y d r o x i d e s from about 0 ° 3.2 A i n g i b b s i t e t o l e s s than 3 A i n i m o g o l i t e , a p p r o p r i a t e t o the edges of a S i 0 4 t e t r a h e d r o n . T h i s would a c c o u n t f o r the c u r l i n g of the g i b b s i t e s h e e t and t h e r e f o r e , the tube s t r u c t u r e of i m o g o l i t e (see f i g u r e 2-1). T h i s s t r u c t u r e would r e q u i r e an e m p i r i c a l f o r m u l a of (HO)^A^O^SiOH and t h i s would a l s o be the sequence of atoms e n c o u n t e r e d on p a s s i n g from the o u t e r t o the i n n e r s u r f a c e of the tube (Farmer e t a l . , 1977). F i g u r e 2-1: Proposed S t r u c t u r e of I m o g o l i t e (Cradwick e_t a l . , 1972). I m o g o l i t e o c c u r r e d i n v o l c a n i c ash s o i l s as a g e l f i l m c o a t i n g weathered pumice p a r t i c l e s b u t , i n c o n t r a s t t o a l l o p h a n e , c o u l d not be found w i t h i n the weathered p a r t i c l e s themselves 45 (Wada and Harward, 1974). T h i s suggested t o Farmer e_t a_l. (1977) t h a t n a t u r a l i m o g o l i t e formed from s o l u t i o n . U s i n g t h i s e v i d e n c e and assuming the m o l e c u l a r arrangement as det e r m i n e d above was c o r r e c t , Farmer e_t a l . (1977) s e t out t o s y n t h e s i z e i m o g o l i t e , u s i n g an i n f r a r e d band a t 348 cm *, d i s t i n c t i v e t o t h i s m i n e r a l , t o m o n i t o r t h e i r s u c c e s s . A d i l u t e s o l u t i o n c o n t a i n i n g h y d r o x y - A l c a t i o n s and o r t h o s i l i c i c a c i d , w i t h A l : S i atomic r a t i o s of about 2:1, was a d j u s t e d t o pH 4.5 and heated t o 96-100°C. A f t e r m a i n t a i n i n g the s o l u t i o n a t t h i s temperature f o r one day, i m o g o l i t e was d e t e c t a b l e and a f t e r f i v e days a maximum y i e l d was a t t a i n e d . T h i s s y n t h e t i c i m o g o l i t e had an IR spectrum and e l e c t r o n d i f f r a c t i o n p a t t e r n which i n d i c a t e d a p r o d u c t o n l y s l i g h t l y l e s s r e g u l a r than the b e s t n a t u r a l specimens and i t s f i b r o u s morphology c o u l d be seen under the e l e c t r o n m i c r o s c o p e . The i m o g o l i t e p r e c u r s o r , p r e s e n t b e f o r e h e a t i n g , was an hydroxyaluminum o r t h o s i l i c a t e s o l c a l l e d " p r o t o - i m o g o l i t e " (Farmer, 1981). P r o t o - i m o g o l i t e formed c o l l o i d a l s u s p e n s i o n s which were w a t e r - c l e a r and s t a b l e i n d e f i n a t e l y . The f r e e z e - d r i e d s u s p e n s i o n gave an i n f r a r e d spectrum s i m i l a r t o t h a t of s y n t h e t i c i m o g o l i t e but whereas i m o g o l i t e had e l e c t r o n d i f f r a c t i o n p a t t e r n s o o o a t 1.4 A, 2.1 A and 4.2 A, p r o t o - i m o g o l i t e showed none of these o or o n l y a d i f f u s e r i n g a t 1.4 A. P r o t o - i m o g o l i t e was, t h e r e f o r e , c o n s i d e r e d t o c o n s i s t of s m a l l fragments of the i m o g o l i t e s t r u c t u r e , the s m a l l e s t p o s s i b l e b u i l d i n g u n i t i s shown i n f i g u r e 2-2 w i t h a charge dependant on the i o n i z a t i o n of AKOB^) groups (Farmer, 1981). 46 F i g u r e 2-2: The S m a l l e s t P o s s i b l e B u i l d i n g U n i t of the I m o g o l i t e S t r u c t u r e (Farmer, 1981) ( H 2 0 ) 3 A 1 0 \ / A l ( O H 2 ) 3 + OH O 0 \ / S i (OH) 2 W i t h i n the p o d z o l i c model c r e d i t i n g f u l v i c a c i d s w i t h the t r a n s p o r t of aluminum, are many mechanisms accounted f o r o n l y by c i r c u m s t a n t i a l e v i d e n c e . Much more of the i r o n and aluminum e n r i c h i n g p o d z o l i c Bf h o r i z o n s can be e x t r a c t e d w i t h a c i d ammonium o x a l a t e than w i t h pyrophosphate, i n d i c a t i n g t h a t most i s p r e s e n t i n an amorphous i n o r g a n i c form r a t h e r than as a complex w i t h o r g a n i c m a t t e r . McKeague e_t a_l. (1971) f e l t t h i s i m p l i e d t h a t i r o n and aluminum were e i t h e r t r a n s p o r t e d w i t h o r g a n i c m a t t e r which was s u b s e q u e n t l y b i o d e g r a d e d o r t h a t these m i n e r a l s were t r a n s l o c a t e d as hydrous o x i d e s o l s . Farmer (1981) f e l t the f i r s t s u g g e s t i o n t o be u n l i k e l y because of the h i g h s t a b i l i t y from m i c r o b i a l d e c o m p o s i t i o n of o r g a n i c complexed aluminum and i r o n i n v o l c a n i c ash s o i l s , s p e c i f i c a l l y the 10,000 year+ age of o r g a n i c s i n b u r i e d A l h o r i z o n s (Wada and H i g a s h i , 1976; H i g a s h i and Wada, 1977). Farmer (1981) a l s o f e l t the second s u g g e s t i o n t o be u n l i k e l y because of the low s o l u b i l i t y of Fe and A l h y d r o x i d e s and the r e a d i n e s s w i t h which A l h y d r o x i d e s of low s a l t c o n t e n t c r y s t a l l i z e t o form g i b b s i t e . G i b b s i t e i s not a t y p i c a l c o n s t i t u e n t of p o d z o l s . I n f a c t , e v i d e n c e f o r the movement of i r o n and aluminum as f u l v i c a c i d complexes c o n c e n t r a t e d on p r o p e r t i e s near the top of the B h o r i z o n where much of the i r o n and aluminum was t i e d up w i t h o r g a n i c m a t t e r . Anderson e_t a l . (1982) argued t h a t these complexes c o u l d have formed _in s i t u when s o l u b l e f u l v i c a c i d s p r e c i p i t a t e d on i n o r g a n i c s e s q u i o x i d e c o a t i n g s . They f e l t t h i s would a l s o e x p l a i n the h i g h e r humic t o f u l v i c r a t i o of Bh h o r i z o n s i n comparison w i t h Bf h o r i z o n s , as the more mobile f u l v i c a c i d s c o u l d p e n e t r a t e f u r t h e r i n t o the m i n e r a l s o i l t han the l e s s mobile humic a c i d s . E a r l i e r work had found t h a t much of the x- r a y amorphous c l a y s i n p o d z o l i c s o i l s c o n s i s t e d of aluminum s i l i c a t e s r e l a t e d t o a l l o p h a n e ( M i t c h e l l and Farmer, 1962; Kirkman e_t a_l. , 1966; Brydon and Shimoda, 1972). In t h e s e , the a l l o p h a n e was assumed t o have formed in s i t u . I m o g o l i t e had been d e t e c t e d by e l e c t r o n m i c r o s c o p y of the c l a y f r a c t i o n i n S c a n d i n a v i a n and German s o i l s , d eveloped on dune sand and on a q u a r t z p a r e n t m a t e r i a l , r e s p e c t i v e l y , but no f u r t h e r p r o o f of i t s presence had been o f f e r e d ( T a i t e_t a_l. , 1978). However, by d i s p e r s i n g the c l a y f r a c t i o n of S c o t t i s h p o d z o l s a t pH 4.0, T a i t e_t a l . (1978) c o n c e n t r a t e d the a l l o p h a n i c m a t e r i a l s , and i m o g o l i t e was p o s i t i v e l y i d e n t i f i e d by e l e c t r o n m i c r o s c o p y . These s o i l s were l o c a t e d on p a r e n t m a t e r i a l s u n a f f e c t e d by r e c e n t v o l c a n i c a c t i v i t y . The d i s c o v e r y of i m o g o l i t e was s i g n i f i c a n t because, i f indeed t h i s m i n e r a l c o u l d o n l y form from s o l u t i o n , the p r e c u r s o r 48 c o u l d w e l l have been p r o t o - i m o g o l i t e . As p r o t o - i m o g o l i t e i s f u l l y mobile i n the p o s i t i v e l y charged B h o r i z o n , aluminum c o u l d move through the s o i l i n t h i s i n o r g a n i c form (Farmer, 1981). In f u r t h e r s t u d i e s , Farmer e_t a_l. (1980) i s o l a t e d i m o g o l i t e i n t h r e e a d d i t i o n a l S c o t t i s h s o i l s . In one of t h e s e , an i m o g o l i t e - l i k e m a t e r i a l was the dominant component of the a c i d - d i s p e r s i b l e c l a y f r a c t i o n of the B 2 h o r i z o n but a l t h o u g h e l e c t r o n m i c r o s c o p y showed t h a t a c o n s i d e r a b l e amount of w e l l - o r d e r e d i m o g o l i t e was p r e s e n t , the i n f r a r e d spectrum was i n t e r m e d i a t e between i m o g o l i t e and p r o t o - i m o g o l i t e . The c l a y was, t h e r e f o r e , c o n s i d e r e d t o be a m i x t u r e of b o t h components. In subsequent papers i m o g o l i t e was d e t e c t e d a g a i n and a g a i n i n p o d z o l i c e n v i r o n m e n t s . Anderson e_t a_l. (1982) found t h i s m i n e r a l i n the Bs h o r i z o n of a number of S c o t t i s h p o d z o l s but i t was not found i n the Bh h o r i z o n s of these s o i l s . C h i l d s e_t a l . (1982) l o c a t e d i m o g o l i t e i n n o n - v o l c a n i c s o i l s of New Z ealand and i t was a l s o found i n Canadian p o d z o l s by Ross and Kodama (1979) and by McKeague and Kodama (1981). In two of these l a s t t h r e e s i t u a t i o n s , i m o g o l i t e appeared t o form the cement of i n d u r a t e d h o r i z o n s l o c a t e d w i t h i n the s o i l s ( C h i l d s e_t a_l. , 1982 ; McKeague and Kodama, 19 79). The d e p o s i t i o n of an a l l o p h a n e w i t h an i n f r a r e d spectrum and c o m p o s i t i o n of p r o t o - i m o g o l i t e was a l s o seen i n h o u s e h o l d water p i p e s where the water s u p p l y had a pH of 4.5 (Farmer, 1981, from u n p u b l i s h e d d ata) and an a l l o p h a n e w i t h a h i g h A l : S i r a t i o r a p i d l y a ccumulated i n a f i e l d d r a i n a t the Rothamsted E x p e r i m e n t a l S t a t i o n , England (Ormerod and Brown, 1978). 49 Farmer (1981) s t u d i e d the e f f e c t of v a r i o u s o r g a n i c a c i d s on the l i b e r a t i o n of aluminum and s i l i c a from i m o g o l i t e . He found t h a t the s t r o n g c o m p l e x i n g a c i d s , m a l o n i c , t a r t a r i c and s a l i c y l i c decomposed p r o t o - i m o g o l i t e c o m p l e t e l y w h i l e m o n o - c a r b o x y l i c a c i d s such as a c e t i c , d i d not decompose p r o t o - i m o g o l i t e and d i d not impede i t s f o r m a t i o n . At pH 4.5, f u l v i c a c i d behaved as a s t r o n g l y c o m p l e x i n g a c i d , c o m p l e t e l y decomposing i m o g o l i t e t o a s o l u b l e A l - f u l v a t e p l u s s i l i c i c a c i d when the molar r a t i o of fulvate-COOH t o A l exceeded about 8. F u l v a t e and p r o t o - i m o g o l i t e formed p r e c i p i t a t e s a t l o w e r r a t i o s of COOHiAl and complete c o p r e c i p i t a t i o n of a l l aluminum and a l l f u l v a t e from s o l u t i o n o c c u r r e d a t a molar r a t i o of u n i t y w i t h p a r t i a l l i b e r a t i o n of s i l i c a from the p r o t o - i m o g o l i t e . At r a t i o s of C00H:A1 of l e s s than 0.3, most of the p r o t o - i m o g o l i t e remained s o l u b l e and m a i n t a i n e d f u l v a t e i n s o l u t i o n by a d s o r p t i o n on "the p r o t o - i m o g o l i t e s o l . Farmer (1981) a l s o e s t i m a t e d t h a t the e q u i l i b r i u m c o n c e n t r a t i o n of s i l i c a n e c e s s a r y t o p r e v e n t the decompositon of i m o g o l i t e t o boehmite was 1 ppm S i C ^ a t 25°C. F u r t h e r c a l c u l a t i o n s l e d t o the c o n c l u s i o n t h a t " t h e r e i s ample SiC>2 i n most s o i l s o l u t i o n s t o ensure t h a t i m o g o l i t e r a t h e r than aluminum h y d r o x i d e s form when a r e a c t i v e aluminum s p e c i e s i s l i b e r a t e d by the w e a t h e r i n g of m i n e r a l s " (Farmer, 1981). The h i g h p r o p o r t i o n of i r o n and aluminum o r g a n i c complexes i n the Bh, the v e r y low p r o p o r t i o n of i r o n and aluminum i n o r g a n i c form i n the Bs and the f a c t t h a t i m o g o l i t e was so f r e q u e n t l y found i n p o d z o l i c h o r i z o n s u n a f f e c t e d by v o l c a n i c a c t i v i t y l e d Farmer and coworkers t o propose a model f o r p o d z o l g e n e s i s which i n c l u d e d t r a n s l o c a t i o n of aluminum as p r o t o - i m o g o l i t e (Farmer, 1981; Anderson et. a_l. , 1982). In t h i s model, the a u t h o r s d i d not q u e s t i o n the r o l e of c o l l o i d a l c h e m i s t r y , as proposed by DeConinck (1980), i n the m o b i l i z a t i o n and subsequent i m m o b i l i z a t i o n of o r g a n i c a c i d s , r a t h e r they q u e s t i o n e d the r o l e these a c i d s p l a y e d i n the t r a n s p o r t a t i o n of i r o n and aluminum. S m a l l o r g a n i c a c i d s , r e l e a s e d by the v e g e t a t i o n , were s t i l l c o n s i d e r e d i m p o r t a n t i n the w e a t h e r i n g of s o i l m i n e r a l s but Farmer (1981) quoted work by A r i s t o v s k a y a and Z y k i n a , 1977, which found m i c r o o r g a n i s m s p r e s e n t i n the s o i l c a p a ble of decomposing these l a c t i c , t a r t a r i c and c i t r i c a c i d - c o m p l e x e s of aluminum and e x c r e t i n g the m e t a l . Farmer (1982) f e l t t h a t when s u f f i c i e n t s i l i c a was p r e s e n t i n the s o i l s o l u t i o n , the aluminum r e l e a s e d by the o r g a n i c a c i d s would form p r o t o - i m o g o l i t e r a t h e r than an aluminum h y d r o x i d e . At pH below 5.0, p r o t o - i m o g o l i t e i s s o l u b l e and s h o u l d move through the p o s i t i v e l y charged B h o r i z o n as a p o s i t i v e s o l . P r o t o - i m o g o l i t e would p r e c i p i t a t e out of the s o i l s o l u t i o n when the pH rose above 5.0, when the p o s i t i v e l y charged s o l s were n e u t r a l i z e d by adsorbed a n i o n s o r when they e n c o u n t e r e d n e g a t i v e l y charged s u r f a c e s such as s m e c t i t e s , i l l i t e s o r v e r m i c u l i t e . I f c o n d i t i o n s were r i g h t , the s o l s might e v e n t u a l l y c r y s t a l l i z e t o form i m o g o l i t e . However, i n a c i d i c s o i l s , p r o t o - i m o g o l i t e might be t r a n s p o r t e d c o m p l e t e l y out of the p r o f i l e (Farmer, 1981). Farmer saw p o d z o l i z a t i o n o c c u r r i n g i n s t a g e s . D u r i n g e a r l y development of the s o i l , b e f o r e d i f f e r e n t i a t i o n of an Ae h o r i z o n , 51 a l umina and s i l i c a were abundant i n the s o i l s o l u t i o n and any f u l v i c a c i d formed e i t h e r p r e c i p i t a t e d ir\ s i t u near the top of the p r o f i l e o r was c a r r i e d downwards as a sorbed phase on p r o t o - i m o g o l i t e . L a t e r , when f u l v i c a c i d was i n e x c e s s , i t began t o t r a n s p o r t aluminum as an a c i d i c complex. The complex p r e c i p i t a t e d out on the i m o g o l i t e and a l l o p h a n e s of the B h o r i z o n , c o m p l e x i n g the aluminum and r e l e a s i n g s i l i c a . T h i s i n t e r a c t i o n iin s i t u between o r g a n i c a c i d s o r c o l l o i d a l o r g a n i c m a t t e r and aluminum, r e s u l t e d i n the f o r m a t i o n of a Bh h o r i z o n , a r e a c t i o n s i m i l a r t o t h a t which produced the humus-rich A h o r i z o n s of a n d o s o l s (Farmer, 1981). Farmer (1982) p o i n t e d o u t t h a t the two s t a g e s of p o d z o l development - m i g r a t i o n of the i n o r g a n i c components f o l l o w e d by the s e p a r a t e movement of o r g a n i c components - may not be w i d e l y s e p a r a t e d i n t i m e . P r o t o - i m o g o l i t e c o u l d be the dominant t r a n s p o r t of aluminum d u r i n g p e r i o d s of h i g h b i o l o g i c a l a c t i v i t y i n summer and the m i g r a t i o n of o r g a n i c c o l l o i d s dominant d u r i n g p e r i o d s of heavy r a i n f a l l . L a t e r , Farmer and F r a s e r (1982) i n c l u d e d i n t h e i r model, a mechanism f o r the movement of i r o n . These a u t h o r s found t h a t no compound analogous t o p r o t o - i m o g o l i t e c o u l d be formed when F e f C l O ^ ) ^ was mixed w i t h S i ( O H ) ^ a t pH 3.7, because h y r o x y i r o n s p e c i e s have l e s s a f f i n i t y f o r s i l i c a than do hydr.oxyaluminum s p e c i e s . However, when i r o n i s p a r t i a l l y s u b s t i t u t e d f o r aluminum i n p r o t o - i m o g o l i t e , the r e s u l t i n g A^O^-Fe2°3~ si°2 - H2° s o l s are a l m o s t as s t a b l e as pure p r o t o - i m o g o l i t e , up t o an F e : A l r a t i o of 1:1 (Farmer, 1982). Beyond t h i s , the s t a b i l i t y d e c l i n e s 52 r a p i d l y . Farmer and F r a s e r (1982) c o n c l u d e t h a t i r o n c o u l d move i n o r g a n i c a l l y i n p o d z o l s as t h i s mixed s o l . I r o n does n o t , however, appear t o s u b s t i t u t e f o r the aluminum i n i m o g o l i t e o r a l l o p h a n e (Farmer, 1982). P o s s i b l e s u p p o r t f o r the movement of aluminum through a p o d z o l as p r o t o - i m o g o l i t e was p r e s e n t e d by Farmer e t <al. , (1984). P r e p a r e d t h i n s e c t i o n s of c o n c r e t i o n s w i t h i n A u s t r a l i a n p o d z o l s r e v e a l e d t h a t the c l e a r , y e l l o w , g l a s s y , i s o t r o p i c o r weakly a n i s o t r o p i c cement of these s t r u c t u r e s was d e p o s i t e d i n l a y e r s as i f from s o l u t i o n . By i n f r a r e d s p e c t r o s c o p y and o x a l a t e and pyrophosphate e x t r a c t i o n , the c o n c r e t i o n s were e s t i m a t e d t o c o n t a i n between 1 and 5 % p r o t o - i m o g o l i t e a l l o p h a n e w i t h o n l y minor amounts of i r o n and o r g a n i c c a r b o n . In c o n t r a s t , no i m o g o l i t e was d e t e c t a b l e i n the s u r r o u n d i n g l o o s e m i n e r a l s o i l . Farmer e_t a_l. (1984) e n v i s i o n e d the d e p o s i t i o n of p r o t o - i m o g o l i t e from s o l u t i o n d u r i n g the s u c c e s s i v e d r y i n g e p i s o d e s t y p i c a l of t h i s c l i m a t e . L o c a l c o n c e n t r a t i o n s of secondary g i b b s i t e and k a o l i n i t e seemed t o suggest by t h e i r p o s i t i o n t h a t a l l o p h a n e i s a p o s s i b l e p r e c u r s o r t o these m i n e r a l s . S t r o n g e r e v i d e n c e t h a t p r o t o - i m o g o l i t e a l l o p h a n e may a c t u a l l y form the cement w i t h i n many p o d z o l B h o r i z o n s was found i n S c o t t i s h s o i l s by Farmer e_t a l . , 1985. T r a n s l u c e n t , p a l e y e l l o w , s t r o n g l y f l u o r e s c e n t , g e l a t i n o u s d e p o s i t s c o u l d be seen i n t h i n s e c t i o n s as c o a t i n g s s u r r o u n d i n g s k e l e t a l sand and s i l t and f o r m i n g t h i c k d e p o s i t s f i l l i n g v o i d s . E l e c t r o n - p r o b e a n a l y s i s of these d e p o s i t s gave atomic r a t i o s a v e r a g i n g ISi:2.48A1:0.29Fe. T h i s aluminum t o s i l i c o n r a t i o f e l l w i t h i n 53 the range t y p i c a l of p r o t o - i m o g o l i t e s o l s formed a t s i l i c i c a c i d c o n c e n t r a t i o n s near the l o w e r l i m i t of t h e i r s t a b i l i t y (Farmer and F r a s e r , 1982) . Farmer e_t a_l. (1985) d i d not d e t e c t the f i b r o u s morphology of ^ i m o g o l i t e w i t h i n t h i n s e c t i o n s nor by s c a n n i n g e l e c t r o n m i c r o s c o p y of a i r - d r y lumps of s o i l . However, f i b r o u s s t r u c t u r e s w i t h a S i : A l r a t i o s i m i l a r t o t h a t of the cement i n the t h i n s e c t i o n s , were v i s i b l e on f r a c t u r e d s u r f a c e s of s o i l s u b j e c t t o c r i t i c a l p o i n t d r y i n g . A l s o , i n l o c a l a r e a s the a l l o p h a n i c d e p o s i t s i n the t h i n s e c t i o n s e x h i b i t e d weak, s t r i a t e d b i r e f r i n g e n c e perhaps caused by c o - m i g r a t i o n and d e p o s i t i o n of l a y e r e d s i l i c a t e s and g i b b s i t e o r from the a l i g n m e n t of i m o g o l i t e tubes a s s o c i a t e d w i t h the a l l o p h a n e . No s u pport was found f o r the c o n t e n t i o n t h a t t h i s a l l o p h a n i c m a t e r i a l a r o s e ^n s i t u e i t h e r from the w e a t h e r i n g of m i n e r a l s w i t h i n the B h o r i z o n o r from the i n d i v i d u a l t r a n s l o c a t i o n of i r o n and aluminum f u l v a t e s and s i l i c i c a c i d . Indeed, e x a m i n a t i o n of m i n e r a l g r a i n s by the l i g h t and s c a n n i n g e l e c t r o n m i c r o s c o p e s r e v e a l e d t h a t w e a t h e r i n g of m i n e r a l s was a t a maximum i n the e l u v i a l and Bhg h o r i z o n s and a t a minimum i n the Bs and C h o r i z o n s . A l s o , s i l i c o n t o aluminum r a t i o s were o f t e n l o w e r i n s i d e the v o i d s than on the o r g a n i c - s t a i n e d s u r f a c e s , a f a c t c o n t r a r y t o the i d e a of A l - f u l v a t e e n r i c h m e n t (Farmer e_t a l . , 1985) . Root r e s i d u e s w i t h i n the g e l a t i n o u s a l l o p h a n i c d e p o s i t seemed t o have t h e i r c e l l s t r u c t u r e p r e s e r v e d by a l l o p h a n e - i m p r e g n a t i o n . The c e l l s t r u c t u r e e x h i b i t e d the c o l o u r , 54 f l u o r e s c e n c e and l a c k of b i r e f r i n g e n c e t y p i c a l of the a l l o p h a n i c g e l but a t y p i c a l of c e l l u l o s e . A l s o , e l e c t r o n probe a n a l y s i s gave S i : A l : F e r a t i o s s i m i l a r t o t h a t o b t a i n e d f o r the g e l d e p o s i t s (Farmer et. a_l. , 1985 ). Farmer (1981) and Anderson e_t a_l. (1982) were s u p p o r t e d by the f i n d i n g s of Yoshinaga e_t a_l. (1984). By e l e c t r o n m i c r o s c o p y , these a u t h o r s d i s c o v e r e d f i b r o u s i m o g o l i t e as g e l f i l m s a s s o c i a t e d w i t h a l l o p h a n e i n f r e s h f r a c t u r e s of a s h a t t e r e d sandstone p a r e n t m a t e r i a l beneath a brown f o r e s t s o i l . T h i s s o i l was u n a f f e c t e d by v o l c a n i c a c t i v i t y . The g e l f i l m s ranged from a few t o 20 mm a c r o s s , were found more o f t e n near the top of the sandstone than a t depth, and were s i t u a t e d i n such a p o s i t i o n as to appear t o have a r i s e n from the o v e r l y i n g s o i l . However, n e i t h e r i m o g o l i t e nor a l l o p h a n e c o u l d be s e p a r a t e d from the c l a y f r a c t i o n of the brown f o r e s t s o i l nor were they found i n o l d f r a c t u r e s of the p a r e n t m a t e r i a l . As p o s t u l a t e d by Yoshinaga e t a l . , t h i s was because i n t e r f e r i n g m a t e r i a l s such as l a y e r s i l i c a t e c l a y s and o r g a n i c m a t t e r were p r e s e n t a t these l o c a t i o n s . I t i s d o u b t f u l whether the i m o g o l i t e found i n the f r e s h f r a c t u r e s c o u l d have a r i s e n _in s i t u from the s e p a r a t e m i g r a t i o n of s i l i c a and aluminum because the S i : A l r a t i o i n the s o i l s o l u t i o n was so l a r g e t h a t a h i g h - s i l i c a type a l l o p h a n e would have been formed. A l s o , the v i r t u a l absence of o r g a n i c carbon i n the s o i l s o l u t i o n may r u l e out the movement of aluminum t o t h i s l o c a t i o n as a f u l v i c complex (Yoshinaga e_t a_l. , 1984). 55 C o n c l u s i o n s Each of the two models p r e s e n t e d f o r p o d z o l g e n e s i s r e l i e s h e a v i l y on c i r c u m s t a n t i a l e v i d e n c e f o r s u p p o r t . The model f a v o r i n g movement of i r o n and aluminum i n an o r g a n i c complex (DeConinck, 1980; Duchaufour, 1982), a c c o u n t s f a i r l y w e l l f o r p r o p e r t i e s v i s i b l e near the s u r f a c e of the s o i l and e x a m i n a t i o n of the s o i l s o l u t i o n seems t o support t h i s h y p o t h e s i s ( B r u c k e r t , 1970; U g o l i n i ejt a_l. , 1977). However, o n l y s u p p o s i t i o n can account f o r the h i g h p r o p o r t i o n of amorphous, i n o r g a n i c i r o n and e s p e c i a l l y aluminum, found a t d e p t h . Farmer and coworkers a l s o r e l y on c i r c u m s t a n t i a l e v i d e n c e t o su p p o r t t h e i r model. T h i s i s the presence of i m o g o l i t e i n the s o i l , i t s f o r m a t i o n from s o l u t i o n i n the l a b o r a t o r y and the s o l u t i o n - d e p o s i t e d " l o o k " of p r o t o - i m o g o l i t e cement. They have not found p r o t o - i m o g o l i t e a c t u a l l y moving through the s o i l i n l y s i m e t e r work. These models are examined i n C h a p t e r 6 as t o how they c o u l d p o s s i b l y r e l a t e t o the f o r m a t i o n of r o o t mats and r o o t c h a n n e l s i n p o d z o l i c s o i l s of s o u t h w e s t e r n B r i t i s h C olumbia. 56 CHAPTER 3 SOIL CLASSIFICATION IN CANADA I n t r o d u c t i o n Taxa i n the Canadian System of S o i l C l a s s i f i c a t i o n (CSSC, 1978) a re d e f i n e d on the b a s i s of o b s e r v a b l e and measurable s o i l p r o p e r t i e s chosen so t h a t t a x a a t h i g h e r l e v e l s " r e f l e c t broad d i f f e r e n c e s i n s o i l e n v i r o n m e n t s t h a t are r e l a t e d t o d i f f e r e n c e s i n s o i l g e n e s i s " (CSSC, 1978). T h i s i s i n c o n t r a s t t o the American system of c l a s s i f i c a t i o n based on s p e c i f i c p r o p e r t i e s which o f t e n , but not n e c e s s a r i l y , r e f l e c t p r o c e s s e s by which the s o i l was formed. The emphasis away from s o i l g e n e s i s i n the U n i t e d S t a t e s : 1. E n a b l e s s o i l s r a t h e r than s o i l - f o r m i n g p r o c e s s e s t o be c l a s s i f i e d . 2. P u t s the f o c u s on the s o i l i t s e l f r a t h e r than on r e l a t e d s c i e n c e s such as geology and c l i m a t o l o g y . 3. A l l o w s s o i l s of unknown g e n e s i s t o be c l a s s i f i e d . 4. E n s u r e s t h a t a l l s o i l s c i e n t i s t s , r e g a r d l e s s of how they view the o r i g i n s of a s o i l , c l a s s i f y i t i n the same manner (Brady, 1974). T h i s d i f f e r e n c e i n emphasis between the two systems means t h a t i n Canada, c l a s s c r i t e r i a are under c o n s t a n t m o d i f i c a t i o n as more i n f o r m a t i o n i s g a t h e r e d about the p r o c e s s e s b e h i n d s o i l f o r m a t i o n , whereas, i n the U. S., m o d i f i c a t i o n of the system t o 57 f i t c u r r e n t c o n c e p t s of s o i l g e n e s i s i s not always n e c e s s a r y . The need f o r c o n s t a n t f i n e t u n i n g i n the Canadian system i s w e l l i l l u s t r a t e d by p a s t r e v i s i o n s made i n the c l a s s i f i c a t i o n of p o d z o l i c s o i l s . I t i s i n t e r e s t i n g t o note how these r e v i s i o n s echo the changing c o n c e p t s of p o d z o l g e n e s i s l i s t e d i n C h a p t e r 1. E a r l y H i s t o r y of the C l a s s i f i c a t i o n System S o i l s u r v e y s , d e s i g n e d t o i d e n t i f y and map the d i f f e r e n t s o i l s of Canada, began i n 1914 u s i n g the c l a s s i f i c a t i o n scheme of the U. S. Bureau of S o i l s . T h i s system had such a broad c o n c e p t of the s o i l " s e r i e s " t h a t o n l y n i n e d i f f e r e n t s e r i e s were mapped throu g h o u t s o u t h w e s t e r n O n t a r i o . From the 1920's t o mid 1940*s, s o i l s u r v e y was a s t r i c t l y p r o v i n c i a l u n d e r t a k i n g w i t h each p r o v i n c e d e v e l o p i n g i t s own system of mapping and c l a s s i f i c a t i o n . In M a n i t o b a , s y s t e m a t i c s o i l s u r v e y d i d not b e g i n u n t i l 1927 when J . H. E l l i s undertook a r e c o n n a i s s a n c e s o i l s u r v e y of the a r e a west of the Red R i v e r e x t e n d i n g t o the U. S. boundary. D u r i n g t h i s i n i t i a l p r o j e c t he developed a system of s o i l c l a s s i f i c a t i o n based on d i s c u s s i o n s w i t h C. C. N i k i f o r o f f , of the R u s s i a n s c h o o l of s o i l s c i e n c e , who was c o n d u c t i n g a s o i l s u r v e y immediately a c r o s s the Manitoba-U. S. b o r d e r . T h i s system proved so u s e f u l i n d e s i g n a t i n g s o i l mapping u n i t s t h a t i t i s s t i l l i n use today i n some Canadian p r o v i n c e s and i n S c o t l a n d . I t wasn't u n t i l the f i r s t meeting of the N a t i o n a l S o i l Survey Committee (NSSC) i n 1945 t h a t s u r v e y o r s from a c r o s s the c o u n t r y got t o g e t h e r t o compare systems and d i s c u s s ways t o b r i n g about g r e a t e r u n i f o r m i t y between the p r o v i n c e s i n a l l a s p e c t s of s o i l s u r v e y 58 work. At t h i s meeting a t e n t a t i v e Canadian f i e l d c l a s s i f i c a t i o n scheme was f i r s t p roposed by P. C. Stobbe. T h i s system was based on t h a t d e v e l o p e d by E l l i s (McKeague and Stobbe, 1978). The f i r s t Canadian taxonomic system was p r e s e n t e d a t the t h i r d meeting of the NSSC i n 1955. A taxonomic r a t h e r than s t r i c t l y f i e l d method of c l a s s i f i c a t i o n was deemed n e c e s s a r y a t t h a t time because: 1. The knowledge of Canadian s o i l s had g r e a t l y i n c r e a s e d between 1945 and 1955. 2. A need had a r i s e n t o o r d e r t h i s i n f o r m a t i o n . 3. The U. S. taxonomic system was seen as t o o c o m p l i c a t e d and t o o t e n t a t i v e f o r Canadian needs. The Canadian system c o n s i s t e d of s i x c a t e g o r i c l e v e l s c o r r e s p o n d i n g t o o r d e r , g r e a t group, subgroup, f a m i l y , s e r i e s and t y p e . The o r d e r s were named Chernozemic, H a l o m o r p h i c , P o d z o l i c , F o r e s t e d Brown, R e g o s o l i c , G l e i s o l i c and O r g a n i c . A f t e r s e v e r a l r e v i s i o n s , the system was o f f i c i a l l y adopted i n 1960 (McKeague and Stobbe, 19 78) . Some M o d i f i c a t i o n s i n the C l a s s i f i c a t i o n of P o d z o l s By the 6 t h meeting of the NSSC i n 1965, the names of the o r d e r s had been changed t o Chernozemic, S p l o n e t z i c , P o d z o l i c , B r u n i s o l i c , R e g o s o l i c , G l e y s o l i c and O r g a n i c . L i k e the R u s s i a n system, the P o d z o l i c o r d e r c o n s i s t e d of b o t h s o i l s on c o a r s e t e x t u r e d p a r e n t m a t e r i a l l e a c h e d of s e s q u i o x i d e s and s o i l s on h e a v i e r p a r e n t m a t e r i a l s l e a c h e d p r i m a r i l y of c l a y . The e l u v i a l A h o r i z o n was d i a g n o s t i c . As a r e s u l t , the A c i d Brown Wooded 59 G reat Group of the B r u n i s o l i c o r d e r c o u l d have a p o d z o l i c Bf h o r i z o n but because the Ae h o r i z o n was l e s s than one i n c h t h i c k or a b s e n t , these s o i l s were not i n c l u d e d i n the p o d z o l i c o r d e r (NSSC, 1965). At the 7 t h m e e t i n g , i n 1968, s o i l s of h i g h base s a t u r a t i o n w i t h B h o r i z o n s e n r i c h e d i n i l l u v i a t e d l a y e r s i l i c a t e c l a y s , were removed from the P o d z o l i c o r d e r and p l a c e d i n t h e i r own o r d e r , the L u v i s o l i c . The Ae h o r i z o n was no l o n g e r c o n s i d e r e d d i a g n o s t i c and, t h e r e f o r e , the B r u n i s o l i c A c i d Brown Wooded s o i l c o u l d now become a g r e a t group of the P o d z o l i c o r d e r . The s e s q u i o x i d e - e n r i c h e d B h o r i z o n was c h a r a c t e r i z e d by the o x a l a t e - e x t r a c t a b l e Fe+Al v a l u e , a procedure d e v e l o p e d by Tamm (1920), and the p e r c e n t o r g a n i c m a t t e r . As a c i d ammonium o x a l a t e e x t r a c t e d b o t h o r g a n i c and i n o r g a n i c amorphous forms of i r o n and aluminum> i t s use i n the 1960's may s t i l l have r e f l e c t e d the e a r l i e r b e l i e f , p r e v a l e n t when the c l a s s i f i c a t i o n scheme was developed i n the 1940's and 50's, t h a t p o d z o l s form through the m i g r a t i o n of humus p r o t e c t e d s e s q u i o x i d e s o l s . Sodium pyrophosphate, an e x t r a c t a n t s p e c i f i c f o r o r g a n i c complexed i r o n and t o a l e s s e r e x t e n t aluminum, was t e s t e d by McKeague e_t a l . (1971). These a u t h o r s found pyrophosphate was b e t t e r a b l e t o s e p a r a t e p o d z o l i c from b r u n i s o l i c , g l e y s o l i c and l u v i s o l i c B h o r i z o n s . I t a l s o r e f l e c t e d the c o n c e p t c u r r e n t a t t h a t t i m e , t h a t i r o n and aluminum were l e a c h e d i n complex form w i t h o r g a n i c a c i d s . The e x t r a c t a n t was, t h e r e f o r e , adopted t o d e f i n e p o d z o l i c B h o r i z o n s i n the Canadian System of S o i l C l a s s i f i c a t i o n , 1978. Moon (1981) q u e s t i o n e d the wisdom of t h i s d e c i s i o n w h i l e 60 e xamining the s o i l s of a climosequence on Vancouver I s l a n d . He found t h a t the s o i l w i t h the g r e a t e s t p o d z o l i c m o r p h o l o g i c a l e x p r e s s i o n d i d not meet the c h e m i c a l c r i t e r i a of 0.6% sodium pyrophosphate e x t r a c t a b l e Al+Fe. He b e l i e v e d t h i s was due t o a r a p i d d e c o m p o s i t i o n of the o r g a n i c l i g a n d s under the optimum e n v i r o n m e n t a l c o n d i t i o n s and w i t h the a i d of a d e r i v e d model and l y s i m e t e r d a t a , showed t h a t the t r a n s l o c a t i o n of i r o n and aluminum from h i g h e r i n the p r o f i l e was the dominant f o r c e r e s p o n s i b l e f o r the f o r m a t i o n of the s e s q u i o x i d e - r i c h B h o r i z o n . O t her p o d z o l i c c r i t e r i a e s t a b l i s h e d a t the 1968 meeting were those of the Ferro-humic g r e a t group. "The upper f o u r i n c h e s (10cm) of the B h o r i z o n c o n t a i n s more than 10% o r g a n i c m a t t e r and the o x a l a t e - e x t r a c t a b l e Fe+Al exceeds t h a t of the C h o r i z o n by 0.8% or more...a Bh h o r i z o n l e s s than 4 i n c h e s (10 cm) t h i c k may o v e r l i e the Bhf h o r i z o n o r the Bhf may d i r e c t l y u n d e r l i e the Ah or Ae" (NSSC, 1968, p. 5 1 ) . However, i n the p r o c e e d i n g s of the e i g h t h meeting (1970) t h i s o r g a n i z a t i o n , now known as the Canadian S o i l Survey Committee (CSSC), recommended the above c r i t e r i a be changed so the Bhf h o r i z o n " u s u a l l y ... i s the uppermost B h o r i z o n , but i n some s o i l s the Bhf may be o v e r l a i n by a B f h o r Bf h o r i z o n " (CSSC, 1970, p. 126). I f the Bhf h o r i z o n was t h i c k enough, the p r o f i l e would be c l a s s i f i e d a Ferro-humic p o d z o l , no m a t t e r a t what depth the o r g a n i c - r i c h h o r i z o n appeared i n the p r o f i l e . T h i s l a t t e r r e v i s i o n soon became a problem i n the c l a s s i f i c a t i o n of p o d z o l i c s o i l s as seen by a recommendation of the E x p e r t Committee on S o i l Survey (1981), t h a t r e s e a r c h be 61 c a r r i e d out t o c h a r a c t e r i z e o r g a n i c m a t t e r o c c u r r i n g a t depth i n some B r i t i s h Columbia p o d z o l s . P r o f i l e s w i t h Bhf h o r i z o n s t h a t do not seem t o f i t the concept of p o d z o l g e n e s i s , as o u t l i n e d by McKeague e_t a_l. (1976), are i n f l u e n c i n g the c l a s s i f i c a t i o n of these s o i l s . These p o d z o l s have t h e i r h i g h e s t a c c u m u l a t i o n of o r g a n i c m a t e r i a l above a r o o t r e s t r i c t i n g l a y e r such as a d u r i c h o r i z o n r a t h e r than d i r e c t l y beneath the Ae or f o r e s t f l o o r . The a c c u m u l a t i o n s meet the c r i t e r i a of a p o d z o l i c Bhf h o r i z o n when they have l e s s than 17% o r g a n i c carbon and are g r e a t e r than 10 cm t h i c k . I f they are the o n l y p o d z o l i c Bhf h o r i z o n i n the p r o f i l e , they w i l l change the c l a s s i f i c a t i o n of the o t h e r w i s e o r g a n i c - p o o r s o i l from a h u m o - f e r r i c t o a f e r r o - h u m i c p o d z o l a l t h o u g h the o r g a n i c c o n t e n t may owe i t s o r i g i n s more t o r o o t d e c o m p o s i t i o n than t o i l l u v i a t i o n . One purpose of t h i s t h e s i s i s t o c h a r a c t e r i z e t h i s o r g a n i c m a t e r i a l , so t h a t d e t e r m i n a t i o n s can be made as t o whether the c l a s s i f i c a t i o n system s h o u l d be m o d i f i e d once a g a i n . C h a r a c t e r i z a t i o n and C l a s s i f i c a t i o n of S o i l O r g a n i c M a t t e r In the p a s t , o b j e c t i v e p r o p e r t i e s of the o r g a n i c m a t t e r have r a r e l y been i n c l u d e d i n the c l a s s i f i c a t i o n c r i t e r i a of s o i l s b o th because m e a n i n g f u l r e l a t i o n s h i p s had not y e t been e s t a b l i s h e d and because the a n a l y s e s were to o time consuming t o be employed on a r e g u l a r b a s i s . However, a number of s t u d i e s have i n d i c a t e d t h a t c e r t a i n c h e m i c a l and m o r p h o l o g i c a l p r o c e d u r e s , performed on the s o i l o r g a n i c m a t e r i a l , may indeed be u s e f u l i n s e p a r a t i n g some p r o b l e m a t i c s o i l s i n t o the major taxonomic groups (Kumada, 1965; 62 Kononova, 1966; Lowe, 1980; DeConinck, 1980; R i g h i , 1984). The o r g a n i c m a t t e r of the s o i l c o n s i s t s of t h r e e major components? undecomposed p l a n t and a n i m a l d e b r i s , p a r t i a l l y decomposed m a t e r i a l and s t a b l e humus, a g e n e r a l l y dark c o l o u r e d , amorphous, c o l l o i d a l substance r e l a t i v e l y r e s i s t a n t t o f u r t h e r d e c o m p o s i t i o n . Humus, i t s e l f , i s a m i x t u r e of l a r g e , complex polymers, s i m p l e r p h e n o l i c compounds and p o l y s a c c h a r i d e s . The polymers are r i c h i n a r o m a t i c r i n g s w i t h a t t a c h e d s i d e c h a i n s and r e a c t i v e f u n c t i o n a l groups - no two may be e x a c t l y a l i k e . The p o l y s a c c h a r i d e s may account f o r 10-30 % of the humus and c o n t a i n more than t e n major sugar t y p e s ( M a r t i n and H a i d e r , 1971) i n c l u d i n g hexoses, p e n t o s e s , deoxyhexoses, amino s u g a r s , sugar a l c o h o l s and u r o n i c a c i d s bound t o g e t h e r i n t o some of the h i g h e s t m o l e c u l a r w e i ght o r g a n i c m o l e c u l e s found i n the s o i l . E x a c t l y how the o r g a n i c m a t t e r i s s t u d i e d depends upon the major o r g a n i c component t o which i t b e l o n g s . Undecomposed p l a n t remains can be examined and even b o t a n i c a l l y o r z o o l o g i c a l l y c l a s s i f i e d w i t h the naked eye. A compound microscope can h e l p to i d e n t i f y p a r t i a l l y decomposed o r g a n i c m a t e r i a l from d i s t i n c t c e l l u l a r remnants of the v a s c u l a r system, p o l l e n g r a i n s , f a e c a l p e l l e t s e t c . C h a r a c t e r i z a t i o n of the humus i s more d i f f i c u l t as i t f i r s t must be s e p a r a t e d from undecomposed m a t e r i a l and from the m i n e r a l s o i l . Even when t h i s i s a c c o m p l i s h e d , the amorphous and complex n a t u r e of humus makes i t i m p o s s i b l e t o d i s t i n g u i s h m o r p h o l o g i c a l l y . I n s t e a d , humus i s examined and c l a s s i f i e d as t o how i t r e a c t s c h e m i c a l l y . Humus may be e x t r a c t e d from the s o i l w i t h 0.1-0.5 N NaOH and/or Na pyrophosphate and f r a c t i o n a t e d by a c i d i f i c a t i o n w i t h B^SO^ i n t o the p r e c i p i t a t e d "humic a c i d " and s t i l l s o l u b l e " f u l v i c a c i d " . A t h i r d f r a c t i o n , "humin", because of a h i g h m o l e c u l a r w e i g h t , l a c k of h y d r o p h i l i c f u n c t i o n a l groups o r because of a s t a b l e a s s o c i a t i o n w i t h the m i n e r a l f r a c t i o n , does not d i s s o l v e i n a l k a l i . I n c l u d e d i n the humin are a l s o the un.decomposed p l a n t remains. Each f r a c t i o n c o n s i s t s of compounds w i t h a wide range of c h e m i c a l p r o p e r t i e s but i n g e n e r a l , f u l v i c a c i d s have a l o w e r m o l e c u l a r w e i g h t , a h i g h e r f u n c t i o n a l group c o n t e n t , and have a l o w e r carbon and n i t r o g e n but a h i g h e r oxygen c o n t e n t than humic a c i d . Decomposed humin appears s i m i l a r t o humic a c i d but f o r r e a s o n s mentioned above, does not d i s s o l v e i n a l k a l i ( S c h n i t z e r , 1978). The f u l v i c a c i d " f r a c t i o n " a l s o c o n t a i n s l a r g e p o l y s a c c h a r i d e s . These can be s e p a r a t e d from the r e m a i n i n g p h e n o l i c component by a d s o r p t i o n of the p o l y p h e n o l s on PVP (Lowe, 1975). The p r o p o r t i o n of the o r g a n i c m a t e r i a l s o l u b l e o n l y i n a l k a l i t o t h a t which i s s o l u b l e i n b o t h a l k a l i and a c i d i s d e s c r i b e d as the h u m i c / f u l v i c r a t i o , n o r m a l l y e x p r e s s e d Ch/Cf, on the b a s i s of carbon c o n t e n t . Lowe (1980) found t h a t t h i s r a t i o and the r a t i o of p o l y p h e n o l i c f u l v i c a c i d s t o t o t a l f u l v i c a c i d s (Ca/Cf) was d i a g n o s t i c f o r a number of d i f f e r e n t g r e a t group h o r i z o n s . For example, a l u v i s o l i c Bt c o u l d be d i s c r i m i n a t e d from a p o d z o l i c Bf h o r i z o n by how i t s o r g a n i c m a t t e r s e p a r a t e d i n t o the d i f f e r e n t e x t r a c t e d f r a c t i o n s . Methods such as these may be v a l u b l e i n a s s i s t i n g w i t h the c l a s s i f i c a t i o n of many m i n e r a l h o r i z o n s . O r g a n i c h o r i z o n s are d e f i n e d i n the Canadian System of S o i l C l a s s i f i c a t i o n (CSSC, 1978) as one w i t h an o r g a n i c carbon component of 17% or g r e a t e r - a v a l u e a p p r o x i m a t e l y e q u a l t o 30% o r g a n i c m a t t e r . Once the carbon r e q u i r e m e n t i s met, a h o r i z o n , i s then c l a s s i f i e d i n t o one of two major groups: LFH or O. An 0 h o r i z o n i s d e v e l o p e d m a i n l y from mosses, ru s h e s and woody m a t e r i a l s and an LFH h o r i z o n , p r i m a r i l y from an a c c u m u l a t i o n of l e a v e s , t w i g and woody m a t e r i a l s . U s u a l l y , LFH h o r i z o n s are not s a t u r a t e d . From t h i s d e s c r i p t i o n of the component v e g e t a t i o n and the u s u a l l y u n s a t u r a t e d s t a t e of the LFH, we can surmise t h a t the LFH i s the u p l a n d o r g a n i c h o r i z o n of most m i n e r a l s o i l s and t h a t O h o r i z o n s are found i n a s e m i - t e r r e s t r i a l (wetland) e n v i r o n m e n t . However, t h i s i s not s t a t e d s p e c i f i c a l l y i n the c l a s s i f i c a t i o n scheme and a c c o r d i n g t o K l i n k a e_t a_l. (1981) i t i s sometimes d i f f i c u l t t o determine i n t o which o r g a n i c group a h o r i z o n s h o u l d be a s s i g n e d , g i v e n the p r e s e n t d e f i n i t i o n s and c r i t e r i a . One s p e c i f i c example i s seen i n a r a i n f o r e s t environment where the l i t t e r l a y e r beneath the t r e e s i s deep, u s u a l l y water s a t u r a t e d and may c o n t a i n a l a r g e component of moss. I s t h i s an LFH or O h o r i z o n ? A n o t h e r example i s a r o o t mat h o r i z o n , u s u a l l y s a t u r a t e d w i t h water, of h i g h o r g a n i c carbon v a l u e , found a t depth w i t h i n the m i n e r a l s o i l . T h i s h o r i z o n does not f i t i n t o e i t h e r group w e l l . Perhaps the c l a s s i f i c a t i o n scheme f o r o r g a n i c s o i l s s h o u l d be made more s p e c i f i c , w i t h c h e m i c a l or p h y s i c a l t e s t s a b l e t o s e p a r a t e the two groups. A n o t h e r problem c o n c e r n s the 17% carbon c u t o f f p o i n t between m i n e r a l and o r g a n i c s o i l s . Does t h i s have any r e l e v a n c e t o s o i l b e h a v i o r ? The American system c l a s s i f i e s water s a t u r a t e d h o r i z o n s w i t h l i t t l e c l a y i n t o the o r g a n i c o r d e r i f they have o n l y 2 0% o r g a n i c m a t t e r , a v a l u e c o r r e s p o n d i n g t o a p p r o x i m a t e l y 12% o r g a n i c C. 6 6 CHAPTER 4 DESCRIPTION OF THE STUDY AREA G e n e r a l D e s c r i p t i o n of the S o i l s Some p o d z o l i c s o i l s of south c o a s t a l B r i t i s h Columbia d i f f e r from the " c l a s s i c a l " p o d z o l s of the l i t e r a t u r e i n t h a t they have c o n c e n t r a t i o n s of o r g a n i c m a t t e r i n v e r t i c a l and o b l i q u e c h a n n e l s and i n h o r i z o n t a l l a y e r s t hroughout the depth of the B h o r i z o n (see F i g u r e 4-1). The c o n c e n t r a t i o n i s e s p e c i a l l y prominent i n seepage zones above and p a r a l l e l t o a r o o t impermeable l a y e r , such as a hardpan o r bedrock. These are c a l l e d " r o o t mats" i n s o i l survey r e p o r t s , a l t h o u g h l i v e r o o t s are o f t e n few i n number or may not be p r e s e n t a t a l l . I n s t e a d , the o r g a n i c m a t e r i a l appears amorphous, greasy t o , the t o u c h , o f t e n w i t h o u t d e t e c t a b l e m i n e r a l g r a i n s and w i t h l i t t l e rubbed f i b r e c o n t e n t . O c c a s i o n a l l y , remnants of wood s t r u c t u r e are d i s c e r n i b l e _in s i t u but when removed from the p r o f i l e , are e a s i l y c r u s h e d between the f i n g e r s and found t o be greasy and w e l l decomposed. The r o o t mats are found a t depths of up t o and g r e a t e r than 1 m and range i n t h i c k n e s s from 1 cm t o more than 40 cm. The c o l o u r of the o r g a n i c m a t t e r i s u s u a l l y dark r e d d i s h brown (5 YR 2/2) but l i g h t e r and d a r k e r m a t e r i a l s are a l s o found. The p r i m a r y s t r u c t u r e i s massive, the secondary s t r u c t u r e i s su b a n g u l a r b l o c k y . In a few l o c a l i z e d a r e a s the s t r u c t u r e appears g r a n u l a r but on c l o s e r i n s p e c t i o n l o o k s l i k e s h o r t p i e c e s 67 of decomposed f i n e r o o t s . S h o r t p i e c e s of dead but undecomposed r o o t s of l a r g e d i a m e t e r are found near the bottom of a few of the p i t s . F i g u r e 4-1: D i a g r a m a t i c R e p r e s e n t a t i o n of a Root Mat and Root Channel i n a P o d z o l i c S o i l ' I LFH A P Bhf root channel Bf root mat The o r g a n i c m a t e r i a l i n the r o o t c h a n n e l s i s s i m i l a r i n morphology, t e x t u r e and s t r u c t u r e t o the r o o t mats but _in s i t u wood s t r u c t u r e i s perhaps more common and when p r e s e n t tends t o f i l l the e n t i r e c h a n n e l . The m i n e r a l s o i l s u r r o u n d i n g the o r g a n i c m a t e r i a l i s of a sandy loam t e x t u r e and w e l l d r a i n e d . S o i l s of the above d e s c r i p t i o n o c c u r s i d e by s i d e w i t h s o i l s w i t h no u n u s u a l o r g a n i c a c c u m u l a t i o n s . I t i s o b v i o u s t h a t the r o o t mats are found i n p o c k e t s , perhaps i n d i p s of the bedrock or pan a l o n g which seepage water r u n s . I f these indeed a r i s e from 68 r o o t s , the c h a n n e l s and h o r i z o n t a l l a y e r s may be remnants of r o o t b a l l s . Numerous v e r y l a r g e c e d a r stumps and fewer l a r g e hemlock stumps are found t h r o u g h o u t the f o r e s t of the Burke Mountain sa m p l i n g s i t e , a l t h o u g h second growth hemlock i s the dominant t r e e t o d a y . L o c a t i o n s Where These S o i l s Are Found S o i l s w i t h " r o o t mat" o r g a n i c a c c u m u l a t i o n s are found i n the h i g h e l e v a t i o n p o d z o l s of the Coast Mountains t h a t s u r r o u n d Vancouver. They are seen s p e c i f i c a l l y on Mt. Seymour, Fromme Mountain, Burke Mountain, i n C y p r e s s Park, on the h i g h e r s l o p e s of the U.B.C. Research F o r e s t and have been r e p o r t e d from the Seymour watershed ( L u t t m e r d i n g , 1981). Root mats are l o c a t e d a t lower e l e v a t i o n s near H o l b e r g , on the n o r t h - w e s t t i p of Vancouver I s l a n d . They have a l s o been r e p o r t e d a l o n g the west c o a s t of the i s l a n d , i n s o i l s u r v e y r e p o r t s (Goldstream s e r i e s , RAB, 1977), and more r e c e n t l y by Sanborn ( p e r s . comm. 1984). Somewhat s i m i l a r s o i l s were s t u d i e d on Vancouver I s l a n d by Lewis (1976). Root mats have a l s o sometimes been found i n the r a i n f o r e s t s near R e v e l s t o k e i n the B.C. i n t e r i o r (H. A. L u t t m e r d i n g , p e r s . comm., 1985). A l l these l o c a t i o n s have i n common a h i g h annual r a t e of p r e c i p i t a t i o n , a p p r o a c h i n g 5000 mm i n some l o c a l i t i e s and s o i l s t h a t do not f r e e z e i n the w i n t e r . They are a l l w i t h i n the C o a s t a l Western Hemlock or Mountain Hemlock B i o g e o c l i m a t i c Zones ( K r a j i n a , 1969). A r o o t r e s t r i c t i n g l a y e r a l o n g which seepage water runs may a l s o be e s s e n t i a l f o r the development of these s o i l s . With r e s p e c t t o o t h e r f a c t o r s - e l e v a t i o n , l e n g t h of 69 growing season, and perhaps bedrock geology - the environments appear q u i t e d i v e r s e . S o i l s s t u d i e d i n t h i s t h e s i s were from the Whonnock s o i l s e r i e s which i s c l a s s i f i e d as a D u r i c F e r r o Humic P o d z o l . Sampling l o c a t i o n s were found between 700 and 730 m on Burke Mountain i n P o r t C o q u i t l a m (49° 19'N 122° 44'W) and a t 920 m near the d o w n h i l l s k i p a r k i n g l o t i n C y p r e s s Bowl, West Vancouver, (49° 24'N 123° 12'W). G e n e r a l Environment of the Coast Mountains A. V e g e t a t i o n The v e g e t a t i o n found on the windward mountain s l o p e s s u r r o u n d i n g Vancouver i s d e t e r m i n e d b o t h by the m i l d , wet c l i m a t e and by the e l e v a t i o n . Below 914 m, the C o a s t a l Western Hemlock Zone (CWH) i s dominant and the v e g e t a t i o n of the Burke Mtn. s i t e i s r e p r e s e n t a t i v e of the wet subzone (CWHb) ( K r a j i n a , 1969). Western hemlock (Tsuga h e t e r o p h y l l a , (Raf.) Sarg.) makes up 90% of the modern o v e r s t o r y but the abundant l a r g e c e d a r stumps i n d i c a t e a much more dominant r o l e p l a y e d by w e s t e r n r e d c e d a r (Thuja p i i c a t a , Donn.) i n the p a s t . P a c i f i c s i l v e r f i r ( A b i e s  a m a b i l i s , (Dougl.) Forbes) i s a l s o f a i r l y common. At the h i g h e r e l e v a t i o n i n C y p r e s s P a r k , v e g e t a t i o n i s t y p i c a l of the f o r e s t subzone of the Mountain Hemlock B i o g e o c l i m a t i c Zone (MHa). ( K r a j i n a , 1969) Here, mountain hemlock (Tsuga m e r t e n s i a n a , (Bong.) C a r r . ) , y e l l o w c e d a r (Chamaecyparis n o o t k a t e n s i s , (D. Don) Spach) and p a c i f i c s i l v e r f i r form the o v e r s t o r y . 70 Hemlocks are noted f o r t h e i r s u r f i c i a l r o o t i n g h a b i t , the p r e f e r e n c e of ammonium or amino a c i d s o v e r n i t r a t e s as a n i t r o g e n source and the need f o r s t e a d y y e t low c o n c e n t r a t i o n s of the o t h e r e s s e n t i a l c a t i o n s (Brooke e_t a_l. , 1970). A c c o r d i n g t o K r a j i n a (1969), n e i t h e r s p e c i e s of hemlock grows w e l l i n n u t r i e n t - r i c h s o i l and i n seepage and h y d r i c m o i s t u r e regimes they are l i m i t e d t o d r i e r humps of o r g a n i c d e b r i s o r b o u l d e r s c o v e r e d w i t h humus. In c o n t r a s t , K r a j i n a f e e l s t h a t b o t h y e l l o w and western r e d c e d a r have a h i g h n u t r i e n t r e q u i r e m e n t and w i l l a t t a i n , optimum growth i n s o i l s a f f e c t e d by c o n t i n u o u s n u t r i e n t - r i c h seepage wate r . P a c i f i c s i l v e r f i r r e q u i r e s a steady supply of water even d u r i n g the w i n t e r months and l i k e c e dar f a v o r s n u t r i e n t - r i c h s o i l s and n i t r a t e s as a n i t r o g e n source ( K r a j i n a , 1969). I t i s an e d a p h i c s p e c i e s i n the CWHZ, l i m i t e d t o the h i g h e s t r a i n f a l l a r e a s or t o seepage en v i r o n m e n t s (Brooke e t a l . , 1970) K r a j i n a (1969) assumes by t h e i r d i s t r i b u t i o n , t h a t none of the dominant c o n i f e r s p r e v a l e n t i n the c o a s t a l s u b a l p i n e can t o l e r a t e h a v i n g t h e i r r o o t s f r o z e n and so are l i m i t e d t o s o i l s t h a t do not f r e e z e . Deep snow, which i s common on the c o a s t , can i n s u l a t e the ground and p r o v i d e these m i l d e r t e m p e r a t u r e s , as w e l l as a steady seepage of melt water through the s o i l u n t i l mid-summer. The deep snow i n the R e v e l s t o k e wet b e l t near Mica Dam a l s o e n s u r e s t h a t the s o i l does not f r e e z e . As a r e s u l t , mountain hemlock i s abundant i n th„is l o c a t i o n , but t h i s time found w i t h Engelmann spruce ( P i c e a e n g e l m a n n i i P a r r y ) and s u b a l p i n e f i r ( A b i e s l a s i o c a r p a (Hook.) N u t t . ) ( K r a j i n a , 1975). 71 The low t e m p e r a t u r e s and h i g h m o i s t u r e c o n t e n t promote slow d e c o m p o s i t i o n of o r g a n i c m a t t e r i n the s u b a l p i n e s o i l s . Brooke e t a l . (19 70) found t h a t l e a v e s remained i n t a c t and o n l y s l i g h t l y decomposed n e a r l y a y e a r a f t e r they had f a l l e n from the t r e e . B. A i r and S o i l C l i m a t e The P a c i f i c Ocean has a moderating e f f e c t on the c l i m a t e of the B r i t i s h Columbian c o a s t . In the w i n t e r , the K u r o s h i o c u r r e n t keeps water t e m p e r a t u r e s warmer than a i r t e m p e r a t u r e s . The A l e u t i a n Low dominates and the Vancouver a r e a i s h i t by a s u c c e s s i o n of storms w i t h heavy c l o u d and p r e c i p i t a t i o n . In summer, the N o r t h P a c i f i c High b r i n g s c l e a r s k i e s and warm tem p e r a t u r e s but even these are moderated by c o o l e r ocean t e m p e r a t u r e s due t o c o l d water u p w e l l i n g o f f the west c o a s t (Brooke e t a l . , 1970). F r e q u e n t l y throughout the y e a r , m o i s t u r e l a d e n c l o u d s from the P a c i f i c Ocean move e a s t w a r d towards the Coast Mountains. As they r i s e o v e r these mountains t h e i r m o i s t u r e c o o l s and condenses, d r o p p i n g as r a i n o r snow. P r e c i p i t a t i o n i n c r e a s e s w i t h e l e v a t i o n a t l e a s t up t o the l e v e l of the c l o u d base (Walker, 1961). Table 4-1 i l l u s t r a t e s the i n c r e a s e i n p r e c i p i t a t i o n w i t h e l e v a t i o n from the N o r t h Shore w a t e r f r o n t t o the top of Grouse Mountain, as r e p o r t e d by Environment Canada (1980). 72 Table 4-1: Change i n p r e c i p i t a t i o n w i t h change i n e l e v a t i o n i n N o r t h Vancouver l o c a t i o n e l e v a t i o n r a i n f a l l s n o w f a l l T o t a l pptn (mm) (cm) (mm) N. Vane wharves 6m 1720.0 51.9 1763.5 N. Va n c - H o l y r o o d 183m 1857.8 72.3 1943.1 N. Van-Grouse Mt 1128m 1773 .7 816.5 2564.6 ( e x t r a c t e d from Environment Canada, 1980) In a d d i t i o n , d a i l y average t e m p e r a t u r e s decrease w i t h e l e v a t i o n , r e s u l t i n g i n heavy snow f a l l s a t h i g h e r l e v e l s from November t o A p r i l . The deep snow i n s u l a t e s the ground and the s o i l seldom f r e e z e s , even i n m i d - w i n t e r . T h i s , combined w i t h a i r t e m p e r a t u r e s which can r i s e above 0°C a t any time of y e a r , produces a dense and s a t u r a t e d snow pack. The water e q u i v a l e n t r a t i o of f r e s h snow i s 10.0; 10 cm of snow m e l t s t o 1 cm of water. Brooke e_t a_l. (1970) quote s t a t i s t i c s c o l l e c t e d by the Seymour Mountain Snow Course which show a snow t o water e q u i v a l e n t r a t i o of 2.36 a t the f i r s t of F e b r u a r y and 1.98 on May 15th. T h i s snow pack does not c o m p l e t e l y melt u n t i l mid-June o r J u l y . A l l t h i s e n s u r e s t h a t s o i l s have a h i g h m o i s t u r e c o n t e n t t h r o u g h o u t the y e a r i n the Mountain Hemlock Zone. Brooke e_t a_l (1970) found t h a t s o i l s - of the Mt. Seymour watershed were a t or above f i e l d c a p a c i t y d u r i n g a l l months i n the l o w e r s u b a l p i n e . In t h i s c a s e , f i e l d c a p a c i t y was measured i n d i r e c t l y w i t h a Colman f i b e r g l a s m o i s t u r e u n i t and was c o n s i d e r e d t o be the m o i s t u r e c o n t e n t of the s o i l a few days f o l l o w i n g two s e p a r a t e 73 heavy r a i n f a l l e v e n t s and under c o n d i t i o n s i n which the s u r f a c e s o i l would not be e x c e s s i v e l y d r i e d by e v a p o r a t i o n . In a d d i t i o n , these a u t h o r s found t h a t the maximum i n s o i l m o i s t u r e o c c u r r e d some time a f t e r a l l the snow pack had m e l t e d . T h i s s u g g e s t s t h a t l a t e r a l movement of water from h i g h e r e l e v a t i o n s keeps the s o i l s c harged w i t h water u n t i l w e l l i n t o J u l y . Burke Mountain, a t a lower e l e v a t i o n , o b t a i n s a s m a l l e r p e r c e n t of i t s t o t a l p r e c i p i t a i o n as snow. However, the i n s u l a t i o n i s not needed as under the m i l d e r a i r t e m p e r a t u r e s the s o i l s do not f r e e z e . The h i g h r a i n f a l l l e v e l s p l u s seepage from h i g h e r e l e v a t i o n s a l o n g the d u r i c h o r i z o n keep the s o i l s permanently m o i s t . A l l t h i s w ater i n w e l l d r a i n e d p r o f i l e s i m p a r t s a h i g h l e a c h i n g p o t e n t i a l t o the s o i l s . Table 4-2 shows monthly mean t e m p e r a t u r e s , average h i g h s and lows and the d a i l y p r e c i p i t a t i o n r e c o r d e d from the c l i m a t e s t a t i o n on H o l l y b u r n Ridge (Environment Canada, 1980). T h i s i s l o c a t e d c l o s e t o the C y p r e s s Bowl sampling s i t e . As no c l i m a t e s t a t i o n i s near the p r o f i l e s d e s c r i b e d on Burke Mountain, the d a t a p r e s e n t e d are t a k e n from the s t a t i o n on C o q u i t l a m Lake a t a lower e l e v a t i o n . C. S u r f i c i a l Geology and Bedrock of the Sampling S i t e s The Whonnock s o i l s e r i e s c o n s i s t s of g r e a t e r than one metre of m o d e r a t e l y c o a r s e - t e x t u r e d g l a c i a l t i l l o v e r bedrock ( L u t t m e r d i n g , 1981). The s u b s o i l has been cemented i n t o a d u r i c h o r i z o n w i t h a h y d r a u l i c c o n d u c t i v i t y measured by McKeague and S p r o u t (1975) of 0.1 t o a few m i l l i m e t r e s p e r hour. Table 4-2: C l i m a t i c Data O b t a i n e d from S t a t i o n s C l o s e t o the Burke Mountain and C y p r e s s Park Sampling S i t e s (Environment Canada, 1980) H O L L Y B U R N R I O G E 49°22'N 123"12'W 951m Daily M a x i m u m Temperatu re 0.5 3.1 3.4 6.6 10.8 Daily M i n i m u m Temperatu re -5.1 - 2 . 9 - 3 . 0 - 0 . 8 1.8 D a l l y T e m p e r a t u r e -23 0.1 03 2.9 6 .3 Standard Deviat ion . Dai ly Temperatu re 2.3 2 0 1.4 1.2 1.2 Ext reme M a x i m u m Temperature 17.B 16.7 1 5 6 20 .0 26 7 Y e a r s of R e c o r d 20 20 20 19 19 Ext reme M i n i m u m Temperature - 2 1 7 - 1 5 . 0 - 1 5 . 0 - 8 . 3 - 4 . 4 Y e a r s of R e c o r d 19 20 19 19 19 Rainfal l 177.5 1 4 7 8 112 4 117.4 130 .3 Snowfa l l 169.2 145.8 146.6 67 .0 11.1 T o t a l P r e c l p t t a l l o n 346.7 293 .5 259.0 184 .3 141.4 Standard Deviat ion. Tota l Precipi tat ion 162.6 1 2 0 3 100.6 81 .3 87 8 Greatest Rainfal l in 24 hours 162.1 100.3 77 .7 111.0 133 1 Y e a r s of R e c o r d 25 26 26 25 26 Greatest Snowfa l l in 24 hours 6 6 0 53.3 50 8 42.4 19.8 Y e a r s of R e c o r d 2 5 26 2 6 25 ? 6 Greatest Precipitat ion in 24 hours 162.1 100.3 86.4 111.0 133.1 Y e a r s of R e c o r d 25 26 26 25 26 D a y s will) R a i n e B 7 11 12 D a y s wrth S n o w 15 12 13 9 2 D a y s wtth Precipi tat ion 19 18 17 16 13 C O O U I T L A M L A K E 4 9 ' 2 2 ' N I 2 2 " 4 8 W 1 6 1 m Dairy M a x i m u m Temperatu re 2.7 5.1 7 1 11.5 15.9 Daily M i n i m u m Temperature - 1 .5 -0.1 0.3 2.6 5.9 D a i l y T e m p e r a t u r e 0 6 2.5 3.7 7.0 10.9 S tandard Deviat ion. Dai ly Temperatu re 1.9 1.5 1 2 1 1 1 3 E x t r e m e M a x i m u m Temperature 13.3 14.4 21 1 26.1 32.6 Y e a r s of R e c o r d 4 5 44 4 5 45 4 5 Ext reme M i n i m u m Temperatu re -21.1 - 1 6 . 7 - 1 2 2 - 5 . 6 - 2 . 2 Y e a r s of R e c o r d 45 45 45 4 5 4 5 Raintal l 445 .5 374.6 334 .5 236 .5 140 6 Snowfa l l 62 .6 23 .2 15.9 1.0 0.0 T o t a l P r e c i p i t a t i o n 508.0 397.8 350 .4 237.4 140 .5 S t a n d a r d Deviat ion , Tota l Precipi tat ion 268.7 1 6 8 5 129.6 110.8 70 .9 Greatest Raintal l in 24 hours 190.5 1 5 2 4 127.8 145.5 113.6 Y e a r s of R e c o r d 56 57 55 57 57 Grea tes t Snowfa l l in 24 hours 66 .0 4 3 2 26.7 1 6 5 0 0 Y e a r s ot R e c o r d 5 5 5? 56 57 5 ' G rea tes t Precip i tat ion in 24 hours 190.5 152.4 127.8 145.5 113.6 Y e a r s ot R e c o r d 56 57 5 5 57 57 D a y s with R a i n 18 17 19 17 13 D a y s with S n o w 6 3 2 0 D a y s with Precip i tat ion 21 18 19 17 13 14,3 18.5 17.7 15 .7 9 7 3.9 1.2 6 8 8 4 .9 7.8 8.0 5 , 7 2.2 - 1 . 7 - 3 7 1.1 8 9.6 13.2 12 .9 10.7 6.0 1.1 - 1 J S.0 e 2.1 1 5 2 .0 1.9 1 3 1.4 2 1 0.6 3 31 .7 33 .3 31 .7 3 0 0 26 . 7 2 2 2 12.8 33 .3 19 20 19 20 20 19 19 - 2 . 2 0.6 0.6 - 3 9 - 7 . 8 - 1 3 . 9 - 2 6 . 7 - 2 6 . 7 20 20 20 20 20 19 19 124 .1 106.9 128.3 193.3 3 2 9 4 306.0 2 6 0 9 2 1 3 4 3 2 0,2 0.0 0.0 0.2 21.0 ' 85 .2 173.9 820.2 2 124 .3 106.8 128 .3 193.5 3 5 0 4 3912 434.8 2954 .3 2 62.4 90.6 9 2 6 104.5 193,8 147.6 126.4 431 6 2 71.4 167.4 115.8 137 2 174 5 153.4 125 0 174.5 26 2 5 26 26 26 24 25 3 8 0.0 0.0 1.5 40.1 60 .5 61 .0 66 .0 26 26 26 26 26 2 5 25 71.4 167.4 115.8 137.2 174 5 153 4 125.0 174.6 26 25 26 26 26 24 2 5 13 8 10 11 16 14 11 129 2 0 0 2 8 14 75 2 13 8 10 11 17 19 21 182 2 16 5 22.0 21 .3 18 1 12 7 7.1 4 3 12.2 1 8.9 11,1 1 1 2 9 0 5.6 2,0 0 1 4 6 1 13.7 16.6 1 6 3 13.6 9.2 4 .5 1.2 8 4 1 1.7 1.5 1.5 1.2 1 1 1.3 1.4 0.6 1 3 3 3 36 .7 34 4 31 .7 25 0 18.9 1 3 3 36.7 43 45 43 4 5 46 46 45 1.7 3 3 4 4 - 0 . 6 - 5 0 - 1 7 8 - 2 2 . 8 - 2 2 . 8 45 44 43 45 46 46 45 130.9 86 4 108 8 204 4 4 0 3 0 474 ,1 529 .2 3466 4 1 0 0 0,0 0.0 0.0 0.0 6 3 39 2 148.2 * 1 130 .9 86.4 108.2 204.4 403 .0 4 8 0 6 568.4 3616.0 1 78.5 6 5 8 79 . 5 108.3 225.7 1 8 7 7 189.2 640.7 1 98.0 128.8 98 .6 136.4 176.5 203 .2 194.3 203 2 56 56 55 57 55 56 57 0.0 0 0 0 0 0.0 t 3 2 7 9 48 3 66 .0 57 57 57 57 57 57 57 98 .0 126.6 98.6 136.4 176.5 203.2 194.3 203 .2 56 56 55 57 55 56 57 13 8 11 13 19 20 20 188 2 0 0 0 0 0 1 4 16 1 13 8 11 13 19 21 22 195 2 Bedrock beneath the study s i t e on Burke Mountain c o n s i s t s of q u a r t z d i o r i t e , w i t h hornblende more abundant than b i o t i t e . The bedrock of C y p r e s s Park i s g r a n i t e , and hornblende i s the o n l y m a f i c m a t e r i a l p r e s e n t i n a p p r e c i a b l e amounts (Roddick, 1965). Other b e d r o c k s common i n the Coast Mountains near Vancouver are g r a n o d i o r i t e , d i o r i t e , gabbro and m i g m a t i t e . As t i l l may c o n s i s t of s t o n e s c a r r i e d from c o n s i d e r a b l e d i s t a n c e , a m i x t u r e of the above l i t h o l o g i e s may be p r e s e n t i n the s u r f i c i a l m a t e r i a l s a t both l o c a t i o n s . However, Brooke e t a_l. (1970) found t h a t most r o c k s sampled from the t i l l on Mt. Seymour resembled the u n d e r l y i n g bedrock, an i n d i c a t i o n t h a t m a t e r i a l may not have been c a r r i e d by the g l a c i e r s as f a r as e x p e c t e d . Brooke and coworkers a l s o found t h a t r o c k s c o l l e c t e d from the s o i l showed c o n s i d e r a b l e c h e m i c a l w e a t h e r i n g and o x i d a t i o n and t h a t a sh, i d e n t i f i e d as Mazama, was p r e s e n t i n s e v e r a l of the p r o f i l e s . CHAPTER 5 MORPHOLOGICAL AND CHEMICAL CHARACTERIZATION OF THE SOILS F i e l d Sampling Nine s o i l s were sampled from a road c u t on Burke Mountain and e i g h t e e n p i t s were l o c a t e d and sampled from b o t h Burke Mountain and C y p r e s s P a r k . Because r o o t mats and r o o t c h a n n e l s were found o n l y i n ve r y l o c a l i z e d a r e a s not e a s i l y r e c o g n i z e d by s u r f a c e morphology, the placement of p i t s was d i f f i c u l t . T h e r e f o r e , p i t s were dug wherever c o n v e n i e n t between the numerous f a l l e n l o g s and dead t r e e s , and those p i t s which c o n t a i n e d no r o o t mats o r c h a n n e l s i n the B h o r i z o n s were r e j e c t e d . In a d d i t i o n f o u r p i t s , l o c a t e d a t two lo w e r e l e v a t i o n s a l o n g the Burke Mountain r o a d , were sampled i n o r d e r t o compare the p r o p e r t i e s of the r o o t mat p o d z o l s w i t h p o d z o l s which c o n t a i n e d more " c l a s s i c a l " f e a t u r e s . P i t s and r o a d c u t s were sampled t o the depth of the d u r i c h o r i z o n u n l e s s c i r c u m s t a n c e s i n the p i t d i d not a l l o w i t . The road c u t s were c l e a r e d back one h a l f t o one metre t o expose a f r e s h s u r f a c e . Where p o s s i b l e , a l l h o r i z o n s were sampled. The s u r f i c i a l humus a l o n g the road c u t on Burke Mountain was o n l y sampled when i t was overhung w i t h f o r e s t v e g e t a t i o n . O r g a n i c m a t e r i a l i n r o o t c h a n n e l s and r o o t mats was sampled s e p a r a t e l y from the m i n e r a l m a t e r i a l , e x c e p t i n some B h o r i z o n s where r o o t c h a n n e l s were t o o f i n e t o remove. 77 S o i l t e x t u r e , c o a r s e fragment c o n t e n t and M u n s e l l c o l o u r were d e t e r m i n e d i n the f i e l d . P i t s were d e s c r i b e d f o r depth and t h i c k n e s s of h o r i z o n s , s t r u c t u r e , c o n s i s t e n c e , presence of m o t t l e s , l o c a t i o n , s i z e and abundance of r o o t s and presence of cementat i o n . Most of the p i t s c o n t a i n i n g r o o t mats and r o o t c h a n n e l s were l o c a t e d on f l a t t o g e n t l y s l o p i n g m i c r o t o p o g r a p h y , o f t e n a t the bottom of a s t e e p e r h i l l . However, a few s o i l p i t s l o c a t e d on s t e e p e r s l o p e s a l s o c o n t a i n e d l a r g e o r g a n i c a c c u m u l a t i o n s above the d u r i p a n and t h e r e f o r e , no c o n c l u s i o n c o u l d be reached about how topography a f f e c t s the p r o b a b i l i t y of r o o t mat f o r m a t i o n . S e v e r a l of the p i t s c o n t a i n e d more than one h o r i z o n t a l o r g a n i c - r i c h l a y e r . In t h i s c a s e , b o t h were c o n s i d e r e d r o o t mats. From the 31 s i t e s sampled, 30 r o o t mat and 20 r o o t c h a n n e l samples were c o l l e c t e d . L a b o r a t o r y Methods on F i e l d C o l l e c t e d Samples The s o i l s were a i r - d r i e d a t 21°C, a g g r e g a t e s c r u s h e d w i t h a wooden r o l l i n g p i n and the s o i l s s i e v e d through a 2 mm s c r e e n t o remove the c o a r s e fragments. A subsample was ground t o 60 mesh and a subsample of t h i s ground t o 100 mesh. A p o r t i o n of each a i r - d r i e d sample was o v e n - d r i e d o v e r n i g h t a t 105°C, c o o l e d i n a d e s i c c a t o r and weighed t o determine m o i s t u r e l o s s as a percentage of a i r - d r i e d w e i g h t . From t h i s , c h e m i c a l d a t a were a d j u s t e d as a p e r c e n t of the o v e n - d r i e d w e i g h t . Samples were a n a l y z e d f o r t o t a l c a r b o n by a Leco I n d u c t i o n Furnace and Carbon A n a l y s e r , model numbers 521 and 572, r e s p e c t i v e l y , a c c o r d i n g t o the method 78 d e s c r i b e d i n the Leco manual. Carbon a n a l y s i s was done on 60-mesh samples w i t h sample w e i g h t s v a r y i n g from 0.07 g f o r h i g h l y o r g a n i c samples t o 0.50 g f o r h o r i z o n s c o n t a i n i n g l i t t l e o r g a n i c m a t e r i a l . T o t a l n i t r o g e n was measured by semi-micro K j e l d a h l , f o l l o w i n g Bremner (1965). Sample weight v a r i e d from 0.2 t o 2.0 g depending on c a r b o n c o n t e n t . Both n i t r o g e n and carbon v a l u e s were measured i n d u p l i c a t e and the mean of each r e c o r d e d . T o t a l s u l p h u r was measured on a F i s h e r S u l p h u r A n a l y z e r and High Temperature Furnace models 475 and 472, r e s p e c t i v e l y , i n accordance w i t h the F i s h e r manual. S o i l r e a c t i o n was determined i n b o t h water and 0.01 M C a C ^ . For water, a 1:1 s o i l : w a t e r s u s p e n s i o n was used f o r m i n e r a l h o r i z o n s , a 1:2 r a t i o f o r r o o t c h a n n e l s and r o o t mats and a 1:4 r a t i o f o r s u r f a c e o r g a n i c h o r i z o n s . R e a c t i o n i n 0.01 M C a C l 2 was determined u s i n g r a t i o s of 1:2, s o i l : 0 . 0 1 M C a C l 2 f o r m i n e r a l h o r i z o n s , r o o t mats and r o o t c h a n n e l s , and a r a t i o of 1:4 f o r s u r f a c e o r g a n i c h o r i z o n s . The pH was measured u s i n g a Radiometer PHM 62 s t a n d a r d pH meter. I r o n , aluminum and s i l i c o n were e x t r a c t e d from s o i l ground t o 100 mesh u s i n g : 1. 0.1 M sodium pyrophosphate (pH 10.0) (Bascomb, 1968). 2. A c i d ammonium o x a l a t e (McKeague and Day, 1966). 3. C i t r a t e - b i c a r b o n a t e s o l u t i o n (pH 7.3) (Weaver e t a l , 1968; Mehra and J a c k s o n , 1960). The ppm of each element w i t h i n each e x t r a c t a n t was measured u s i n g atomic a b s o r p t i o n s p e c t r o p h o t o m e t r y on a P e r k i n - E l m e r 306 s p e c t r o p h o t o m e t e r . These elements were them c a l c u l a t e d as a p e r c e n t of the t o t a l s o i l . I r o n was measured i n an a i r - a c e t y l e n e flame w h i l e aluminum and s i l i c o n were de t e r m i n e d u s i n g the h i g h e r temperature n i t r o u s o x i d e - a c e t y l e n e f l a m e ; I t s h o u l d be noted t h a t the v a l u e s r e a d on the atomic a b s o r p t i o n u n i t f o r i r o n , aluminum and s i l i c o n i n c i t r a t e - b i c a r b o n a t e s o l u t i o n , were very u n s t a b l e , a f f e c t i n g the p e r c e n t a c c u r a c y of these numbers. A l s o , the s i l i c o n s t a n d a r d s were p r e p a r e d s e p a r a t e l y from s t a n d a r d s c o n t a i n i n g b o t h i r o n and aluminum, as s i l i c o n i n t e r f e r e s w i t h i r o n . Presence of the two elements i n the same s t a n d a r d s o l u t i o n w i l l b a d l y o v e r e s t i m a t e the i r o n v a l u e s i n the s o i l . Humic and f u l v i c a c i d s were e x t r a c t e d from s o i l samples i n 0.1 M sodium pyrophosphate:0.1 M NaOH f o l l o w i n g the methods of Lowe (1980) e x c e p t t h a t the S o r v a l l Model RC2B c e n t r i f u g e was s e t at a speed of 6000 rpm i n s t e a d of 5000 rpm ( S c h u p p l i and McKeague, 1984). A s o i l t o t o t a l e x t r a c t a n t r a t i o of 0.75 - 1.0 g carbon t o 300 mL e x t r a c t a n t was used. The f u l v i c a c i d s were s e p a r a t e d i n t o p o l y p h e n o l i c and p o l y s a c c h a r i d e - r i c h f r a c t i o n s by a d s o r p t i o n of the p o l y p h e n o l i c a c i d s on t o p o l y v i n y l p y r r o l i d o n e (Lowe, 1975). The t o t a l c arbon of the humic a c i d , t o t a l f u l v i c a c i d and the p o l y s a c c h a r i d e f r a c t i o n s was de t e r m i n e d by the W a l k l e y - B l a c k wet o x i d a t i o n p r o c e d u r e ( A l l i s o n , 1965). The p e r c e n t C i n the p o l y p h e n o l i c f r a c t i o n was found by s u b t r a c t i o n of the p o l y s a c c h a r i d e carbon from the t o t a l f u l v i c c a r b o n . R a t i o s of humic carbon t o f u l v i c carbon ( C h / C f ) , and r a t i o s of p o l y p h e n o l i c c a r b o n t o t o t a l f u l v i c carbon (Ca/Cf) were c a l c u l a t e d . The pe r c e n t a g e of the t o t a l c arbon i n the s o i l t h a t 80. was e x t r a c t e d by the Na pyrophosphate:NaOH s o l u t i o n was e s t i m a t e d from the r a t i o : Humic C + F u l v i c C x 100 = %Ce T o t a l C i n the s o i l sample The micromorphology of the r o o t mats and c h a n n e l s was s t u d i e d u s i n g the W i l d e - L i e t z D i a l u x 2 phase c o n t r a s t m i c r o s c o p e . S l i d e s were p r e p a r e d by t e a s i n g s m a l l fragments of the o r g a n i c m a t e r i a l i n t o d i s t i l l e d water f o r m i n g a s u s p e n s i o n d i l u t e enough to a l l o w the passage of l i g h t . Column Study The method used t o s y n t h e s i z e p r o t o - i m o g o l i t e was adapted from Wada e_t a_l. (1979) but w i t h a molar r a t i o of 0.516 S i : A l i n s t e a d of 0.497. Farmer et. a l . (1977) r e p o r t e d t h a t a s l i g h t e x c e s s of s i l i c a o v e r the t h e o r e t i c a l v a l u e was n e c e s s a r y t o i n h i b i t boehmite f o r m a t i o n . Reagents r e q u i r e d were as f o l l o w s : 1. 4% t e t r a e t h y l o r t h o s i l i c a t e s t o c k s o l u t i o n : 40g of ( C H 3 C H 2 0 ) 4 S i was added t o 1 l i t r e of e t h a n o l 2. A1C1 3:6H 20 3. 0.1 M NaOH S o l u t i o n A was p r e p a r e d by d i s s o l v i n g 0.900 g of A1C1 3:6H 20 i n t o 400 mLs of d i s t i l l e d w ater. S o l u t i o n B was p r e p a r e d by measuring 10 mL of the t e t r a e t h y l o r t h o s i l i c a t e s t o c k s o l u t i o n i n t o 400 mL of d i s t i l l e d w ater. S o l u t i o n A was then i m m e d i a t e l y mixed w i t h s o l u t i o n B. With a b u r e t t e 0.1 M NaOH was s l o w l y d r i p p e d i n t o the m i x t u r e o v e r s e v e r a l hours, u n t i l the pH re a d between 4.5 and 5.0 ( p r e f e r a b l y 4.8, as the pH w i l l drop s l i g h t l y 81 over the next 12 h o u r s ) . T h i s w i l l r e q u i r e 80-90 mLs NaOH p e r l i t r e of p r o t o - i m o g o l i t e . The r e s u l t i n g s o l u t i o n was made up t o 1 l i t r e . I t was o p a l e s c e n t i f the 0.1 M NaOH had been added f a i r l y q u i c k l y but c l e a r e d on s t a n d i n g o v e r n i g h t , as r e p o r t e d by Farmer (1981). The e l u e n t f o r the " n o - i m o g o l i t e " c o n t r o l columns was pr e p a r e d by measuring 10 mLs of e t h a n o l and 90 mLs of 0.1 M NaOH i n t o 800 mLs of water. The pH was then a d j u s t e d w i t h a c e t i c a c i d , t o c o r r e s p o n d t o the pH of the p r o t o - i m o g o l i t e s o l u t i o n and made up t o 1 l i t r e w i t h d i s t i l l e d w ater. The columns were s e t up as f o l l o w s : 1. R o t t e d wood was c o l l e c t e d from a D o u g l a s - f i r (Pseudostuga menz i e s i i ( M i r b e l ) Franco) stump i n Lynn V a l l e y , N o r t h Vancouver. T h i s m a t e r i a l had a c o l o u r of 2.5YR 3/4 and a l t h o u g h wood s t r u c t u r e was seen i n p l a c e , - t h i s s t r u c t u r e was c r u s h e d w i t h s l i g h t p r e s s u r e between thumb and f o r e f i n g e r i n t o a "grea s y " mass w i t h no f i b r o u s c o n t e n t . 2. In the l a b o r a t o r y , t h i s m o i s t o r g a n i c m a t e r i a l was ground t o pass a 2 mm s i e v e . The m o i s t u r e c o n t e n t was then d e t e r m i n e d by d r y i n g the r o t t e d wood o v e r n i g h t i n an oven s e t a t 105°C. In a l l of t h r e e r e p l i c a t e s , the m o i s t u r e c o n t e n t was 70%. 3. Ottawa sand was washed as f o l l o w s . A f t e r s o a k i n g i n 2 N HCl f o r s e v e r a l hours, the sand was f i l t e r e d u s i n g s u c t i o n f i l t r a t i o n and washed t w i c e w i t h 0.1 N HC l . I t was then r i n s e d 6 t i m e s w i t h d i s t i l l e d w ater. 82 4. C a r l S c h l e i c h e r and S c h u e l l Co. No. 289 A s h - f r e e A n a l y t i c a l F i l t e r P u l p was washed w i t h 0.1 N H C l , f i l t e r e d w i t h s u c t i o n and then r i n s e d a p p r o x i m a t e l y f o u r t i m e s w i t h d i s t i l l e d w ater. The f i l t e r p aper was o v e n - d r i e d , o v e r n i g h t , a t 105°C 5. In c o n s t r u c t i n g the columns, two p i e c e s of p l a s t i c n e t t i n g were c u t t o f i t o v e r the h o l e s i n the bottom of the column. A p i e c e of 100% c o t t o n , l o o s e l y woven m a t e r i a l was then c u t t o the same s i z e and p l a c e d o v e r the m a t t i n g . One cm of g l a s s beads was l a y e d down o v e r these m a t e r i a l s . S i x t y grams of a i r - d r y Ottawa sand formed the next t i e r . Over t h i s was p l a c e d 35 g m o i s t o r g a n i c m a t t e r from the r o t t e d stump, mixed i n w a t e r w i t h 2.5 g o v e n - d r i e d f i l t e r p u l p . The upper most l a y e r c o n s i s t e d of 100 g a i r - d r y Ottawa sand. See F i g u r e 5-1. As m a t e r i a l was l a i d down, the whole column was s a t u r a t e d w i t h water t o remove a i r b u b b l e s . The " n o - o r g a n i c m a t t e r " c o n t r o l columns were s e t up as above, e x c e p t 2.5 g of f i l t e r paper mixed w i t h Ottawa sand r e p l a c e d the o r g a n i c l a y e r . See F i g u r e 5-1. Column study No. 1 was conducted as f o l l o w s . P r o t o - i m o g o l i t e was s l o w l y d r i p p e d through n i n e columns c o n t a i n i n g o r g a n i c m a t t e r , and through t h r e e c o n t r o l columns w i t h no o r g a n i c m a t t e r t i e r , a t the r a t e l i s t e d i n Table 6-1. The " n o - i m o g o l i t e " e l u e n t , a t the same r a t e as the p r o t o - i m o g o l i t e , was d r i p p e d through t h r e e a d d i t i o n a l c o n t r o l columns, each c o n t a i n i n g an o r g a n i c t i e r . Figure 5-1: Set Up of Column Study proto-imogolite • • * sand rotted wood sand control solution sand proto-imogolite 00 84 A f t e r one month, t h r e e of the p r o t o - i m o g o l i t e - o r g a n i c columns were removed from the s t u d y , an a d d i t i o n a l t h r e e columns and the c o n t r o l columns were removed a f t e r two months. The f i n a l t h r e e p r o t o - i m o g o l i t e - o r g a n i c columns were r e t a i n e d t o be used i n the second column s t u d y . The column m a t e r i a l s were a i r - d r i e d and the o r g a n i c t i e r ground t o pass t h r o u g h a 100 mesh s i e v e . The f i l t e r paper, used p r i m a r i l y t o improve the s t r u c t u r e of the column, was t o o f i b r o u s to pass t h r o u g h the s i e v e , so was removed from the o r g a n i c and m i n e r a l s o i l and weighed s e p a r a t e l y f o r a n a l y s i s . The t h r e e t i e r s of a l l columns were e x t r a c t e d w i t h sodium pyrophosphate and a c i d ammonium o x a l a t e , and the p e r c e n t aluminum and s i l i c o n measured by atomic a b s o r p t i o n . A second column study was s e t up t o measure e x a c t l y how much aluminum and s i l i c o n was absorbed from each a d d i t i o n of p r o t o - i m o g o l i t e and how much carbon was r e l e a s e d a f t e r each t r e a t m e n t i n the " n o - i m o g o l i t e " c o n t r o l columns. S i x columns c o n t a i n i n g an o r g a n i c t i e r and t h r e e columns c o n t a i n i n g o n l y sand and f i l t e r paper, were s e t up as i n Column study No. 1. A t o t a l of f o u r l i t r e s of p r o t o - i m o g o l i t e was d r i p p e d t h rough t h r e e of the o r g a n i c - f i l l e d columns and the t h r e e m i n e r a l columns, a t the r a t e shown i n Ta b l e 6-2. The " n o - i m o g o l i t e " e l u e n t was d r i p p e d through an a d d i t i o n a l t h r e e o r g a n i c columns a t the same r a t e . As each 250 mL of l e a c h a t e passed through the columns i t was a n a l y z e d by atomic a b s o r p t i o n f o r ppm A l and S i , and i t s pH was r e c o r d e d . The ppm c a r b o n i n the l e a c h a t e of the " n o - i m o g o l i t e " c o n t r o l 85 column was measured by the W a l k l e y - B l a c k method ( A l l i s o n , 1965) w i t h the carbon found i n the e l u e n t s u b t r a c t e d from the l e a c h a t e v a l u e . However, the carbon i n the i m o g o l i t e column l e a c h a t e c o u l d not be d e t e r m i n e d by t h i s method because of i t s h i g h c h l o r i d e c o n t e n t ( A l l i s o n , 1965). I t was, t h e r e f o r e , e s t i m a t e d from the absorbance of l i g h t by the l e a c h a t e a t 600nm wavelength i n a Bausch and Lomb S p e c t r o n i c 20. T h i s v a l u e was then compared w i t h absorbance v a l u e s of a " n o - i m o g o l i t e " c o n t r o l l e a c h a t e when the a c e t i c a c i d i n the e l u e n t had been r e p l a c e d w i t h 0.1 M HCl and the e x a c t c a r b o n v a l u e had been measured on the A s t r o T o t a l Carbon A n a l y z e r , model 1850. In a d d i t i o n , the t h r e e r e m a i n i n g p r o t o - i m o g o l i t e - o r g a n i c columns from column study No. 1 were t r e a t e d as f o l l o w s : 1. A f u r t h e r f o u r l i t r e s of p r o t o - i m o g o l i t e were d r i p p e d through one of the columns a t the r a t e shown i n Table 6-2. T h i s column, t h e r e f o r e , was t r e a t e d w i t h p r o t o - i m o g o l i t e f o r a t o t a l of 3 months. 2. F u l v i c a c i d s , e x t r a c t e d w i t h d i s t i l l e d water from r o t t i n g wood were d r i p p e d through a n o t h e r of the columns p r e v i o u s l y t r e a t e d f o r two months w i t h p r o t o - i m o g o l i t e . The f u l v i c a c i d s were a l s o l e a c h e d through a column c o n t a i n i n g o r g a n i c m a t t e r w i t h no p r e v i o u s p r o t o - i m o g o l i t e t r e a t m e n t . The carbon of the e x t r a c t e d f u l v i c a c i d s and of the l e a c h a t e , were measured by W a l k l e y - B l a c k a n a l y s i s . 3. The e l u e n t s o l u t i o n used i n the " n o - i m o g o l i t e " c o n t r o l s was d r i p p e d through the t h i r d column, p r e v i o u s l y l e a c h e d 86 w i t h two months p r o t o - i m o g o l i t e . The l e a c h a t e was a n a l y z e d f o r A l and S i . R e s u l t s and D i s c u s s i o n Based on p e r c e n t c a r b o n , twenty-two of the t h i r t y r o o t mats were c l a s s i f i e d as o r g a n i c h o r i z o n s (Oh) and the r e m a i n i n g e i g h t c l a s s i f i e d as m i n e r a l ( B h f ) . Seventeen of the twenty r o o t c h a n n e l s a l s o c o n t a i n e d g r e a t e r than 17% carbon and of the re m a i n i n g t h r e e , a l l had between 15 and 17% C. The h i g h e s t v a l u e f o r a r o o t mat was 31.3% C and f o r a r o o t c h a n n e l was 28.7% C. T h i s i s compared t o v a l u e s of 30-51% C f o r humus of the LFH, i n d i c a t i n g t h a t a l t h o u g h m i n e r a l g r a i n s were o f t e n not d e t e c t a b l e by hand t e x t u r i n g , much of the o r g a n i c a c c u m u l a t i o n s i n the B h o r i z o n d i d indeed c o n t a i n i n o r g a n i c m a t e r i a l . See Table 5-1. H o r i z o n s i m m e d i a t e l y s u r r o u n d i n g the r o o t mats u s u a l l y had very low p e r c e n t c a r b o n v a l u e s . F o r example, o f t e n t h i s o r g a n i c a c c u m u l a t i o n r e s t e d on the d u r i c h o r i z o n , which c o n t a i n e d l e s s than 1% C and the h o r i z o n i m m e d i a t e l y above had so l i t t l e c a rbon i t c o u l d be c l a s s i f i e d a Bf h o r i z o n . M i n e r a l m a t e r i a l through which the r o o t c h a n n e l s r a n a l s o tended t o have low carbon v a l u e s . T h i s may not always be r e f l e c t e d i n the r e s u l t s as i t was sometimes d i f f i c u l t t o s e p a r a t e out the f i n e r o o t c h a n n e l s from the m i n e r a l s o i l . T o t a l n i t r o g e n was r e l a t i v e l y low as judged by a carbon t o n i t r o g e n r a t i o a v e r a g i n g 28 f o r r o o t m a t s . However, as the C/N of the s u r f i c i a l humus was w i t h i n a s i m i l a r range, see Table 5-1, a r a t i o t h i s wide seems a p p r o p r i a t e f o r t h i s f o r e s t e d s i t u a t i o n . 87 N i t r o g e n t o s u l p h u r r a t i o s ranged from 5 t o 7 and averaged 5.9 and 6.2 f o r the r o o t mats and r o o t c h a n n e l s , r e s p e c t i v e l y . See Table 5-1 f o r a c t u a l s u l p h u r v a l u e s . These are s l i g h t l y l o w e r than r a t i o s r e p o r t e d f o r the humus of the LFH of the U.B.C. Research F o r e s t by C a r t e r ( 1 9 8 3 ) . He r e p o r t e d mean r a t i o s r a n g i n g from 7.1 t o 8.3 but w i t h D o u g l a s - f i r as the dominant o v e r s t o r y t r e e . Note the s i m i l a r i t y between the r o o t mat and r o o t c h a n n e l samples i n the r e s u l t s l i s t e d i n Table 5-1, and the d i f f e r e n c e s between these and the s u r f i c i a l humus. Table 5-1 - Average and Range of P e r c e n t Carbon, N i t r o g e n and S u l p h u r V a l u e s found i n the Root Mats, Root Channels and S u r f i c i a l Humus H o r i z o n s S t u d i e d Root Root S u r f i c i a l mats c h a n n e l s humus % carbon average 20.46 20.28 42. 73 % carbon range 10-31 15-29 30-51 # samples a n a l y z e d 30 20 21 % n i t r o g e n average 0.740 0.777 1.536 % n i t r o g e n range 0.438- 0.447- 0.917-1.562 1.611 1.974 C/N average 28 27 26 C/N range 16-39 18-34 21-37 # samples a n a l y z e d 28 20 12 % s u l p h u r average 0.127 0.130 % s u l p h u r range 0.0804- 0.0861-0.190 0.223 # samples a n a l y z e d 17 10 88 S o i l r e a c t i o n i n a l l h o r i z o n s was a c i d and extreme v a l u e s o c c u r r e d near the top of the p r o f i l e . V a l u e s of 3.0 - 4.0, i n d i s t i l l e d water, were common i n the l i t t e r and e l u v i a l h o r i z o n s on Burke Mountain and even the pH of the l o w e r B h o r i z o n was u s u a l l y w e l l below 5.0. In C ypress Park, the A h o r i z o n was a l s o very a c i d b u t the upper B h o r i z o n had a pH (H^O) g r e a t e r than 4.6 and the l o w e r B h o r i z o n and r o o t mat had a pH v a l u e between 5.0 and 5.5. See Appendix A. C a r t e r (1983) found e x t r e m e l y a c i d r e a c t i o n s i n s u r f i c i a l humus of the U.B.C. Research F o r e s t , an area which i s s i m i l a r l y s i t u a t e d t o Burke Mountain, but s l i g h t l y f u r t h e r e a s t a l o n g the F r a s e r V a l l e y . Thomas (1967) noted t h a t pH v a l u e s l e s s than 4.0 i n d i c a t e d the presence of f r e e i n o r g a n i c 2 + a c i d s , as the m i n e r a l s o i l i s b u f f e r e d by Al(OH) t o pH 5 (Bohn e t a l . , 1979) and o r g a n i c m a t t e r i s b u f f e r e d t o pH 4-5 by the d i s s o c i a t i o n c o n s t a n t of c a r b o x y l groups ( B r u c k e r t and R o u i l l e r , 1979). Free i n o r g a n i c a c i d s u s u a l l y a r i s e from the o x i d a t i o n of s u l p h i d e s and n i t r i t e s and t h i s may imply t h a t the s o i l s of the Coast Mountains are i n f l u e n c e d by a c i d r a i n . Data c o l l e c t e d by Environment Canada ( N i k l e v a , 1982) seem t o r e f u t e t h i s . The pH, i o n c o n c e n t r a t i o n and c o n d u c t i v i t y were measured i n r a i n f a l l c o l l e c t e d a t s t a t i o n s around the lower m a i n l a n d a f t e r 12 major storms between January and March, 19 82 . R e s u l t s l i s t e d i n Table 5-2 show t h a t r a i n f a l l pH i s l o w e s t i n downtown Vancouver and i n c r e a s e s w i t h e l e v a t i o n i n the Coast Mountains. In a d d i t i o n , the c o n d u c t i v i t y of r a i n f a l l i s h i g h e s t i n the c i t y and the c o n c e n t r a t i o n of ammonium, s u l p h a t e and n i t r a t e i o n s i s 2.5 - 5.0 t i m e s h i g h e r here than i n the mountains. 89 As t h i s i s o n l y a p r e l i m i n a r y study w i t h l i m i t e d d a t a , these r e s u l t s do not e x c l u d e the p o s s i b i l i t y of n i t r o g e n and s u l p h u r e m i s s i o n s b e i n g r e s p o n s i b l e f o r some of the a c i d i c p r o p e r t i e s of the s o i l . F o r i n s t a n c e , the amount of r a i n f a l l which f e l l i n each a r e a was not i n c l u d e d i n the r e p o r t . The lower i o n c o n c e n t r a t i o n and c o n d u c t i v i t y found i n r a i n f a l l of the mountains may s i m p l y be a p r o d u c t of d i l u t i o n . As i t r a i n s h a r d e r and more o f t e n on Grouse and Seymour Mountains and i n P o r t Moody, more t o t a l a c i d s may be d e p o s i t e d i n the s o i l s . Table 5-2 - pH, C o n d u c t i v i t y and I o n i c C o n c e n t r a t i o n of R a i n f a l l i n the Lower M a i n l a n d downtown P t . Moody Grouse Mt. Seymour Vancouve r pH 4.54 4.74 5.01 4.91 c o n d u c t i v i t y 18.2 11.1 7.6 9.8 US/cm) i o n c o n c e n t r a t i o n !4 NH,+ 0.382 0.073 S 0 4 2 1.32 0.5 • N0 3" 1.356 0.475 s e l e c t e d d a t a from N i k l e v a , 1982 S o i l r e a c t i o n was measured i n both d i s t i l l e d water and i n 0.01 M C a C l 2 a f t e r John Omueti (1984, u n p u b l i s h e d d ata) r e p o r t e d anomalous r e s u l t s from two p r o f i l e s a l s o i n c l u d e d i n t h i s s t u d y . The pH v a l u e s o b t a i n e d on s o i l s u s p e n s i o n s i n d i s t i l l e d water are 9 0 u s u a l l y a c o n s i s t e n t n u m b e r o f pH u n i t s h i g h e r t h a n t h o s e o f t h e s a m e s a m p l e s m e a s u r e d i n a s a l t s o l u t i o n . T h e r e f o r e , i t i s o f t e n c o n s i d e r e d a w a s t e o f t i m e t o p e r f o r m b o t h o p e r a t i o n s ( T h o m a s , 1 9 6 7 ) . H o w e v e r , O m u e t i f o u n d t h a t a l t h o u g h s u r f i c i a l h o r i z o n s o f p r o f i l e s 2 8 a n d 29 w e r e t h e e x p e c t e d h a l f a p H u n i t h i g h e r i n d i s t i l l e d w a t e r t h a n i n s a l t s o l u t i o n , t h e v a l u e s c o n v e r g e d l o w e r i n t h e p r o f i l e u n t i l s o i l r e a c t i o n i m m e d i a t e l y a b o v e t h e d u r i c h o r i z o n w a s i d e n t i c a l i n t h e t w o s u p e r n a t a n t s . I n t h i s t h e s i s o n l y some o f t h e s o i l s f o l l o w e d t h e a b o v e p a t t e r n . S o i l r e a c t i o n i n p r o f i l e s 2 8 a n d 29 r e m a i n e d c o n s i s t e n t l y h i g h e r i n w a t e r t h a n i n s a l t s o l u t i o n t h r o u g h o u t t h e e n t i r e d e p t h o f t h e s o i l , h o w e v e r , a n u m b e r o f d i f f e r e n t p r o f i l e s d i d e x h i b i t t r e n d s s i m i l a r t o t h o s e f o u n d b y O m u e t i , s e e p H d a t a o f p r o f i l e s 14 a n d 2 0 i n A p p e n d i x A . A c c o r d i n g t o T h o m a s a n d H a r g r o v e ( 1 9 8 4 ) t h e s e a n o m a l o u s r e s u l t s c a n b e e x p l a i n e d b y t h e s e s q u i o x i d e s c o a t i n g t h e m i n e r a l g r a i n s o f t h e s o i l s . When p H i s m e a s u r e d w i t h a s a l t s o l u t i o n , t h e c a t i o n i s a b l e t o r e p l a c e t h e +3 A l o n t h e e x c h a n g e c o m p l e x a n d i n c r e a s e t h e h y d r o n i u m i o n c o n c e n t r a t i o n i n t h e s u p e r n a t a n t b y t h e s u b s e q u e n t h y d r o l y s i s . H o w e v e r , a t t h e s a m e t i m e t h e a n i o n o f t h e s a l t s o l u t i o n w i l l e x c h a n g e w i t h t h e h y d r o x y l g r o u p s o f t h e s e s q u i o x i d e s a n d t h e t o t a l e f f e c t o f s a l t a d d i t i o n i s m i n i m i z e d . T h e p H g o v e r n s m a n y o f t h e c h e m i c a l r e a c t i o n s a n d b i o l o g i c a l a c t i v i t i e s i n t h e s o i l a n d s o u l t i m a t e l y c o n t r o l s t h e f o r m s a n d s o l u b i l i t y o f t h e i o n i c s p e c i e s p r e s e n t . C h e m i c a l l y a c t i v e a l u m i n u m c a n e x i s t i n a v a r i e t y o f f o r m s w i t h i n a p o d z o l , t h e p r o p o r t i o n s o f w h i c h a r e c o n t r o l l e d b y t h e p H a n d m i n e r a l o g i c a l 91 c o m p o s i t i o n of the system. At a pH below 5.0 aluminum i s exchangeable on n e g a t i v e s o i l c o l l o i d s as hexa-aqua aluminum ( A l (H^O) ) . At a pH below 4.7 t h i s i s the predominant form of aluminum i n the s o i l ( B a r n h i s e l and B e r t s c h , 1982 ; Bohn e_t a l . , + 3 1979). As the pH i n c r e a s e s , the A l r e a c t p r o g r e s s i v e l y w i t h the h y d r o x y l i o n s t o form monomeric and p o l y m e r i c hydroxyaluminum +2 + complexes such as Al(OH) and A l f O H ^ • These forms are p r e d o m i n a n t l y non-exchangeable, and they c o a t the c l a y p a r t i c l e s i n a monolayer, l o w e r i n g the c a t i o n exchange c a p a c i t y . They may even impart a n e t p o s i t i v e charge t o the s o i l (Coleman and Thomas, 1967). Aluminum may a l s o be p r e s e n t i n the s o i l as an o r g a n i c complex, as complex hydroxy p o l y m e r i c compounds o c c u p y i n g the i n t e r s t i t i a l space of 2:1 l a y e r s i l i c a t e s and as d i s c r e t e amorphous or c r y s t a l l i n e phases of o x i d e s and h y d r o x i d e s ( B a r n h i s e l and B e r t s c h , 1982). In p o d z o l s , f r e e aluminum o x i d e s and h y d r o x i d e s are p r e s e n t o n l y i n s m a l l amounts, p o s s i b l y due t o t h e i r i n s t a b i l i t y i n the presence of s i l i c i c a c i d ( R u s s e l l , 1973; G u i l l e t and S o u c h i e r , 1982). C h e m i c a l l y a c t i v e i r o n can a l s o e x i s t as amorphous o x i d e s and h y d r o x i d e s f o r m i n g d i s c r e t e p a r t i c l e s but not monolayers on the s u r f a c e of c l a y s . I r o n r e a d i l y forms complexes w i t h o r g a n i c a c i d s . In a d d i t i o n , i r o n can be reduced t o a d i v a l e n t c a t i o n a t low pH and/or under w a t e r l o g g e d c o n d i t i o n s . F e r r o u s i r o n can be h e l d by the c a t i o n exchange complex but because i t i s much more +3 s o l u b l e than Fe , under r e d u c i n g c o n d i t i o n s , i r o n i s e a s i l y l e a c h e d from the s o i l . F e r r i c i r o n i s not found i n the F e + ^ form 92 at a pH g r e a t e r than 3.0 and so does not s i t on the exchange s i t e s of most p o d z o l i c s o i l s ( G u i l l e t and S o u c h i e r , 1982). C h e m i c a l l y a c t i v e s i l i c a can be found i n p o d z o l s as the s o l u b l e m o n o s i l i c i c a c i d o r p r e c i p i t a t e d i n an amorphous form as s i l i c a g e l or i n b i o o p a l s ( p h y t o l i t h s ) . P r e c i p i t a t e d s i l i c a g e l r a r e l y remains i n the f r e e s t a t e . I t i s e i t h e r adsorbed on the s u r f a c e of very f i n e l y d i v i d e d q u a r t z or by e l e c t r o p o s i t i v e g e l s such as A l ( O H ) ^ o r FefOH)^. S i l i c a g e l s adsorbed by alumina may l e a d t o the n e o f o r m a t i o n of a l l o p h a n e s i n s p o d i c h o r i z o n s ( G u i l l e t annd S o u c h i e r , 1982). The t h r e e e x t r a c t a n t s used t o e x t r a c t i r o n , aluminum and s i l i c o n each removed a d i f f e r e n t f r a c t i o n of these elements from the s o i l . Sodium pyrophosphate ( a b b r e v i a t e d "Pyro" i n the t a b l e s ) i s c o n s i d e r e d s e l e c t i v e f o r o r g a n i c a l l y - c o m p l e x e d i r o n , a c i d ammonium o x a l a t e (Ox) e x t r a c t s t h i s f r a c t i o n as w e l l as amorphous forms of i n o r g a n i c i r o n , and c i t r a t e b i c a r b o n a t e d i t h i o n i t e (CBD) e x t r a c t s a l l of the above p l u s the c r y s t a l l i n e i r o n o x i d e s (McKeague e_t a_l. , 1971). In r e a l i t y the d e m a r c a t i o n between the t h r e e e x t r a c t a n t s i s not t h i s c l e a r c u t . For i n s t a n c e , o x a l a t e removes more i r o n from magnet i t e and o l i v i n e than does CBD (McKeague, 1978). A l s o , the o r g a n i c - c o m p l e x e d i r o n of t h i s s t u d y , as r e p r e s e n t e d by pyrophosphate e x t r a c t i o n , may be s l i g h t l y h i g h e r than a c t u a l l y o c c u r s i n the s o i l . T h i s i s because, d u r i n g the pyrophosphate o p e r a t i o n , a c e n t r i f u g a t i o n speed was used t h a t was t o o low t o s p i n down m i c r o c r y s t a l l i n e i r o n o x i d e s p e p t i z e d by the e x t r a c t a n t (Jeanroy and G u i l l e t , 1981). The case f o r aluminum i s somewhat d i f f e r e n t . O r g a n i c 93 c o m p l e x e d a l u m i n u m i s r e m o v e d b y s o d i u m p y r o p h o s p h a t e b u t t h i s e x t r a c t a n t a l s o r e m o v e s 5% o f t h e a l u m i n u m f r o m a l l o p h a n e ( P a r f i t t , 1 9 8 3 ) . O x a l a t e i s t h e b e s t e x t r a c t a n t f o r i n o r g a n i c a m o r p h o u s f o r m s o f a l u m i n u m , r e m o v i n g a l l t h e a l u m i n u m f r o m t h e o x i d e s , h y d r o x i d e s a n d f r o m a l l o p h a n e . I t a l s o r e m o v e s t h e o r g a n i c c o m p l e x e d a l u m i n u m ( F a r m e r e_t a _ l . , 1 9 8 3 ; P a r f i t t , 1 9 8 3 ) . C B D e x t r a c t s o r g a n i c - c o m p l e x e d a l u m i n u m , i n o r g a n i c a m o r p h o u s a n d s o m e c r y s t a l l i n e a l u m i n u m o x i d e s a n d h y d r o x i d e s b u t i s o n l y a p a r t i a l e x t r a c t a n t o f t h e a l u m i n u m f r o m a l l o p h a n e ( P a r f i t t , 1 9 8 3 ; F a r m e r e_t a _ l . , 1 9 8 3 ) . I n a f e w h o r i z o n s C B D v a l u e s a r e s l i g h t l y l o w e r t h a n p y r o p h o s p h a t e . T h i s i s a t t r i b u t e d t o t h e i n s t a b i l i t y o f t h e C B D m e a s u r e m e n t o n a t o m i c a b s o r p t i o n w h i c h made t h e o p e r a t i o n m u c h l e s s r e p r o d u c i b l e . T h e s i l i c o n e x t r a c t e d b y a c i d a m m o n i u m o x a l a t e i s b e l i e v e d b y P a r f i t t ( 1 9 8 3 ) t o b e s o l e l y f r o m t h e s i l i c o n o f a l l o p h a n e - l i k e m a t e r i a l . F r o m t h i s , t h e a m o u n t o f s p e c i f i c f o r m s o f i r o n a n d a l u m i n u m c a n b e e s t i m a t e d , a s i n T a b l e 5 - 3 . I n t h e m i n e r a l s o i l s o f B u r k e M o u n t a i n a n d C y p r e s s P a r k , i r o n v a l u e s i n a l l e x t r a c t s w e r e h i g h e s t n e a r t h e t o p o f t h e B h o r i z o n . H e r e t h e y c o m m o n l y r a n g e d b e t w e e n 1 a n d 2 % , b u t d r o p p e d f a i r l y q u i c k l y t o l o w v a l u e s i n t h e B f a b o v e t h e r o o t m a t . I r o n u s u a l l y , b u t n o t a l w a y s , i n c r e a s e d i n t h i s u n d e r l y i n g o r g a n i c - r i c h l a y e r . N o i n c r e a s e i n i r o n w a s n o t e d i n r o o t m a t s o f C y p r e s s P a r k ( s e e A p p e n d i x A , p r o f i l e s 1 1 - 1 5 ) . E x t r a c t a b l e i r o n i n r o o t c h a n n e l s u s u a l l y r e f l e c t e d t h e p o s i t i o n o f t h e c h a n n e l i n t h e s o i l . M o r e i r o n w a s e x t r a c t e d f r o m c h a n n e l s n e a r 94 Table 5-3 - E s t i m a t i o n s of the Forms of I r o n and Aluminum i n the S o i l U s i n g V a r i o u s E x t r a c t a n t s F r a c t i o n 1. Organic-complexed Fe 2. I n o r g a n i c amorphous Fe 3. C r y s t a l l i n e Fe o x i d e s and h y d r o x i d e s 4. A l l o p h a n e A l 5. A l l o p h a n e A l / S i r a t i o 6. A l l o p h a n e c o n t e n t a = McKeague e_t a l . b = P a r f i t t , 1983 c = o n l y t r u e i n so c o n c e n t r a t i o n s E x t r a c t a n t pyrophosphate Fe Ox. Fe - P y r o . F e a , C CBD Fe - o x a l a t e Fe a,° Ox. A l - Py r o . A l Ox. A l - P y r o . A l x AtWt S i o x a l a t e S i AtWt A l O x a l a t e Si° % S i i n s o i l a l l o p h a n e s ( c a . 14%) , 19 71 i l s w i t h low magnetite the top of the p r o f i l e than near the bottom, a l t h o u g h an i n c r e a s e was o f t e n noted i n the r o o t mat h o r i z o n up t o the l e v e l found i n the B h f l . High e x t r a c t a b l e i r o n v a l u e s were found i n c h a n n e l s r u n n i n g through m i n e r a l s o i l a l s o h i g h i n i r o n . An i n c r e a s i n g p e r c e n t i r o n was removed from the s o i l by sodium pyrophosphate, a c i d ammonium o x a l a t e and CBD as e x p e c t e d . P r o f i l e 30 on Burke Mtn. c o n t a i n e d the o n l y r o o t mat w i t h an i r o n v a l u e above 2%. I r o n v a l u e s of 2-5% were seen i n r o o t c h a n n e l s of p r o f i l e s 9, 28, and 30. A v a l u e of 6% pyrophosphate e x t r a c t a b l e i r o n was ta k e n from a r o o t c h a n n e l i n p r o f i l e 16 but 9 5 t h i s h i g h v a l u e c o r r e s p o n d e d t o t h e h i g h i r o n a l s o e x t r a c t e d f r o m t h e m i n e r a l s o i l o f t h i s p r o f i l e . A l l o t h e r r o o t m a t s , r o o t c h a n n e l s a n d m i n e r a l s o i l h a d r e l a t i v e l y l o w e x t r a c t a b l e i r o n v a l u e s . F o r a c o m p a r i s o n o f t h e a v e r a g e i r o n , a l u m i n u m a n d s i l i c o n e x t r a c t e d b y p y r o p h o s p h a t e a n d a c i d a m m o n i u m o x a l a t e f r o m r o o t m a t s a n d c h a n n e l s o n B u r k e M o u n t a i n a n d C y p r e s s P a r k , s e e T a b l e 5 - 4 . T a b l e 5 - 4 - A v e r a g e a n d R a n g e o f P y r o p h o s p h a t e a n d O x a l a t e E x t r a c t a b l e F e , A l a n d S i i n r o o t m a t s a n d r o o t c h a n n e l s RM RC RM ( + R C ) B u r k e M t . B u r k e M t . C y p r e s s P k . 1 . P y r o p h o s p h a t e %Fe a v e r a g e 1.23 2.07 0.45 (RM o n l y ) %Fe r a n g e 0 . 5 6 - 3 . 7 0 0 . 3 4 - 5 . 7 9 0 . 2 3 - 0 . 8 2 %A1 a v e r a g e 6.62 6.30 1.86 %A1 r a n g e 2 . 3 8 - 9 . 7 4 3 . 7 4 - 1 0 . 0 3 1 . 5 2 - 2 . 1 7 % S i a v e r a g e 0.43 0.44 0.09 % S i r a n g e 0 . 0 8 - 1 . 1 8 0 . 0 4 - 1 . 4 0 0 . 0 8 - 0 . 1 0 2 . O x a l a t e %Fe a v e r a g e 1 . 3 0 2 . 0 5 0 . 5 0 ( R M o n l y ) %Fe r a n g e 0.62-3.70 0.34-5.92 0.26-0.94 %A1 a v e r a g e 7 . 2 4 6 . 5 2 8 . 5 0 %A1 r a n g e 2 . 6 1 - 1 0 . 5 2 3 . 9 4 - 1 0 . 3 9 8 . 0 1 - 8 . 8 8 % S i a v e r a g e 0 . 6 2 0 . 4 8 * 2 . 7 9 % S i r a n g e 0 . 0 7 - 2 . 1 9 0 . 0 2 - 1 . 5 9 2 . 4 0 - 3 . 1 5 96 A l u m i n u m r e s u l t s w e r e s u r p r i s i n g . A l t h o u g h p y r o p h o s p h a t e a l u m i n u m v a l u e s o f t e n i n c r e a s e d f r o m t h e t o p t o t h e b o t t o m o f t h e p r o f i l e t h e y h a d u s u a l l y d r o p p e d t o o r w e r e a t 1 - 1 . 5 % A l i n t h e h o r i z o n i m m e d i a t e l y o v e r l y i n g t h e r o o t m a t . I n t h e r o o t m a t , v a l u e s i n c r e a s e d d r a m a t i c a l l y , a s u p t o 1 0 . 5 % A l w a s r e m o v e d b y p y r o p h o s p h a t e . A l u m i n u m v a l u e s w e r e a l s o h i g h i n t h e r o o t c h a n n e l s a n d i n c o n t r a s t t o i r o n , t h e p e r c e n t e x t r a c t e d i n c r e a s e d f r o m t h e t o p t o t h e b o t t o m o f t h e c h a n n e l . I m m e d i a t e l y b e l o w t h e r o o t m a t i n t h e d u r i c h o r i z o n , p y r o p h o s p h a t e a l u m i n u m v a l u e s w e r e v e r y l o w . S e e A p p e n d i x A f o r p r o f i l e d a t a . A c i d a m m o n i u m o x a l a t e a l u m i n u m v a l u e s w e r e h i g h e r t h a n p y r o p h o s p h a t e , b u t i n B h f h o r i z o n s , r o o t m a t s a n d r o o t c h a n n e l s o n B u r k e M o u n t a i n , t h e i n c r e a s e w a s o n t h e w h o l e , s l i g h t . I n t h e s e h i g h l y o r g a n i c m a t e r i a l s , m o s t o f t h e a l u m i n u m w a s b o u n d w i t h t h e o r g a n i c m a t t e r o r w a s a t l e a s t i n a f o r m b o t h e x t r a c t a n t s c o u l d r e m o v e . A l s o i n t h e s e h o r i z o n s , t h e C B D a l u m i n u m a p p r o x i m a t e l y e q u a l l e d t h e a l u m i n u m e x t r a c t e d w i t h p y r o p h o s p h a t e , a n d s i l i c o n v a l u e s w e r e l o w . I n B h o r i z o n s w i t h l o w c a r b o n v a l u e s o n B u r k e M o u n t a i n , i n t h e r o o t m a t o f p r o f i l e 1 0 a n d i n a l l h o r i z o n s r e g a r d l e s s o f o r g a n i c c o n t e n t i n C y p r e s s P a r k , t h e a l u m i n u m e x t r a c t e d b y o x a l a t e w a s o f t e n m o r e t h a n d o u b l e t h a t e x t r a c t e d w i t h p y r o p h o s p h a t e , i m p l y i n g t h a t a l a r g e p r o p o r t i o n o f a m o r p h o u s i n o r g a n i c a l u m i n u m w a s p r e s e n t ( s e e T a b l e 5 - 5 ) . A s C B D v a l u e s i n t h e s e h o r i z o n s w e r e l o w e r t h a n o x a l a t e b u t h i g h e r t h a n p y r o p h o s p h a t e , m u c h o f t h e o x a l a t e m i n u s p y r o p h o s p h a t e a l u m i n u m may b e p r e s e n t a s a l l o p h a n e - l i k e c o n s t i t u e n t s , o n l y a p o r t i o n o f 97 which CBD can e x t r a c t . T h i s i s s u b s t a n t i a t e d by the o x a l a t e e x t r a c t a b l e s i l i c o n v a l u e s which are much h i g h e r i n h o r i z o n s where the gap between pyrophosphate and o x a l a t e A l v a l u e s i s wide. In f a c t , thoughout the s t u d y , the l a r g e r the d i f f e r e n c e between pyrophosphate and o x a l a t e A l , the h i g h e r i n p r o p o r t i o n t o the aluminum was the o x a l a t e s i l i c o n v a l u e . A c c o r d i n g t o P a r f i t t (1983), a l l o p h a n e i s r e s p o n s i b l e f o r the s i l i c o n e x t r a c t e d by o x a l a t e . T h i s i s i l l u s t r a t e d w e l l i n Table 5-5. The B h f l h o r i z o n of p r o f i l e 2 has a h i g h %C; pyrophosphate, o x a l a t e and CBD e x t r a c t a b l e A l are a p p r o x i m a t e l y the same and s i l i c o n e x t r a c t e d by o x a l a t e i s low. The Bhf2 h o r i z o n has a lower %C, the o x a l a t e A l i s much h i g h e r than pyrophosphate o r CBD and the s i l i c o n e x t r a c t e d by o x a l a t e i s h i g h . I t i s i n t e r e s t i n g t o note t h a t where o x a l a t e s i l i c o n v a l u e s are h i g h (>1%) but pyrophosphate s i l i c o n i s low, the pH of t h a t h o r i z o n i s above 4.8. See f o r example C y p r e s s Park p r o f i l e s , Appendix A. Table 5-5 P r o f i l e 2 - A B h f l h o r i z o n w i t h a h i g h %C and the u n d e r l y i n g Bhf2 h o r i z o n w i t h a lower %C. %C %A1 % S i h o r i z o n p y r o Ox CBD p y r o Ox CBD B h f l 9.97 1.29 1.36 1.23 0.10 0.11 0.15 Bhf2 5.42 1.41 5.18 1.37 0.08 1.4 4 0.17 98 In a d d i t i o n t o the pH and m i n e r a l c o n s t i t u e n t s , the c h e m i c a l p r o p e r t i e s of the s o i l are a l s o determined by i t s o r g a n i c component. In t u r n , the amount and e x a c t c o m p o s i t i o n of s o i l o r g a n i c m a t t e r depends on the p h y s i c a l and c h e m i c a l environment under which the s o i l was formed, as w e l l as the o r i g i n of the o r g a n i c d e b r i s . O r g a n i c m a t t e r added t o a t r o p i c a l s o i l has a d i f f e r e n t f a t e from t h a t of a p r a i r i e s o i l and b o t h from t h a t of a p o d z o l . Even w i t h i n a p o d z o l , o r g a n i c m a t e r i a l found i n the l i t t e r l a y e r i s n o r m a l l y q u i t e d i f f e r e n t i n appearance t o t h a t of the B h o r i z o n and t h i s d i f f e r e n c e i s a l s o r e f l e c t e d i n the c h e m i c a l p r o p e r t i e s of each h o r i z o n . Lowe (1980) found t h a t upon c h e m i c a l e x t r a c t i o n of the o r g a n i c m a t t e r w i t h NaOH:Na pyrophosphate, one c o u l d d i s c r i m i n a t e between the LFH, Ah and Bf h o r i z o n s by how the carbon of. the e x t r a c t f r a c t i o n a t e d upon a c i d i f i c a t i o n . In g e n e r a l , Lowe found t h a t the humic t o f u l v i c r a t i o (Ch/Cf) of the l i t t e r was h i g h , a v e r a g i n g 3.25 i n the F and FH h o r i z o n s t e s t e d and g r e a t e r than 8.0 i n the H h o r i z o n a l o n e . In these same h o r i z o n s the p o l y p h e n o l i c f u l v i c t o t o t a l f u l v i c (Ca/Cf) was low, always l e s s than 0.5. In c o n t r a s t , Lowe found t h a t p o d z o l i c B h o r i z o n s had low Ch:Cf r a t i o s , a v e r a g i n g 0.21 and the Ca/Cf averaged 0.61, meaning more than 6 0% of the t o t a l f u l v i c s were p o l y p h e n o l i c . The Ah h o r i z o n s measured had a Ch/Cf va l u e between the two extremes and a Ca/Cf s i m i l a r t o the l i t t e r l a y e r . These f i g u r e s make sense when we c o n s i d e r the c o n d i t i o n s of g e n e s i s of p o d z o l i c s o i l s . In temperate r e g i o n s , p o d z o l s are formed under a c o l d , h i g h r a i n f a l l environment c o n d u c i v e t o slow 99 and i n c o m p l e t e d e c o m p o s i t i o n of o r g a n i c m a t e r i a l . The b i o l o g i c a l breakdown of the c o n i f e r o u s f o r e s t l i t t e r r e l e a s e s n e g a t i v e l y charged o r g a n i c a c i d s whose m o b i l i t y i n the a c i d s o i l s o l u t i o n depends upon t h e i r s i z e , t h e i r r a t i o of h y d r o p h i l i c t o h y d r o p h o b i c p a r t s and the presence of n e u t r a l i z i n g c a t i o n s . Those t h a t are m obile are l e a c h e d by e x c e s s r a i n w a t e r i n t o the B h o r i z o n where upon p o l y m e r i z a t i o n i n t o l a r g e r m o l e c u l e s or upon charge n e u t r a l i z a t i o n on r e a c t i o n w i t h i n o r g a n i c c a t i o n s they become i n s o l u b l e . The immobile compounds s y n t h e s i z e d d u r i n g d e c o m p o s i t i o n are l e f t b e h i n d a t the s o i l s u r f a c e a l o n g w i t h a much h i g h e r p r o p o r t i o n of p o l y s a c c h a r i d e s than found i n the B h o r i z o n . Upon c h e m i c a l e x t r a c t i o n of the o r g a n i c m a t t e r , the f u l v i c a c i d f r a c t i o n (Cf) i s c o n s i d e r e d t o c o n s i s t of the once a c i d - s o l u b l e a c i d s of d e c o m p o s i t i o n p l u s the p o l y s a c c h a r i d e s . The humic a c i d f r a c t i o n (Ch) i s a s s o c i a t e d w i t h the a c i d - i n s o l u b l e o r g a n i c a c i d s . I f r o o t d e c o m p o s i t i o n i s the main f a c t o r i n the g e n e s i s of the r o o t mats and r o o t c h a n n e l s , one might e x p e c t the r e s u l t i n g o r g a n i c m a t e r i a l t o behave i n a p a t t e r n s i m i l a r t o t h a t o u t l i n e d by the above model: As the r o o t s decompose, s m a l l o r g a n i c a c i d s would be r e l e a s e d t h a t are s o l u b l e i n the r a i n w a t e r l e a c h i n g through the s o i l . These would then be removed t o the m i n e r a l s o i l o r ground water and the a c i d - i n s o l u b l e o r g a n i c m o l e c u l e s , abundant upon d e c o m p o s i t i o n of the r o o t ' s l i g n i n , would remain i n the c h a n n e l w i t h any p o l y s a c c h a r i d e s undecomposed i n t h i s a c i d , perhaps a n a e r o b i c , low n i t r o g e n e nvironment. Upon c h e m i c a l e x t r a c t i o n of the o r g a n i c m a t t e r , the Ch/Cf and Ca/Cf of the r o o t mats and r o o t c h a n n e l s would be s i m i l a r t o t h a t of the l i t t e r l a y e r . R e s u l t s were j u s t o p p o s i t e t o those p r e d i c t e d by the model d e s c r i b e d . The Ch/Cf v a l u e was low, always l e s s than 0.5 and o f t e n near 0.2, i n d i c a t i n g abundant f u l v i c a c i d s and l i t t l e humics. The Ca/Cf v a l u e was h i g h - g r e a t e r than 70% of the f u l v i c a c i d s were p o l y p h e n o l i c r a t h e r than p o l y s a c c h a r i d e i n c h a r a c t e r . No d i f f e r e n c e was noted between the o r g a n i c c h a r a c t e r i s t i c s of the r o o t mats as compared t o r o o t c h a n n e l s . McKeague (1981) r e p o r t e d a h u m i c r f u l v i c r a t i o of a r o o t mat i n the Goldstream s e r i e s on Vancouver I s l a n d which i s i n c o n t r a s t t o the above and i n f a c t , does seem t o su p p o r t the e x p e c t e d model. He o b t a i n e d a Ch/Cf v a l u e of 1.8 i n d i c a t i n g t h a t most of the e x t r a c t e d o r g a n i c s were l a r g e humic m o l e c u l e s . He c o n c l u d e d t h a t t h i s was an i n d i c a t i o n of _in s i t u r o o t d e c o m p o s i t i o n . As McKeague had o b t a i n e d h i s sample from the B.C. M i n i s t r y of Environment, a n o t h e r sample of t h i s h o r i z o n was o b t a i n e d from H. A. L u t t m e r d i n g and r e a n a l y s e d i n t h i s t h e s i s . R e s u l t s o b t a i n e d were v e r y d i f f e r e n t from McKeague's and they agreed i n s t e a d w i t h the r o o t mats of Burke Mtn. and C y p r e s s P a r k . A Ch/Cf of 0.26 and a Ca/Cf of 0.66 i n d i c a t e most of the e x t r a c t e d o r g a n i c s were p o l y p h e n o l i c f u l v i c a c i d s . In an attempt t o e x p l a i n the d i s c r e p a n c y , McKeague sent h i s sample t o be a n a l y s e d by an independant t e c h n i c i a n i n the U.B.C. l a b . T h i s t e c h n i c i a n o b t a i n e d a Ch/Cf and Ca/Cf v a l u e of 0.26 and 0.67, r e s p e c t i v e l y . A comparison of methods showed the Ottawa l a b o r a t o r y used a l a r g e r sample w e i g h t t o e x t r a c t a n t r a t i o and d i d not wash the humic a c i d s by r e d i s s o l v i n g them i n a l k a l i and r e p r e c i p i t a t i o n i n a c i d , two f a c t o r s t h a t w i l l s i g n i f i c a n t l y a f f e c t r e s u l t s ( S c h u p p l i and McKeague, 1984). Perhaps the c o n c e n t r a t i o n of o r g a n i c m a t t e r i n the McKeague e x t r a c t a n t was so h i g h , the s m a l l e r f u l v i c m o l e c u l e s were o c c l u d e d by the p r e c i p i t a t i n g humic m o l e c u l e s and the two f r a c t i o n s were n e v e r washed c l e a n by r e d i s s o l u t i o n and r e p r e c i p i t a t i o n . McKeague d i d r e p o r t t h a t h i s a n a l y s i s of a Bhf h o r i z o n above a d u r i c h o r i z o n i n the S a r i t a s e r i e s had a Ch/Cf of 0.2, the same as the o v e r l y i n g Bf h o r i z o n ( p e r s . comm). Perhaps a s m a l l e r %C t o e x t r a c t a n t r a t i o was used i n t h i s c a s e . In a d d i t i o n , McKeague's l a b o r a t o r y r e a n a l y z e d the G oldstream rootmat and o b t a i n e d a v a l u e below 0.5, a l t h o u g h method d i f f e r e n c e s s t i l l p r e v e n t e d i d e n t i c a l r e s u l t s i n the Ottawa and Vancouver l a b o r a t o r i e s . The p e r c e n t of the r o o t mat carbon e x t r a c t e d by NaOH-pyrophosphate (%Ce) was always h i g h , sometimes a p p a r e n t l y g r e a t e r than 100%. Very l i t t l e carbon remained i n the "humin" f r a c t i o n . The h i g h v a l u e s i n d i c a t e b o t h a h i g h degree of d e c o m p o s i t i o n of the o r g a n i c m a t e r i a l and t h a t f a l s e assumptions were used i n c a l c u l a t i n g the W a l k l e y - B l a c k p e r c e n t carbon v a l u e s . I t would appear t h a t more carbon was o x i d i z e d d u r i n g a n a l y s e s than e x p e c t e d by the e f f i c i e n c y f a c t o r of 1.25 and/or t h a t the o +4 assumed average change i n o x i d a t i o n s t a t e from C t o C was i n c o r r e c t . I f the e f f i c i e n c y f a c t o r was a t f a u l t , the carbon i n the r o o t mats and c h a n n e l s was l i k e l y i n a more " a c t i v e " form than n o r m a l l y e n c o u n t e r e d i n o r g a n i c h o r i z o n s ( A l l i s o n , 1965). 102 The humic t o f u l v i c and p o l y p h e n o l i c t o t o t a l f u l v i c r a t i o s f o r the Bf and s u r f i c i a l Bhf were as e x p e c t e d f o r a p o d z o l and i n the same range as t h a t of the r o o t mats. I t i s d o u b t f u l the r o o t mats c o u l d be s t a t i s t i c a l l y d i f f e r e n t i a t e d , on the b a s i s of e x t r a c t e d o r g a n i c m a t t e r r a t i o s , from a normal p o d z o l i c Bhf h o r i z o n . See Table 5-6. Table 5-6 - Average and range of humic t o f u l v i c a c i d r a t i o s ( C h / C f ) , p o l y p h e n o l i c f u l v i c t o t o t a l f u l v i c a c i d r a t i o s (Ca/Cf) and p e r c e n t of t o t a l carbon e x t r a c t e d (%Ce) Ch/Cf Ca/Cf %Ce S u r f i c i a l humus (HI) 2.44 0.44 62 range 0 .60-4.71 0.24-0. 68 50-73 Upper Bhf h o r i z o n 0.34 0.72 83 range 0 .16-0.64 0.49-0. 79 65-99 P o d z o l i c Bf 0.11 0.62 75 range 0 .08-0.14 0.45-0. 72 56-91 Root Mats (H2) 0.23 0.73 97 range 0 .13-0.39 0.66-0. 81 81-115 Root Mats (Bhf) 0.32 0.66 76 range 0 .11-0.47 0.53-0. 77 61-92 Root c h a n n e l s 0.22 0.70 93 range 0 .17-0.28 0.61-0. 79 61-107 The e x t r a c t e d carbon d a t a showed some v a r i a t i o n between s i t e s . F o r example, the r o o t mats of Cy p r e s s Park appeared t o be 103 l e s s w e l l decomposed than those of Burke Mountain. T h i s would e x p l a i n the h i g h e r p r o p o r t i o n of p o l y s a c c h a r i d e s t o p o l y p h e n o l i c f u l v i c a c i d s , the l o w e r p e r c e n t e x t r a c t e d c a r b o n , and a humic t o f u l v i c r a t i o i n one of the r o o t mats of 0.47. The numbers c o u l d a l s o be e x p l a i n e d by a s m a l l e r r e l a t i v e c o n t r i b u t i o n of i l l u v i a t e d f u l v i c a c i d s vs in s i t u d e c o m p o s i t i o n i n the f o r m a t i o n of the o r g a n i c m a t e r i a l making up the r o o t mats. Some of the more c o n v e n t i o n a l B h o r i z o n s of C y p r e s s Park showed s i m i l a r r e s u l t s t o the C y p r e s s Park r o o t mats. These may a l s o be under the i n f l u e n c e of r o o t d e c o m p o s i t i o n . The Ch/Cf r a t i o s of o r g a n i c m a t e r i a l i n the LFH was always w e l l above 1.0, e x c e p t f o r the H l a y e r of a l o c a l i z e d a r e a sampled e a s t of the Burke Mountain road c u t . The HI h o r i z o n of p r o f i l e s 18, 19, 20, 22, 23, 24, was much t h i c k e r than the o t h e r sampled s o i l s , v e r y b l a c k and amorphous. I t appeared t o be an e x c e l l e n t example of a w e l l developed s u r f a c e o r g a n i c , however, i t s c h e m i c a l p r o p e r t i e s were u n u s u a l . The s u r f i c i a l humus i n p i t s numbered 18 and 19 had Ch/Cf v a l u e s of 0.88 and 0.60, r e s p e c t i v e l y , and the Ca/Cf v a l u e s were h i g h . These H l a y e r s a l s o had much h i g h e r o x a l a t e e x t r a c t a b l e A l than o t h e r s u r f i c i a l o r g a n i c h o r i z o n s , a p p r o a c h i n g 5%, compared t o l e s s than 0.5%. In f a c t , i t had p r o p e r t i e s a p p r o a c h i n g a r o o t mat! Under the microscope the c e l l u l a r n a t u r e of the o r g a n i c m a t e r i a l f i l l i n g the mats and c h a n n e l s c o u l d be d e t e r m i n e d . R e f e r t o photographs i n Appendix C. In one h o r i z o n p o l l e n g r a i n s of A b i e s spp. were found w i t h i n a c l o d of o r g a n i c m a t t e r t a k e n from a depth of 78 cm. T h i s would i n d i c a t e t h a t a t l e a s t some 104 s u r f i c i a l m a t e r i a l c o n t r i b u t e d t o the o r g a n i c m a t t e r w i t h i n the r o o t c h a n n e l s and mats. In summary, the p r o p e r t i e s e x h i b i t e d by the r o o t mats and r o o t c h a n n e l s seem f u l l of a p p arent c o n t r a d i c t i o n s . M o r p h o l o g i c a l c h a r a c t e r i s t i c s p o i n t t o g e n e s i s by r o o t d e c o m p o s i t i o n and c h e m i c a l p r o p e r t i e s c r e d i t p o d z o l i z a t i o n f o r the o r i g i n of these o r g a n i c a c c u m u l a t i o n s . The r o o t c h a n n e l s show the g r o s s morphology of l a r g e b r a n c h i n g r o o t s , the t i p s of which o f t e n e x t e n d i n t o the r o o t mat h o r i z o n . O c c a s i o n a l l y , above the d u r i c h o r i z o n , a s h o r t p i e c e of undecomposed r o o t of l a r g e d i a m e t e r can be found w i t h i n the o r g a n i c m a t e r i a l . No m i n e r a l g r a i n s can be d e t e c t e d i n most c h a n n e l s or mats by hand t e x t u r i n g and under the phase c o n t r a s t microscope the c e l l u l a r n a t u r e of the m a t e r i a l i s e a s i l y seen. In a d d i t i o n , wood s t r u c t u r e can sometimes be d i s t i n g u i s h e d _in s i t u , a l t h o u g h , when t h i s s t r u c t u r e i s removed from the p r o f i l e , and c r u s h e d between the f i n g e r s , i t s w e l l decomposed s t a t e i s r e v e a l e d . The C:N r a t i o of the r o o t m a t e r i a l i s i n the same range as t h a t of the s u r f i c i a l humus. In c o n t r a s t , no wood s t r u c t u r e can be seen i n most of the o r g a n i c m a t t e r a c c u m u l a t i o n s . I n s t e a d , the m a t e r i a l appears dark and amorphous and the few l i v e r o o t s found are f i n e t o v e r y f i n e r a t h e r than the 1-5 cm i n d i a m e t e r i n d i c a t e d by the s i z e of the r o o t c h a n n e l s . Why would l a r g e , c o a r s e r o o t s have grown t o the d u r i c h o r i z o n i n the p a s t , y e t no t r a c e of these c o u l d be found today? The c h e m i c a l p r o p e r t i e s of the o r g a n i c m a t e r i a l were 105 c o m p l e t e l y o p p o s i t e t o what might be e x p e c t e d f o r decomposing wood, i f the humus of the LFH was used as a model. O x a l a t e e x t r a c t a b l e aluminum was h i g h - up t o h a l f the %C v a l u e , and much h i g h e r than t h a t e x t r a c t e d from the s u r r o u n d i n g m i n e r a l s o i l . T h i s l a r g e i n c r e a s e was not m i r r o r e d by the e x t r a c t a b l e i r o n v a l u e s , however. The humic t o f u l v i c r a t i o s and p o l y p h e n o l i c f u l v i c t o t o t a l f u l v i c r a t i o s put the p r o p e r t i e s of the e x t r a c t e d o r g a n i c much c l o s e r t o those of a p o d z o l i c Bf than t o the decomposing wood of the LFH. In f a c t , the c h e m i c a l p r o p e r t i e s make the r o o t mats and r o o t c h a n n e l s much more " p o d z o l i c " i n c h a r a c t e r than the c o n v e n t i o n a l Bhf and Bf h o r i z o n s , w i t h Fe + A l v a l u e s an o r d e r of magnitude l a r g e r than those r e q u i r e d t o meet p o d z o l i c c l a s s i f i c a t i o n . While g e n e t i c h i s t o r y of these s o i l s cannot be e s t a b l i s h e d by l a b o r a t o r y s t u d i e s a l o n e , s e v e r a l p o s s i b l e e x p l a n a t i o n s f o r the f o r m a t i o n of r o o t mats and c h a n n e l s w i t h the above p r o p e r t i e s are p r e s e n t e d i n C h a p t e r 6. With the a i d of a column s t u d y , one of these models i s then t e s t e d . C l a s s i f i c a t i o n of the Root Mats As a r o o t mat i s "a l a y e r of m i n e r a l or o r g a n i c s o i l o r s o i l m a t e r i a l a p p r o x i m a t e l y p a r a l l e l t o the l a n d s u r f a c e t h a t has c h a r a c t e r i s t i c s a l t e r e d by p r o c e s s e s of s o i l f o r m a t i o n " (CSSC, 1978, p. 22) i t i s a s o i l h o r i z o n , and as such s h o u l d be c l a s s i f i e d . I f i t has g r e a t e r than 17% o r g a n i c carbon i t i s an o r g a n i c h o r i z o n by the Canadian c l a s s i f i c a t i o n system (CSSC, 1978). When o r g a n i c , i t has been l a b e l l e d H2 i n b u l l e t i n s 1 0 6 p u b l i s h e d b y t h e M i n i s t r y o f E n v i r o n m e n t , V i c t o r i a , b u t a s o r g a n i c s o i l c l a s s i f i c a t i o n i s s o m e w h a t p r o b l e m a t i c , c l a s s i f i c a t i o n a s a n H a n d a s a n 0 h o r i z o n w i l l b e c o n s i d e r e d h e r e . B e c a u s e a r o o t m a t i s c o m p o s e d o f w o o d y m a t e r i a l s a n d i s n e a r l y a l w a y s s a t u r a t e d w i t h w a t e r i t may m e e t t h e c l a s s i f i c a t i o n c r i t e r i a o f a n 0 h o r i z o n . I f p u t i n t o t h i s g r o u p i n g i t s h o u l d b e c l a s s i f i e d a s f o l l o w s . R o o t m a t s s t u d i e d o n B u r k e M o u n t a i n a n d i n C y p r e s s P a r k a r e a l l w e l l d e c o m p o s e d . T h e y h a v e l e s s t h a n 10% b y v o l u m e o f r u b b e d f i b e r a n d t h e p y r o p h o s p h a t e i n d e x i s 3 o r l e s s . T h e y r a t e 9 - 1 0 o n t h e v o n P o s t s c a l e , a s t h e r e i s v e r y l i t t l e r e c o g n i z a b l e p l a n t s t r u c t u r e a n d n e a r l y a l l t h e p e a t e s c a p e s b e t w e e n t h e f i n g e r s . A s s u c h t h e s e r o o t m a t s w o u l d b e c l a s s i f i e d a s O h . O n t h e o t h e r h a n d , b e c a u s e t h e w a t e r m o v i n g t h r o u g h t h e s e m a t e r i a l s may b e w e l l a e r a t e d a n d b e c a u s e t h e r o o t m a t s a r e a s s o c i a t e d w i t h a f o r e s t e n v i r o n m e n t , t h e y may b e m o r e a p p r o p r i a t e l y c l a s s i f i e d H 2 . I f a r o o t m a t c o n t a i n s l e s s t h a n 17% o r g a n i c c a r b o n i t c a n b e c l a s s i f i e d a s a B h f h o r i z o n a s a l l r o o t m a t s h a v e a h u e o f 7 . 5 Y R o r r e d d e r , c o n t a i n a t l e a s t 0 . 6 % p y r o p h o s p h a t e e x t r a c t a b l e A l + F e , h a v e a r a t i o o f p y r o p h o s p h a t e e x t r a c t a b l e ( F e + A l ) t o c l a y ( < 0 . 0 0 2 mm) o f m o r e t h a n 0 . 0 5 a n d h a v e a n o r g a n i c C c o n t e n t g r e a t e r t h a n 5% ( C S S C , 1 9 7 8 ) . I t c a n n o t b e c l a s s i f i e d a B h h o r i z o n w h e n t h e p y r o p h o s p h a t e e x t r a c t a b l e i r o n i s g r e a t e r t h a n 0 . 3 % . T h e r o o t m a t w i l l m e e t t h e c r i t e r i a o f a " p o d z o l i c B h f " i f i t s m i n i m u m t h i c k n e s s i s g r e a t e r t h a n 10 c m . H o w e v e r , t h e r o o t m a t s d o d i f f e r f r o m t h e c o n v e n t i o n a l B h f h o r i z o n s f o u n d d i r e c t l y b e n e a t h t h e L F H o r A e h o r i z o n s b y t h e a m o u n t o f p y r o p h o s p h a t e a n d 107 o x a l a t e aluminum found w i t h i n t h e i r m a t e r i a l s . See Table 5-7. Table 5-7 - Average P e r c e n t Carbon and P e r c e n t Pyrophosphate and O x a l a t e E x t r a c t a b l e Fe and A l i n the Root Mat Bhf Compared t o More C o n v e n t i o n a l Bhf H o r i z o n s Found Near the Top of the P r o f i l e C o n v e n t i o n a l Root Mat Bhf Bhf avg. range avg. % c 7.36 5.27-13.16 13.63 % Fe (Pyro) 1.22 0.11- 4.85 0.68 % Fe (Ox) 1.35 0.13- 5.05 0.80 % A l (Pyro) 1.41 0.55- 2.60 3.60 % A l (Ox) 1.91 0.57- 4.55 6 .73 I t s h o u l d be noted t h a t l i t t l e m o r p h o l o g i c a l or c h e m i c a l d i f f e r e n c e s were d e t e c t e d between r o o t mats w i t h a carbon c o n t e n t g r e a t e r than 17% and those w i t h s l i g h t l y l e s s than 17% o r g a n i c c a r b o n . In t h i s case the c u t o f f p o i n t between the two c l a s s i f i c a t i o n s seems v e r y a r t i f i c a l . The American system, which c l a s s i f i e s s o i l s low i n c l a y as o r g a n i c i f they have g r e a t e r than 20% o r g a n i c m a t t e r , may b e t t e r s e p a r a t e r o o t mats w i t h few d i s c e r n a b l e m i n e r a l g r a i n s from those w i t h a more o b v i o u s m i n e r a l component. U s i n g the system as i t now s t a n d s , i t i s v e r y i m p o r t a n t t h a t c l a s s i f i c a t i o n of these s o i l s be made on an o v e n - d r i e d b a s i s . A i r - d r y r o o t mats and c h a n n e l s averaged 23% and 20% m o i s t u r e , r e s p e c t i v e l y , compared t o 7% m o i s t u r e i n c o n v e n t i o n a l Bhf 108 h o r i z o n s , 5% i n Bf h o r i z o n s and 13% i n the humus of the LFH. One r o o t mat s t i l l h e l d 30% m o i s t u r e a f t e r a i r - d r y i n g , a p r o b a b l e f u n c t i o n of b o t h the o r g a n i c and aluminum c o n t e n t . C o r r e c t i o n f o r o v e n - d r i e d weight "bumped" most of the p r o b l e m a t i c Bhf h o r i z o n s i n t o the o r g a n i c c l a s s i f i c a t i o n . The r o o t c h a n n e l s are not h o r i z o n t a l l a y e r s and t h e r e f o r e , do not need t o be c l a s s i f i e d . R a t h e r , they s h o u l d be d e s c r i b e d under a d d i t i o n a l n o t e s i n s o i l survey r e p o r t s . 109 CHAPTER 6 POSSIBLE ORIGINS OF THE ANOMOLOUS ORGANIC MATERIAL Proposed Models of Root Mat/Channel G e n e s i s D u r i n g t h i s s t u d y , f o u r p o s s i b l e hypotheses emerged t o account f o r the presence of o r g a n i c m a t t e r i n c h a n n e l s throughout the B h o r i z o n and i n mats above the d u r i c h o r i z o n . 1. Roots of mature f o r e s t t r e e s grew down through the co a r s e t e x t u r e d m i n e r a l s o i l , s e e k i n g the water t h a t c o l l e c t e d a l o n g the hardpan d u r i n g p e r i o d s of drought . The r o o t s had the f o r c e t o push m i n e r a l g r a i n s up and a p a r t . The r o o t s d i e d and decomposed l e a v i n g a greasy o r g a n i c h o r i z o n . 2. T h i s h o r i z o n d e v e l o p e d through a c l a s s i c a l l y " p o d z o l i c " p r o c e s s . F u l v i c a c i d s c a r r y i n g Fe and A l moved from the l i t t e r l a y e r and upper h o r i z o n s t o p r e c i p i t a t e out a l o n g the hardpan. 3. P a r t i c u l a t e m a t t e r , o r i g i n a t i n g from the s u r f a c e l i t t e r was washed down r o o t c h a n n e l s and o t h e r f a v o r e d pathways. I t was suspended i n the water moving l a t e r a l l y through the c o a r s e t e x t u r e d s o i l above the hardpan and e v e n t u a l l y c o l l e c t e d i n p o c k e t s . 4. A c o m b i n a t i o n of the above h y p o t h e s e s , a c t i n g t o g e t h e r . Hypotheses 1 and 3 r e q u i r e an a d d i t i o n a l mechanism t o account f o r the en r i c h m e n t of the o r g a n i c m a t e r i a l w i t h i r o n and 110 e s p e c i a l l y aluminum. At l e a s t t h r e e p o s s i b i l i t i e s can be put f o r w a r d and not s u r p r i s i n g l y , these c o r r e s p o n d t o the suggested mechanisms of p o d z o l g e n e s i s l i s t e d i n C h a p t e r 1. 1. I r o n and aluminum move i n d e p e n d a n t l y as i n o r g a n i c c a t i o n s from the m i n e r a l s o i l i n t o the o r g a n i c - r i c h h o r i z o n s . Van Schuy l e n b o r g h and Bruggenwert (1965) and P e t e r s e n (1976) found t h a t a t pH 4.0, the s o l u b i l i t y of A l + 3 was h i g h enough t o account f o r p o d z o l f o r m a t i o n . A l s o , the s o l u b i l i t y of i r o n , under r e d u c i n g c o n d i t i o n s , i s h i g h (Stobbe and W r i g h t , 1959). T h i s i s a l e s s s a t i s f a c t o r y mechanism i n s o i l s w i t h r e a c t i o n s above 5.0 because s o l u b i l i t y of b o t h elements a t t h i s pH i s v e r y low. 2. Aluminum and perhaps some i r o n move i n t o the o r g a n i c - r i c h l a y e r s as the p o s i t i v e l y charged c o l l o i d , p r o t o - i m o g o l i t e . In b o t h the above c a s e s , aluminum and i r o n would p r e c i p i t a t e out i n the o r g a n i c h o r i z o n through r e a c t i o n w i t h n e g a t i v e l y charged o r g a n i c a c i d s . 3. The o r g a n i c m a t e r i a l i n the c h a n n e l s and mats has been e n r i c h e d w i t h i l l u v i a t e d i r o n and aluminum-organic complexes. These p r e c i p i t a t e out s p e c i f i c a l l y i n the r o o t mats and c h a n n e l s due t o a change i n s o i l pH, i o n i c +3 c o n c e n t r a t i o n o r due t o c a t i o n i c b r i d g i n g by Fe and +3 A l t o o r g a n i c m o l e c u l e s a l r e a d y p r e s e n t i n these o r g a n i c - r i c h zones. The l a t t e r mechanism may cause the i n s o l u b i l i t y of the o r g a n i c complex through i n c r e a s e i n I l l s i z e and n e u t r a l i z a t i o n of ch a r g e . I t has been shown t h a t many c o n i f e r s growing on a c i d i c s o i l s not o n l y have a t o l e r a n c e t o h i g h aluminum l e v e l s i n the s o i l b ut a l s o a c t u a l l y take t h i s element up i n t o t h e i r f o l i a g e (Messenger e_t a_l. , 1978). Messenger (1975) found t h a t e a s t e r n hemlock (Tsuga c a n a d e n s i s (L.) C a r r . ) was an e f f e c t i v e f o l i a r aluminum a c c u m u l a t o r and t h a t a h i g h c o n c e n t r a t i o n of e x t r a c t a b l e aluminum was a l s o p r e s e n t i n the humus-rich s u r f a c e s o i l s beneath f o r e s t s t a n d s dominated by t h i s s p e c i e s . These f o r e s t f l o o r e n v i r o n m e n t s a l s o had a l a r g e c a p a c i t y f o r the p r o d u c t i o n of " c r e n i c a c i d " , the name g i v e n by the e a r l y R u s s i a n r e s e a r c h e r s t o c o l o u r e d o r g a n i c m o l e c u l e s , r e l e a s e d from v e g e t a t i o n , a b l e t o d i s s o l v e and c h e l a t e m e t a l s . As the l i t t e r i s decomposed, the aluminum may be r e l e a s e d i n c o m b i n a t i o n w i t h a mobile a c i d . D a v i d and D r i s c o l l (1984) measured the aluminum p a s s i n g t h rough a s p o d o s o l s u b j e c t t o at m o s p h e r i c a c i d d e p o s i t i o n a t hardwood and c o n i f e r s i t e s i n the Ad i r o n d a c k Mountains, New York. They found l o w e r s o l u t i o n pH v a l u e s and h i g h e r t o t a l aluminum c o n c e n t r a t i o n s i n the s o i l s o l u t i o n of the c o n i f e r s i t e . F u r t h e r m o r e , 85% and 65% of the aluminum i n the B h o r i z o n s o i l s o l u t i o n a t the hardwood s i t e and the c o n i f e r s i t e , r e s p e c t i v e l y , was i n the s o i l s o l u t i o n of the l i t t e r l a y e r b e f o r e coming i n c o n t a c t w i t h the m i n e r a l s o i l . Aluminum i n t h i s a c i d s o i l seemed t o be t a k e n up by p l a n t r o o t s and l a t e r r e l e a s e d i n t o the l i t t e r l a y e r upon d e c o m p o s i t i o n of the l e a v e s . However, e s p e c i a l l y w i t h s u r f i c i a l r o o t i n g s p e c i e s such a s hemlocks ( K r a j i n a , 1969) c y c l i n g may mean e x a c t l y t h a t , 112 c y c l i n g . The same p o p u l a t i o n of aluminum, r e l e a s e d from the f o l i a g e t h r o u g h d e c o m p o s i t i o n , may be once a g a i n p i c k e d up by the t r e e r o o t s . On f o r e s t e d s i t e s i n t h i s s t u d y , aluminum may be absorbed by r o o t s of hemlock t r e e s , t r a n s p o r t e d t o the l e a v e s , r e l e a s e d upon d e c o m p o s i t i o n and washed down f a v o r e d pathways, such as r o o t c h a n n e l s , i n c o m b i n a t i o n w i t h o r g a n i c a c i d s . The aluminum may then b i n d w i t h o t h e r o r g a n i c s i n the c h a n n e l , and through d e c o m p o s i t i o n the carbon t o aluminum r a t i o d e c r e a s e d w i t h t i m e . How these Suggested Models F i t the P r o p e r t i e s Found I t appears t h a t a t l e a s t p a r t of the o r g a n i c m a t t e r i n c h a n n e l s and mats on Burke Mountain and i n C y p r e s s Park arose through the d e c o m p o s i t i o n of r o o t s . Many c h a n n e l s had the g r o s s morphology of l a r g e b r a n c h i n g r o o t s . Much of the o r g a n i c m a t t e r f i l l i n g the c h a n n e l s and i n l o c a l i z e d a r e a s of the mats had the f i b r o u s morphology of wood _in s i t u , a l t h o u g h the "wood" was t o o decomposed t o m a i n t a i n i t s f i b r o u s n a t u r e when c r u s h e d between the f i n g e r s . T h i s "wood" o f t e n f i l l e d the c h a n n e l s c o m p l e t e l y and a d a r k e r a r e a c o u l d be seen a l o n g the edge of the c h a n n e l which resembled "bark". The g r a n u l a r s t r u c t u r e of some of the o r g a n i c m a t e r i a l l o o k e d l i k e s h o r t p i e c e s of decomposed f i n e r o o t s . S h o r t p i e c e s of dead, but undecomposed r o o t s of l a r g e d i a m e t e r were o c c a s i o n a l l y found a t depth w i t h i n the mat and, the c e l l u l a r n a t u r e of the decomposed m a t e r i a l c o u l d be seen under the m i c r o s c o p e . In a d d i t i o n , the mats were l o c a t e d i n a r e a s where r o o t s were l i k e l y t o c o n c e n t r a t e . They were found above a 113 hardpan a l o n g which seepage water r a n , beneath a f a i r l y c o a r s e t e x t u r e d , w e l l - d r a i n e d s o i l . In t i m e s of drought i t would be advantageous f o r a t r e e t o be a b l e t o c o l l e c t seepage water and d i s s o l v e d n u t r i e n t s moving a l o n g the pan from h i g h e r e l e v a t i o n s . The d i s t r i b u t i o n of o r g a n i c m a t t e r was by no means u n i f o r m . T h i n c h a n n e l s of o r g a n i c m a t e r i a l were surrounded by s o i l s w i t h a very low %C v a l u e and the r o o t mat p r o f i l e as a whole was o f t e n surrounded by s o i l w i t h no u n u s u a l o r g a n i c a c c u m u l a t i o n s , a d i s t r i b u t i o n e a s i l y a t t r i b u t a b l e t o the p r e f e r e n c e of r o o t i n g h a b i t . Why l a r g e r o o t s can not be found t o t h i s depth today may be due t o the predominance of hemlock i n the second growth f o r e s t . Hemlock i s known f o r i t s s u r f i c i a l r o o t i n g h a b i t and p r e f e r e n c e f o r n u t r i e n t s i n stea d y but low c o n c e n t r a t i o n s ( K r a j i n a , 1969). The l a r g e c e d a r stumps p r e v a l e n t i n the f o r e s t of Burke Mountain i n d i c a t e a l a r g e r r o l e p l a y e d by c e d a r i n the p a s t . Cedar and P a c i f i c S i l v e r F i r b o t h have a h i g h n u t r i e n t r e q u i r e m e n t and ac h i e v e optimum growth i n s o i l s a f f e c t e d by n u t r i e n t - r i c h seepage water ( K r a j i n a , 1969). Other e v i d e n c e f o r a r o o t - d e r i v e d o r i g i n of the o r g a n i c m a t e r i a l i s found i n the t h i c k n e s s of some of the r o o t mats, up to 40 cm w i t h few d e t e c t a b l e m i n e r a l g r a i n s . Where d i d the m i n e r a l m a t e r i a l go? I t would r e q u i r e the a c t i v e p r e s s u r e of r o o t s , o r a l a n d s l i d e o v e r s u r f i c i a l m a t e r i a l , the l a t t e r of which t h e r e i s no e v i d e n c e , to c r e a t e the space the o r g a n i c m a t e r i a l s f i l l . S u r f i c i a l m a t e r i a l may have l a t e r c o n t r i b u t e d t o the o r g a n i c 1 1 4 m a s s i n t h e c h a n n e l s , w a s h i n g d o w n p a t h s o f l e a s t r e s i s t a n c e c r e a t e d b y d e c o m p o s i n g r o o t s . E v i d e n c e f o r t h i s w a s g i v e n b y p o l l e n g r a i n s f o u n d i n t h e r o o t m a t o f P r o f i l e 2 5 . I t s h o u l d b e n o t e d h o w e v e r , t h a t o n B u r k e M o u n t a i n a n d i n C y p r e s s P a r k , m o s t c h a n n e l s d i d n o t o b v i o u s l y e x t e n d t o t h e s u r f a c e a n d t h a t n o e m p t y " p i p e s " w e r e f o u n d . I t s e e m s p r o b a b l e t h a t t h e o r g a n i c m a t e r i a l w i t h i n t h e s e s o i l s w a s s e c o n d a r i l y e n r i c h e d w i t h a l u m i n u m , a n d t o a l e s s e r e x t e n t , i r o n . I f l i v e t r e e r o o t s w e r e c a p a b l e o f a b s o r b i n g a n d s t o r i n g u p t o 10% a l u m i n u m , s u r e l y t h i s w o u l d h a v e b e e n n o t e d i n p r e v i o u s s t u d i e s . A l s o , a s t h e p e r c e n t a l u m i n u m i s o f t e n u p t o h a l f t h e p e r c e n t c a r b o n v a l u e , t h e h i g h a l u m i n u m c o u l d b e d u e t o t h e r e l a t i v e d e c o m p o s i t i o n o f c a r b o n . H o w e v e r , t h e c e l l u l a r n a t u r e o f t h e o r g a n i c m a t t e r a n d t h e r e s i d u a l w o o d s t r u c t u r e i n s o m e o f t h e m a t e r i a l m a k e s t h i s m u c h d e c o m p o s i t i o n s e e m d o u b t f u l . T h e l o w r e a c t i o n o f t h e s o i l s o n B u r k e M o u n t a i n w o u l d a l l o w a l u m i n u m t o s i t o n t h e e x c h a n g e s i t e s a s A l + ^ ( B o h n e_t a _ l . , 1 9 7 9 ) . T h i s e l e m e n t i s a l s o s o m e w h a t s o l u b l e w i t h i n t h e s o i l s o l u t i o n a t t h i s p H . D r i s c o l l e_t a _ l . ( 1 9 8 4 ) f o u n d t h a t i n o r g a n i c m o n o m e r i c a l u m i n u m l e v e l s i n c r e a s e d i n s t r e a m s y s t e m s o f t h e A d i r o n d a c k M o u n t a i n s , a s p H v a l u e s d e c r e a s e d . U n d e r t h e c o n d i t i o n s o f l o w +3 s o i l p H f o u n d o n B u r k e M o u n t a i n , A l c o u l d m o v e w i t h p e r c o l a t i n g r a i n w a t e r i n t o t h e r o o t c h a n n e l s w h e n t h e s o i l s a r e s a t u r a t e d , a s t h e c h a n n e l s a r e t h e p a t h w a y s o f l e a s t r e s i s t a n c e i n t h e s o i l . T h e p o s i t i v e c a t i o n m i g h t r e a c t w i t h t h e n e g a t i v e l y c h a r g e d a c i d s r e l e a s e d f r o m d e c o m p o s i t i o n o f r o o t s o r s u r f i c i a l m a t e r i a l , a n d b o t h b e c o m e n e u t r a l i z e d a n d i n s o l u b l e . I n a d d i t i o n , l i v e h e m l o c k 115 +3 r o o t s c o u l d a b s o r b A l from the exchange complex o r as i t moves w i t h i n the s o i l s o l u t i o n . Messenger (1975) found t h a t the e a s t e r n hemlock had e s p e c i a l l y h i g h l e v e l s of aluminum i n i t s f o l i a g e . A h i g h aluminum l e v e l i n the h o r i z o n of one l o c a l i z e d a r e a on Burke Mountain s u g g e s t s some mechanism must be b r i n g i n g aluminum t o the s o i l s u r f a c e . T h i s mechanism l e s s e a s i l y e x p l a i n s the h i g h aluminum l e v e l of r o o t mats on C y p r e s s Park and beneath some of the m i n e r a l h o r i z o n s on Burke M o u n t a i n . Here, m i n e r a l s o i l pH i s i n the range of 4.7-5.4 ( H 2 O ) , and a l t h o u g h the aluminum c o n t e n t of the r o o t mat r e a c h e s as h i g h as 9%, the s o i l i s t o o b a s i c f o r h i g h s o l u b i l i t y of the aluminum c a t i o n (Bohn e_t a_l. , 1979) A l s o , r o o t s on C y p r e s s Park seem c o n c e n t r a t e d i n the LFH. Few e x t e n d f a r enough i n t o the B h o r i z o n t o absorb l a r g e q u a n t i t i e s of the aluminum weathered from the m i n e r a l s o i l . Farmer (1981) f e l t t h a t the aluminum r e l e a s e d by w e a t h e r i n g i n a p o d z o l i c s o i l had a h i g h enough a f f i n i t y f o r the s i l i c o n i n the s o i l s o l u t i o n t h a t i t would r e a c t t o form p r o t o - i m o g o l i t e r a t h e r than aluminum h y d r o x i d e s . T h i s p o s i t i v e l y charged p r o t o - i m o g o l i t e s o l would be f u l l y m o b ile a t a pH l e s s than 5.0 and c o u l d move th r o u g h the p o s i t i v e l y charged B h o r i z o n . I t would p r e c i p i t a t e out of s o l u t i o n when the pH r i s e s above 5.0, when i t s charge was n e u t r a l i z e d by adsorbed a n i o n s o r when i t s p o s i t i v e c h a r g e s e n c o u n t e r e d n e g a t i v e l y charged s u r f a c e s . U s i n g e l e c t r o n m i c r o s c o p y , i n f r a r e d s p e c t r o s c o p y and x - r a y d i f f r a c t i o n , McKeague and Kodama (19 81) d e t e c t e d i m o g o l i t e i n the cement of the d u r i c h o r i z o n of the Whonnock s o i l s e r i e s on Burke 116 M o u n t a i n . They f e l t t h a t movement of p r o t o - i m o g o l i t e t h rough the a c i d m i n e r a l s o i l was p l a u s i b l e and, as the s t a b i l i t y of the p r o t o - i m o g o l i t e s o l d e c r e a s e d above 5.0 (Farmer and F r a s e r , 1982), the h i g h r e a c t i o n of the b a s a l t i l l c o u l d r e s u l t i n the p r e c i p i t a t i o n of p r o t o - i m o g o l i t e and perhaps the e v e n t u a l c e m e n t a t i o n of the h o r i z o n . C h i l d s e_t a_l. (1983) found t h a t i m o g o l i t e was a l s o p r e s e n t i n the cement of i n d u r a t e d h o r i z o n s i n New Z e a l a n d p o d z o l s . One such s o i l had p r o p e r t i e s somewhat s i m i l a r t o the Whonnock s o i l s e r i e s of t h i s s t u d y . The One Tree P o i n t p r o f i l e c o n t a i n e d l i t t l e v o l c a n i c ash, had i n d u r a t e d h o r i z o n s w i t h v e r y f i r m c o n s i s t e n c e , and had low weathered Fe t o weathered A l r a t i o s . I t a l s o p o s s e s s e d a r o o t mat a t a depth of 62 cm w i t h an o r g a n i c carbon c o n t e n t of 20% and an aluminum v a l u e of o v e r 9%. L i k e r o o t mat h o r i z o n s i n C y p r e s s P a r k , pyrophosphate aluminum was much lower than o x a l a t e aluminum and o x a l a t e - e x t r a c t a b l e s i l i c o n was h i g h . The presence of p r o t o - i m o g o l i t e a l l o p h a n e was d e t e c t e d t h roughout the p r o f i l e by these a u t h o r s and i t was found t h a t p r e d i c t i o n s of t h i s m i n e r a l by o x a l a t e e x t r a c t a b l e s i l i c o n v a l u e s ( a f t e r P a r f i t t , 1983) and by i n f r a r e d s p e c t r o s c o p y (Farmer e t a l . , 1980), showed good agreement i n the h o r i z o n s t e s t e d . They e s t i m a t e d a v a l u e of 18% p r o t o - i m o g o l i t e a l l o p h a n e i n the r o o t mat h o r i z o n by the h i g h o x a l a t e e x t r a c t a b l e s i l i c o n . In a d d i t i o n , up t o 5% f u l l y c r y s t a l l i z e d i m o g o l i t e was d e t e c t e d by e l e c t r o n m i c r o s c o p y i n the c l a y sample of the Bs h o r i z o n . P r o t o - i m o g o l i t e appeared t o cause i n d u r a t i o n of the m i n e r a l h o r i z o n s by f i l l i n g the a v a i l a b l e pore s p a c e s . 117 I f i m o g o l i t e i s r e s p o n s i b l e f o r the cement of the d u r i c h o r i z o n i m m e d i a t e l y u n d e r l y i n g the r o o t mat h o r i z o n s (McKeague and Kodama, 1981) and i f inde e d , i m o g o l i t e can o n l y form from a s o l u t i o n of p r o t o - i m o g o l i t e (Farmer and F r a s e r , 1978), perhaps t h i s m o bile a l u m i n o s i l i c a t e can a l s o c o n t r i b u t e t o the aluminum c o n c e n t r a t i o n of the o r g a n i c - r i c h mats and c h a n n e l s . I t i s i n t e r e s t i n g t o note t h a t i n the p r e s e n t s t u d y , whenever the pyrophosphate aluminum l e v e l of B h o r i z o n s and o r g a n i c a c c u m u l a t i o n s i s s u b s t a n t i a l l y l e s s than the o x a l a t e aluminum l e v e l , the o x a l a t e s i l i c o n l e v e l i s always h i g h (see e s p e c i a l l y the C y p r e s s Park r o o t mat h o r i z o n s ) . In a d d i t i o n , A l ( o x ) - A l ( p y r o ) / S i ( o x ) i s a p p r o x i m a t e l y 2, a l t h o u g h o f t e n a s l i g h t l y h i g h e r r a t i o i s found. Farmer (1984) r e p o r t e d t h a t the e x c e s s aluminum i n the r a t i o c o u l d a r i s e from e x t r a c t i o n of t h i s element from i n t e r s t r a t i f i e d hydroxyaluminum s p e c i e s . He f e l t t h a t the o x a l a t e - s o l u b l e S i v a l u e a l o n e , i s a s u r e r b a s i s f o r an e s t i m a t i o n of the p e r c e n t a l l o p h a n e p r e s e n t . In the r o o t mats of C y p r e s s P a r k , l e v e l s of a l l o p h a n e were c a l c u l a t e d by the method of P a r f i t t (1983). V a l u e s ranged between 17 and 23 p e r c e n t a l l o p h a n e . Column Study T e s t i n g the P r o t o - i m o g o l i t e Model A column study was u n d e r t a k e n t o t e s t a mechanism by which decomposing r o o t s c o u l d become e n r i c h e d w i t h h i g h aluminum l e v e l s , t h r o u g h a d s o r p t i o n from p r o t o - i m o g o l i t e . For p e r i o d s r a n g i n g from 2.5 weeks t o 3 months a s o l u t i o n of 0.01 M p r o t o - i m o g o l i t e was s l o w l y l e a c h e d t h rough a column of r o t t i n g 118 wood sandwiched between l a y e r s of Ottawa sand. Two c o n t r o l s were a l s o s e t up. The f i r s t was i d e n t i c a l w i t h the p r o t o - i m o g o l i t e column but l e a c h e d w i t h a s o l u t i o n of the same pH and approximate i o n i c c o n c e n t r a t i o n but w i t h o u t the aluminum and s i l i c o n . In the second c o n t r o l , the p r o t o - i m o g o l i t e s o l u t i o n was d r i p p e d through columns f i l l e d o n l y w i t h the Ottawa sand. To s i m u l a t e r a i n f a l l e v e n t s , p e r i o d s of p r o t o - i m o g o l i t e l e a c h i n g were a l t e r n a t e d w i t h p e r i o d s r a n g i n g from 16 hours t o 3 days, when no s o l u t i o n was added. R e s u l t s were e n c o u r a g i n g . A f t e r the f i r s t 250 mLs of p r o t o - i m o g o l i t e were l e a c h e d through the o r g a n i c - f i l l e d column, the l e a c h a t e was the y ellow-brown of f u l v i c a c i d s . The p r o t o - i m o g o l i t e was s i m p l y r e p l a c i n g the d i s t i l l e d water used t o make up the columns. The next 250 mLs of p r o t o - i m o g o l i t e i m m e d i a t e l y i m m o b i l i z e d the f u l v i c a c i d s i n the column and the l e a c h a t e was as c l e a r as d i s t i l l e d w ater. I t remained c l e a r t h roughout the d u r a t i o n of the e x p e r i m e n t . In c o n t r a s t , the l e a c h a t e from the o r g a n i c c o n t r o l was s t i l l s t a i n e d y e l l o w - b r o w n and c o n t i n u e d t o show a t l e a s t some c o l o u r even a f t e r i t was l e a c h e d f o r t h r e e months w i t h w a t e r . See photographs i n Appendix D. The o r g a n i c m a t t e r and sand were removed from the columns, a i r - d r i e d and a n a l y z e d f o r pyrophosphate and a c i d ammonium o x a l a t e e x t r a c t a b l e aluminum. A f t e r 1 month of l e a c h i n g , the o r g a n i c m a t t e r of the columns c o n t a i n e d 2% o x a l a t e e x t r a c t a b l e aluminum and a f t e r 2 months, the o r g a n i c m a t e r i a l c o n s i s t e d of F i g u r e 6 - 1 : P e r c e n t A l u m i n u m , E x t r a c t e d f r o m O r g a n i c M a t t e r a n d S a n d , b y A c i d A m m o n i u m O x a l a t e a n d N a P y r o p h o s p h a t e A f t e r 1 a n d 2 M o n t h s T r e a t m e n t w i t h P r o t o - i m o g o l i t e 1 month p r o t o -i m o g o l i t e 2 months p r o t o -i m o g o l i t e o r g a n i c c o n t r o l p y r o % A l 1 .47 1 .47 1 .42 0 . 0 1 0 . 0 1 0 . 0 1 Ox A l 2 . 0 5 1 . 9 5 1 .98 0 . 0 1 0 . 0 1 0 . 0 1 p y r o % A l 64 66 78 0 . 0 1 0 . 0 1 0 . 0 1 Ox A l 2 . 5 3 2 . 5 5 2 . 7 3 0 . 0 1 0 . 0 1 0 . 0 1 p y r o % A l 0 . 0 3 0 . 0 3 0 . 0 3 0 . 0 0 0 . 0 0 0 . 0 0 I ) \ / M u m i n u m v a l u e s o f a l l 3 r e p l i c a t e s a r e g i v e n 120 2.5% o x a l a t e aluminum. D u p l i c a t e columns showed good agreement and pyrophosphate aluminum v a l u e s were a l s o h i g h . See F i g u r e 6-1. N e i t h e r the Ottawa sand nor the o r g a n i c m a t t e r of the c o n t r o l s c o n t a i n e d s i g n i f i c a n t aluminum. O x a l a t e - e x t r a c t a b l e s i l i c o n v a l u e s averaged 0.57% and 0.80% f o r 1 and 2 months p r o t o - i m o g o l i t e t r e a t m e n t , r e s p e c t i v e l y , and c o r r e s p o n d e d w i t h p y r o p h o s p h a t e - e x t r a c t a b l e s i l i c o n v a l u e s a v e r a g i n g 0.43% and 0.48% f o r the same p e r i o d s . The f u l v i c a c i d s of the d e c a y i n g wood seemed c a p a b l e t o some e x t e n t of s c a v e n g i n g aluminum from the a l u m i n o s i l i c a t e s o l u t i o n and r e l e a s i n g s i l i c o n . A f t e r each 250 mL of s o l u t i o n was added t o the column, the l e a c h a t e was a n a l y z e d by atomic a b s o r p t i o n f o r ppm aluminum and s i l i c o n . The s t a r t i n g c o n c e n t r a t i o n of the l a b o r a t o r y s y n t h e s i z e d p r o t o - i m o g o l i t e was 100 ppm A l and 54 ppm S i . For the f i r s t few days, the o r g a n i c m a t t e r i n the columns adsorbed a l l of the aluminum added. The l e a c h a t e c o n t a i n e d 0 ppm aluminum and 20 ppm s i l i c o n . Upon each a d d i t i o n the pH dropped from a p p r o x i m a t e l y 4.5 i n the p r o t o - i m o g o l i t e e l u e n t t o 3.3 i n the subsequent l e a c h a t e , i n d i c a t i n g t h a t the adsorbed aluminum was exchanging w i t h hydrogen i o n s on the o r g a n i c m a t e r i a l . The amount adsorbed d e c r e a s e d w i t h time but s t i l l averaged 50-60% ( A l ) a f t e r 2.5 weeks and 4 l i t r e s of 0.01 M p r o t o - i m o g o l i t e had l e a c h e d t h rough the column. See Table 6-1. Even a f t e r an o r g a n i c - f i l l e d column had been t r e a t e d f o r 2-3 months w i t h p r o t o - i m o g o l i t e , the o r g a n i c m a t t e r was s t i l l a b l e t o adsorb an average of 10% aluminum from the e l u e n t . 121 I t i s i n t e r e s t i n g t o note t h a t the amount of aluminum adsorbed by the o r g a n i c m a t t e r i n c r e a s e d w i t h time between l e a c h i n g p e r i o d s . For example, o n l y 5 0% of the aluminum from p r o t o - i m o g o l i t e was adsorbed on A p r i l 24, a day a f t e r 500 mLs had been put t h rough the column. On A p r i l 27, a f t e r a 3 day p e r i o d when no l e a c h i n g took p l a c e , 60% aluminum was adsorbed. See Table 6-1. A l s o , the c o l o u r of the water c o n t r o l l e a c h a t e c o r r e s p o n d e d e x a c t l y w i t h the h i g h e r a d s o r p t i o n v a l u e s . The more aluminum adsorbed, the d a r k e r was the water l e a c h a t e , see Table 6-1 f o r ppm C d a t a . T h i s i n d i c a t e s t h a t f u l v i c a c i d - l i k e M a t e r i a l was b e i n g c o n s t a n t l y r e l e a s e d . I t b u i l t up d u r i n g the p e r i o d of i n a c t i v i t y and more was a v a i l a b l e t o r e a c t w i t h the aluminum o r t o be l e a c h e d out by the water i n the c o n t r o l columns. Carbon r e l e a s e d from the p r o t o - i m o g o l i t e o r g a n i c columns was e s t i m a t e d by the p e r c e n t absorbance of l i g h t a t 600 nm w a v e l e n t h . T h i s i n d i r e c t method seemed t o i n d i c a t e t h a t l e s s than 1 ppm c a r b o n was found i n t h i s l e a c h a t e . A c o n c e n t r a t i o n of 100 ppm aluminum i s of course very h i g h f o r a r e a l s o i l s o l u t i o n and o r g a n i c i m m o b i l i z a t i o n may be due t o n e u t r a l i z a t i o n of a c i d i c c h arges by t h i s h i g h c o n c e n t r a t i o n of c a t i o n s . In c o n t r a s t , the aluminum i n a p r o t o - i m o g o l i t e s o l u t i o n of v e r y low c o n c e n t r a t i o n may i n s t e a d be complexed by the a c i d s and the two move out of the r o o t l a y e r as a mobile complex. For t h i s r e a s o n , a s o l u t i o n w i t h o n l y 5 ppm aluminum was d r i p p e d through an o r g a n i c column and the aluminum of the l e a c h a t e measured by atomic a b s o r p t i o n . A l t h o u g h the e x p e r i m e n t was o n l y c o n t i n u e d f o r a few days w i t h a t o t a l of 1 l i t r e p r o t o - i m o g o l i t e 122 Table 6-1 - P e r c e n t Aluminum and S i l i c o n Adsorbed From P r o t o - i m o g o l i t e by O r g a n i c Columns and ppm Carbon r e l e a s e d by the C o n t r o l Columns (3 r e p l i c a t e s ) Date A p r i l mL p-im* (or H 20) P r o t o - i m o g o l i t e Columns % A l % S i adsorbed adsorbed Org. C o n t r o l s ppm C r e l e ased 10 500 100 83 90 11 750 100 100 100 67 61 61 59 50 54 11 1000 100 100 100 80 80 76 13 14 10 12 1250 98 99 97 46 52 48 35 34 36 12 1500 87 91 86 65 69 67 9 8 10 15 1750 99 100 98 22 22 22 58 64 65 15 2000 88 84 83 61 61 59 14 10 10 16 2250 80 81 79 46 44 44 19 20 19 18 2500 72 80 75 24 28 26 26 28 30 18 2750 61 60 65 35 35 35 7 8 9 19 3000 68 68 68 31 31 33 14 13 16 23 3250 73 74 72 30 30 30 42 44 45 23 3500 46 41 50 31 30 33 7 8 9 24 3750 49 50 51 30 28 30 13 12 14 27 4000 66 60 56 30 26 28 24 23 20 c u m u l a t i v e mL p r o t o - i m o g o l i t e o r water added 1 2 3 s o l u t i o n p u t t h r o u g h t h e c o l u m n , n o a l u m i n u m w a s f o u n d i n t h e l e a c h a t e a n d i t s c o l o u r i n d i c a t e d m u c h l e s s c a r b o n t h a n w a s p r e s e n t i n t h e w a t e r c o n t r o l . T h e o r g a n i c a c i d s d i d n o t a p p e a r t o p e p t i z e t h e p r o t o - i m o g o l i t e s o l n o r c a r r y t h e a l u m i n u m o u t i n c o m p l e x f o r m . I t i s a l s o i m p o r t a n t t o k e e p i n m i n d t h a t t h e r e w o u l d l i k e l y b e m u c h m o r e f u l v i c a c i d s a v a i l a b l e f o r r e a c t i o n i n t h e p r e v i o u s l y " p r o t e c t e d " r o t t i n g w o o d c o l l e c t e d f o r t h e c o l u m n s t u d y t h a n f r o m r o o t s s l o w l y d e c o m p o s i n g i n a s e e p a g e e n v i r o n m e n t . T o s e e i f t h e r o o t m a t s c o u l d b e s u b s e q u e n t l y e n r i c h e d w i t h f u l v i c a c i d s l e a c h i n g f r o m t h e s o i l s u r f a c e , a c i d s w e r e e x t r a c t e d w i t h d i s t i l l e d w a t e r f r o m r o t t i n g w o o d . T h e r e s u l t i n g y e l l o w - b r o w n l i q u i d w a s d r i p p e d i n t o a c o l u m n p r e v i o u s l y l e a c h e d f o r 2 m o n t h s w i t h p r o t o - i m o g o l i t e . A c c o r d i n g t o F i g u r e 6 - 1 t h e o r g a n i c m a t t e r s h o u l d c o n t a i n 2 . 5 % A l . A s a c o n t r o l , f u l v i c a c i d s w e r e a l s o l e a c h e d t h r o u g h a n o r g a n i c c o l u m n w i t h n o p r e v i o u s p r o t o - i m o g o l i t e t r e a t m e n t a n d t h e r e f o r e , w i t h a v e r y l o w a l u m i n u m c o n c e n t r a t i o n . A l t h o u g h t h e o r g a n i c a c i d s e x t r a c t e d f r o m t h e r o t t i n g w o o d h a d c o l o u r e d t h e d i s t i l l e d w a t e r a y e l l o w - b r o w n , a f t e r p a s s i n g t h r o u g h a c o l u m n p r e v i o u s l y t r e a t e d w i t h p r o t o - i m o g o l i t e , t h e l e a c h a t e w a s a s c l e a r a s d i s t i l l e d w a t e r . T h e a l u m i n u m - o r g a n i c m a t t e r h a d i m m o b i l i z e d t h e c o l o u r e d o r g a n i c a c i d s . T h e l e a c h a t e o f t h e c o n t r o l w a s t h e s a m e c o l o u r o r m u c h d a r k e r t h a n t h e a d d e d e x t r a c t e d f u l v i c a c i d s a n d t h e ppm C o f t h e l e a c h a t e w a s u s u a l l y m u c h h i g h e r . S e e p h o t o g r a p h s i n A p p e n d i x D a n d T a b l e 6 - 2 . 124 Table 6-2 - ppm C i n F u l v i c A c i d P r i o r t o and Subsequent t o T h e i r L e a c h i n g Through Two O r g a n i c Columns; The F i r s t P r e v i o u s l y T r e a t e d With P r o t o - i m o g o l i t e and the Second Not Date ppm C i n ppm C i n ppm C i n A p r i l f u l v i c a c i d l e a c h a t e #1 l e a c h a t e #2 11 45.44 4.73 76.98 11 45.44 4.57 35.65 12 49.86 7.01 45.98 16 64.81 9.43 107.90 18 72.94 5.31 43.81 19 35.61 4.84 54.56 19 35.61 3.17 31.81 23 37.05 6.56 55.97 23 37.05 3.66 35.90 24 44.25 4.03 38.44 27 61.02 6.80 57.67 l e a c h a t e #1 i s the l e a c h a t e from the column p r e v i o u s l y t r e a t e d f o r 2 months w i t h p r o t o - i m o g o l i t e l e a c h a t e #2 i s the l e a c h a t e from the c o n t r o l column w i t h no p r e v i o u s p r o t o - i m o g o l i t e t r e a t m e n t and no aluminum The above r e s u l t s seem t o i n d i c a t e t h a t i f indeed p r o t o - i m o g o l i t e i s moving through these s o i l s , the o r g a n i c m a t e r i a l of decomposing wood c o u l d adsorb aluminum from t h i s c o l l o i d and r e l e a s e a t l e a s t a p o r t i o n of the s i l i c o n . The mechanism by which t h i s would o p e r a t e i s i l l u s t r a t e d i n F i g u r e 6-2. Because n e i t h e r the aluminum nor the f u l v i c a c i d s are l e a v i n g the r o o t mat environment the p e r c e n t aluminum would i n c r e a s e and the Ch/Cf decrease w i t h t i m e . In a d d i t i o n , f u l v i c a c i d s l e a c h i n g from the s o i l s u r f a c e c o u l d r e a c t w i t h the aluminum a l r e a d y h e l d by the decomposing r o o t s and p r e c i p i t a t e out i n t h i s e n v i r o n m e n t . Of c o u r s e , i f s m a l l f u l v i c a c i d s were themselves c a r r y i n g aluminum, t h i s element and f u l v i c a c i d s i n the r o o t mats and c h a n n e l s would be f u r t h e r e n r i c h e d . F i g u r e 6-2: D i a g r a m a t i c R e p r e s e n t a t i o n of I n o r g a n i c P r o t o - i m o g o l i t e Moving Through the S o i l and R e a c t i n g w i t h F u l v i c A c i d s R e l e a s e d by Decomposing Roots Duripan 126 The p r o t o - i m o g o l i t e t h e o r y of p o d z o l i z a t i o n as e n v i s i o n e d by Farmer (1980) has come under c r i t i c i s m from v a r i o u s s o u r c e s . Buurman and van Reeuwyk (1984) f e e l the presence of i m o g o l i t e w i t h i n B h o r i z o n s can be e x p l a i n e d by i t s n e o f o r m a t i o n from s i l i c a p e r c o l a t i n g w i t h i n the s o i l s o l u t i o n and from aluminum r e l e a s e d by d e c o m p o s i t i o n of o r g a n i c complexes. The a u t h o r s q u e s t i o n the t u r n o v e r r a t e of Al-humus complexes as quoted by Farmer e_t a_l. (1980) and a l s o f e e l t h a t s i m p l e o r g a n i c a c i d s such as c i t r i c , l a c t i c , o x a l i c , m a l i c , s u c c i n i c , g l u c u r o n i c , v a n i l l i c , p-coumaric and p - h y d r o x y b e n z o i c may r e s i s t decompositon f o r a long enough p e r i o d t o be an i m p o r t a n t agent i n the t r a n s p o r t a t i o n of aluminum through t o the B h o r i z o n . Chesworth and Macias-Vasquez (1985) a n a l y z e d the problem of an o r g a n i c vs i n o r g a n i c mechanism r e s p o n s i b l e f o r p o d z o l g e n e s i s , i n terms of the range of pH and e l e c t r o d e p o t e n t i a l (pE) common i n p o d z o l i c s o i l s and i n terms of the s o l u b i l i t y of v a r i o u s forms of i r o n , aluminum and s i l i c o n a t these pH and pE l e v e l s . They found t h a t i f amorphous aluminum and i r o n h y d r o x i d e s were used to determine the s o l u b i l i t i e s of the m e t a l s i n the s o i l s o l u t i o n and t h a t i f q u a r t z was r e s p o n s i b l e f o r the s o l u b i l i t y of s i l i c a , a g e o c h e m i c a l fence c o u l d be c o n s t r u c t e d t h a t a ccounted f o r p r e c i p i t a t i o n of amorphous phases w i t h i n the B h o r i z o n . I t c o u l d not a c c o u n t , however, f o r the f o r m a t i o n of the Ae h o r i z o n under a l l b u t the most a c i d c o n d i t i o n s . By adding the e f f e c t of o r g a n i c m a t t e r t o t h e i r pH-pE diagram, they were a b l e t o c o n s t r u c t a g e o c h e m i c a l fence s e p a r a t i n g c o n d i t i o n s under which an a l b i c h o r i z o n s would form c o n s i s t e n t w i t h those found i n the 127 r e a l s o i l . In c o n t r a s t , Chesworth and Macias-Vasquez c o u l d f i n d no e v i d e n c e t h a t i m o g o l i t e c o u l d c o n t r o l the m o b i l i t y of aluminum under the pH and pE of a p o z o l i c s o i l , t o form the Ae h o r i z o n but found t h a t once A l had been m o b i l i z e d by a n o t h e r mechanism, i m o g o l i t e c o u l d c o n t r o l i t s p r e c i p i t a t i o n w i t h i n the B h o r i z o n . In f a i r n e s s t o Farmer, however, h i s t h e o r y of p o d z o l i z a t i o n does not depend on the s o l u b i l i t y of i m o g o l i t e w i t h i n the a l b i c h o r i z o n . I m o g o l i t e i s a m i n e r a l he sees forming w i t h i n the lower B h o r i z o n , i f c o n d i t i o n s are r i g h t , from " p r o t o - i m o g o l i t e " . P r o t o - i m o g o l i t e , i t s e l f , would form from the aluminum r e l e a s e d upon the d e c o m p o s i t i o n of s m a l l a c i d s and from the s i l i c a i n the s o i l s o l u t i o n and i t would not p r e c i p i t a t e i m m e d i a t e l y out of s o l u t i o n , i f the s o i l pH i s below 5.0 and i f n e g a t i v e s u r f a c e s are not a v a i l a b l e t o adsorb i t . I n s t e a d i t would t r a v e l t h r ough the s u b s o i l and p r e c i p i t a t e when c o n d i t i o n s change, such as under the h i g h e r pH of the lo w e r B h o r i z o n . C o n c l u s i o n s From the e v i d e n c e g a t h e r e d on Burke Mountain and i n C y p r e s s Park a l l h y potheses proposed f o r the g e n e s i s of the r o o t mats and c h a n n e l s may have some v a l i d i t y . The predominant f o r c e r e s p o n s i b l e i n an i n d i v i d u a l a r e a may be dependant upon the p r e v a l e n t e n v i r o n m e n t a l c o n d i t i o n s , such as s o i l pH, t e x t u r e and m i n e r a l o g y , i n t e r a c t i n g w i t h the t r e e s p e c i e s growing on the s i t e . M o r p h o l o g i c a l e v i d e n c e s u g g e s t s t h a t l a r g e t r e e r o o t s p l a y an i m p o r t a n t r o l e i n p u s h i n g a s i d e the s o i l and c r e a t i n g the 128 i n i t i a l space f o r o r g a n i c m a t e r i a l s t o f i l l . However, p a r t i c u l a t e m a t t e r p e r c o l a t i n g down paths of l e a s t r e s i s t a n c e from the s o i l s u r f a c e , must a l s o c o n t r i b u t e t o the o r g a n i c m a t e r i a l , as e v i d e n c e d by p o l l e n g r a i n s found w i t h i n one p r o f i l e a t a depth of 78 cm. As the r o o t s are f u r t h e r decomposed, the r o l e of p a r t i c u l a t e m a t t e r i n f i l l i n g the c h a n n e l s may become even more i m p o r t a n t . High aluminum l e v e l s imply t h a t p o d z o l i c mechanisms must a l s o c o n t r i b u t e t o the b u l k of m a t e r i a l w i t h i n the c h a n n e l s and mats and s u p p o r t can be found f o r b o t h mechanisms of p o d z o l g e n e s i s p r e s e n t e d i n C h a p t e r 2. I f p r o t o - i m o g o l i t e does indeed move through these w e l l weathered s o i l s , perhaps the r o o t mats and c h a n n e l s on Burke Mountain and i n C y p r e s s Park are a t d i f f e r e n t s t a g e s of development. As the r o o t s decompose, they r e l e a s e f u l v i c a c i d s which p r e c i p i t a t e w i t h the p r o t o - i m o g o l i t e m i g r a t i n g a t a pH below 5.0. As more f u l v i c a c i d s are r e l e a s e d they scavenge the aluminum from the p r o t o - i m o g o l i t e and r e l e a s e the s i l i c a . I f r o o t s grow down i n t o the B h o r i z o n they may be a b l e t o absorb the + 3 aluminum from p r o t o - i m o g o l i t e moving through the s o i l , from A l s i t t i n g on the exchange, and upon d e c o m p o s i t i o n from o r g a n i c complex. The aluminum would then be c y c l e d upwards where i t would be r e l e a s e d t o e n r i c h the LFH and the r o o t c h a n n e l s c l o s e r t o the s u r f a c e . I t w i l l r e q u i r e the r e s e a r c h of the n e x t few y e a r s t o determine i f the p r o t o - i m o g o l i t e t h e o r y of p o d z o l i z a t i o n has any v a l i d i t y and t h e r e f o r e , i f i t can be a p p l i e d t o the g e n e s i s of aluminum r i c h r o o t mats and c h a n n e l s . 129 SUMMARY AND CONCLUSIONS Mats and c h a n n e l s of h i g h o r g a n i c c o n t e n t w i t h i n p o d z o l s of the Coast Mountains s u r r o u n d i n g Vancouver were c h a r a c t e r i z e d f o r a number of m o r p h o l o g i c a l and c h e m i c a l p r o p e r t i e s . Based on these a n a l y s e s the f o l l o w i n g c o n c l u s i o n s c o u l d be drawn: 1. The mats tended t o s i t above a hardpan o r p a r t i c l e s i z e d i s c o n t i n u i t y , ranged from 1 cm t o more than 40cm t h i c k and were l o c a t e d a t depths of a p p r o x i m a t e l y one metre under a r e l a t i v e l y c o a r s e t e x t u r e d m i n e r a l s o i l . The c h a n n e l s r a n o b l i q u e l y and v e r t i c a l l y through the s o i l , o f t e n had the g r o s s morphology of r o o t s and were up t o 5 cm wide. Both c h a n n e l s and mats c o n t a i n e d o r g a n i c m a t e r i a l t h a t was "greasy" t o the touch and had a c e l l u l a r n a t u r e under the m i c r o s c o p e . O c c a s i o n a l l y remnants of wood s t r u c t u r e c o u l d be determined jun s i t u but when removed from the p r o f i l e the s t r u c t u r e was e a s i l y c r u s h e d between the f i n g e r s , o f t e n w i t h no r e s i d u a l f i b e r c o n t e n t . 2. Most of the c h a n n e l s and mats of Burke Mountain c o n t a i n e d g r e a t e r than 17% o r g a n i c carbon on an o v e n - d r i e d b a s i s and few m i n e r a l g r a i n s c o u l d be d e t e c t e d . Carbon v a l u e s i n C y p r e s s Park tended t o be lower, m i n e r a l g r a i n s were o b v i o u s and the r o o t s appeared l e s s w e l l decomposed. P e r c e n t t o t a l n i t r o g e n and s u l p h u r v a l u e s were r e l a t i v e l y low a t b o t h s i t e s but C/N and N/S r a t i o s were f a i r l y t y p i c a l f o r o r g a n i c m a t e r i a l of a f o r e s t e d s i t e . S o i l r e a c t i o n of s u r f a c e o r g a n i c h o r i z o n s was e x t r e m e l y 130 low but v a l u e s i n c r e a s e d w i t h depth. The pH of the lower h o r i z o n s of C y p r e s s Park were n o t a b l y h i g h e r than those of Burke M o u n t a i n . I r o n e x t r a c t e d w i t h sodium pyrophosphate, a c i d ammonium o x a l a t e and c i t r a t e b i c a r b o n a t e d i t h i o n i t e was u s u a l l y h i g h e s t near the top of the B h o r i z o n , where v a l u e s commonly ranged between 1 and 2%, but dropped t o f a i r l y low v a l u e s w i t h depth. W i t h i n the r o o t mats, e x t r a c t a b l e i r o n sometimes i n c r e a s e d a g a i n , up t o the l e v e l found near the top of the B h o r i z o n , a l t h o u g h no i n c r e a s e was n o t e d a t s i t e s sampled i n C y p r e s s P a r k . E x t r a c t a b l e i r o n i n r o o t c h a n n e l s u s u a l l y r e f l e c t e d the amount of i r o n i n the s u r r o u n d i n g m i n e r a l s o i l . In c o n t r a s t t o i r o n , aluminum i n a l l e x t r a c t a n t s i n c r e a s e d d r a m a t i c a l l y i n the mats and c h a n n e l s over v a l u e s found i n the m i n e r a l s o i l . In some r o o t mat h o r i z o n s , g r e a t e r than 10% aluminum ( o f t e n more than h a l f the p e r c e n t carbon v a l u e ) c o u l d be e x t r a c t e d by a c i d ammonium o x a l a t e . In most s o i l s on Burke Mountain, pyrophosphate aluminum l e v e l s a l m o s t e q u a l l e d o x a l a t e aluminum, o x a l a t e s i l i c o n was low, the humic t o f u l v i c r a t i o was w e l l below 0.5 and the p o l y p h e n o l i c t o t o t a l f u l v i c r a t i o was h i g h . T h i s s u g g ested t h a t most of the aluminum was bound w i t h the o r g a n i c m a t e r i a l . Data g a t h e r e d from C y p r e s s Park s i t e s p r e s e n t e d a s l i g h t l y d i f f e r e n t p i c t u r e . While o x a l a t e aluminum l e v e l s averaged g r e a t e r than 8%, pyrophosphate e x t r a c t a b l e aluminum l e v e l s were much l o w e r than o x a l a t e aluminum and o x a l a t e s i l i c o n v a l u e s were h i g h . The r a t i o of [ o x a l a t e A l - pyrophosphate A l / o x a l a t e S i ] 131 was a p p r o x i m a t e l y 2 i n d i c a t i n g the presence of a m i n e r a l s i m i l a r t o the p r o t o - i m o g o l i t e a l l o p h a n e found by C h i l d s e_t a_l. (1983 ) i n an i n d u r a t e d New Zealand p o d z o l . T h i s New Zealand s o i l a l s o had a r o o t mat w i t h 20% ca r b o n , 9% aluminum and a h i g h o x a l a t e s i l i c o n v a l u e . The humic t o f u l v i c r a t i o s were sometimes h i g h e r and the p o l y p h e n o l i c f u l v i c t o t o t a l f u l v i c r a t i o s were lower than those found on Burke Mountain. At b o t h s i t e s , r o o t mats and r o o t c h a n n e l s have s i m i l a r v a l u e s i n a l l c h e m i c a l e x t r a c t a n t s e x c e p t f o r those of i r o n . In the l a t t e r case the mats and c h a n n e l s seem t o r e f l e c t t h e i r p o s i t i o n i n the m i n e r a l s o i l . 3. The r o o t mats c o u l d e i t h e r be c l a s s i f i e d as o r g a n i c o r m i n e r a l depending on t h e i r p e r c e n t carbon c o n t e n t . I t was ve r y i m p o r t a n t t h a t c l a s s i f i c a t i o n be made on an o v e n - d r i e d b a s i s as the h i g h l y o r g a n i c mats and c h a n n e l s r e t a i n e d r e l a t i v e l y more water on a i r - d r y i n g than s u r f i c i a l o r g a n i c h o r i z o n s and the s u r r o u n d i n g m i n e r a l s o i l s . I f the carbon c o n t e n t was g r e a t e r than 17%, the h o r i z o n s met b o t h the c l a s s i f i c a t i o n c r i t e r i a of an 0 and of an H h o r i z o n . They have been c l a s s i f i e d as H2 i n t h i s r e p o r t as t h i s d e s i g n a t i o n seems t o b e t t e r r e f l e c t t h e i r a s s o c i a t i o n w i t h a f o r e s t e d e nvironment. The Canadian system s h o u l d be more s t r o n g l y c l a r i f i e d and l e s s s u b j e c t i v e i n r e g a r d s t o o r g a n i c h o r i z o n c l a s s i f i c a t i o n . When the r o o t mat c o n t a i n e d l e s s than 17% ca r b o n , pyrophosphate e x t r a c t a b l e i r o n p l u s aluminum was more than an o r d e r of magnitude g r e a t e r than t h a t r e q u i r e d t o meet p o d z o l i c c l a s s i f i c a t i o n . I t a l s o met the c r i t e r i a of a " p o d z o l i c Bhf" 132 when i t was g r e a t e r than 10 cm t h i c k . On s o i l d e s c r i p t i o n forms, r o o t c h a n n e l s s h o u l d be d e s c r i b e d under a d d i t i o n a l n o t e s . 4. I t seems c e r t a i n t h a t a t l e a s t i n i t i a l l y , r o o t d e c o m p o s i t i o n was i n v o l v e d i n the g e n e s i s of the o r g a n i c - r i c h zones. P a r t i c u l a t e o r g a n i c m a t t e r , p e r c o l a t i n g down p a t h s of l e a s t r e s i s t a n c e (decomposing r o o t c h a n n e l s ) may a l s o add t o the bul k of m a t e r i a l i n the mats and c h a n n e l s , as seen by p o l l e n g r a i n s found a t depths of 78 cm. P o d z o l i c p r o c e s s e s must a l s o p l a y a r o l e but j u s t as the mechanisms of p o d z o l g e n e s i s i n the m i n e r a l s o i l are s t i l l somewhat u n c l e a r , so too are the means of i r o n and aluminum enr i c h m e n t of the accumulated o r g a n i c m a t e r i a l . On Burke Mountain, c h e m i c a l p r o p e r t i e s suggest the t r a n s p o r t of aluminum i n o r g a n i c complex. The pH i s so low i n these s o i l s + 3 t h a t the exchange complex must be co v e r e d w i t h A l . As r o o t s are p l e n t i f u l w i t h i n the top of the B h o r i z o n and w i t h i n the r o o t c h a n n e l s of many p r o f i l e s , these c o u l d be c y c l i n g the m e t a l s t o the s u r f a c e and from here the complex may move down the r o o t + 3 c h a n n e l s . A l s o , a t an a c i d pH, enrichment from A l , s o l u b l e i n the s o i l s o l u t i o n , cannot be r u l e d o u t . In c o n t r a s t , the c h e m i c a l p r o p e r t i e s of C y p r e s s Park s o i l s s uggest t h a t a l a r g e p o r t i o n of the aluminum w i t h i n the r o o t mats i s p r e s e n t as a l l o p h a n e w i t h an A l : S i r a t i o c l o s e t o t h a t found i n i m o g o l i t e . In a d d i t i o n , many of the B h o r i z o n s on b o t h Burke Mountain and C y p r e s s Park have a much h i g h e r o x a l a t e aluminum than pyrophosphate aluminum, a h i g h o x a l a t e s i l i c o n v a l u e and a number are p a r t i a l l y cemented. On Burke Mountain the s t r o n g cement of the d u r i c h o r i z o n has been shown t o c o n s i s t of aluminum 133 and s i l i c o n (McKeague and Kodama, 1981). C y p r e s s Park s o i l s d i f f e r e d from s o i l s of Burke Mountain i n s e v e r a l o t h e r r e s p e c t s . They had a h i g h e r pH a t which the s o l u b i l i t y of aluminum would be very low and i t s importance on the exchange complex would be much l e s s . The r o o t s of the p r o f i l e s examined on C y p r e s s Park were c o n c e n t r a t e d w i t h i n the l i t t e r l a y e r and d i d not v e n t u r e f a r i n t o the B h o r i z o n . A l l of t h i s s u g g e s t s a s m a l l e r amount of aluminum would be c y c l e d by v e g e t a t i o n . The remains of r o o t s were f a i r l y o b v i o u s w i t h i n the r o o t mat and t h i s i s r e f l e c t e d i n humic t o f u l v i c and p o l y p h e n o l i c f u l v i c t o t o t a l f u l v i c r a t i o s t h a t are o f t e n not as extreme as those of Burke Mountain. These r a t i o s c o u l d a l s o be i n t e r p r e t e d as h a v i n g a s m a l l e r i n f l u e n c e by p e r c o l a t i n g f u l v i c a c i d s . A column study demonstrated t h a t i f p r o t o - i m o g o l i t e was indeed moving through the m i n e r a l s o i l , i t c o u l d r e a c t w i t h f u l v i c a c i d - t y p e m o l e c u l e s , r e l e a s e d upon d e c o m p o s i t i o n of o r g a n i c m a t e r i a l s , and b o t h aluminum and f u l v i c a c i d would p r e c i p i t a t e . Research r e p o r t e d by Farmer (1981) suggested t h a t i f the f u l v i c a c i d c o n c e n t r a t i o n was much h i g h e r than t h a t of the p r o t o - i m o g o l i t e , the f u l v i c a c i d would scavenge the aluminum from the p o s i t i v e c o l l o i d and r e l e a s e s i l i c o n . C o - p r e c i p i t a t i o n would occur a t a l o w e r r a t i o of COOH:Al. Which e v e r mechanisms of p o d z o l i z a t i o n are found i n the f u t u r e t o be v a l i d , i t seems r e a s o n a b l e t o assume t h a t s i m i l a r mechanisms t o those o p e r a t i n g i n the m i n e r a l s o i l , are e n r i c h i n g the r o o t mats w i t h Fe and A l . T h e r e f o r e , r o o t mats w i t h carbon 134 c o n t e n t s l e s s than 17% are c o r r e c t l y c l a s s i f i e d a " p o d z o l i c " Bhf h o r i z o n . 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Amorphous c l a y c o n s t i t u e n t s of s o i l s . Adv. Agron. 26:211-260. Wada, K. and T. H i g a s h i . 1976. The c a t e g o r i e s of aluminum- and iron-humus complexes i n Ando s o i l s d e t e r m i n e d by s e l e c t i v e d i s s o l u t i o n . J . S o i l S c i . 27:357-368. Wada, K. and N. Yo s h i n a g a . 1969. The s t r u c t u r e of i m o g o l i t e . Amer. M i n e r . 54:50-71. Wada, K., N. Yo s h i n a g a , H. Yotsumoto, K. Ibe and S. A i d a . 1970. C l a y M i n e r a l s 8:487-489. Walker, E. R. 1961. A s y n o p t i c c l i m a t o l o g y f o r p a r t s of the western C o r d i l l e r a . M c G i l l U n i v . A r t i e M e t e o r o l o g y Research Group, M e t e o r o l o g i c a l P u b l i c a t i o n # 35, S c i e n c e Report #8. 218pp. Weaver, R. M., J . K. S y e r s and M. L. J a c k s o n . 1968. D e t e r m i n a t i o n of s i l i c a i n c i t r a t e - b i c a r b o n a t e - d i t h i o n i t e e x t r a c t s of s o i l . S o i l S c i . Soc. Amer. P r o c . 32:497-501. W r i g h t , J . R. and M. S c h n i t z e r . 1963. M e t a l l o - o r g a n i c i n t e r a c t i o n s a s s o c i a t e d w i t h p o d z o l i z a t i o n . S o i l S c i . Soc. Amer. P r o c . 27:171-176. 145 W r i g h t , J . R., M. S c h n i t z e r and R. L e v i c k . 1958. Some c h a r a c t e r i s t i c s of the o r g a n i c m a t t e r e x t r a c t e d by d i l u t e i n o r g a n i c a c i d s from a p o d z o l i c B h o r i z o n . Can. J . S o i l S c i . 38:14-22. Y o s h i n a g a , N. and S. Aomine. 1962a. A l l o p h a n e i n some Ando s o i l s . S o i l S c i . P l a n t N u t r . 8:6-13. Y o s h i n a g a , N. and S. Aomine. 1962b. I m o g o l i t e i n some Ando s o i l s . S o i l S c i . P l a n t N u t r . 8:22-29. Yos h i n a g a , N., M. N a k a i , T. Minagawa and T. Henmi. 1984. Fo r m a t i o n of i m o g o l i t e and a l l o p h a n e i n s h a t t e r e d sandstone u n d e r l y i n g brown f o r e s t s o i l . S o i l S c i . P l a n t N u t r . 30:555-567. Appendix A: C h e m i c a l P r o p e r t i e s of the s o i l s a t the Burke Mountain and C y p r e s s Park Sampling S i t e s P r o f i l e 1 - Road c u t on Burke Mountain H o r i z o n Depth T e x t u r e % C T %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) i J. P y r o Ox CBD Pyro Ox CBD P y r o Ox CBD H 20 C a C l , Ch/Cf Ca/Cf %Ce LF 10-04 O • H 04-00 O 42.29 1.60 26 0.55 3.56 3.03 3.11 0.24 50 Ae 00-02 LS 2.10 0.084 25 3.79 3.29 Bhf 02-36 SL 5.63 0.180 31 1.60 1.61 1.84 1.64 1.86 1.64 0.14 0.20 0.19 4.60 4.12 Bf 1 36-61 SL 2.55 0.084 30 0.21 0.55 0.54 0.97 1.99 1.23 0.08 0.54 0.20 4.76 4.41 Bf 2 61-89 SL 1.71 0.050 34 0.21 0.59 0.57 0.77 1.24 0.96 0.09 0.29 0.25 4.72 4.56 H2 89-95 O 22.02 0.738 30 0. .1278 0. 77 0.83 0.76 8.72 9.24 8.71 0.62 0.62 0.62 4.73 4.29 0.17 0.74 102 Ccg 95 + FSL 0.60 0.014 42 0.04 0.41 0.44 0.30 0.75 0.32 0.06 0.28 0.00 4.96 5.03 RC 44-60 O 25.58 0.928 28 0. .1461 1.39 1.54 1.59 8.62 8.99 8.61 0.55 0.60 0.53 4.38 4.31 0.23 0.72 107 Notes: 1. The r o o t c h a n n e l had the shape of a l i v e b r a n c h i n g r o o t and e x t e n d e d from 25 cm t o 10cm above the H2 h o r i z o n . 2. The sampled r o o t c h a n n e l was 6 cm wide. 3. The C h o r i z o n was s t r o n g l y cemented 4. The HI was sampled s l i g h t l y back from the road c u t , i n the f o r e s t . P r o f i l e 2 - Road c u t on Burke Mountain H o r i z o n Depth T e x t u r e % C T %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 1 P y r o Ox CBD Pyro Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LFH 25-00 0 Ae 00-05 LS 1.45 0.062 23 3.54 3.01 Bhf 05-26 SL 9.97 0.327 31 1.55 1.57 1.67 1.29 1.36 1.23 0.10 0.11 0.15 3.94 3.54 0.44 0.79 94 Bhf 2 26-43 SL 5.42 0.195 28 0.61 2.08 2.21 1.41 5.18 1.37 0.08 1.44 0.17 4.95 4.52 Bf 43-70 SL 2.16 0.0 70 31 0.21 0.72 0.69 0.85 2.89 1.27 0.06 0.96 0.18 4.95 4.73 H2 70-73 0 20.35 0.808 25 1.43 1.50 1.58 8.27 9.28 7.96 0.99 1.21 1.04 4.49 4.41 0.21 0.68 97 Ccg 73 + FSL 0.56 RC 45-65 O 24.92 0.843 30 0.1513 0.75 0.85 0.80 8.63 8.93 8.42 0.80 0.84 0.75 4.47 4.27 0.28 0.74 100 Notes: 1. The p r o f i l e was a heterogeneous m i x t u r e of 60% " r e d " Bf s o i l and 40% Bhf m a t e r i a l . 2. In p l a c e s , the H2 s p l i t v e r t i c a l l y i n t o two 2 cm h o r i z o n s s e p a r a t e d by 10 cm o f Bf m a t r i x . 3. No s u i t a b l e HI h o r i z o n was a v a i l a b l e to sample. 4. The r o o t c h a n n e l was 2 cm wide. P r o f i l e 3 - Road c u t on Burke Mountain H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe % A l % S i pH e x t r a c t e d (era) P y r o Ox CBD Py r o Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/C£ Ca/Cf %Ce LF 10-05 0 H 05-00 O 33.73 1.122 30 0.33 1.05 0.02 3.41 Ae 00-03 SL 2.74 0.123 22 3.48 2.99 Bhf 03-10 SL 8.63 0.346 25 1.52 1.59. .1.71 0.59 0.59 0.55 0.05 0.05 0.14 3 .5 8 3 .2 0 0.51 0.75 71 B£l 10-30 SL 3.05 0.113 27 0.16 0.75 0.84 0.96 3.21 1.52 0.07 0.85 0.22 4.83 4.70 0.10 0.63 70 B£2 30-52 SL 4.95 0.164 30 0.36 0.77 0.82 1.39 2.18 1.70 0.12 0.38 0.20 4.62 4.20 H2 52-68 O 29.34 0.971 30 0.1529 0.56 0.62 0.66 7.12 7. 45 7.03 0.28 0.29 0.24 4.45 4.19 0.39 0.73 81 Bfc 68-92 SL 3 .92 0.113 35 0.46 0.67 0.84 1.51 2.66 2.00 0.14 0.60 0.35 4.77 4.42 Ccg 92 + SL 0.79 0.022 35 0.10 0.39 0.35 0.33 0.75 0.38 0.05 0.24 0.08 4.84 4.69 Notes: 1. Very t h i c k H2 h o r i z o n . 2. Moderate c e m e n t a t i o n i n the B f c , s t r o n g i n the d u r i c h o r i z o n . P r o f i l e 4 - Road c u t on Burke Mountain H o r i z o n Depth T e x t u r e %C C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 1 Pyro Ox CBD Pyro Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 20-05 O H 05-00 O 30.45 0.917 33 1.38 1.19 0.00 3.87 3.38 2.86 0.53 72 Ae 00-01 SL Bf 1 01-30 SL 3.83 0.192 20 1.36 1.40 1.58 0.62 0.64 0.63 0.07 0.05 0.13 4.26 3.70 Bf2 30-71 SL 3.54 0.101 35 0.60 0.72 0.80 1.28 1.36 1.22 0.09 0.12 0.15 4.46 4.20 0.08 0.72 88 H2 71-74 O 25.68 0.850 30 0.1382 2.05 2.09 2.10 7.40 7. 76 7.34 0.20 0.24 0.27 4.45 4.16 0.17 0.73 100 Ccg 74+ FSL 0.38 0.010 38 0.06 0.30 0.39 0.18 0.51 0.24 0.04 0.20 0.07 4.92 4.71 Notes: 1. The Ae was too t h i n t o sample. 4^ CO P r o f i l e 5 - Road c u t on Burke Mountain H o r i z o n Depth T e x t u r e %c T C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 P y r o Ox CBD Pyro Ox CBD P y r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LFH 18-00 O Ae 00-04 SL Bf 1 04-33 SL 4.58 0.165 28 0.60 0.98 1.11 1.30 3.16 1.77 0.09 0.74 0.22 4.47 4.26 Bf 2 33-91 SL 2.75 0.090 30 0.35 0.39 0.54 1.29 1.50 1.31 0.17 0.25 0.22 4.65 4.53 0.10 0.65 88 H2 91-99 O 23.89 0.855 28 0.1417 0.99 1.13 1.04 9.45 10.19 9.18 0.78 0.82 0.78 4.46 4.19 0.18 0.69 103 Ccg 99 + FSL 0.42 URC1 11-13 O 21.15 0.679 31 1.76 1.75 1.93 6.76 7.03 6.80 0.33 0.33 0.35 4.38 4.20 0.18 0.74 99 LRC1 32-35 O 19.83 0.686 29 0.34 0.34 0.36 8.06 8.18 7.64 0.67 0.73 0.73 4.46 4.34 0.21 0.68 103 RC2 25-28 O 18.97 0.640 30 0.1105 1.13 1.57 1.54 7.80 8.32 7.74 0.88 1.02 0.86 4.43 4.41 0.17 0.65 96 Notes: 1. Two samples were taken from r o o t c h a n n e l #1 - the upper c h a n n e l (URC) and the l o w e r c h a n n e l (LRC) -to compare the p r o p e r t i e s of each. 2. The Ae and LFH were too h i g h on the ro a d c u t to sample. P r o f i l e 6 - P i t i n the f o r e s t b e h i n d p r o f i l e 5 on Burke Mountain H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) Pyro Ox CBD Pyro Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 33-04 0 H 04-00 0 47.54 1.877 25 0.23 0.00 3.17 2.56 2.86 0.25 55 Ae 00-04 SL 2.25 0.105 21 3 .62 3 .21 Bhf 04-05 SL Bf 1 05-37 SL 4.01 0.120 33 0.43 0.95 1.01 1.22 3.65 1.87 0.04 1.06 0.23 4.84 4.58 Bf2 37-92 LS 4.96 0.166 30 0.47 0.71 0.81 2.16 3.12 2.73 0.25 0.55 0.45 4.61 4.33 H2 92-94 0 18.06 0.541 33 0.0998 1.19 1.36 1.34 8.28 8.92 8.38 0.86 0.93 0.89 4.62 4.38 0.14 0.66 115 Ccg 94 + SL 0.65 RC 46-49 O 19.35 0.672 29 1.32 1.33 1.45 4.40 4.62 4.44 0.19 0.22 0.22 4.38 4.05 Notes: 1. The v a s t m a j o r i t y of r o o t s were i n the l i t t e r l a y e r . Very few r o o t s we re found i n the Bhf and the top of the B f l . 2. Abundant c o a r s e b u t few f i n e r o o t s were p r e s e n t i n the lower B f l . Only a few c o a r s e r o o t s were found i n the Bf2. 3. The Bhf was too t h i n t o sample. P r o f i l e 8 - Road c u t on Burke Mountain H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe (cm) Pyro Ox CBD LFH 12-00 O Ae 00-03 SL 1.31 0.052 25 Bf 1 03-13 SL 4.06 0.137 30 0.50 1.04 1.18 Bf2 13-44 SL 2.66 0.064 28 0.22 0.99 1.09 Bhf 44-65 SL 8.05 0.230 27 0.0458 1.04 1.15 1.19 Bf 3 65-85 SL 4.10 0.155 26 0.30 0.66 0.74 H2 85-87 O 18.13 0.98 1.07 0.96 BC 87+ SL % A l % S i pH e x t r a c t e d Pyro Ox CBD P y r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce 3.82 3.57 1.53 3.06 2.25 0.16 0.76 0.37 4.63 4.44 0.08 0.69 87 0.75 2.71 1.30 0.06 0.88 0.22 5.23 4.76 1.07 1.19 1.02 0.05 0.08 0.13 4.26 3.83 0.53 0.75 80 1.48 3.05 2.29 0.12 0. 70 0.37 4.61 4.54 0.12 0.61 91 7.85 9.70 8.54 1.05 1.62 1.42 4.75 4.45 Notes: 1. The s o i l would be c l a s s i f i e d as a F e r r o - h u m i c p o d z o l a l t h o u g h the Bhf h o r i z o n was not d i r e c t l y beneath the Ae. 2. There were abundant c o a r s e and p l e n t i f u l f i n e r o o t s i n the Bhf. T h i s h o r i z o n may a c t u a l l y have been a r o o t mat forming o v e r the p a r t i a l l y cemented B f 3 . 3. The s t r u c t u r e i s p a r t i a l l y cemented t h r o u g h o u t the p r o f i l e . P r o f i l e 9 - In the f o r e s t , 10 m b e h i n d p r o f i l e 3 H o r i z o n Depth T e x t u r e %c T C/N %S % Fe % A l % S i pH (cm) P y r o Ox CBD Pyro Ox CBD P y r o Ox CBD H 20 C a C l 2 LF 05- 03 O H 03- 0 O 49.23 Ae 00- 01 SL Bf 1 01- 31 SL 4.95 0.212 23 1.14 1.70 2.02 1.51 2.90 2.02 0.14 0.63 0.28 4.57 4.33 Bf2 31- 62 SL 3.07 0.112 27 0.38 0.79 1.09 1.02 2.12 1.34 0.06 0.48 0.19 4.72 4.49 Bf 3 62-100 SL 4. 12 0.136 30 0.91 1.08 1.27 1.92 2.21 2.12 0.20 0.31 0.29 4.63 4.33 Bf 4 100-140 SL 4.17 0.129 33 0.83 1.00 1.04 1.98 2.35 2.12 0.22 0.29 0.33 4.70 4.39 Bhf* 140-142 SL 13.41 0.438 31 1.07 8.00 2.00 Cc 142 + SL RC 61- 63 O 20.75 0.815 25 3.43 3.31 6.68 6.82 0.25 0.26 4.55 4.23 e x t r a c t e d Ch/Cf Ca/Cf %Ce Notes: 1. Water seeped q u i c k l y i n t o the bottom of the p i t making the Bhf* v e r y d i f f i c u l t t o sample. 2. There were many dead, decomposing coarse r o o t s i n the Bf3 and Bf4 but no l i v e r o o t s . 3. There were p l e n t i f u l medium and c o a r s e r o o t s i n the LFH, Ae, and B f l , few t o v e r y few r o o t s i n the Bf 2 . P r o f i l e 10 - Road c u t on Burke Mountain H o r i z o n Depth T e x t u r e %c T C/N %S % Fe % A l % S i PH e x t r a c t e d (cm) Py r o Ox CBD Pyro Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 10-04 O H 04-00 O 48.66 Ae 00-02 SL Bhf 02-07 SL 7.32 0.278 26 1.63 1.61 1.91 0.55 0.57 0.57 0.09 0.05 0.19 3.69 3.32 Bf 07-12 SL 4.37 0.127 34 0.87 1.03 1.21 1.18 1.86 1.63 0.10 0.38 0.35 4.50 4.17 Bhf2 12-40 SL 6 .99 0.234 30 0.92 1.04 1.26 2.54 2.91 2.61 0.32 0.40 0.46 4.46 4.29 0.20 0.70 79 Bfg 40-70 SL 2.52 0.083 31 0.43 0.60 0.78 0.75 1.46 0.87 0.06 0.35 0.07 4.74 4.64 H2 70-74 O 17.30 0.665 26 0, .1303 1.91 1.73 1.63 5.27 10.52 7.23' 0.18 2.19 0.94 4.81 4.44 Ccg 74 + SL URC1 15-17 SL 15.00 0.447 34 0, .0861 1.83 1.94 2.00' 5.16 5.42 5.22 0.50 0.57 0.61 4.47 4.27 0.20 0.68 85 LRC2 34-37 O 19.02 0.672 28 0, .1363 1.32 1.68 1.74 7.44 7.69 0.81 0.91 4.57 4.28 Notes: 1. The upper 40 cm of the p r o f i l e was very b l o t c h y w i t h the Bf and Bhf m a t e r i a l a c t u a l l y t o o i n t e r m i x e d to sample s e p a r a t e l y . 2. The upper r o o t c h a n n e l runs i n t o the p r o f i l e w i t h i n a m a t r i x of Bf m a t e r i a l . 3. The lower r o o t c h a n n e l runs a c r o s s the p r o f i l e . P r o f i l e 11 - C y p r e s s Park, f o r e s t near d o w n h i l l s k i p a r k i n g l o t H o r i z o n Depth T e x t u r e %C %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 1 P y r o Ox CBD Pyro Ox CBD Pyro Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 30-05 0 H 05-00 O 47.84 1.284 37 1.23 0.00 3.57 3.14 2.06 0.44 56 Ae 00-05 SL 3.09 0.135 23 3.91 3.53 Bhf 1 05-24 SL 6 .75 0.240 28 0.66 1.23 1.62 1.44 4.55 2.36 0.07 1.50 0.28 4.77 4.54 0.23 0.60 81 Bhf2 24-30 SL 9.86 0.433 23 0.96 1.38 1.81 1.91 7.26 3.34 0.10 2.30 0.31 4.89 4.68 0.34 0.49 65 Bhf3* 30-42 SL 13.42 0.596 23 0.0824 0.82 0.94 1.44 2.17 8.01 3.55 0.10 2 .65 0.23 4.99 4.75 0.47 0.53 61 Bf 42 + SL 2.87 0.130 22 0.09 0.27 0.52 0.62 3.37 0.93 0.06 1.37 0.15 5.21 5.11 0.14 0.45 49 No t e s : 1. Many decomposing r o o t remains were s t i l l v i s i b l e i n the Bhf3*, o n l y v e r y few f i n e r o o t s were a l i v e i n t h i s h o r i z o n a t the p r e s e n t time. 2. The Bhf2 l o o k e d a c t u a l l y t o be a g r a d u a l t r a n s i t i o n from the B h f l w i t h l i t t l e r o o t remains t o the Bhf 3 * . 3. Some of the r o o t c h a n n e l s i n the Bhf3 and the few p r e s e n t i n the Bf were the r e d o f decomposing wood. 4. There were many g r a v e l s and c o b b l e s p r e s e n t i n the B f . The r o o t s seemed to have grown o v e r t h e s e . P r o f i l e s 12 and 13 - C y p r e s s Park, Bhf h o r i z o n s w i t h no u n d e r l y i n g r o o t mat H o r i z o n Depth T e x t u r e %C %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) Pyro Ox CBD Py r o Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce 12 Bhf 04-13 SL 6.53 0.238 27 0.62 0.78 1.36 0.97 1.07 0.98 0.10 0.12 0.09 4.12 3.71 0.64 0.79 82 13 Bhf 03-13 SL 5.31 0.314 17 0. 11 0.13 0.25 1.09 4.16 1.57 0.08' 1.43 0.22 5.16 4.57 0.48 0.69 71 Notes: 1. Both p r o f i l e s had abundant r o o t s i n the LFH but few r o o t s i n the u n d e r l y i n g m i n e r a l s o i l . P r o f i l e 14 - C y p r e s s Park, near p r o f i l e 11 H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe * A l % S i pH (cm) Pyro Ox CBD Pyro Ox CBD Pyr o Ox CBD H 20 C a C l 2 LFH 30-00 O Ae 00-03 SL 9.12 0.315 29 3.68 3.30 Bhf 03-20 SL 7.19 0.232 31 0.73 1.15 1.52 1.89 4.07 2.72 0.07 0.80 0.33 4.61 4.21 Bf 20-41 SL 2.88 0.104 28 0.28 0.64 0.98 0.79 3.31 1.33 0.06 1.15 0.21 4.83 4.80 Bhf2* 41-46 SL 12.23 0.564 22 0.0804 0.23 0.26 0.43 1.90 8.84 3.10 0.08 3.15 0.23 5.16 4.91 Cc 46 + SL RC 20-41 0 18.52 0.628 29 1.93 8.27 2.40 e x t r a c t e d Ch/Cf Ca/Cf %Ce 0.11 0.58 66 Notes: 1. Found the Bhf2 by f o l l o w i n g a r o o t c h a n n e l w i t h i n the " f i r m " Bf. T h i s l e d d i r e c t l y t o the r o o t mat. 2. Bf seemed s l i g h t l y cemented. 3. Abundant r o o t s i n the LFH, o n l y a few i n the Bhf, none below 20 cm. 4. Root c h a n n e l was 1.5 cm wide. P r o f i l e 15 - C y p r e s s Park, .5 km e a s t of p r o f i l e s 11 and 14 H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe % A l % S i pH (cm) Pyro Ox CBD Pyro Ox CBD Pyr o Ox CBD H 20 C a C l 2 LFH 32-00 O Ae 00-03 SL B h f l 03-23 SL 6.45 0.280 23 0.51 0.63 0.88 1.56 2.84 2.14 0.07 0.60 0.34 4.74 4.29 Bf 23-40 SL 2.94 0.141 21 0.17 0.31 0.58 0.74 3.47 1.22 0.06 1.32 0.19 5.12 4.82 Bhf2* 40-41 SL 9 .83 0.597 16 0.31 0.30 0.58 1.52 8.88 3.18 0.08 2.94 0.23 5.44 5.00 Cc 41 + SL Notes: 1. The Bhf2 * c o n t a i n e d no l i v e r o o t s b u t many r o o t remains ( o u t e r b a rk, e t c . ) i and w h i t e f u n g a l m y c e l i a . 2. The B h f l and Bf c o n t a i n e d many decomposing r o o t c h a n n e l s , some were q u i t e l a r g e i n the B f l . 3. There were abundant l i v e r o o t s i n the LFH, none i n the Ae o r Bf, few, f i n e i n the B h f l . e x t r a c t e d Ch/Cf Ca/Cf %Ce 0.29 0.73 83 P r o f i l e 16 - Road Cut on Burke Mountain Hor i z o n Depth T e x t u r e %C„ %N T C/N %S % Fe % A l % S i pH (cm) Py r o Ox CBD Pyro Ox CBD P y r o Ox CBD H 20 C a C l 2 LFH 20-00 O Ae 00-01 SL B h f l 01-14 SL 13.16 0.498 26 4.85 5.05 5.38 2.60 2.59 2.53 0.12 0.10 0.21 4.27 3.95 Bhf2 14-53 SL 6.15 0.233 26 2.96 2.98 3.27 1.48 1.57 1.42 0.09 0.07 0.14 4.48 4.20 Bf 53-94 LS 2.48 0.078 32 0.31 0.33 0.50 1.21 1.48 1.41 0.14 0.27 0.28 4.77 4.48 Ccg 94+ FSL RC 46-54 O 20.59 0.619 33 0.1032 5.79 5.92 6.70 4.98 5.39 4.78 0.26 0.22 0.39 4.67 4.32 e x t r a c t e d Ch/Cf Ca/Cf %Ce 0.26 0.61 61 No t e s : 1. There was a very t h i n r o o t mat a t c o n t a c t w i t h Ccg (not s a m p l a b l e ) . 2. Many s m a l l decomposing r o o t c h a n n e l s were p r e s e n t i n the B h f l and Bhf2. morphology. 3. The c o l o u r of the r o o t c h a n n e l s were " b r i c k " r e d and b l a c k . Can i d e n t i f y " g r o s s " r o o t P r o f i l e 17 - P i t in the f o r e s t on the e a s t s i d e of the Burke Moun H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe (cm) Pyro Ox CBD LF 20-10 0 H 10-00 0 50.54 0.17 Ae 00-01 SL Bhf 1 01-13 SL 7.51 0.302 25 1.15 1.24 1.36 Bhf2 13-44 SL 6.70 0.225 31 0.91 0.95 1.16 H2 44-45 0 25.51 1.562 16 0.77 0.79 0.84 Bhf3 45-76 SL 6.44 0.215 30 0.73 0.76 0.98 H3 76-80 0 24.77 0.850 27 0.1339 1.59 1.69 1.65 Bfc 80+ LS 3.82 0.125 31 0.50 0.61 0.68 Notes: 1. Abundant r o o t s i n the LFH, p l e n t i f u l c o a r s e r o o t s i n the o n l y very few below. 2. Cedar codominant w i t h hemlock. i n r o a d c u t % A l % S i pH e x t r a c t e d Pyro Ox CBD P y r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce 0.25 0.00 3.44 2.86 1.79 1.96 1.70 0.16 0.21 0.22 4.14 3.83 2.03 2.22 2.11 0.17 0.22 0.26 4.44 4.14 0.25 0.69 84 4.07 4.17 3.90 0.10 0.07 0.15 4.37 4.02 1.41 1.47 1.34 0.07 0.07 0.14 4.30 4.10 6 .43 6.43 5.88 0.19 0.20 0.20 4.28 4.01 0.30 0.78 99 1.39 1.44 1.28 0.09 0.17 0.16 4.66 4.18 B h f l and Bhf2. Few f i n e r o o t s i n H2 and P r o f i l e 18 - P i t i n the f o r e s t on the e a s t s i d e of the Burke Mountain r o a d c u t H o r i z o n Depth T e x t u r e %C %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 ± P y r o Ox CBD Pyro Ox CBD P y r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 37-23 O H 23-00 0 38.95 1.814 21 4.00 0.00 4.20 3.77 0.88 0.68 73 B h f l 00-19 SL 5.68 0.253 22 0.76 0.80 1.02 1.35 1.43 1.35 0.12 0.15 0.19 4.37 3.88 0.34 0.74 86 Bhf2 19-41 SL 6.27 0.268 23 0.69 0.72 0.91 1.55 1.70 1.53 0.17 0.19 0.16 4.28 3.85 H2 41-42 O 23.92 0.923 26 0.1340 0.99 1.05 1.07 3.81 4.05 3.61 0.08 0.08 0.13 4.16 3.87 Bhf3 42-71 SL 5.97 0.234 26 0.56 0.66 0.81 1.65 1.90 1.68 0.20 0.25 0.23 4.25 3.95 Bhf4 71-79 SL 5.70 0.220 26 0.46 0.55 0.70 1.60 1.89 1.77 0.12 0.21 0.20 4.38 4.12 Bf c 79 + LS 3.10 0.085 36 0.21 0.44 0.50 1.18 1.68 1.36 0.10 0.29 0.17 4.42 4.24 Notes: 1. Some remains of undecomposed dead r o o t s i n H2 and n e a r bottom of the p i t . 2. Very t h i c k , b l a c k HI, (unusual compared to p r e v i o u s p i t s ) . 3. Abundant r o o t s i n LFH, p l e n t i f u l , medium but o n l y few f i n e r o o t s i n B h f l and Bhf2, few to v e r y few be 1ow. 4. Bhf3 and Bhf4 had many r o o t c h a n n e l s i n a m i n e r a l m a t r i x , but they were t o o s m a l l t o sample s e p a r a t e l y . P r o f H e 19 - P i t in the f o r e s t on the e a s t s i d e of the Burke Mountain r o a d c u t H o r i z o n Depth T e x t u r e %C C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 1 Pyro Ox CBD Pyro Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 31-25 0 H 25-00 0 33.72 1.201 28 1.55 4.90 0.02 4.29 3.87 0.60 0.72 69 B h f l 00-11 SL 5.29 0.208 25 0.67 0.71 0.97 1.28 1.36 1.29 0.06 0.13 0.10 4.24 3.93 Bhf2 11-3 2 SL 5.28 0.185 29 0.65 0.61 0.86 1.33 1.34 1.32 0.10 0.12 0.14 4.22 3.96 H2 32-46 0 20.80 0.663 31 0.1067 1.23 1.24 1.28 4.33 4.70 4.45 0.11 0.08 0.12 4.36 3.89 0.30 0.81 86 Bf 46-55 SL 4.27 0.128 33 0.48 0.55 0.66 1.28 1.31 1.16 0.09 0.10 0.11 4.34 4.07 H3 55-63 0 28.62 0.813 35 0.1346 1.30 1.45 1.45 7.92 8.67 8.01 0.13 0.16 0.16 4.28 3.92 0.14 0.80 100 Bf c 63 + LS 3.67 0.117 31 0.35 0.45 0.54 1.25 1.28 1.14 0.08 0.10 0.10 4.57 4.11 Notes: 1. Abundant r o o t s i n LFH, p l e n t i f u l , medium but very few f i n e r o o t s i n B h f l , v e r y few r o o t s below B h f l . 2. One r o o t c h a n n e l c o n t i n u e s from the s u r f a c e t o the H2. 3. The HI i s v e r y t h i c k and b l a c k . P r o f i l e 20 - P i t i n the f o r e s t on the e a s t s i d e of the Burke H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe (cm) Pyro Ox LF 44-15 O H 15-00 O 34.67 0.27 B h f l 00-15 SL 6.07 0.224 27 0.56 0.59 Bhf2 15-45 SL 8.60 0.330 26 0.67 0.78 Bhf3* 45-47 SL 16.43 0.6 09 27 0.91 0.97 Bf 47-75 SL 4.78 0.130 37 0.38 0.48 H2 75-78 O 21.44 0.549 39 0.1028 1.37 1.61 B f c 78 + SL Notes: 1. Can see v e i n s o f m i n e r a l i n Bhf3*. 2. There i s seepage a t the bottom of the p i t above the 3. Bf had s m a l l r o o t c h a n n e l s and many c o b b l e s . Bhf3* 4. Abundant r o o t s i n LFH, abundant c o a r s e and medium r be 1 ow. Mountain ro a d c u t % A l % S i pH e x t r a c t e d CBD Py r o Ox CBD Py r o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce 1.95 0.00 4.17 3.57 0.74 1.30 1.43 1.31 0.11 0.16 0.17 4.32 3.95 0.38 0.77 80 0.99 2.08 2.06 2.18 0.13 0.18 0.16 4.36 3.92 1.07 5.05 4.98 5.02 0.20 0.23 0.27 4.21 3.99 0.60 1.70 1.95 1.76 0.15 0.22 0.21 4.26 4.27 1.69 8.87 9.36 9.05 0.96 1.04 0.97 4.42 4.14 B f c . s i t s a l o n g top of c o b b l e s . iots i n B h f l and Bhf2, few t o v e r y few r o o t s (_n P r o f H e 21 - P i t i n the f o r e s t on the e a s t s i d e of the Burke Mountain r o a d c u t H o r i z o n Depth T e x t u r e %C %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 P y r o Ox CBD Py r o Ox CBD Py r o Ox CBD H 2 ,0 C a C l , Ch/Cf Ca/Cf %Ce LF 07-05 O H 05-00 O 46.74 0.14 0 .28 0.00 3. 43 2. ,87 B h f l 00-26 SL 7.83 0.309 25 0.74 0.74 0.93 1.29 1, .39 1. ,24 0. .07 0.08 0. .15 4. 31 3 , .92 0. ,47 0.77 73 Bhf2 26-57 SL 7.04 0.230 31 0.80 0.90 1.08 2.01 2 .30 2. .08 0. .14 0.19 0. ,21 4. 33 3. .95 H2 57-60 O 26.47 0.866 31 0.1442 0.91 0.99 1.04 5.30 5 .53 5. .09 0. .11 0.11 0. .15 4. 35 3. .91 0, .35 0.75 90 Bhf 3 60-88 SL 8.53 0.276 31 0.66 0.70 0.84 2.42 2 .67 2. .48 0. .15 0.18 0. .20 4. 27 4. .05 0, .16 0.79 93 Bhf4 88-90 L 9.07 0.282 32 0.42 0.45 0.54 3.19 3 .41 3. .14 0. .17 0.22 0. ,23 4. 45 4, , 10 Bfc 9 0+ SL 1.86 0.051 37 0.11 0.37 0.29 0.76 0 .88 0. .70 0. .08 0.14 0. ,11 Notes: 1. Found a p i e c e of c o a r s e , dead r o o t a t 35cm which extended to the d u r i c h o r i z o n . 2. Abundant r o o t s i n LFH and B h f l , v e r y few f i n e r o o t s i n Bhf2. P r o f i l e 22 - P i t i n the f o r e s t on the e a s t s i d e of the Burke Mountain r o a d c u t H o r i z o n Depth T e x t u r e %C C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 1 Pyro Ox CBD Py r o Ox CBD Py r o Ox CBD H. !° C a C l , Ch/Cf Ca/Cf %Ce LF 32-26 O H 26-00 O 34.83 1.650 21 0.89 3 .07 0.00 4. 29 4, .00 B h f l 00-09 SL 7.97 0.340 23 0.73 1.02 1.08 2.25 2 .70 2. .53 0. .18 0.40 0. .28 4. 53 4, .28 Bf 1 9-30 SL 4.28 0.138 31 0.27 0.51 0.53 1.70 1 .78 1, .81 0. .16 0.25 0. .21 4. 76 4. .43 Bf 2 30-39 SL 2.08 0.062 34 0.21 0.41 0.42 1.00 1 .25 1. .06 0. .15 0.26 0. .20 4. 71 4, .42 Bhf2* 39-40 SL 15.61 0.5 89 27 0.76 0.88 0.85 8.21 8 .28 8, .22 0, .92 1.10 0. .90 4. 51 4, .25 Cc 40 + SL 0.93 0.019 48 0.06 0.43 0.29 0.46 0 .67 0 .52 0, .07 0.18 0, .12 5. ,26 Notes: 1. S m a l l r o o t c h a n n e l s t h r o u g h o u t B h o r i z o n s . 2. The upper h o r i z o n s l o o k e d churned i n p a r t of the p r o f i l e . 3. Abundant c o a r s e and medium r o o t s i n Bhf, few, i medium and very few f i n e r o o t s i n Bf 1. 4. T h i c k , b l a c k HI. A s e c t i o n o f the upper p r o f i l e appeared c h u r n e d . P r o f i l e 23 - P i t i n the f o r e s t on the e a s t s i d e of the Burke Mountain ro a d c u t H o r i z o n Depth T e x t u r e %cT %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) Pyro Ox CBD Pyro Ox CBD Pyro Ox CBD H-0 C a C l , Ch/Cf Ca/Cf %Ce LF 17-12 O H 12-00 0 Ae 00-02 SL 2.11 0.115 18 B h f l 02-17 SL 8.33 0.321 26 1.80 1.99 1.93 0.98 0.99 0.90 0.08 0.06 0.10 4.03 3.60 Bhf2 17-46 SL 6.36 0.237 27 0.66 0.74 0.88 1.59 1.68 1.57 0.11 0.14 0.14 4.57 3.92 Bhf3* 46-52 SL 12.84 0.491 26 0.86 0.91 1.05 2.38 2.61 2.49 0.12 0.14 0.17 4.40 3.92 0.38 0.77 86 Bhf4 52-77 SL 6.03 0.223 27 0.50 0.57 0.65 1.83 1.78 1.72 0.15 0.21 0.22 4.35 3.98 H2 77-79 0 21.91 0.700 31 0.79 0.83 0.82 5.84 6.20 6.04 0.24 0.27 0.27 4.40 3.99 Cc 79 + SL 1.05 0.026 39 0.08 0.44 0.29 0.48 0.73 0.52 0.06 0.23 0.14 5.17 4.66 Notes: 1. Bhf3* appeared c l o s e r t o an F than an H i n s t a t e of d e c o m p o s i t i o n , (not g r e a s y ) . 2. Abundant medium and few f i n e r o o t s t o the Bh£3*. P i t was c l o s e t o t r e e s . 3. The HI h o r i z o n was 22 cm deep on one s i d e of the p i t , e x t e n d i n g down i n t o the m i n e r a l s o i l . P r o f i l e 24 P i t i n the f o r e s t on the e a s t s i d e of the Burke Mountain ro a d c u t H o r i z o n Depth T e x t u r e %C %N T C/N %S % Fe % A l % S i pH (cm) Pyro Ox CBD Pyr o Ox CBD Pyro Ox CBD H,0 C a C l , LF 27-18 0 H 18-00 0 36.95 1.623 23 0.1948 0.47 3.68 0.01 4.11 3.64 Ae 00-02 SL Bhf 02-21 L 8.11 0.262 31 1.23 1.24 1.47 1.61 1.68 1.48 0.09 0.09 0. .12 4.58 4.07 B f l 21-56 SL 4.80 0.164 29 0.59 0.64 0.86 2.15 2.30 2.01 0.20 0.24 0. .24 4.53 4.38 Bf2 56-72 SL 2.48 0.085 29 0.38 0.44 0.69 0.97 1.62 1.23 0.07 0.35 0. ,24 4.82 4.49 C 72 + SL 0.52 0.016 32 0.06 0.32 0.38 0.24 0.66 0.29 0.06 0.20 0. .04 5.08 4.66 RC1 18-19 SL 16.38 0.540 30 1.57 1.78 1.86 6.82 6.91 6.89 0.46 0.52 0. .50 4.58 4.24 RC2 30-56 SL 16.38 0.619 26 0.0894 1.23 1.28 1.44 4.34 4.36 4.43 0.13 0.15 0. .23 4.56 4.12 RC3 66-69 0 18.39 0.668 28 1.01 1.15 1.20 10.03 10.39 9.84 1.40 1.59 1, .29 4.60 4.37 e x t r a c t e d Ch/Cf Ca/Cf %Ce 0.29 0.66 69 Notes: 1. Many s m a l l r o o t c h a n n e l s throughout t h a t were too s m a l l t o s e p a r a t e from the m i n e r a l s o i l . 2. Abundant r o o t s i n LFH, abundant medium, v e r y few f i n e r o o t s i n Bhf, o n l y few, medium r o o t s below. 3. C h o r i z o n was not cemented and no o r g a n i c l a y e r was found above i t . 4. RC1 l i e s h o r i z o n t a l l y , RC2 bran c h e s a t i t s base and has the g r o s s morphology of a r o o t . 5. C h a r c o a l was o b v i o u s i n HI and RC1. -J P r o f i l e 25 - P i t i n the f o r e s t on the west s i d e of the Burke Mountain r o a d c u t H o r i z o n Depth T e x t u r e %c T C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) Pyro Ox CBD Py r o Ox CBD Py r o Ox CBD H,0 C a C l , Ch/Cf Ca/Cf %Ce LF 21-16 0 H 16-00 0 47.22 0.20 0.23 0.00 3.40 Ae 00-01 SL B f c l 01-22 SL 4.29 0.133 32 1.27 2.24 1.97 1.48 2.24 1.97 0.13 0.37 0.31 4.78 4.27 0.12 0.62 71 Bfc2 22-42 SL 2.l'7 0.071 30 0.14 0.71 0.94 0.78 3.01 1.24 0.04 0.95 0.15 4.93 4.87 Bf 42-64 SL 2.36 0.077 30 0.28 0.49 0.68 0.87 1.12 1.05 0.09 0.23 0.25 4.59 4.59 Bfc3 64-78 SL 3.50 0.116 30 0.38 0.83 0.97 1.64 2.67 2.05 0.17 0.51 0.35 4.70 4.44 H2 78-85 O 19.03 0.737 26 1.16 1.28 1.29 8.36 8.33 8.26 0.72 0.84 0.68 4.36 4.29 0.18 0.67 107 Bfc4 85 + SL 1.11 0.033 33 0.14 0.42 0.29 0.57 0.67 0.56 0.07 0.15 0.15 5.35 4.62 RC 42-45 O 17.93 0.566 32 0.84 6.31 0.41 Notes: 1. Many s m a l l r o o t c h a n n e l s t h r o u g h o u t t h a t were too s m a l l t o s e p a r a t e from the m i n e r a l s o i l . 2. B f c l and Bfc3 were very " r e d " (7.5YR 4/4). They resembled an O r t s t e i n . 3. Bfc4 i s the d u r i c h o r i z o n . 4. A l l h o r i z o n s but the Ae, Bf and H2 are weakly cemented. 5. Abundant r o o t s i n LFH and B f c l , p l e n t i f u l medium r o o t s i n the Bfc2 and B f c 3 , o n l y few, f i n e r o o t s i n H2. P r o f i l e 26 - P i t i n the f o r e s t on the west s i d e of the Burke Mountain r o a d c u t H o r i z o n Depth T e x t u r e %C C/N *S % Fe % A l % S i pH e x t r a c t e d (cm) 1 1 Pyro Ox CBD Py r o Ox CBD Pyro Ox CBD H,0 C a C l 2 Ch/Cf Ca/Cf %Ce LF 33-14 0 H 14-00 0 49.67 0.14 0.32 0.00 3.14 Ae 00-03 SL 3.24 0.103 31 4.25 3.85 B h f l 03-26 SL 7.53 0.283 27 1.47 1.55 1.60 1.74 1.77 1.63 0.06 0.09 0.15 4.37 3.92 0.26 0.76 90 Bhf2 26-46 SL 8.45 0.323 26 0.84 0.91 1.10 2.27 2.39 2.28 0.15 0.16 0.18 4.49 3.97 0.24 0.75 95 Bhf3* 46-56 SL 15.24 0.603 25 0.89 1.04 1.17 3.98 4.23 3.91 0.27 0.31 0.26 4.52 3.98 0.30 0.77 92 Bf 56-86 SL 3.36 0.107 32 0.32 0.46 0.53 1.52 1.77 1.66 0.18 0.31 0.29 4.56 4.33 H2 86-92 0 21.83 0.6 93 31 0.1299 0.91 0.99 1.00 9.74 10.01 9.36 1.18 1.21 1.13 4.56 4.32 Cc 92 + SL 1.15 0.029 39 0.21 0.67 0.18 RC 63-66 O 19.54 0.790 25 0.1129 0.74 0.85 0.92 5.16 5.52 5.24 0.30 0.33 0.30 4.53 4.00 0.26 0.79 96 Notes: 1. Bf h o r i z o n was s l i g h t l y cemented. 2. Abundant r o o t s i n LFH, p l e n t i f u l medium and c o a r s e r o o t s i n B h f l , p l e n t i f u l f i n e and v e r y f i n e r o o t s i n B hf3* but no r o o t s below. 3. RC and Bhf3* o r g a n i c m a t t e r i s composed of many f i n e , b roken decomposed r o o t s t h a t g i v e a g r a n u l a r appearance t o the o r g a n i c m a t t e r . P r o f i l e 27 - P i t i n the f o r e s t on the west s i d e of the Burke Mountain ro a d c u t H o r i z o n Depth T e x t u r e %c T C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) Pyr o Ox CBD Pyro Ox CBD Pyro Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 33-20 0 H 20-00 0 44.64 1.690 26 0.48 0.00 3.27 2.74 4.71 0.25 57 Ae 00-03 SL 1.53 0.080 19 3.51 3.06 Bhf 03-20 SL 6.01 0.239 25 1.65 1.77 1.96 1.00 1.03 1.00 0.07 0.05 0.11 4.24 3.75 B f l 20-42 SL 4.57 0.183 25 0.91 1.40 1.52 1.49 3.02 2.09 0.14 0.82 0.28 4.64 4.25 Bf2 42-77 SL 3.51 0.116 30 0.48 0.69 0.79 1.55 2.05 1.75 0.17 0.35 0.29 4.61 4.38 H2 77-80 0 17.98 0.701 26 0.59 0.63 0.61 8.52 8.59 8.00 0.45 0.51 0.46 4.48 4.38 Cc 80+ SL 0.86 0.022 39 0.16 0.32 0.34 0.41 0.55 0.42 0.05 0.12 0.11 5.22 4.71 RC1 42-45 0 19.03 0.781 24 2.21 2.21 2.23 4.50 4.60 4.45 0.14 0.15 0.18 4.51 4.14 RC2 30-35 0 20.75 0.973 21 0.1367 1.75 1.74 1.90 3.74 3.94 3.69 0.07 0.09 0.11 4.41 4.00 Not e s : 1. There were many s m a l l r o o t c h a n n e l s i n the B f l and Bf2 but c o u l d not s e p a r a t e t h e s e from the o r g a n i c - p o o r m a t r i x . 2. RC1 i s 8 cm wide and e x t e n d s back i n t o the p r o f i l e . I t c o n t a i n s no l i v e r o o t s , has a massive s t r u c t u r e and i s g r e a s y . 3. The RC2 s i t s o v e r a r o c k . I t c o n t a i n s many f i n e r o o t s and i s g r a n u l a r i n ap p e a r a n c e (because o f broken p i e c e s of f i n e r o o t s ) . P r o f i l e 28 - P i t i n the f o r e s t on the west s i d e of the Burke Mountain ro a d c u t H o r i z o n Depth T e x t u r e %C %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 1 Pyro Ox CBD Pyro Ox CBD Pyr o Ox CBD H 20 C a C l 2 Ch/Cf Ca/Cf %Ce LF 20-08 H 08-00 0 43.26 1.679 26 0.11 0.44 0.00 3.35 2.86 Ae 00-03 SL 1.65 0.089 19 3.70 3.17 Bhf 03-22 SL 6.79 0.261 26 1.24 1.49 1.64 1.89 2.13 2.08 0.17 0.35 0.33 4.40 4.03 Bhf 2 22-52 SL 5.93 0.256 23 0.98 1.04 1.29 1.51 1.61 1.45 0.13 0.14 0.22 4.38 3.94 0.30 0.73 92 H2 52-55 0 23.32 0.9 76 24 2.26 2.28 2.16 5.84 5.92 5.88 0.23 0.22 0.25 4.26 3.95 Bhf3 55-92 SL 6.47 0.214 30 0.59 0.69 0.84 2.54 3.06 2.72 0.29 0.37 0.43 4.44 4.07 Cc 92 + SL RC 36-45 O 24.72 1.360 18 4.60 4.32 4.87 4.90 4.88 0.07 0.07 0.13 Notes: 1. The r o o t c h a n n e l i s 6 cm wide and s i t s o b l i q u e l y . 2. The Bhf was v e r y " r e d " (5 YR 3/3). 3. There were abundant medium, p l e n t i f u l c o a r s e r o o t s to the Bhf2, but v e r y few f i n e r o o t s . 4. There were no r o o t s i n the H2 o r below. P r o f i l e 29 - P i t i n the f o r e s t on the west s i d e of the Burke Mountain road c u t H o r i z o n Depth T e x t u r e %c T C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) Pyro Ox CBD Pyro Ox CBD Py r o Ox CBD H,0 C a C l Ch/Cf Ca/Cf %Ce LF 37-10 O H 10-00 0 40.53 1.974 21 0.25 1.25 0.00 3.53 3.05 Ae 00-02 SL 2.43 0.099 24 3.75 B h f l 02-30 SL 7.21 0.297 24 1.11 1.23 1.27 1.22 1.28 1.20 0.11 0.11 0.13 4.16 3.70 0.36 0.78 86 Bhf2 30-55 SL 6.04 0.237 25 0.79 0.85 0.98 1.72 1.89 1.69 0.10 0.14 0.17 4.48 4.07 0.22 0.74 99 Bhf3 55-69 SL 6.37 0.207 31 0.60 0.65 0.80 2.05 2.19 1.96 0.13 0.17 0.18 4.44 4.12 H2 6 9-82 0 23.14 0.777 30 0.1298 1.15 1.32 1.33 6.46 6.74 6.58 0.19 0.20 0.19 4.61 4.16 0.24 0.75 98 BC 82 + SL 0.18 0.32 0.40 1.02 1.44 1.18 0.06 0.30 0.28 4.90 4.31 No t e s : 1. There were many s m a l l r o o t c h a n n e l s i n the B h f l , Bhf2 and Bhf3 2. There were abundant c o a r s e and medium r o o t s i n the B h f l , few medium r o o t s i n the Bhf2, v e r y few f i n e r o o t s i n the H2. P r o f i l e 30 - P i t i n the f o r e s t on the west s i d e of the Burke Mountain ro a d c u t H o r i z o n Depth T e x t u r e %C %N„, C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) 1 Pyro Ox CBD P y r o Ox CBD P y r o Ox CBD H,0 C a C l , Ch/Cf Ca/Cf %Ce LF 35-14 0 H 14-00 0 51.30 0.11 0.2 1 0.00 3.45 2.96 Ae 00-01 SL B h f l 01-24 SL 7.97 1.14 1.30 1.41 1.03 1.05 0.97 0.09 0.09 0.14 4.25 3.75 Bf 24-58 SL 4.28 0.87 0.84 1.03 0.91 0.94 0.87 0.11 0.10 0.13 4.49 4.02 H2 58-90 0 31.30 0.1896 3.70 3 .70 3.54 5.57 5.67 5.53 0.09 0.10 0.11 4.55 4.01 0.38 0.74 81 Bhf2 90 + SL RC 47-53 0 28.73 1.611 0.2226 5.05 4.63 4.25 5.42 5.56 5.29 0.04 0.02 0.06 4.32 3.96 Notes: 1. The H2 h o r i z o n i s v e r y deep and i t e x t e n d s down between 40% c o b b l e s i n B h f 2 . 2. Found t h r e e p i e c e s of c o a r s e dead r o o t s a t a p p r o x i m a t e l y 50-60 cm, l y i n g o b l i q u e l y i n the p i t . 3. Remnants of good c o a r s e r o o t s t r u c t u r e found i n the H2. P r o f i l e 31 - P i t in the f o r e s t near the begi n n ing of the Burke Mountain r o a d , e l e v a t i o n 320 m H o r i z o n Depth T e x t u r e %c T %N C/N %S % Fe % A l % S i PH e x t r a c t e d (cm) P y r o Ox CBD Pyro Ox CBD Pyro Ox CBD H,0 C a C l , Ch/Cf Ca/Cf %Ce LFH 09-00 0 Ae 00-05 SL 1.00 0.036 28 4.58 4.08 Bf 1 05-26 LS 4.14 0.187 22 0.35 1.64 2.73 1.04 5.53 2.55 0.06 2.28 0.20 5.26 4.86 Bf2 26-49 LS 2.60 0.127 20 0.15 0.85 1.49 0.59 3.98 1.45 0.05 1.48 0.21 5.19 4.93 Bf3 49-77 LS 2.58 0.133 19 0.15 0.85 1.34 0.64 3.12 1.27 0.04 1.23 0.18 5.25 5.00 0.13 0.59 56 Bf 4 77-97 SL 3.61 0.177 20 0.31 2.07 2.45 0.92 4.44 1.88 0.04 1.41 0.14 5.19 4.82 Bfg 97+ LS 1.97 0.077 26 0.29 1.25 1.52 0.58 2.39 1.06 0.06 0.79 0.13 5.34 4.93 Notes: 1. P l e n t i f u l r o o t s t o bottom of B f 3 . 2. The Bf4 i s r e d d e r and f i n e r t e x t u r e than the o v e r l y i n g h o r i z o n s (5YR 3/3). 3. There was seepage water coming i n q u i c k l y a t 97 cm, above uncemented but compact b a s a l t i l l . 4. The B f l was p a r t i a l l y cemented. P r o f i l e 32 - P i t in the f o r e s t near the b e g i n n i n g of the Burke Mountain r o a d , e l e v a t i o n 320 m H o r i z o n Depth T e x t u r e %c„ %N C/N %S % Fe % A l % S i pH (cm) 1 Pyro Ox CBD Pyro Ox CBD P y r o Ox CBD H,0 C a C l , LFH 10-00 0 Ae 00-03 SL 0.93 0.049 19 4.13 B f l 03-15 LS 3.48 0.119 29 0.38 0.89 1.27 1.04 2.82 1.59 0.12 0.78 0.24 4.83 4.42 Bf2 15-40 LS 1.88 0.069 27 0.10 0.48 0.86 0.54 2.46 0.98 0.07 0.86 0.16 4.97 4.97 Bm 40-82 LS 1.20 0.046 26 0.03 0.39 0.52 0.34 1.77 0.58 0.03 0.66 0.11 5.21 5.16 Bfg 82-99 LS 1.57 0.074 21 0.17 0.60 0.70 0.57 1.66 0.77 0.04 0.51 0.13 5.26 4.91 C 99 + LS e x t r a c t e d Ch/Cf Ca/Cf %Ce Notes: 1. Some ce m e n t a t i o n of s t r u c t u r e t h r o u g h o u t B f l to Bm. 2. The HI i s very t h i n . 3. Water was s e e p i n g a l o n g b a s a l t i l l . P r o f i l e 33 - P i t i n the f o r e s t h a l f way up the Burke Mountain road. , e l e v a t i o n 520 m H o r i z o n Depth T e x t u r e %c T %N T C/N %S % Fe % A l % S i pH (cm) Pyro Ox CBD Pyro Ox CBD Py r o Ox CBD H o0 C a C l , LFH 03-00 O B f l 00-17 SL 2.46 0.126 t20 0.14 0.53 1.11 0.68 2.08 1.23 0.04 0 .64 0.20 5.18 4.94 Bm 17-4'8 SL 1.22 0.064 19 0.02 0.60 1.13 0.37 2.37 0.92 0.03 0 .87 0.08 5.44 5.33 Bm2 48-76 SL 1.92 0.095 20 0.05 0.76 1.34 0.43 3.06 1.24 0.02 1 .22 0.16 5.23 5.24 Bf2 76-93 LS 2.90 0.154 19 0.28 0.76 1.11 0.73 2.93 1.32 0.06 0 .97 0.22 5.18 4.71 Cg 93 + LS 0.29 0.011 26 0.00 0.57 0.41 0.16 0.62 0.22 0.00 0 .27 0.07 5.74 5.32 Notes: 1. The Cg i s compact : b a s a l t i l l of f i n e sand and s t o n e s w i t h no c e m e n t a t i o n . 2. There i s seepage a l o n g the Cg. e x t r a c t e d Ch/Cf Ca/Cf %Ce 3. There are p l e n t i f u l medium and few f i n e r o o t s t h r o u g h o u t . P r o f i l e 34 - P i t i n the f o r e s t h a l f way up the Burke Mountain road. , e l e v a t i o n 520 m H o r i z o n Depth T e x t u r e » c T %N C/N %S % Fe % A l % S i pH e x t r a c t e d (cm) Py r o Ox CBD Pyro Ox CBD P y r o Ox CBD H,0 C a C l . Ch/Cf Ca/Cf %Ce LFH 10-00 O Ae 00-03 SL 2.74 Bf 03-26 SL 4.31 0.170 25 0.49 0.50 6.75 1.07 1.27 1.08 0.09 0.21 0.20 4.77 4.30 0.35 0.70 79 Bfg 26-66 SL 2.34 0.100 23 0.34 0.50 0.88 0.68 2.14 0.98 0.04 0.72 0.15 5.31 4.78 eg 66+ SL 0.76 0.024 31 0.04 0.35 0.27 0.27 0.82 0.36 0.03 0.34 0.03 5.44 Notes: 1. Water seeped i n t o bottom of the p i t . 2. Medium m o t t l e s were common i n the B f g . 3. Abundant medium and c o a r s e l i v e r o o t s t h r o u g h o u t p i t . 1 6 4 Appendix C: The o r g a n i c - r i c h m a t e r i a l f i l l i n g the mats and c h a n n e l s as seen w i t h a W i l d e - L i e t z D i a l u x 2, phase microscope P r o f i l e 30 - Root Channel m a t e r i a l a t 500 X m a g n i f i c a t i o n 1 6 5 P r o f i l e 25 - c e l l u l a r n a t u r e of the H2 h o r i z o n , 125 X m a g n i f i c a t i o n P r o f i l e 25 - p o l l e n g r a i n s found a t a p p r o x i m a t e l y 78 cm w i t h i n the H2 h o r i z o n Colouc erf \ead\aie. after ~\5o ™li of pnsto-imo<jolLte Was put ikrou^i a Column CBivfainir^ W< C o l o u r o"f Icchaie <Aer 150 mU of Waio- Wa5 pU-t lUlTBugVl a CoLvnh C O r V t d i r v r v j t 5 o i O r ^ o n i o A f t e r a t o t a l of 750 ml e l u e n t has lea c h e d t h r o u g h the column the p r o t o - i m o g o l i t e l e a c h a t e i s as c l e a r as d i s t i l l e d w a t e r . The l e a c h a t e from the o r g a n i c c o n t r o l column i s the y e l l o w brown of f u l v i c a c i d s Even a f t e r 3.25 1 of e l u e n t has le a c h e d t h rough the o r g a n i c c o n t r o l , the l e a c h a t e i s s t i l l c o l o u r e d y ellow-brown H Ch Ch S e t Up of Columns - Note the y e l l o w brown of the l e a c h a t e of the 3 o r g a n i c c o n t r o l columns on the l e f t F u l v i c a c i d s l e a c h e d t h rough a column p r e v i o u s l y l e a c h e d w i t h p r o t o - i m o g o l i te -J 

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