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Distribution of carbohydrates and their associations with metals ions in selected gleysols Thompson, Cedric Basil Hilton 1973

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THE DISTRIBUTION OF CARBOHYDRATES AND THEIR ASSOCIATIONS WITH METAL IONS IN SELECTED GLEYSOLS by C E D R I C B A S I L T H O M P S O N A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN THE DEPARTMENT OF SOIL SCIENCE We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 9, 1973 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by h i s representatives. It i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of *SO I L. S C / B ft/ C.6 The University of B r i t i s h Columbia Vancouver 8, Canada Date A f K ' l , 1 o t £ - ,/7 73 ABSTRACT Three Gleysols from the Lower Fraser V a l l e y were selected to study the d i s t r i b u t i o n of hexoses: and pentoses and t h e i r association with i r o n , aluminum, magnesium and calcium. A sequential extraction pro-cedure was developed. The various stages, of the extr a c t i o n procedure displayed unique patterns of hexose and pentose d i s t r i b u t i o n . The hexose to pentose d i s t r i b u t i o n r a t i o s showed a greater accumulation of hexoses than pentoses i n the upper A horizons but the reverse was observed i n the lower horizons. Consistent hexose to pentose r a t i o s of less than 1 . 0 f o r the d i l u t e acid extraction were observed. Generally, pentose rete n t i o n r e l a t i v e to hexoses increased with depth. Comparative d i s t r i b u t i o n s of sugars with the metal ions studied were as follows: a) Water extraction indicated that hexoses and calcium formed close associations i n the Ap and Ah horizons and pentoses with i r o n and aluminum formed close associations i n the lower horizons. b) The d i l u t e acid extraction indicated that pentoses were associated with aluminum and to a. l e s s e r extent with i r o n throughout the p r o f i l e . c) The combined pyrophosphate and potassium phosphate extraction indicated that i r o n and aluminum were c l o s e l y r e l a t e d with pentoses or hexoses i n the Ap and Ah h o r i -zons whereas pentoses appeared to form close r e l a t i o n s h i p s with i r o n , magnesium and aluminum i n the lower horizons» d) The pyrophosphate extraction indicated a; r e l a t i o n s h i p between hexoses, iron and aluminum i n the upper Ap and Ah horizons while pentoses, magnesium and aluminum appeared to be associated i n the lower hor-izons . e) The potassium sulphate extraction indicated that pentoses or hexoses were c l o s e l y r e -lated to aluminum i n the Ap and Ah horizons but pentoses appeared to be associated with magnesium and aluminum i n the lower horizons. f ) The Chelex - 1 0 0 extraction indicated a r e -l a t i o n s h i p of hexoses with aluminum through-out the profile., LI La TABLE OF CONTENTS PAGE ACKNOWLEDGEMENTS i ABSTRACT . . . . . i i LIST OF TABLES AND ILLUSTRATION . . . . . . . . i v SECTION I INTRODUCTION 1 I I LITERATURE REVIEW 3 I I I MATERIALS AND METHODS 33 IV RESULTS AND DISCUSSION 1. GENERAL CHARACTERISTICS OF SAMPLES . . 43 2. HEXOSE DISTRIBUTION . . . . . . . . 44 3. PENTOSE DISTRIBUTION . . . . . . 56 4. HEXOSE/PENTOSE RATIOS . . . . . . . . 63 5. COMPARATIVE DISTRIBUTION OF HEXOSES AND PENTOSES WITH IRON, ALUMINUM, CALCIUM AND MAGNESIUM . 67 V SUMMARY AND CONCLUSION . . . . . . . . 79 VI LITERATURE CITED ...» 86 i v . LIST OF TABLES AND ILLUSTRATION TABLE PAGE I . D i s t r i b u t i o n of sugars i n h y d r o l y s a t e of org a n i c matter. (Gupta, Sowden and Stobbe. 1963) . 7 II A . P h y s i c a l c h a r a c t e r i s t i c s of samples . . . . 45 I I B . Chemical C h a r a c t e r i s t i c s of h o r i z o n samples .• . . 46 I I I . Hexose d i s t r i b u t i o n i n f r a c t i o n s . 47 IV. Pentose d i s t r i b u t i o n i n f r a c t i o n s . 57 V. Hexose/Pentose r a t i o s . . . . . . . 66 V I . Comparative d i s t r i b u t i o n of hexoses and pentoses w i t h Fe, Ca, A l and Mg ...... ... . ... . . 68 FIGURE I . Flow Sheet: S e q u e n t i a l E x t r a c t i o n procedure . . . . . . . . 42 ACKNOWLEDGEMENTS. The author wishes to express h i s deepest sense of a p p r e c i a t i o n and g r a t i t u d e to the f o l l o w i n g persons without whose p a t i e n t a s s i s t a n c e t h i s t h e s i s would not have been p o s s i b l e : t o Dr. L. E. Lowe f o r h i s f r i e n d l y help and guidance d u r i n g the course of t h i s study, and Dr. C. A. Rowles, Chairman, Department of Sloi l S cience. t o the other members of the Research Committee, Dr. L. M. L a v k u l i c h , and e s p e c i a l l y Dr. T.M. B a l l a r d f o r h i s h e l p f u l c r i t i c i s m and encourage-ment. to a l l the l a b o r a t o r y s t a f f e s p e c i a l l y B. von S p i n d l e r , C a r l i e n Godkin and Ann H a r r i s f o r t h e i r extreme patience and a s s i s t a n c e d u r i n g the l a b o r a t o r y e x e r c i s e . t o Dr. L. M. L a v k u l i c h f o r h i s help i n l o c a t i n g the sampling s i t e s and c o n s t r u c t i v e d i s c u s s i o n of the i n v e s t i g a t i o n . and l a s t l y to the N a t i o n a l Research C o u n c i l of Canada f o r the f i n a n c i a l support d u r i n g the course of t h i s work. 1. INTRODUCTION Carbohydrates, and i n p a r t i c u l a r polysacchar-ides, play an important r o l e i n s o i l s by influ e n c i n g t h e i r physical conditions, a f f e c t i n g cation exchange capacity, the reten t i o n of anions, complexing of metals, and generally a f f e c t i n g the mine r a l i z a t i o n of associated elements by acting as an energy source f o r heterotrophic organisms. Although the main stimulus f o r i n v e s t i g a t i o n of carbohydrates has originated from t h e i r influence on the s o i l physical condition, the tendency has been to study t h i s group of organic substances mainly from an a n a l y t i c a l point of view. I t i s the purpose of t h i s study to: (1) develop a method of extraction which s e l e c t i v e l y and progressively extracts organic matter and associated cations. (2) describe the s o i l as a whole e n t i t y by way of d i s t r i b u t i o n of the constituents. (3) demonstrate d i f f e r e n t i a t i o n of p r o f i l e c h a r a c t e r i s t i c s by way of d i f f e r e n t carbo-hydrate and i o n i c association trends. In order to achieve t h i s a sequential procedure of extraction was u t i l i z e d . On survey of the l i t e r a t u r e , i t was f e l t that no reference was made to the influence of ions and other organic constituents on the present carbohydrate 2. status of the s o i l s . I t therefore became apparent that a h o l i s t i c approach was a more r e a l i s t i c one i n achiev-ing the goals of study on carbohydrates. To pay attention to a group of compounds without acknowledge-z ment of associated constituents i s to ignore relevant material i n the continuum of s o i l s . However, due to the l i m i t e d time a v a i l a b l e , the scope of the study was confined to a few associations of carbohydrates with metal ions. Gleysols were chosen for the study because very l i t t l e information has been compiled on t h i s group of s o i l s , and because of the widespread d i s t r i b u t i o n of poorly drained s o i l s . 3. LITERATURE REVIEW INTRODUCTION Carbohydrates are by f a r the large s t and not the l e a s t important food source of l i v i n g organisms. They are photosynthesized by plants v i a the u t i l i z a t i o n of carbon dioxide and water through a tran s f e r of energy from s u n l i g h t . A s i m p l i f i e d expression of t h i s r e a c t i o n i s : nC0 o + nH o0 (HCHO) + n0 o 2 2 n 2 On incorporation of carbohydrate substances into the s o i l , they become an i n t e g r a l part of the s o i l organic matter, forming complexes with various materials. The o r i g i n a l forms of the carbohydrates are r a p i d l y changed on incorporation and many new polysaccharides are r e -synthesized by s o i l micro-organisms. Therefore, these polysaccharides are quite d i f f e r e n t from those of plants and animal material and should be studied i n t h i s l i g h t . Although much i s known about the nature and function of many polysaccharides synthesized by i n d i v i d u a l organisms, very l i t t l e i s known about the polysaccharides that are synthesized i n the s o i l environment, which by i t s e l f i s quite unique and d i s t i n c t i n that i t integrates a great v a r i e t y of b i o l o g i c a l forms. I t i s indeed, very s u r p r i s i n g that there i s such neglect, because s o i l s not only support the majority of higher plants, but also they are the chief habitat f o r micro-organisms. The q u a n t i t i e s of carbohydrate substances added to s o i l s 4. a s p l a n t r e s i d u e s a n d t h o s e s y n t h e s i z e d b y t h e i n d i g -e n o u s m i c r o - o r g a n i s m s a r e e n o r m o u s , S h o r e y a n d L a t h r o p ( 5 9 ) , f i r s t r e p o r t e d t h e p r e s e n c e o f s u g a r i n s o i l . T h e e v o l u t i o n o f f u r f u r a l o n h e a t i n g t h e s o i l i n h y d r o c h l o r i c a c i d w a s r e g a r d e d a s e v i d e n c e f o r t h e p r e s e n c e o f p e n t o s a n s , a m o u n t s o f f u r f u r a l b e i n g c o n s i d e r e d p r o p o r t i o n a l t o t h e a m o u n t s o f p e n t o s a n o r p e n t o s e . S u b s e q u e n t l y , s e v e r a l r e p o r t s w e r e made o f i s o l a t i o n o f v a r i o u s c a r b o h y d r a t e s f r o m s o i l s . C a r b o h y d r a t e s c o n s t i t u t e 5 t o 20% o f t h e s o i l o r g a n i c m a t t e r ( 2 3 , 2 7 , 7 1 , 7 8 ) . B e c a u s e a l a r g e p r o p o r t i o n o f t h e s e c a r b o h y d r a t e s c a n o n l y b e r e c o v e r e d a f t e r h a r s h c h e m i c a l t r e a t m e n t , t h e i r i s o l a t i o n i n t a c t i s e x t r e m e l y d i f f i c u l t . C l e a r l y , t h e g r e a t c o m p l e x i t y w h i c h d o e s e x i s t i n t h e s o i l c a u s e s s o i l s c i e n t i s t s t o q u e r y t h e f o r m s i n w h i c h t h e y o c c u r , t h e i r a m o u n t s , modes o f i s o l a t i o n a n d c h a r a c t e r i z a t i o n . To d a t e , o n l y a f e w o f t h e a n s w e r s a r e k n o w n . W i t h t h e u s e o f m o r e a d v a n c e d c h e m i c a l , p h y s i c a l , p h y s i c o - c h e m i c a l a n d b i o l o g i c a l t e c h n i q u e s , a l o t m o r e q u e s t i o n s may e v e n t u -a l l y b e a n s w e r e d . C L A S S I F I C A T I O N AND C O M P O S I T I O N 1 . C L A S S I F I C A T I O N : . ( 2 3 ) E v e n t h o u g h a v a r i e t y o f o r g a n i s m s c o n t r i b u t e s t o t h e c o n t e n t o f c a r b o h y d r a t e s i n s o i l s , o n l y a l i m i t e d 5. number of them have been p o s i t i v e l y i d e n t i f i e d . C o n t i n -u a l l y , the chemical and b i o l o g i c a l processes of degrad-a t i o n and s y n t h e s i s a l t e r t h e i r s t r u c t u r e s . F u r t h e r -more, d e s t r u c t i o n and m o d i f i c a t i o n d u r i n g h y d r o l y s i s and e x t r a c t i o n are l i a b l e to occur. A small amount of monosaccharides have been found i n the f r e e s t a t e w h i l e the r e s t have been found i n the bound s t a t e . The f o l l o w i n g carbohydrates have been i s o l a t e d from s o i l s : (23) Monosaccharides: Hexoses (glucose, g a l a c t o s e , mannose, f r u c t o s e ) Pentoses (ara b i n o s e , x y l o s e , r i b o s e , fucose, rhamnose) D i s a c c h a r i d e s (sucrose, c e l l o b i o s e , g e n t i o -biose) O l i g o s a c c h a r i d e s ( c e l l o t r i o s e ) P o l y s a c c h a r i d e s ( c e l l u l o s e , h e m i c e l l u l o s e ) Amino Sugars (glucosamine, galactosamine, N-acetyl-D-glucosamine) Sugar A l c o h o l s ( m a n n i t o l , i n o s i t o l ) Sugar Acids ( g a l a c t u r o n i c , g l u c u r o n i c ) Methylated sugars (2-0-methyl-D-xylose, 2-0-methyl-D-arabinose, 2-0-methyl rhamnose, 4-0-methyl g a l a c t o s e ) 2. COMPOSITION: The presence of such a wide v a r i e t y of sugars 6. makes i t d i f f i c u l t to measure the t o t a l s o i l carbo-h y d r a t e s . The i n s t a b i l i t y of some of the monomers under harsh c o n d i t i o n s ( s t r o n g a c i d - 72% H^SO^) o n l y aggravates an a l r e a d y c r u c i a l s i t u a t i o n . There i s bound to be some d e s t r u c t i o n d u r i n g h y d r o l y s i s . M i l d methods however, o n l y recover up to 30% of the t o t a l s o i l carbohydrates. Free monosaccharides c o n s t i t u t e l e s s than 1% of the s o i l carbohydrates, and e x t r a c t e d p o l y s a c c h a r i d e s have r a r e l y accounted f o r more than 20%. Approximately another 10% may c o n s i s t of c e l l u l o s e (28). Swincer et a l . (71), have r e p o r t e d an e x t r a c t i o n method t h a t enables almost complete e x t r a c t i o n of carbohydrates from s o i l . They contend t h a t m a t e r i a l removed by t h e i r v i g o r o u s e x t r a c t i o n procedure i s s i m i l a r to t h a t of m a t e r i a l s removed b y l e s s e f f i c i e n t methods. In some mi n e r a l and o r g a n i c s o i l s , glucose c o n s t i t u t e s a major percentage (42 - 54%) of the t o t a l sugars i n a l l the h o r i z o n s . U s u a l l y , the other sugars formed i n decreasing order are g a l a c t o s e , mannose, arabinose, x y l o s e , rhamnose, fucose and r i b o s e (23). A s i m i l a r range of sugars has been found by Gupta, Sowden and Stobbe (27), showing a dominance of g a l a c -t o s e , glucose and mannose i n a podzol, a chernozem and a g l e y s o l . The data, i s presented i n Table 1. Glucose c o n s t i t u t e s o n e - t h i r d of the carbohydrates, i n mineral h o r i z o n s and one-half i n f o r e s t l i t t e r s which have not 7. TABLE I DISTRIBUTION OF SUGARS IN HYBROLYSATE OF ORGANIC MATTER (Gupta, Sowden and Stobbe, 1963) Podzol Chernozemic G l e y s o l i c Ao B Ah B Ap % o f t o t a l sugars Galactose 15 16 14 15 15 Glucose 54 35 36 34 .31 Mannose 15 16 16 14 15 Arabinose 5 9 15 12 15 Xylose 4 9 8 8 11 Fucose-Ribose 3 6 3 5 5 Rhamnose 4 9 8 12 8 T o t a l sugar mg/g OM 161 80 95 68 156 OM mg/g s o i l . 730 140 62 20 24 8. undergone e x t e n s i v e degradation. The r e l a t i v e concen-t r a t i o n of the sugar monomers mannose, arabinose, x y l o s e , fucose, r i b o s e and rhamnose and the presence of 2-0-methyl rhamnose and 4-0-methyl g a l a c t o s e i n s o i l i n d i c a t e s t h e i r m i c r o b i a l o r i g i n (17, 82). The t o t a l sugar content g e n e r a l l y decreases r a p i d l y w i t h depth i n s o i l s . However, the r e v e r s e was. observed i n a podzol w i t h permafrost ( f i g . 1, p. 106 -Gupta. ( 2 3 ) ) , and was. a t t r i b u t e d to churning of organic matter by f r o s t a c t i o n . A l s o , i n a solo.netzic s o i l pro-f i l e , the amount of carbohydrate carbon was higher i n the B than i n the A. h o r i z o n (31). These d i f f e r e n c e s ; i n the amount of t o t a l carbohydrates among v a r i o u s s o i l s can be a t t r i b u t e d to d i f f e r e n c e s i n v e g e t a t i o n , degree of o r g a n i c accumulation i n d i f f e r e n t h o r i z o n s , m i c r o f l o r a , and a n a l y t i c a l a r t i f a c t s . Free carbohydrates are present o n l y i n small q u a n t i t i e s i n s o i l s and tend to be i n a steady s t a t e which depends on f a c t o r s , such as moisture, temperature, r e a c t i o n (pH), t e x t u r e , organic matter content, micro-f l o r a , and v e g e t a t i o n i n and on the s o i l . S o i l c e l l u l o s e may c o n t a i n 65% - 82% glucose and thus the m a t e r i a l i s p r i m a r i l y a glucose polymer (33). In c o n t r a s t , " h e m i c e l l u l o s e s " , the group of p o l y s a c c h a r -i d e s found i n c e l l w a l l s of p l a n t s i n a s s o c i a t i o n w i t h l i g n i n as an amorphous phase enveloping the c e l l u l o s e s t r a n d s , c o n s i s t s of v a r y i n g amounts of D-xylose, 9. L-arabinose, D-glucuronic acid, 4-0-methyl-D-glucuronic acid, D-and-L-galactose D-mannose, L-rhamnose, and L-fucose (79). There are as yet no s a t i s f a c t o r y methods av a i l a b l e f o r separation and p u r i f i c a t i o n of these materials. E a s i l y hydrolysed carbohydrates, r e f e r r e d to i n s o i l science l i t e r a t u r e as "polysaccharides", extracted by mild treatment i n v o l v i n g hot water, d i l u t e acids, a l k a l i s and buffers, c o n s t i t u t e a large percentage of plant material, but only a small percentage of s o i l organic matter. They are frequently i n s o l u b l e i n water and non-reducing and are made up of monosaccharide units linked together. At l e a s t two -OH groups i n each sugar u n i t are used f o r linkage to other sugars.. With end units only one -OH i s involved i n bonding. The polymers are u s u a l l y produced from b a c t e r i a , both as capsular and e x t r a c e l l u l a r polysaccharides (79). I t i s very d i f f i c u l t to i s o l a t e i n d i v i d u a l polysaccharides because of the continuous process of synthesis and degradation of polysaccharides that occurs i n s o i l s , thereby r e s u l t -ing i n a considerable v a r i a t i o n i n the amount of polymers of d i f f e r i n g sizes and aomposition. I t appears that s o i l s r i c h i n organic matter contain large amounts of polysaccharides. The polysacch-arides i s o l a t e d from the upper mineral horizon beneath mor have been found to be smaller i n quantity and of lower molecular weight than the polysaccharides i s o l a t e d 10. from a mull (6)„. The presence of small amounts of nitrogen and ribose suggest the p o s s i b i l i t y that s o i l polysaccharides are of microbial o r i g i n (21). According to Keefer and Mortensen (35), s o i l polysaccharides undergo continuous degradation and resynthesis and are products of microbial a c t i v i t y . Furthermore, that they are not derived d i r e c t l y from higher plants i s sub-st a n t i a t e d by the low proportion of D-xylose and D-glucose (82). The presence of mannose, rhamnose and hexosamine also indicates t h e i r microbial o r i g i n . Uronic acids, c h i e f l y D-glucuronic, D-galactur-onic and D-mannuronic acids, which are widely d i s t r i b u t e d i n the plant kingdom, probably r e s u l t from the oxidation of the primary a l c o h o l i c group to a carboxyl group. Their presence i n s o i l s was f i r s t reported by Shorey and Martin (61). The uronic acid values reported by workers f o r mineral and organic s o i l s ranged from 0 - 1 2 to 8 - 47 mg. per gram of organic matter r e s p e c t i v e l y . The occurrence of glucosamine and galactosamine (8, 9, 26, 62, 65, 66) has been reported and one instance of N-acetyl-D glucosamine (64), has been reported. The former two amino sugars account f o r nearly a l l of the hexosamine i n s o i l hydrolysates. Glucosamine (chitosamine) i s found i n c h i t i n (a s k e l e t a l polysaccharide of Crustacea and fungi) and i n mucoproteins and mucopolysaccharides and the l a t t e r i n chondroitin sulphuric acid of c a r t i l a g e and tendons. 1 1 . Amino sugar n i t r o g e n c o n s t i t u t e s from 1 to 11% ( 8 , 2 6 , 6 5 , 6 8 ) , of the t o t a l n i t r o g e n present i n s o i l s - . S o i l type ( 6 2 , 6 3 ) , depth i n s o i l p r o f i l e ( 6 2 , 6 7 ) , and d i f f e r e n t crop r o t a t i o n s ( 2 6 , 6 6 ) , are some of the f a c t o r s t h a t a f f e c t the t o t a l q u a n t i t y of amino sugars. The o r i g i n of glucosamine i n s o i l s i s u n c e r t a i n although m i c r o b i a l o r i g i n i s i n d i c a t e d ( 7 7 ) . I t i s known t h a t mucopolysaccharides of many micro-organisms c o n t a i n galactosamine. Glucosamine could a l s o o r i g i n a t e from c h i t i n . THE SOURCE, SYNTHESIS, TRANSFORMATION AND DEGRADATION OF SOIL CARBOHYDRATES: 1 . SOURCE AND SYNTHESIS': Undoubtedly, the major p o r t i o n of s o i l carbo-hydrates i s d e r i v e d p r i m a r i l y from p l a n t m a t e r i a l s , w h i l e a s i g n i f i c a n t p o r t i o n a l s o o r i g i n a t e s from animal r e s i d u e s and from m i c r o b i a l r e s i d u e s . V e g e t a t i o n con-t r i b u t e s carbohydrates i n the form of mono-, o l i g o - , and p o l y s a c c h a r i d e s ( c h i e f l y c e l l u l o s e and hemicellulose). The s t r u c t u r a l c l a s s e s , represented i n s o i l o r ganic matter i n c l u d e g l u c o s i d e s , n e u t r a l p o l y s a c c h a r i d e s and a c i d sugars ( 2 3 ) . However, i t i s q u i t e obvious t h a t very few unchanged p l a n t p o l y s a c c h a r i d e s occur i n s o i l at any s p e c i f i c time. On a d d i t i o n , p l a n t m a t e r i a l s are r a p i d l y decomposed by the s o i l microbes ( 1 2 , 2 4 , 6 9 ) . Even c e l l u l o s e , which i s a c h e m i c a l l y r e s i s t a n t polymer, i s 12. q u i t e r a p i d l y degraded by the complex of endo- and exoenzymes possessed by s o i l f u n g i , b a c t e r i a and a c t i n o -mycetes (2). Other p l a n t p o l y s a c c h a r i d e s such as s t a r c h , h e m i c e l l u l o s e , p e c t i c substances, gums and mucilages, are l e s s s t a b l e , s u g g e s t i n g t h a t most p o l y s a c c h a r i d e s found i n s o i l s are of m i c r o b i a l o r i g i n . M u c i l a g i n o u s s e c r e t i o n s by the r o o t caps o f many pla n t s , are a - p o s s i b l e e x c e p t i o n . Some evidence t h a t p o l y s a c c h a r i d e s i s o l a t e d from s o i l s are of m i c r o b i a l o r i g i n has been g i v e n i n the p r e v i o u s s e c t i o n . However, the s t r o n g e s t and most d i r e c t e v i d e n c e has been pr e s e n t e d by Mortensen and Ke e f e r (35), u s i n g g l u c o s e and a l f a l f a , t i s s u e s u b s t r a t e s l a b e l l e d w i t h r a d i o a c t i v e c arbon. A f t e r i n c u b a t i o n , they examined the d i s t r i b u t i o n of r a d i o a c t i v i t y among d i f f e r e n t sugars i n a p o l y s a c c h a r i d e e x t r a c t e d from the s o i l . A l l sugars i s o l a t e d were found t o be l a b e l l e d , even though t h e r e was c o n s i d e r a b l e v a r i a t i o n i n s p e c i f i c a c t i v i t y . The changes i n the s p e c i f i c a c t i v i t y of the d i f f e r e n t sugars w i t h time i n d i c a t e d t h a t not o n l y s o i l p o l y s a c c h a r i d e s , but a l s o t h e i r component sugars undergo c o n t i n u a l d e g r a d a t i o n and r e s y n t h e s i s . I t t h e r e f o r e f o l l o w s t h a t non-carbohydrate m a t e r i a l s may sometimes ac t as p r e c u r s o r s f o r s o i l p o l y s a c c h a r i d e s . The sugars examined were g l u c o s e , a r a b i n o s e , g a l a c t o s e , f u c o s e , mannose, rhamnose, x y l o s e and u r o n i c a c i d s . Mehta-et a l . ( 4 9 ) , c l a i m t h a t s o i l b a c t e r i a are 13. capable of producing p o l y s a c c h a r i d e s c o n t a i n i n g a l l the sugars found i n s o i l s except arabinose and g a l a c t o s e . The l a t t e r are probably d e r i v e d from other sources. Very l i t t l e i s known about the p o l y s a c c h a r i d e s produced by most of the s o i l b a c t e r i a ( 3 9 , 5 3 ) . Consequently, i t i s d i f f i c u l t t o e s t a b l i s h the o r i g i n of some of the carbo-hydrates c o n t a i n i n g n u c l e i c and u r o n i c a c i d s . Animals c o n t r i b u t e a sm a l l p o r t i o n of the s o i l carbohydrates i n the form of glycogen, s n a i l g a l a c t a n , n u c l e i c a c i d s , c h i t i n ( 5 2 ) , and the p o l y s a c c h a r i d e s c o n t a i n i n g n i t r o g e n and sulphur. T h e . l a t t e r ones are of immense importance t o animals and c o n s i s t of h y a l u r o n i c a c i d ( m u c o i t i n ) , c h o n d r o i t i n s u l f a t e , h e p a r i n , and hepar i n s u l p h a t e . Studies w i t h pur c u l t u r e s are not l i k e l y to throw much l i g h t on the s i t u a t i o n i n the s o i l i t s e l f . The complexity of the n a t u r a l s o i l environment ensures t h a t at l e a s t the e x o c e l l u l a r p o l y s a c c h a r i d e s produced w i t h i n i t d i f f e r c o n s i d e r a b l y from those obtained i n the l a b o r a t o r y from e i t h e r pure or mixed c u l t u r e s even w i t h the use of the same carbon s u b s t r a t e s . Tissues of r e c e n t l y dead m i c r o b i a l c e l l s , p a r t -i c u l a r l y the c e l l w a l l s , probably c o n t r i b u t e to many of the p o l y s a c c h a r i d e s t h a t p e r s i s t i n the s o i l ( 5 3 , 8 2 ) . I t has been e s t a b l i s h e d t h a t hexosamines and other sugars are important c o n s t i t u e n t s of the polymers which make up the c e l l w a l l s of b a c t e r i a ( 5 3 ) , and a c t i n o -14. mycetes (64), while c h i t i n , a polysaccharide composed at l e a s t predominantly of N-acetyl-glucosamine residues (22), i s the main constituent of fungal c e l l walls (64). The composition of av a i l a b l e plant substrates influences the kind of polysaccharides synthesized i n the s o i l s , but the nature of t h i s e f f e c t i s not under-stood. The kind of crop growing on the s o i l would be expected to influence the microbes i n the rhizosphere. 2. TRANSFORMATIONS AND DEGRADATIONS:. According to Reese (53), f a c t o r s a f f e c t i n g the transformations of s o i l polysaccharides are the kind of sugar(s), modification of the sugar moiety, linkage types, extent of branching and the o r i e n t a t i o n of chains which influence the amorphous to c r y s t a l l i n e superstructure. S o i l polysaccharides, he claims, are e s s e n t i a l l y mixtures of the components of the organisms present i n the s o i l so analysis of these organisms w i l l g r e a t l y s i m p l i f y and promote the i d e n t i f i c a t i o n of the s o i l polysaccharides. I t i s obvious though, that the s i t u a t i o n i s not as simple as t h i s . Fungal walls consist of t h i n chitinous (or less often, c e l l u l o s i c ) substance v a r i a b l y thickened with ^-glucans, d-mannans, and heterogeneous glycans. Bac-t e r i a contain various modifications of the insoluble chitinous wall (eg. muramic acid) and i n addition, capsular material outside of the w a l l . The rate of d e c o m p o s i t i o n i s g r e a t e s t f o r the simple polymers of the common sugars, the most r a p i d r a t e s being those of g l u c a n s , x y l a n s , and mannans of h i g h e r p l a n t s . As the polymers i n c r e a s e i n c o m p l e x i t y , they become more r e s i s t a n t t o enzymic h y d r o l y s i s . Consequently, the r e s i d u a l s o i l p o l y s a c c h a r i d e i s main l y d e r i v e d from more complex c e l l w a l l s of micro-organisms. M a t e r i a l s i s o l a t e d by W h i s t l e r and K i r b y (82), were found t o be more r e s i s t a n t t o decomposition than many p l a n t p o l y -s a c c h a r i d e s . A l s o , i n pure c u l t u r e , c e r t a i n s o i l micro-organisms ( e g . Chromobacterium v i o l a c e u n and A z o t o b a c t e r i n d i c u s ) produced p o l y s a c c h a r i d e s which were not r a p i d l y a t t a c k e d when added t o s o i l s (41, 42, 44, 4 5 ) . However, the p o l y s a c c h a r i d e s produced by many o t h e r s o i l micro-organisms s u f f e r extremely r a p i d d e g r a d a t i o n , up t o 75% of t h e i r carbon b e i n g c o n v e r t e d to CO2 a f t e r i n c u b a t i o n f o r f o u r weeks (44, 45). In c o n t r a s t , o n l y about 10% of the carbon of the p o l y -s a c c h a r i d e from A z o t o b a c t e r i n d i c u s was l o s t i n the same time. Roughly, the order o f i n c r e a s i n g s t a b i l i t y of p l a n t c a r b o h y d r a t e s i s the f o l l o w i n g : r e d u c i n g sugars,- non-reducing c a r b o h y d r a t e s , p e c t i n , h e m i c e l l u — l o s e s and c e l l u l o s e s . At the end of a growing season, a c o n s i d e r a b l e amount of h i g h e r p l a n t p o l y s a c c h a r i d e r e t u r n s t o the s o i l . I t i s r a p i d l y c o n v e r t e d t o m i c r o b i a l t i s s u e , the e f f i c i e n c y o f c o n v e r s i o n b e i n g v e r y low, and the t o t a l organxc matter xn the soxl drops quxckly. Thxs involves the action of both b a c t e r i a and fungi f i x i n g themselves to the substrate or penetrating i t . In addition, some exo-enzymes may d i f f u s e to the substrate The strong adsorptive action of c l a y would tend to minimize the amount of enzymes d i f f u s i n g to any great distance away from t h e i r o r i g i n a l s i t e of production. Some enzymes are c o n s t i t u t i v e , i,.e_. produced regardless of the substrate being consumed, while others are inductive, i..e. induced by the presence of the substrat Complex polysaccharide d i g e s t i o n proceeds i n both ways, but the a b i l i t y to produce the required enzymes i s l i m i t e d to a r e l a t i v e l y few organisms. These, then, become dominant members of the m i c r o f l o r a . Often dead c e l l s may be digested by t h e i r own i n t r a c e l l u l a r en-zymes. Such au t o l y s i s has not been evaluated, yet i t suggests that many organisms which have the a b i l i t y to synthesize a polysaccharide also produce the enzymes fo r i t s d i g e s t i o n . An i n i t i a l fragmentation of the i n s o l u b l e sub-s t r a t e may be a general p r e r e q u i s i t e to the action of h y d r o l y t i c enzymes. In complex systems composed of several s t r u c t u r a l components, the removal of an encrusting substance or of side groups from a polymer chain may be required. Several enzymes, including amylase, c e l l u l a s e , hemicellulase, polygalacturanase, and invertase have been found to play a r o l e i n the transformation of various carbohydrates (49). Phytase (32), xylanase (61), and glucose oxidase also have been detected and these too may play a r o l e i n the transformation and. synthesis of carbohydrates. A look at the types of enzymes shows b a s i c a l l y what changes are brought about. The endo-polysaccharases ( a c t i v i t y i n random fashion) produce a wide v a r i e t y of products. The rate of hydro-l y s i s by these enzymes increases with degree of poly-merization. In contrast, the exopolysaccharases, removing one monomer or dimer at a time from the non-reducing end of the polymer chain are consequently slower acting. These are important i n the degradation of polymers only a f t e r the endo-enzymes have brought about a considerable increase i n the number of chains. On these-short chains, t h e i r action decreases r a p i d l y from tetramer to trimer to dimer. F i n a l l y , the glycosidases represent the term-i n a l enzymes i n the process of hydrolyzing polysacch-arides to simple sugars. The type of glycosidase involved depends on the nature of the aglycone, that i s , whether i t i s another sugar u n i t or a l k y l or a r y l u n i t . Undoubtedly, some changes can take place with-out the inte r v e n t i o n of micro-organisms but humification can only reach completion v i a t h e i r mediation. I t appears that the f i n a l stage of humus formation pro-18. ceeds mainly by physico-chemical processes, without the p a r t i c i p a t i o n of micro-organisms (34). I t appears that carbohydrates can u l t i m a t e l y reappear as aromatic substances v i a the shikimic acid pathway. I t i s evident that carbohydrates decomposed e a r l i e r are sources of s t r u c t u r a l units i n molecules of humus substances (amino acids, proteins and polyphenolic substances) through diverse transformations during met-abolism and resynthesis by micro-organisms. The carbohydrate by-products of microbial reactions can be protected from degradation, by four mechanisms: ( i ) L i v i n g Tissue: L i v i n g t i s s u e i s e s s e n t i a l l y r e s i s -tant to degradation. Large amounts of carbohydrates are contained i n t h i s b i o -mass and thereby protected from degrada-t i o n . After death t h i s material becomes r e l a t i v e l y less r e s i s t a n t to attack. ( i i ) Adsorption: Resistance to breakdown may be enhanced by adsorption to clays (38, 57). Lynch and Cotnoir (18, 38), found that adsorption to clays decreases rate of breakdown. 14 Adsorption of C - l a b e l l e d poly-saccharide by k a o l i n i t e saturated with 19. d i f f e r e n t exchange cations was varied with the type of cation present ( 5 7 ) . 3 + Their e f f e c t s decreased i n order Fe , A l 3 + , H +, C a 2 + , Mg 2 +, Na +. Hence, ex-changeable cations w i l l influence the degree of decomposition. Also reactions with metals (e.g. copper) ( 4 3 ) , confer resistance on plant gums and capsular polysaccharides of s o i l b a c t e r i a , to microbial degradation. ( i i i ) Condensation: Processes s i m i l a r to those described for browning reactions i n food products, invo l v i n g the condensation of carboxyl groups with amino-derivatives, may also explain the s t a b i l i t y of some carbohy-drate materials i n s o i l ( 3 4 ) . ( i v ) I n a c c e s s i b i l i t y : Some polysaccharides are probably shielded from attack by being present i n parts of the s o i l that are in a c c e s s i b l e to s o i l organisms, e.g. i n t e r l a m e l l a r spaces ( 5 5 ) . The influence of s o i l type and such environ-mental v a r i a b l e s as s o i l temperature, moisture content, aeration, pH, nutrient status and agronomic treatment, upon decomposition and synthesis of s o i l carbohydrates 20. i s p o o r l y understood (73). These f a c t o r s probably operate i n much the same way as they do w i t h organic m a t e r i a l s . H i g h l y a e r o b i c c o n d i t i o n s favour r a p i d metabolic a c t i v i t y and the conversion of the l a r g e p a r t of the organic m a t e r i a l s t o CG^, whereas under anaerobic c o n d i t i o n s , decomposition i s much slower. I t has been demonstrated (30), t h a t aggregate-s t a b i l i z i n g m a t e r i a l s (presumably carbohydrates) are s y n t h e s i z e d i n sucrose-amended s o i l under both aerobic and anaerobic c o n d i t i o n s but d e t e r i o r a t e r a p i d l y w i t h oxygen, and w h i l e oxygen i s excluded aggregation per-s i s t s . Decomposition would a l s o be f a c i l i t a t e d by c u l t i v a t i o n s i n c e s o i l a e r a t i o n i s improved. This decomposition may i n v o l v e i n c r e a s e d p r o d u c t i o n of r e l e v a n t enzymes as a r e s u l t of general s t i m u l a t i o n of the m i c r o b i a l p o p u l a t i o n , and the exposure of prev-i o u s l y i n a c c e s s i b l e p o l y s a c c h a r i d e s (55). The metabolic r a t e of the m i c r o b i a l p o p u l a t i o n as a whole i n c r e a s e s w i t h temperature up to about 37° C. I t has been suggested (54), t h a t the m i c r o b i a l popu-l a t i o n at low temperatures produces more aggregating substances (probably p o l y s a c c h a r i d e s ) whereas high temperatures favour r a p i d decomposition of the s o i l b i n d i n g agents. In s p i t e of the v a r i o u s p r o t e c t i v e mechanisms, most of the p o l y s a c c h a r i d e s end up as CG^, and the high l e v e l of carbohydrate present i n s o i l s can l a r g e l y be a t t r i b u t e d to an adequate supply of p l a n t 21. materials. Consequently, the timing of addition has some bearing on the composition and the quantity of the r e s u l t a n t polysaccharides.. In s p i t e of the various transformations that take place, the i n d i c a t i o n i s that the differences i n the polysaccharides from d i f f e r e n t Great S o i l Groups i n t h e i r monosaccharide composition are very small (37). The paucity of studies i n t h i s area p r o h i b i t s further conclusive g e n e r a l i z a t i o n . THE SIGNIFICANCE OF SOIL CARBOHYDRATES. Undoubtedly, the study of s o i l carbohydrates has been mainly stimulated by the ind i c a t i o n s of t h e i r influence on the physical conditions of the s o i l . A l l the r o l e s they play i n the s o i l include t h e i r e f f e c t on the cation exchange capacity (due to the uronic acid u n i t s ) , the reten t i o n of anions (due to amino groups, but only i n a c i d i c s o i l s ) , and generally, carbon metabolism, thereby a f f e c t i n g mineralization of assoc-iated elements involving stimulation of b i o l o g i c a l a c t i v i t y (for example, by acting as an energy source f o r heterotrophs) and f i n a l l y complexing of metals (43). Several reports (40, 46, 70), indicated that m i c r o b i a l l y produced gums could bind s o i l p a r t i c l e s i n t o stable aggregates and these reports have attracted the attention of many workers. Recently, several workers (14, 30, 44, 45), have reportedly confirmed these observations. Further, i t i s believed (6, 18, 20, 40, 41, 81), that the presence i n the s o i l of organisms that produce aggregate s t a b i l i z i n g gums when c u l t i v a t e d i n the laboratory, i s enough to suggest that these gums w i l l also occur i n s o i l s and accordingly should s t a b i l i z e natural s o i l aggregates. These micro-b i a l gums have been extracted from a wide v a r i e t y of s o i l s and i t has been deomonstrated that the extracted polysaccharides are able to s t a b i l i z e s o i l aggregates (48, 54, 82). Although the s t a t i s t i c a l l y s i g n i f i c a n t cor-r e l a t i o n s were not very close, since methods employed were crude estimates of the polysaccharide and aggre-gate s t a b i l i z a t i o n , i t has been demonstrated that c o r r e l a t i o n s do e x i s t between the polysaccharide con-tent and the degree of aggregation (1, 54, 79, 80). G r i f f i t h ' s (24), review c r i t i c i z e d the c o r r e l a t i o n s on the grounds that since methods f o r the quantitative estimation of microbial polysaccharides i n s o i l s have not been developed, i t has not been possible to eval-uate accurately the contribution of these materials to aggregation. Further, i t has been pointed out (71), that probably only c e r t a i n of the polysaccharides present i n s o i l s are responsible f o r aggregate s t a b i l -i z a t i o n . Oades. et a l . (51), having developed and used qua n t i t a t i v e methods of high p r e c i s i o n , found that the c o r r e l a t i o n of aggregate s t a b i l i t y with both composition 23. and t o t a l amount of neutral sugar constituents was no better than with other organic materials. Others also have found b a c t e r i a l l y produced gums d i f f e r i n g consid-erably i n t h e i r effectiveness (14, 44, 45), and that some plant products such as c e l l u l o s e exert no i n f l u -ence on aggregate s t a b i l i t y (25). Although the composition of polysaccharides i n a s o i l under old pasture was s i m i l a r to the composition of polysaccharides i n the same s o i l type which had been under a wheat fallow f o r 40 years, there were dif f e r e n c e s between the treatments with respect to the amounts of carbohydrates present i n the s o i l and ease with which they were extracted (72). Therefore, the d i s t r i b u t i o n of the polysaccharides might be important since only a portion of a polymer may be e f f e c t i v e . Mehta et a l . (48), postulated that i f the polysaccharides are the e s s e n t i a l cements i n the aggregates, periodate or acid hydrolysis should d i s -rupt t h e i r molecules and thereby decrease aggregation. The periodate oxidises sugars containing c i s - g l y c o l groups, then the p a r t l y oxidised polymers are r e a d i l y degraded i n a l k a l i n e s o l u t i o n i n t o various non-poly-meric fragments. Polymers cleaved i n t h i s way can no longer act as bridges between the s o i l p a r t i c l e s form-ing an aggregate (73). On addition of dextrans or s o i l polysaccharides to the dispersed s o i l , the a r t i f i c i a l aggregates formed l o s t t h e i r s t a b i l i t y when treated with d i l u t e (0.01 M) sodium periodate and sodium borate (pH 9.6) (48). However, on examination of natural s o i l aggre-gates, (Mehta et al_. (43)), the treatment was found to be i n e f f e c t i v e and concluded that other s t a b i l -i z i n g agents were involved. In s o i l s of lower organic matter content, periodate treatment has effected a marked decrease i n aggregate s t a b i l i t y (23). Also, others have shown that s o i l s incubated with addi t i o n a l organic matter showed increased aggregate s t a b i l i t y which was l a r g e l y associated with periodate-sensitive materials (30, 79). Greenland et a l . (23), have shown that perm-e a b i l i t y of beds of aggregates could be reduced by periodate treatment. Williams ejt a l . (83) showed that the p r i n c i p a l f a c t o r c o n t r o l l i n g penetration of poly-v i n y l alcohol (PVA) molecules i s probably the s i z e of the s o i l pores i n r e l a t i o n to the s i z e of the polymers. PVA adsorption along the pore walls i s e s s e n t i a l l y an i r r e v e r s i b l e process. The adsorbed molecules hinder or prevent the movement of other molecules i n s o l u t i o n . In a s i m i l a r manner, n a t u r a l l y occurring organic matter, e.g. carbohydrates can reduce the extent of adsorption of other substances and v i c e versa. The water poten-t i a l gradient was also an important f a c t o r . The degree of branching and c r o s s - l i n k i n g modifies the ease of adsorption. 25. Mucilages and gums can undesirably reduce the si z e of s o i l pores i n f i n e textured s o i l s (56). In such s o i l s , microbial production of gums and mucilages i n the few pores may narrow the pores to a point where t h e i r permeability i s reduced appreciably (3). This could also occur i n submerged s o i l s whereby the important coarse pores may have t h e i r permeability reduced (3). Therefore, i t can be concluded that polysaccharides do influence aggregate s t a b i l i t y prob-ably mostly i n c u l t i v a t e d s o i l s of r e l a t i v e l y low organic matter content, but where other s t a b i l i z i n g agents e x i s t , polysaccharides may be of l i t t l e addit-i o n a l benefit or even hinder permeability. F u l v i c acid has frequently been shown to contain a polysaccharide component. Kononova (34), states that the f u l v i c acids, on complexing cations of the a l k a l i and a l k a l i n e earth metals play an important part i n the formation of s o i l s , e s p e c i a l l y of the podzolic and chernozemic groups. I t i s not known to what extent the polysaccharide component i s responsible f o r t h i s e f f e c t . Studies by McKeague (47), have shown that without organic matter, the s o i l has l i t t l e capacity f o r reduction. High amounts of s o l u b i l i z e d i r o n found i n reduced s o i l s with high organic matter con-tent, were consistent with the commonly observed maximum bleaching of gleying s o i l s just below the 26. h o r i z o n of o r g a n i c accumulation. Presumably, reduc-i n g carbohydrates p l a y an important p a r t i n l i g h t of the above d i s c u s s i o n . S e v e r a l sugars normally produced i n the s o i l may i n h i b i t the p r e c i p i t a t i o n of phosphorus by i r o n and aluminum ( 2 ) , and favour the l e a c h i n g of these s e s q u i o x i d e s from the upper to the lower horizons os some s o i l s . The m i n e r a l i z a t i o n of carbohydrates c o n t a i n i n g phosphorus and n i t r o g e n , supply i n o r g a n i c phosphorus and n i t r o g e n to the p l a n t . In a d d i t i o n , energy and carbon f o r v a r i o u s f u n g i , b a c t e r i a and actinomycetes are s u p p l i e d by carbohydrates. Undoubtedly, i n v e s t i -g a t i o n of t h i s category of s o i l o r ganic matter i s necessary t o acquaint s o i l s c i e n t i s t s w i t h the pro-cesses: of s o i l f o r m a t i o n and the s t a t u s of s o i l s i n g e n e r a l . EXTRACTION, PURIFICATION, FRACTIONATION • AND METHODS! OF ANALYSIS: Most competent reviews of these f a c e t s of carbohydrate s t u d i e s have been pu b l i s h e d by Swincer et a_l. ( 7 3 ) , and Gupta ( 2 3 ) . To avoid redundancy, the e n t i r e spectrum i s not presented here. Of sub-s t a n t i a l consequence though, i s the approach of Swincer et a l . (73), t o an i d e a l e x t r a c t a n t , which must meet the f o l l o w i n g c r i t e r i a . The i d e a l e x t r a c t a n t must: a) be non-degradative. 27. b) give a s u f f i c i e n t l y complete extraction for materials to be representative of the t o t a l . c) be equally e f f e c t i v e f o r a l l s o i l s . d) extract s e l e c t i v e l y carbohydrate materials. They recognised that no extractant has been able to meet these c r i t e r i a . The main aim of most studies has:; been to i s o l a t e from the s o i l , a sample of r e l a t i v e l y pure polysaccharide material f o r c h a r a c t e r i z a t i o n . Accordingly, Swincer et a l . (73), proceeded to a three stage chemical extraction procedure preceded by u l t r a -sonic d i s p e r s i o n . This has been the f i r s t step from a naive approach to a more r e a l i s t i c one. The com-p l e x i t y of the types of organic substances and t h e i r chemical, physical and physico-chemical associations with other organic and inorganic materials, obviously necessitates gradual chemical extraction aided by mechanical d i s p e r s i o n . The exploratory procedures have ably demonstrated t h i s and serve as a guideline fo r developing a more meaningful extraction procedure. In addition to extracting carbohydrate materials to completion, i t i s also necessary to i d e n t i f y and c l a s s i f y carbohydrates and other simultaneously extract-able materials i n order to i n t e r p r e t possible associa-tions between these constituents. In developing an e x t r a c t i o n procedure the following facets should be taken i n t o account: 28. The ease of s o l u b i l i t y i n mild extractants. This gives an i n d i c a t i o n of the ease of release of organic substances under mild conditions of chemical change. The ease of release i s dependent on the amount of energy involved i n binding the s o i l c onstituents. The s o l u b i l i t y of organic matter by d i f -ferent types of extractants and combinations of extractants. This gives an i n d i c a t i o n of the mechanisms involved i n binding and part-i a l l y the ease of release of organic sub-stances „ Gradual dispersion of s o i l aggregates. The greater the degree of dispersion necessary to release a s o i l constituent, the more t i g h t l y i t i s bound and/or the more c e n t r a l l y i t i s located within an aggregate. Sequence of extractants. Extracting sequentially attempts to obtain d i s t i n c t homogeneous extracts which permit c l a r i f i c a t i o n of binding mechanisms of d i f f e r e n t types in v o l v i n g d i f f e r e n t c o nstituents. The larger the number of i d e n t i f i a b l y d i f f e r e n t extractants, the 2 9 . greater the c l a r i f i c a t i o n . Both s t r u c t u r a l and energy r e l a t i o n s h i p s can be i n v e s t i -gated . 5 . I d e n t i f i c a t i o n of extractable materials. Other simultaneously extractable materials must be recognized as possibly contributing to the process of aggregation. 6 . Residue Composition. A l l materials must be accounted f o r and those i n the residue may e x h i b i t spec-i f i c and d i f f e r e n t properties from the others previously extracted. Also extrac-t i o n of homogeneous constituents to completion i s d i f f i c u l t . 7 . Extraction yields.. The r e l a t i v e amounts of d i f f e r e n t extracted materials i n d i c a t e the r e l a t i v e contributions to the aggregation process. 8. Polymer degradation. Although polymer degradation i s probably unavoidable, the extent of degrad-ation should be minimized. Extractants commonly found useful f o r i s o l a t i o n of polysaccharide from s o i l s include water, aqueous buffers and complexing agents, d i l u t e mineral acids and a l k a l i s . 30. WATER: This has been a popular extractant because of the s i m p l i c i t y of the extraction, r e l a t i v e l y low simul-taneous extraction of humic materials and the ease of subsequent p u r i f i c a t i o n (8, 75). Hot water extraction has proven more e f f i c i e n t but autohydrolysis occurs with temperatures above 70 degrees centigrade (73). AQUEOUS BUFFERS AND COMPLEXING AGENTS': Sodium pyrophosphate and sodium EDTA, have been used as complexing agents (5, 6), and as buffer solutions (6). These afford minimum a l t e r a t i o n of the polysaccharides. Schweitzer's reagent (Cupra-ammonium hydroxide) i s considered e f f e c t i v e f o r extracting c e l l u l o s e (28). DILUTE MINERAL.ACIDS AND CATION EXCHANGE RESINS: Di l u t e mineral acids are f a r more e f f e c t i v e f o r extracting carbohydrate substances than humic materials. Repeated treatments with strong solutions apparently hydrolyses bonds between polysaccharides and humic materials. Extractants used include d i l u t e (0.1N) hydrochloric acid (7), h y d r o f l u o r i c acid (71), amberlite IR - 120, cation exchange r e s i n (5). ALKALIS: D i l u t e sodium hydroxide has not only been the c l a s s i c a l extractant f o r s o i l organic matter but frequently has proven to be the most potent of a l l the extractants. Large amounts of humic materials have 31. always been extracted simultaneously with carbohydrates. Further, i t i s claimed by many workers that autooxid-ation or hydrolysis of polymers occurs with t h i s alka-l i n e treatment. SEQUENTIAL EXTRACTION: Swincer et a l . (71), employed the following chemical extraction sequence a f t e r u l t r a s o n i c d i s -persion: 1) IN HCl at 20° centigrade 2) 0.5N NaOH 3) Acetic anhydride with 2.5% cone. H^SO^ at 60° centigrade 4) F i n a l hydrolysis with 72% H 2S0 4 A . " l i g h t f r a c t i o n " obtained by a densimetric f l o t a t i o n procedure (19), contained from 10 - 50% of the t o t a l s o i l carbohydrate. Of the remainder, 10 -20% occurs i n the acid extract, 30 - 50% i n the sodium hydroxide extract, 20 - 30% i n the acetic anhydride extract and 10 - 20% may be l e f t i n the f i n a l residue. The sequential approach has the advantage of progressive removal of material which eliminates further recombination of each type of material extracted. This multiple approach also has the advantage of s e l e c t i v i t y of material i n a s p e c i f i c order which leads to better understanding of the binding processes i n -volved f o r each f r a c t i o n . There are l i m i t a t i o n s to t h i s s e l e c t i v i t y because of incompleteness of treatment at any one stage being dependent on the bonds being broken. The s p e c i f i c compounds being removed at one stage may contain bonds which might escape attack by an extractant employed at a l a t e r stage. This r e s u l t s i n the incompleteness of the l a t e r stage. The sequen-t i a l approach also gives an almost complete extraction because of the d i v e r s i t y of extractants used. 33. MATERIALS AND METHODS For the study of carbohydrates i n p o o r l y - d r a i n -ed s o i l s , s o i l h o r i z o n s were sampled i n three s o i l s r e p r e s e n t i n g three s e r i e s i n the g l e y s o l i c order at the beginning of the summer i n m i l d l y r a i n y c o n d i t i o n s . The samples were a i r - d r i e d and crushed to pass through a 2 mm. s i e v e . I t i s not known to what extent d r y i n g and c r u s h i n g a f f e c t the d i s t r i b u t i o n of carbohydrate f r a c t i o n s , although some i n f l u e n c e on l e v e l s of water s o l u b l e c o n s t i t u e n t s i s l i k e l y . Drying i s , however, necessary to minimize d i f f e r e n c e s between samples a r i s i n g o n l y from d i f f e r e n c e s i n f i e l d moisture con-d i t i o n s at the time of sampling. A c l a s s i f i c a t i o n of the s o i l s i n v e s t i g a t e d along w i t h the t o p o g r a p h i c a l f e a t u r e s of the sampling s i t e s are given i n the t a b l e I I A . The h o r i z o n samples were used to study carbo-hydrate d i s t r i b u t i o n according to the e x t r a c t i o n pro-cedure presented i n a l a t e r s e c t i o n , and f o r charac-t e r i z a t i o n by standard methods i n d i c a t e d below. P a r t i c l e s i z e d i s t r i b u t i o n was determined by the hydrometer method, f o l l o w i n g d e s t r u c t i o n of the o r g a n i c matter w i t h hydrogen peroxide ( 1 5 ) . S o i l pH was measured i n a 0.01M C a C ^ suspension ( r a t i o 1:2.5) us i n g a Beckman Zeromatic pH meter. T o t a l carbon content was determined w i t h a Leco I n d u c t i o n Furnace and Carbon Analyzer ( 4 ) , and t o t a l n i t r o g e n by a 34. s e m i - m i c r o - k j e l d a h l procedure (10). C a t i o n exchange c a p a c i t y and exchangeable c a t i o n s were determined by the n e u t r a l 1.0N ammonium acetate procedure (13). Hexose and pentose contents i n s o i l e x t r a c t s were determined as follows:, a l i q u o t s of s o i l e x t r a c t s were hydrolyzed by treatment i n IN H2S0^ and auto-c l a v i n g ' f o r one hour at 121° c e n t i g r a d e and 15 P.S.I. (1 6 ) . The h y d r o l y s a t e was then a p p l i e d t o a chrom-ato g r a p h i c column of Ion R e t a r d a t i o n r e s i n AG-11A8 (Bio-Rad, Richmond, C a l i f o r n i a ) p r e v i o u s l y washed w i t h 0.25M NH 4C1 (pH 8.0) f o l l o w e d by d i s t i l l e d water. The column was e l u t e d w i t h d i s t i l l e d water and the e l u a t e c o l l e c t e d f o r e s t i m a t i o n of hexose and pentose content Hexose and pentose contents were estimated by the anthrone (11), and the a n i l i n e acetate (76), c o l o r i -m e t r i c procedures r e s p e c t i v e l y . The amounts of hexose and pentoses are determined as glucose and x y l o s e e q u i v a l e n t s r e s p e c t i v e l y and are not absolute quant-i t i e s . E x t r a c t e d c a t i o n s were i n a l l cases determined by atomic a b s o r p t i o n spectroscopy u s i n g a Perkin-Elmer Model 303 spectrophotometer. EXTRACTION OF CARBOHYDRATE FRACTIONS An e x t r a c t i o n procedure was developed, based on a s e r i e s of e x t r a c t r a n t s of i n c r e a s i n g s o l u b i l i z i n g s t r e n g t h , accompanied by p r o g r e s s i v e l y g r e a t e r d i s -p e r s i o n of s o i l aggregates, t h a t would y i e l d a s e r i e s of polysaccharide f r a c t i o n s with concurrently r e -leased cations. D e t a i l s of the procedure employed are given below, followed by a discussion of the r a t i o n a l e for the methods selected. A. flow sheet f o r the extrac-t i o n procedure i s presented as F i g . 1. Stage A: 10 gm. s o i l samples were shaken f o r 1 minute with 50 ml. of water i n 100 ml. p l a s t i c centrifuge tubes. Tubes were then centrifuged at 2500 g. (R.C.F.) f o r 10 minutes. The supernatant s o l u t i o n was decanted, the f l o a t i n g material was f i l t e r e d o f f , and the f i l t r a t e saved f o r analysis as F r a c t i o n A. Stage B: The residue from stage A was then extracted four times with 50 ml. of 0.1N I-^SQ^ each time by dispersing the suspension i n a water bath f o r 15 minutes. Dispersion i n the water bath involved the use of the DisOntegrator Ul t r a s o n i c cleaner supplied by U l t r a s o n i c In-dustr i e s Inc., N.Y., with system No. Forty and Generator Model No. G.-40 Cl-P with power out-put 80 watts. The tank had a half gallon capacity. The tubes were then centrifuged at 2500 g. (R.C.F.) f o r 15 minutes each time, the supernatant s o l u t i o n decanted o f f and saved for analysis as Fraction,B. Stage C: The residue from stage B was then extracted with 50 ml. of d i s t i l l e d water d i s -3 6 . persing the suspension i n a water bath f o r 15 minutes. The tubes were then centrifuged f o r 15 minutes and the s o l u t i o n decanted o f f and saved f o r analysis as F r a c t i o n C. Stage D:. The residue from stage C was then extracted three times with 50 ml. of 0.05M N a 4 P 2 ° 7 + IN K 2S0 4 (pH 7.0) by dispersing the suspension i n a water .:bath f o r 15 minutes each time. The tubes were then centrifuged at 6000 g. (R.C.F.) f o r 15 minutes. The The supernatant s o l u t i o n was then decanted o f f and saved f o r analysis as F r a c t i o n D. Stage F: The residue from stage D was then extracted twice with 200 ml. of 0.05N NaOH by shaking i n an end-to-end shaker f o r one hour each time. The tubes (500 ml.) were then centrifuged f o r 15 minutes at 6000 g. (R.C.F.) and the supernatant decanted o f f and saved for analysis as F r a c t i o n F. Stage G:. The residue from stage F was then hydrolyzed with 25 ml. of 72% H 2S0 4 f o r 15 minutes and the hydrolysate d i l u t e d to IN H 2S0 with d i s t i l l e d water. The d i l u t e d hydrolysate was then refluxed f o r 16 hours a f t e r which i t was allowed to c o o l . Then the hydrolysate was f i l t e r e d and saved f o r analysis as F r a c t i o n G. 37. Stage DD, DDD and DS were not i n the main sequence of ex t r a c t i o n . The f r a c t i o n s were obtained as follows: Stage DP.".: The residue from stage C was extracted with 0.05M Na^j^Oy (pH 7.0) i n a s i m i l a r man-ner as i n stage D to give F r a c t i o n DP. Stage DS: The residue from stage C was ex-tracted with I N K^SO^ i n a s i m i l a r manner as i n stage D to give F r a c t i o n DS. Stage DDD: The residue from stage C was ex-tracted with 50 ml. of d i s t i l l e d water and 1.76 gm. of Chelex-100 r e s i n i n the sodium form by shaking the suspension for 15 hours i n an end-to-end shaker. The supernatant solu t i o n obtained a f t e r c e n t r i f u g a t i o n at 6000 g. (R.C.F.) f o r 15 minutes,was decanted o f f and save f o r analysis as F r a c t i o n DDD. I n i t i a l l y , i n developing the extr a c t i o n pro-cedure, no attempt was made to extract carbohydrate material free of other organic constituents. The approach enta i l e d the removal of carbohydrates with successive treatments so that l o c a t i o n and ease of access played an important r o l e i n determining the amounts of material extracted. Presumably, the more e a s i l y accessible materials would be extracted f i r s t , f o r they are less l i k e l y to be t i g h t l y bound than those within the aggregates because of t h e i r more recent time 38. of deposition. This approach can be considered to represent at l e a s t a recent record of the state of carbohydrates i n the horizon and when rel a t e d to a p r o f i l e , gives some record of the carbohydrate d i s -t r i b u t i o n within. In order to d i f f e r e n t i a t e between the d i f f e r e n t binding mechanisms, i t i s also necessary to extract carbohydrate materials i n a s e l e c t i v e man-ner, i n t h i s case by using d i f f e r e n t types and strengths of extracting s o l u t i o n s . The various stages were r a t i o n a l i z e d as follows:: Stage A: With as many binding agents as e x i s t i n the s o i l , i t i s to be expected that the f r e e l y water soluble portion of carbohydrates would not be sub-s t a n t i a l . The amount of material extracted would mainly be dependent on the amount of water used and the degree of d i s p e r s i o n . Since the s o i l had been dried before extraction, only a very l i m i t e d comparison i s i n order. This can only represent p a r t i a l l y what would occur on the wetting and drying of the s o i l i n the f i e l d . Its importance would conceivably include i t s influence on immediate energy a v a i l a b i l i t y to organisms even though t h i s may not be the only energy source a v a i l a b l e at the time. This portion can also i n d i c a t e the amounts av a i l a b l e f o r leaching to lower horizons during chang-ing wet and dry conditions. The carbohydrates may or may not be bound to ions i n the s o i l and may also i n d i c a t e an equilibrium state between soluble and 39. in s o l u b l e m a terial. Stage B: The d i l u t e acid extractant was used to s o l u b i l i z e material at a s l i g h t l y lower pH than the s o i l pH and should represent part of the normal f u l v i c acid f r a c t i o n obtained a f t e r a c i d i f i c a t i o n of the sodium hydroxide extract. These f r a c t i o n s would not be d i r e c t l y comparable because of the l i m i t e d degree of dispersion i n the d i l u t e acid extraction compared with that achieved with sodium hydroxide i n the conventional e x t r a c t i o n . I t i s possible that the s l i g h t l y more acid conditions can s o l u b i l i z e carbo-hydrates which had p r e c i p i t a t e d out under higher pH conditions or were bound through acid soluble compon-ents. The extent of hydrolysis should not be very great due to the d i l u t i o n of the extractant and the low temperature during e x t r a c t i o n . Stage C: This stage was simply intended to remove excess acid and the remainder of carbohydrates extracted by the d i l u t e a c i d . Stage D: The sodium pyrophosphate should r e -move ions involved i n bridge-bonding of carbohydrate material to clays and other organic matter, thereby re l e a s i n g them usually into the s o l u t i o n . The concen-trated s a l t should provide a homo-ionic surface of potassium, e s p e c i a l l y f o r the c l a y and other organic materials, thereby minimizing bridging through other ions. The combination of e f f e c t s i s designed to obtain 40. some i n d i c a t i o n of the .ions and the carbohydrate mat-e r i a l s t h a t were i n v o l v e d i n the b r i d g i n g ( a d s o r p t i o n ) mechanism by a s s o c i a t i n g those c o n s t i t u e n t s r e l e a s e d s i m u l t a n e o u s l y . Stage F: The powerful d i s p e r s i n g e f f e c t of t h i s a l k a l i has been demonstrated f r e q u e n t l y and was used to e x t r a c t more s t r o n g l y bound m a t e r i a l and mat-e r i a l which was excluded from e x t r a c t i o n due to incom-p l e t e d i s p e r s i o n of the sample. Stage G: This h y d r o l y s i s was used to measure the remainder of carbohydrates t h a t were too l a r g e to d i s s o l v e i n the s o l u t i o n s or t h a t were too t i g h t l y bound t o be e x t r a c t e d by any of the previous e x t r a c t -ants . Stage DD.:. A comparison can t h e r e f o r e be made between the ions and carbohydrate m a t e r i a l s r e l e a s e d by these two methods (D and DD) of e x t r a c t i o n as' some d i f f e r e n t bridges may be expected to p e r s i s t or sever i n the presence of the complexing agent alone. Stage DS:. A s i m i l a r comparison w i t h stage D can be made and t h i s should i n d i c a t e the e f f e c t of p r o v i d i n g o p p o r t u n i t y f o r a homo-ionic s u r f a c e without any a i d from complexation. This should i n d i c a t e the str e n g t h s of the i o n i c b ridges w i t h r e s p e c t to those p o s s i b l y formed through potassium. Stage DDD; A comparison can be made between the s o l i d and l i q u i d forms of c h e l a t i n g (complexing) 41. agents even though t h e i r f u n c t i o n a l groups are d i f -f e r e n t . This could i n d i c a t e how the degree of pene-t r a b i l i t y a f f e c t s the d i s s o l u t i o n of bridge bonds. On the other hand, the d i f f e r e n c e i n f u n c t i o n a l groups can i n d i c a t e t h e i r s u s c e p t i b i l i t y to d i s s o l u t i o n because of t h e i r d i f f e r e n t binding strengths. FIGURE I Flew Sheet: Sequential Extraction Procedure 10 grins < 2 mm SOIL WATER (1 x SO mis) - shake for 1 min. - centrifuge - 2500 g for 10 mins. - f i l t e r off light fraction -* Decant -+ Fraction A STAGE A Residue IN H2S04 (4 x 50 mis) s i / - disperse (4 x 15 mis,) - centrifuge - 2500 g for 15 mins. -. Decant -*• Fraction B AGE B Residue H 2 d (1 x 50 mis) - as in B t Fraction C STAGE C Residue^ 0.05 KNa.P_07 + INK2S6[J(FH = 7.0) ( 3 x 50 mis) r- disperse ( 3 x. 15 mins.) - centrifuge .- 6000 g for 1 5 mins. - Decant -»• Fraction D STAGE D Residue 05 NNaOH (2 x 200 mis) - shake for 1 hr. - centrifuge - 6000 g for 1 5 mins. - Decant •+ Fraction F :NK2SO4 • - as in D + Fraction PS •-STAGE D3 04 MNa^ PjO, (pH =7.0) - as in D •* Fraction DD '"•STAGE DD STAGE F Residue Final Hydrolysis - 25 mis of 72% (15 mins.) - dilute to INH2S04 - reflux for 16 hrs. - f i l t e r •* Decant •+ Fraction G CHELEX-100 (Na ) (1.76 gms + 50 mis H20) shake for 15 hrs. centrifuge - 6000 g for 15 mins. Decant •+ Fraction DDD *STAGE DDD STAGE G ft Not part of main sequence. 43 RESULTS AND DISCUSSION GENERAL CHARACTERISTICS OF SAMPLES The tabulated physico-chemical properties of the samples are presented i n Tables IIA and IIB. Sample pH ranged from 4.30 to 5.75. There was a general increase i n pH with depth i n each s o i l p r o f i l e . The clay content ranged from 31.9 to 59.5 percent and appeared to be highest i n Ap and Ah hor-izons with the exception of the Cg horizon of the Langley ser i e s which was highest f o r that s o i l . The s i l t and sand contents ranged from 39.2 to 61.2, and 0.2 to 9.3 percent r e s p e c t i v e l y . The t o t a l carbon and nitrogen contents ranged from 0.1 to 9.9 and 0.01 to 0.58 percent r e s p e c t i v e l y . The t o t a l carbon and nitrogen generally decreased with depth, with the exception of the Ah^ horizon of the Hazelwood serie s which was higher i n the upper adja-cent horizon but not as high as the Ah^ horizon. The carbon to nitrogen r a t i o s ranged from 8.3 to 19.0 and did not show remarkable uniformity with depth. The t o t a l c a t i o n exchange capacity decreased with depth with the appropriate i n d i c a t i o n of a clay s i z e p a r t i c l e accumulation i n the Btg horizon of the Langley s e r i e s . There was at general increase i n exchange-able calcium and magnesium contents with depth, the former showing a greater increase. 44. The y i e l d s of hexoses and pentoses released at each stage of the extraction sequence expressed as ug/g of s o i l and as percentages of the t o t a l extract-able hexoses and pentoses are presented i n Table I I I and IV. HEXOSE DISTRIBUTION Stage A. Water Soluble Hexoses The water soluble hexoses extracted ranged from zero to 2,475 ug/g s o i l whereas the percentages of the t o t a l extractable hexoses f o r the corresponding horizons ranged from zero to 4.7%. There was a general decrease i n the amount of hexoses with depth, c o r r e l a t i n g with the t o t a l carbon contents, except i n the Hazelwood series where there was an increase i n the hexoses to the Ah^ horizon, then a decrease i n the Cg horizon. There was a s i m i l a r c o r r e l a t i o n between the percentages of the hexoses. Probably, the most notable feature of t h i s stage was that the Btg horizon yielded no water soluble hexoses. Stage B. Hexoses Soluble i n D i l u t e Acid (0.1N H 2S0 4) The amounts of hexoses soluble i n d i l u t e acid ranged from 9 to 4,950 pg/g of s o i l amounting to 0.18 to 20.8% of the t o t a l extractable hexoses. In the Langley s e r i e s , the highest amounts of hexoses were observed i n the Ah and Ap horizons cor-responding with the t o t a l carbon contents. However, TABLE IIA PHYSICAL CHARACTERISTICS OF SAMPLES S o i l Sub groups Series Topography Horizons Depth (ins) Sand (%) S i l t (%) Clay (%) Humic Eluviated Gleysol Langley Level to depressional Ap Ah Aeg 0 - 9 9 - 2 0 26 - 35 5.3 5.0 2.0 45.4 44.6 53.6 49.3 50.4 44.4 Btg 35 - 45 2.8 49.8 47.4 Cg 52+ 0.5 46.0 53.5 Orthic Gleysol Hatzic Level Ap Bg 0 - 8 8 - 2 0 1.3 0.3 39.2 48.6 59.5 51.1 Cg 28+ 0.2 55.8 44.0 Orthic Humic Gleysol Hazelwood Level to depressional Ah 1 Bg *Ah 2 0 - 1 0 15 - 23 23 - 32 0.8 1.5 0.3 61.2 53.3 45.8 38.0 45.2 -53.9 Cg 36+ 9.3 58.8 31.9 •^According to the current Canadian classification Ah 0 should read Ah. TABLE IIB CHEMICAL CHARACTERISTICS OF HORIZON SAMPLES Total Total C/N Exchangeable Cations ( m e / 1 0 0 g ) Series Horizon pH .. C N ;  (%) (%) ratio Na K Ca Mg (me/lOOg) Langley Ap 4.35 9.9 0.58 ' 17.1 0.4 0.4 3.4 7.3 58.0 Al 4.35 9.5 0.50 19.0 0.3 0,2 3.1 6.4 48.6 Aeg 5.10 0.4 0.04 9.8 0.6 <0.2 8.3 5.8 24.2 - Btg 5.60 0.2 0.02 12.0 0.8 0.3 11.6 7.3 39.4 Cg 5.75 0.1 0.01 10.7 0.7 0.5 9.8 6.4 28.8 Hatzic Ap 4.30 4.6 0.49 9.4 0.2 0.4 2.1 5.2 49.0 Bg 4.65 0.8 0.10 8.3 0.1 0.1 3.7 7.3 36.4 Cg 4.70 0.5 0.06 8.8 0.2 0.1 6.9 9.4 19.8 Hazelwood Ah 1 4.40 4.5 0.42 10.7 0.1 0.1 1.3 5.3 37.3 Bg 4.30 1.9 0.15 12.4 0.1 0.3 2.1 5.0 35.7 Ah2 4.50 2.6 0.23 11.4 0.2 0.2 4.6 6.4 36.2 Cg 4.60 0.3 0.03 9.7 0.2 0.2 6.3 6.3 24.3 TABLE III HEXOSE DISTRIBUTION IN FRACTIONS (yg heKcse/g soil) (figures in parenthesis represent fraction - hexose as percent or total extractable hexose) S e r l e s Langley Hatzic Hazelwood Horizons Stages Ap Ah Aeg Btg Cg Ap Bg Cg Ah Bg Ah Cg 2,475 541 230 < 1 45 396 90 < 1 45 90 117 23 A (4.7) (1.2) (3.7) (<0.1) (3.5) (1.4) U.3) (<0.1) (0.2) (1.1) (1.7) (0.5) 3,060 4,950 450 9.0 270 696 540 360 1,584 180 468 360 B (5.8) (9.3) (7.3:) (0.2) (20.8) (2.5) (7.9) (7.8) (5.5) (.2.3) (6.8) (e.7) 138 180 < 1 < 1 158 170 135 180 54 432 90 113 C (0.4) (0.3) (<0.1) (<0.1) (12.1) (0.5) (2.0) (3.9) (0.2) (5.4) (1.3) (2.7) 8,100 6,500 9 < 1 168 2,228 1,202 405 1,225 432 108 90 D (15.2) (12.1) (0.2) (<0.1) (12.9) (6.2) (17.5) (8.7) (4.3) (5.4) (1.6) (2.2) 5,700 5,400 450 135 405 2,228 567 630 3,375 635 567 270 DD (10.7) (10.1) (7.3) (2.7) (31.0) (6.2) (8.3) (13.6) (11.8) (7.9) (8.2) (6.5) 920 2,700 108 540 3&0 2,835 1,215 600 783 270 24 338 DS (1.7) (5.0) (1.7) (10.7) (29.0) (7.9) (17.7) (13.0) 12.7) (3.4) (0.4) (6.1) 801 781 248 189 203 1,418 216 180 1,134 473 365 113 DDD (1.5) (1.8) (4.0) (3.8) (16.5) (3.9) (3.2) (3.9) (4.0) (5.9) (5.3) (2.7) 17,370 16,200 1,368 1,800 216 13,230 1,215 600 8,675 4,050 1.890 SOO F (32.7) (30.2) (22.0) (35.7) (16.6) (37.7) (17.7) (12.7) (30.2) (50.6) (27.5) (21.6) 24,375 26,250 3,712 3,094 475 19,125 4,320 3,400 15,000 2,625 3,750 2,500 G (45.8) (49.0) (59.8) (61.4) (36.6) (53.1) (62.9) (73.4) (52.2) (32.8) (54.5) (60.1) Total- " . " Extractable 53,118 53,570 6,210 5,038 1,298 36,045 6,867 4,630 28,733 8,006 6,882 4,160 Hexoses Total extractable hexoses represents the sum of fractions A, B, C, D, F and G. 48. the Ah h o r i z o n y i e l d e d a much higher q u a n t i t y than d i d the Ap h o r i z o n . The Aeg, Btg and Cg f o l l o w e d the same p a t t e r n as the water s o l u b l e hexoses. The r a t i o of a c i d e x t r a c t a b l e to water e x t r a c t a b l e hexoses was s u b s t a n t i a l l y higher i n the Ah than the Ap h o r i z o n (7.7 and 1.2 r e s p e c t i v e l y ) . The Aeg h o r i z o n y i e l d e d t w i c e the amount of hexoses w h i l e the Cg h o r i z o n y i e l d e d s i x times as much hexoses obtained by water e x t r a c t i o n . Again, the Btg h o r i z o n f a i l e d to y i e l d a s i z e a b l e p o r t i o n of i t s hexose content. In the H a t z i c s e r i e s , there was a general decrease i n the amounts of hexoses e x t r a c t e d but there was an i n c r e a s e i n the percentages w i t h depth of pro-f i l e . The hexoses y i e l d e d i n stage A and stage B p a r a l l e l e d each o t h e r . This may i n d i c a t e s i m i l a r types of hexose-containing substances- being s o l u b i l i z e d by a s t r o n g e r agent w i t h more i n s o n a t i o n or t h a t the reagent had no e f f e c t and the in c r e a s e d d i s p e r s i o n was r e s p o n s i b l e f o r the increa s e d y i e l d of water s o l u b l e hexoses. A l s o t h i s may i n d i c a t e the removal of some ions by the a c i d e x t r a c t a n t . In the Hazelwood s e r i e s , there i s a l s o a general decrease i n the amounts of hexoses e x t r a c t e d w i t h depth, w i t h the exception of the lower y i e l d from the Bg h o r i z o n . Again, there i s the i n c r e a s e i n per-centage of hexoses w i t h depth, excepting the Bg h o r i z o n . The y i e l d of hexoses i n stage B do not p a r a l l e l those 49. of stage A, except w i t h regard to the high l e v e l s obtained from the Ah^ h o r i z o n . The i n c r e a s e s i n y i e l d over stage A i n each h o r i z o n are at l e a s t f i v e f o l d except the Bg h o r i z o n which i s o n l y t w o - f o l d . G e n e r a l l y , the i n d i c a t i o n i s t h a t the d i l u t e a c i d e f f e c t i v e l y severed bonds y i e l d i n g s i z e a b l e p o r t i o n s of the hexoses contained i n the r e s p e c t i v e h o r i z o n s , e s p e c i a l l y the Cg h o r i z o n s . Stage D. Hexoses S o l u b l e i n 0.05M N a 4 P 2 0 7 + IN K 2 S 0 4 (pH 7.0) The y i e l d s of e x t r a c t a b l e hexoses f o r t h i s e x t r a c t i o n ranged from zero to 8,100 ug/g of s o i l and the percentages of t o t a l e x t r a c t a b l e hexoses ranged from zero to 17.5. In the Langley s e r i e s , the Ap and Ah horizons y i e l d e d copious q u a n t i t i e s of hexoses whereas the Aeg and Btg h o r i z o n s y i e l d e d n e g l i g i b l e amounts. The percentages of hexoses i n the Ap, Ah and Cg horizons r e s p e c t i v e l y were 15.2, 12.1 and 12.9, i n d i c a t i n g s i m i l a r e q u i l i b r i u m c o n d i t i o n s . The H a t z i c s e r i e s showed a general decrease i n the amount of hexoses e x t r a c t e d w i t h depth but the percentage of hexoses e x t r a c t e d was f a r g r e a t e r i n the Bg h o r i z o n than i n the Ap and Cg h o r i z o n s . The r e s u l t s i n d i c a t e t h a t t h i s e x t r a c t a n t severed more bonds of t h i s type i n the Bg h o r i z o n than i t d i d i n the other 50. h o r i z o n s . Therefore, t h i s type of bond i s probably more t y p i c a l of the Bg h o r i z o n than the others". The Hazelwood s e r i e s showed a general i n c r e a s e i n y i e l d of hexoses. The low - h i g h - low - high a l t e r n a t i n g p a t t e r n of the hexoses y i e l d e d from the Ah, Bg, Ah 2, Cg h o r i z o n s was the opposite of the high - low - high - low a l t e r n a t i n g p a t t e r n of the t o t a l carbon f o r the corresponding h o r i z o n s . The percent-age y i e l d i n the Bg h o r i z o n was again the h i g h e s t . The i n d i c a t i o n i s t h a t the Bg h o r i z o n appears to be o p p o s i t e to t h a t of the Btg h o r i z o n . A p o s s i b l e e x p l a n a t i o n l i e s i n the d i f f e r e n c e i n c l a y contents between the Btg and Bg h o r i z o n s . Stage DD. Hexoses S o l u b l e i n 0.05M N a 4 P 2 0 ? (pH 7.0) A g r e a t e r degree of d i s p e r s i o n of the samples was d i s p l a y e d i n t h i s stage than any of the other p a r a l l e l stages. The amounts of hexoses e x t r a c t e d ranged from 135 to 5,700 /ag/g of s o i l w h i l e the per-centages of t o t a l e x t r a c t a b l e hexoses ranged from 2.7 to 31.0. In the Langley s e r i e s , the y i e l d of hexoses was again very high as i n stage D and s i m i l a r percent-ages were obtained f o r the Ap and the Ah h o r i z o n s . The Aeg, Btg and Cg h o r i z o n s y i e l d e d very much higher amounts of hexoses than stage D i n a somewhat p a r a l l e l 51. pattern. Accordingly, the d i l u t e buffer s o l u t i o n extracted 31 percent of the t o t a l hexoses from the Cg horizon. According to the above, i t follows that the buffered s a l t s o l u t i o n was more e f f e c t i v e i n the Ap and Ah horizons while the buffer s o l u t i o n was most e f f e c t i v e i n the lower horizon i n rele a s i n g hexoses. In the Hatzic s e r i e s , the y i e l d s of hexoses showed a steep decline from the Ap to the Bg horizon and a s l i g h t increase i n the Cg horizon. However, the percentages showed a continued increase with depth of p r o f i l e . In the Hazelwood s e r i e s , the amounts of hexoses extracted showed a s i m i l a r decrease with depth as i n stage D but the amounts of extracted hexoses were a l l higher. Correspondingly, the percentages were higher but the high - low - high - low pattern of the t o t a l carbon was followed. I t i s evident that the amounts of hexoses extracted generally decrease with depth but the percent-ages do not follow s i m i l a r patterns i n a l l cases. Stage DS. Hexoses Soluble i n IN K2SC>4 This e x t r a c t i o n always yielded the c l e a r e s t s o l u t i o n of the p a r a l l e l D stages. The amounts of hexoses extracted ranged from 24 to 2,835 ug/g of s o i l while the percentages of t o t a l extractable hexoses ranged from 0.4 to 29.0. The Langley ser i e s showed a low - high - low -high - low sequence i n the amounts of hexoses e x t r a c t e d from the Ap, Ah, Aeg, Btg and Cg horizons r e s p e c t i v e l y . The q u a n t i t i e s e x t r a c t e d from the upper Ah and Ap hor-iz o n s are f a r l e s s than t h a t e x t r a c t e d i n the stages D and DD, w i t h an anomalously low amount from the Ap h o r i z o n . The Aeg h o r i z o n y i e l d e d an i n t e r m e d i a t e amount, the Btg a g r e a t e r amount and the Cg an i n t e r -mediate q u a n t i t y of hexoses when compared w i t h t h e i r c o u n t e r p a r t s i n stages D and DD. The percentages of t o t a l e x t r a c t a b l e hexoses showed a general i n c r e a s e w i t h depth but the Aeg hor i z o n s were the same as the Ap h o r i z o n s , i n d i c a t i n g a s i m i l a r e q u i l i b r i u m c o n d i t i o n . Of note i s the f a c t t h a t the pyrophosphate b u f f e r alone and the concentrated s a l t s o l u t i o n alone y i e l d e d sim-i l a r percentages of hexoses w h i l e the combined e x t r a c t -ants i n the Cg h o r i z o n y i e l d e d l e s s . The H a t z i c s e r i e s showed a general decrease w i t h depth i n p r o f i l e i n the amounts of hexoses ex-t r a c t e d but the y i e l d s were s l i g h t l y h i gher than those i n stage D. This i n d i c a t e s t h a t potassium sulphate i s most e f f e c t i v e alone i n t h i s s o i l , e s p e c i a l l y on the Bg h o r i z o n . The K 2 S 0 4 - s e n s i t i v e m a t e r i a l i n the Bg h o r i z o n i s probably q u i t e d i f f e r e n t from t h a t which i s e x t r a c t e d by the pyrophosphate b u f f e r s o l u t i o n alone. The Hazelwood s e r i e s showed a decrease from the Ah t o the Ah 2 h o r i z o n i n the amounts of hexoses e x t r a c t e d , then a s u b s t a n t i a l i n c r e a s e i n the Cg hor-53. izon. The percentages of hexoses showed a s i m i l a r pattern as i n stage D, that i s , opposite to the carbon pattern, although the amounts were not as high. Stage DDD.. Hexoses Soluble i n Chelex-100 Na* The amounts of hexoses extracted ranged from 113 to 1,418 ug/g of s o i l and the percentages of t o t a l extractable hexoses ranged from 1.5 to 16.5. In the Langley s e r i e s , the amounts of hexoses extracted showed a general decreasing trend with depth and the values were les s than f o r any other comparable stages. The values did not p a r a l l e l those of stage DD and at best only p a r t i a l l y s i m i l a r chelating solu-b i l i t y properties can be presumed. The percentages of hexoses showed an increasing trend with depth which i s a d i f f e r e n t pattern from stage DD. In any case, the percentage f o r the Cg horizon showed that both chelating agents were e f f i c i e n t f o r t h i s horizon. In the Hatzic s e r i e s , the amounts: of hexoses extracted showed a general decrease with depth but the percentages of hexoses were f a i r l y s i m i l a r i n d i c a t i n g an equilibrium condition throughout the p r o f i l e f o r t h i s extractable m a t e r i a l . In the Hazelwood s e r i e s , the amounts of hexoses extracted showed a general decrease with depth, however, the percentage values f o r the Ah^ and Cg horizons were h a l f those f o r the Bg and Ah 2 horizons. This could i n d i c a t e some accumulation i n the former horizons. 54. Stage F. 0.05N NaOH Soluble Hexoses The amounts of hexoses extracted ranged from 2,160 to 17,370 ug/g of s o i l and the percentages of t o t a l extractable hexoses ranged from 12.7 to 50.6. In the Langley s e r i e s , the NaOH extractable hexoses showed a general decrease with depth except that the Aeg horizon indicated some depletion and the Btg horizon some accumulation. The only other stage where a s i m i l a r e f f e c t was shown was with the IN K^SO^ s o l u t i o n . The percentage values accentuated t h i s e f f e c t to a greater degree. In the Hatzic s e r i e s , the NaOH extractable hexoses showed a general decrease with depth as did the percentage values. In the Hazelwood s e r i e s , the NaOH extractable hexoses showed a 50 percent decrease per horizon with depth. However, the percentage values showed some accumulation i n the Bg horizon. Stage G. F i n a l Hydrolysis A large portion of the hexoses f o r most hor-izons was shown to be very t i g h t l y bound. The e a s i l y extractable hexoses removed i n the previous stages, can therefore be l a b e l l e d the l a b i l e portion and t h i s stage represents the stable polysaccharides. I t might be suggested that t h i s large portion of stable material i s p a r t i a l l y responsible f o r the basic s t a b i l i t y of microaggregates while the various l a b i l e f r a c t i o n s 55. modify them dynamically into various larger aggre-gates. In the Langley s e r i e s , there i s a general decrease i n amounts of stable hexoses with depth while the percentages show a gradual increase from the Ap to the Btg horizon and a f a l l i n the Cg horizon. The i n d i c a t i o n i s that even though larger quantities of stable hexoses reside i n the upper horizons, greater percentages accumulate i n the lower Btg horizons. The s t a b i l i z a t i o n of a larger percentage of hexoses i n the Btg horizon could p a r t i a l l y be accounted f o r by a cl a y accumulation. The d i s t r i b u t i o n of c e l l u l o s e cannot explain these trends. In the Hatzic s e r i e s , the amounts of hexoses again show a general decrease with depth. The per-centages show the reverse i n d i c a t i n g a greater s t a b i l -i z a t i o n at the lower depths of hexoses. In the Hazelwood s e r i e s , the amounts of hexoses show a s i m i l a r a l t e r n a t i n g high - low - high - low sequence as the t o t a l carbon. However, the percentages show an increasing trend from the Bg to the Cg horizon with the Ah^ horizon having a s i m i l a r value as the Ah^ horizon. TOTAL EXTRACTABLE HEXOSES The t o t a l extractable hexoses c o n s i s t i n g of stages A, B, D, F and G i n the Ap and Ah horizons, were very much higher than the r e s t . In general, i t can be 56. said that the organic A horizons contain the greatest amounts of hexoses but the lower horizons have a la r g e r proportion of t h e i r hexoses s t a b i l i z e d . In the buried Ah^ horizon, the absence of continued s u r f i c i a l a d dition of organic material has changed i t s character i n that even though i t has a higher t o t a l carbon con-tent than the Bg h o r i z o n , the t o t a l extractable hexoses are l e s s , whereas amount of hexoses f i x e d i s greater i n the Ah^ horizon than i n the Bg horizon. Further i n v e s t i g a t i o n of the above observation concerning the Ah^ horizon may lead to a method of i t s c h a r a c t e r i z -ation and d i f f e r e n t i a t i o n . I t should be noted that the nature of the e x t r a c t i o n procedure gives reason to believe that most, i f not a l l , of the carbohydrates were extracted from the s o i l . PENTOSE DISTRIBUTION Stage A. Water Soluble Pentoses The water soluble pentoses ranged from 80 to 608 pg/g of s o i l and the percentages of t o t a l extract-able pentoses ranged from 0.3 to 4.7. In the Langley s e r i e s , s i m i l a r q u a ntities were extracted from the Ap and Cg horizons and from the Ah, Aeg and Btg horizons. The Cg horizon yielded the highest percentage while the Ah and the Btg were r e l -a t i v e l y low. TABLE IV PENTOSE DISTRIBUTION IN FRACTIONS (ug pentose/g soil) (figures in parenthesis represent fraction pentose as percent of total extractable pentoses) Series Horizons Langley Hatzic Hazel wood Stages Ap Ah Aeg Btg Cg Ap Bg Cg Al^ Bg Ah2 Cg 450 113 169 113 450 90 80 225 585 608 608 563 A (1.1) (0.3) (1.3) (0.7) (4.7) (0.3) (0.7) (1.6) (2.3) (3.4.) (4-.0) (3.7) B 5,940 5,062 2,430 3,330 3,600 2,925 2,925 3,038 3,735 3,060 3,060 2,925 (15.5) (14.2) (18.5) (21.9) (37.9) (9.2) (26.6) (22.0) (14.9) (17.3) (20.2) (19.2) 50 < 1 160 100 57 40 40 5 > 240 245 210 100 C (0.1) (<0.1) (1.2) (0.7) (0.6) (0.1) (0.4) (0.4) (0.9) (1.4) (1.3) (0.7) D 4,275 4,005 450 333 1,125 1,800 405 1,350 2,025 1,755 1,013 2,025 (11.1) (11.2) (3.4) (2.2) (11.8) (5.7) (3.7) (9.8) (8.0) (9.9) (6.7) (13.3) DD 3,960 3,960 338 608 720 1,800 405 540 2,093 1,857 1,953 1,688 (10.3) (10.4) (2.7) (4.0) (7.6) (5.7) (3.7) (3.9) (8.3) (10.5) (12.9) (11.1) DS 10,125 10,125 900 1,575 2,700 720 900 450 2,093 1,620 1,620 1,654 (26.3) (28.4) (6.9) (10.3) (28.4) (2.3) (8.1) (3.3) (8.3) (9.2) (10.7) (11.0) DDD 563 675 450 113 450 788 101 225 551 743 585 563 (1.5) (1.9) (3.4) (0.7) (4.7) (2.5) (0.8) (1.6) (2.2) (4.2) (3.9) (3.7) F 13,050 11,880 1,800 3,600 1,350 11,880 1,440 2,880 6 ,413 4,725 3,915 4,050 (33.9) (33.4) (13.7) (23.6) (14.2) (37.3) (13.1) (20.8) (25.5) (26.7) (25.3) (26.5) 15,000 14,875 8,250 7,500 2,813 15,125 6,125 6,563 12,093 7,188 5,438 5,438 G (39.0) (41.8) (62.8) (49.2) (29.6) (47.5) (55.6) (47.5) (48.1) (40.7) (35.8) (35.8) Total Extractable Pentoses 38,444 35,620 13,146 15,250 9,512 31,860 11,015 13,820 25,158 17,682 15,178 15,263 Total extractable pentoses represents the sum of fractions A, B, C, D, F and G. 58. In the Hatzic s e r i e s , the y i e l d s of pentoses showed a general increase with depth as did the percentage y i e l d s . In the Hazelwood s e r i e s , s i m i l a r amounts were extracted f r o the horizons but there was an increase i n percentage y i e l d s with depth. No c l e a r o v e r a l l trends were shown by the y i e l d s of pentoses but the percentage values showed and increasing trend with depth. Stage B. Pentoses Soluble i n D i l u t e Acid The pentose y i e l d s ranged from 2,430 to 5,940 ug/g of s o i l and percentages of t o t a l extractable pentoses from 9.2 to 26.6. In the Langley s e r i e s , the amounts of pentoses extracted decreased from the Ap to the Aeg horizon and then increased further to the Cg horizon showing some depletion i n the Aeg horizon and accumulation i n the lower Btg and Cg horizons. The percentage values showed a general increase i n depth from the Ah h o r i -zon, but the Ap horizon was s l i g h t l y higher than the Ah horizon. The i n d i c a t i o n i s that although there i s a depletion i n qua n t i t i e s i n the Aeg area, t h i s portion of the t o t a l pentoses which i s soluble i n d i l u t e acid increases: with depth. In the Hatzic s e r i e s , the amounts of pentoses extracted increased very l i t t l e with depth whereas the percentages, although increasing with depth, showed 59. some accumulation i n the Bg horizon. In the Hazelwood s e r i e s , the amounts of pentoses extracted showed a decrease with depth while the percentages showed an increase. The general trends were, even though there might be depletions and accumulations i n the quantit-ie s of pentoses, that t h i s portion of the pentoses always showed a general increase with depth. Stage D. Pentoses Soluble i n 0.05M Na 4P 20 7 + IN K 2SD 4 (pH 7.0) The amounts of pentoses extracted ranged from 338 to 4,275 ug/g of s o i l and the percentages of t o t a l extractable pentoses from 2.2 to 13.3. In the Langley s e r i e s , the amounts of pentoses extracted and the percentages of pentoses showed not only a decrease down to the Btg horizon but an accum-u l a t i o n i n the Cg horizon. Similar trends were observed i n the Hatzic s e r i e s . In the Hazelwood s e r i e s , the y i e l d s of pentoses showed the same trend as the above. The percentages also showed the same pattern, with the Ah 2 horizon having the lowest value. Stage DD. Pentoses Soluble i n 0.05M Na 4P 20 7 (pH 7.0) The y i e l d s of pentoses, ranged from 338 to 3,960 pg/g of s o i l and the percentages of t o t a l ex-60. t r a c t a b l e pentoses ranged from 2.7 to 12.9. In the Langley s e r i e s , the amounts of pentoses extracted decreased down to the Aeg horizon, and then increased to the Cg horizon. The values shov/ed that l e s s pentoses were released by pyrophosphate alone, except i n the Aeg and the Btg horizons whose y i e l d s were greater. The percentages showed a s i m i l a r pattern. In the Hatzic s e r i e s , s i m i l a r q u a n t i t i e s were released from the Ap and Bg horizons but the Cg hor-izon yielded l e s s with the pyrophosphate alone. In the Hazelwood s e r i e s , the amounts of pent-oses extracted followed the high - low - high - low sequence of the t o t a l carbon whereas the percentages showed a general increase with depth. Stage DS. Pentoses Soluble i n IN K2SC>4 The y i e l d s of pentoses ranged from 450 to 10,125 ug/g of s o i l and the percentages of extractable pentoses ranged from 2.3 to 28.4. In the Langley s e r i e s , the y i e l d s and percent-ages of pentoses showed a decrease down to the Aeg horizon, then an increase to the Cg horizon. However, the values were about twice as great as those f o r the buffer solutions of stages D and DD. In the Hatzic s e r i e s , the y i e l d s and percent-ages of pentoses showed an increase down to the Bg horizon, then a decrease i n the Cg horizon. This s i t u a t i o n was opposite to that determined for both of 61. the buffer solutions and the values f o r the Ap and Cg horizons were l e s s . In the Hazelwood s e r i e s , the y i e l d s of pentoses showed a s l i g h t decrease with depth whereas the per-centages showed an increase. Stage DDD. Pentoses Soluble i n Chelex-100 Na"1" The amounts of pentoses extracted ranged from 101 to 788 jag/g of s o i l and the percentages of t o t a l extractable pentoses ranged from 0.7 to 4.7. In the Langley s e r i e s , the amounts of pentoses extracted were r e l a t i v e l y s i m i l a r , except f o r the Btg horizon which was f a r lower. The values were lower than those of the pyrophosphate buffer alone i n a l l of the horizons except the Aeg horizon. The percentage values showed a general increase with depth except f o r the Btg horizon which indicated that the materials were not susceptible to chelating agents i n the s o l i d form. In the Hatzic s e r i e s , the amounts of pentoses extracted and percentages showed a s i m i l a r pattern as fo r the pyrophosphate buffer alone, though the values were l e s s . In the Hazelwood s e r i e s , the amounts of pent-oses extracted showed a s i m i l a r pattern to the pyro-phosphate buffer, whereas the percentage values showed a s l i g h t l y d i f f e r e n t pattern. 6 2 . Stage F. Pentoses S o l u b l e i n 0.05N NaOH The NaOH s o l u b l e pentoses ranged from 1,350 to 13,050 ug/g of s o i l and the percentages of e x t r a c t -able pentoses ranged from 13.1 to 37.3. In the Langley s e r i e s , the y i e l d s of pentoses and percentages showed l a r g e amounts r e s i d i n g i n the Ap and Ah horizons v/ith a d e p l e t i o n i n the Aeg h o r i z o n and an accumulation i n the Btg h o r i z o n . In the H a t z i c s e r i e s , h i g h amounts i n the Ap h o r i z o n and low amounts e x t r a c t e d i n the Bg h o r i z o n , compared w i t h the Cg h o r i z o n , f o l l o w e d the pa t t e r n s of both pyrophosphate b u f f e r s o l u t i o n s . In the Hazelwood s e r i e s , the amounts of pent-oses e x t r a c t e d showed a decreasing trend w i t h depth whereas the percentage values were q u i t e s i m i l a r show-i n g some e q u i l i b r i u m throughout the p r o f i l e . Stage G. F i n a l H y d r o l y s i s In the Langley s e r i e s , s i m i l a r amounts and percentages of e x t r a c t a b l e pentoses f o r the organic Ah and Ap h o r i z o n s , s m a l l e r than f o r the e l u v i a t e d h o r i z o n , i n d i c a t e d t h a t the pentoses were s t r o n g l y bound i n the Aeg h o r i z o n . The Btg and Cg values were l e s s . However, the s t a b l e pentoses showed a. decrease w i t h depth. In the H a t z i c s e r i e s , the y i e l d s of pentoses showed a d e p l e t i o n i n the Bg h o r i z o n yet the percentage values showed a r e l a t i v e accumulation of s t a b l e forms of pentoses i n t h i s horizon. In the Hazelwood s e r i e s , the y i e l d s of pent-oses and percentages showed a decrease with depth down to the Ah 2 horizon and further, an increase i n the Cg horizon. The general pattern indicated appeared to be the reverse of that obtained f o r the d i s t r i b u t i o n of hexoses. TOTAL EXTRACTABLE PENTOSES The Langley seri e s yielded very high values for the A horizons, s l i g h t depletion i n the Aeg hor-izon and an accumulation i n the Btg horizon i n a general decrease with depth. In the Hatzic s e r i e s , a pentose 'sink' i n the Bg with comparable amounts i n the Ap and Cg hor-izons were observed. In the Hazelwood s e r i e s , a general s l i g h t decrease with depth, with quite s i m i l a r values i n the Ah^ and Cg horizons were observed. Results f o r stage C were ignored i n both hexoses and pentoses d i s t r i b u t i o n analysis because they were thought to be i n s i g n i f i c a n t . HEXOSE:PENTOSE RATIOS (Table V) A comparison of hexoses and pentoses was made to i n d i c a t e trends of r e l a t i v e sugar accumulations according to depth of p r o f i l e . The r a t i o s varied from 64. l e s s t h a t 0.01 t o 5.70 f o r i n d i v i d u a l e x t r a c t i o n s . I n t h e L a n g l e y s e r i e s , most o f t h e v a l u e s showed a d e c r e a s e o f hexoses i n r e l a t i o n t o p e n t o s e s . The h i g h l y o r g a n i c Ap and Ah h o r i z o n s had n o t a b l y h i g h e r r a t i o s t h a n t h e Aeg, B t g and Cg h o r i z o n s . Most o f t h e r a t i o s f o r Ap and Ah h o r i z o n s were g r e a t e r t h a n one e x c e p t f o r 0.1N F^SO^ and IN K^SO^ e x t r a c t s , i n d i -c a t i n g t h a t amounts o f hexoses were g e n e r a l l y g r e a t e r t h a n p e n t o s e s . I n t h e H a t z i c s e r i e s , t h e r e was a s i m i l a r d e c r e a s e w i t h d e p t h e x c e p t w i t h t h e Chelex-100 and p y r o p h o s p h a t e b u f f e r s o l u t i o n s ( w i t h and w i t h o u t K^SOQ) where t h e r e was an a c c u m u l a t i o n i n t h e Bg h o r i z o n o f hexoses as opposed t o p e n t o s e s . A g a i n , i n t h e 0.1N H2S0 4 e x t r a c t , t h e v a l u e s were below one, i n d i c a t i n g t h a t hexoses were g e n e r a l l y g r e a t e r t h a n p e n t o s e s . I n t h e Hazelwood s e r i e s , t h e d e c r e a s e w i t h d e p t h was v e r y c l e a r l y shown. A l l t h e r a t i o s f o r t h e Ah^ h o r i z o n e x c e p t f o r 0.1N H2S0 4 ( w i t h and w i t h o u t p y r o p h o s p h a t e ) were above one, i n d i c a t i n g a g e n e r a l l y g r e a t e r o c c u r r e n c e o f hexoses t h a n p e n t o s e s . These o b s e r v a t i o n s may i n d i c a t e t h a t : 1) m i c r o b i a l d e g r a d a t i o n o f p e n t o s e s o c c u r s l e s s r a p i d l y , t h a t i s p e n t o s e c o n t a i n i n g c a r b o h y d r a t e s a r e bound more t i g h t l y , t h u s p r e v e n t i n g r a p i d d e g r a d a t i o n . 6 5 . 2) t h a t hexoses are c o n v e r t e d to pentoses to a g r e a t e r e x t e n t than the r e v e r s e . However, the e q u i l i b r i u m t h a t may e x i s t between hexoses and pentoses i n s o i l a g g r e g a t i o n f a v o u r s the r e t e n t i o n of pentoses, e s p e c i a l l y i n the lower h o r i z o n s . TABLE V HEXOSE/PENTOSE RATIOS Horizons Langley Platzic Hazelwood Stages Ap A l Aeg Btg Cg Ap Bg Cg Ah Bg Ah ? Cg b t a g e 5.50 5.70 1.36 * 0.1 4.40 1.10 * 1.08 0.15 0.19 0.04 S t ^ e 0.52 0.98 0.19 0.01 0.08 0.31 0.19 0.12 0.42 0.06 0.15 0.12 b t ^ g e 1.89 1.63 0.02 * 0.15 1.24 2.97 0.30 0.61 0.25 0.11 0.04 S t ^ | e 1.44 1.46 1.33 0.22 0-56 1.24 1.40 1.17 1.47 0.34 0.27 0.16 S t f f e 0.09 0.27 0.12 0.34 0.13 3.94 1.35 1.33 0.37 0.17 0.02 0.02 DS S H | e 1.42 1.45 0.55 0.68 0.45 1.80 2.13 0.80 2.06 0.64 0.62 G.20 S t ^ g e 1.33 1.36 0.76 0.50 0.16 1.11 0.84 0.21 1.35 0.86 0.45 0.22 5 t ^ g e 1.63 1.77 0.45 0.41 0.17 1.26 0.71 0.52 1.24 0.37 0.69 0.42 Hexoses extracted were too low tc determine ratio. 6 7 . COMPARATIVE DISTRIBUTION OF HEXOSES AND PENTOSES  WITH IRON, ALUMINUM, CALCIUM AND MAGNESIUM LANGLEY SERIES: Stage A. Water Extraction The r e s u l t s showed an increase from zero p.p.m. i n the Ap horizon to 2069 p.p.m. of i r o n plus aluminum extracted i n the Cg horizon. Only the A horizons yielded any calcium while no magnesium was extracted. The i n d i c a t i o n i s that i n the Ap and Ah horizons, the hexoses and pentoses are associated with calcium whereas i n the Aeg and Cg horizons, they are mainly associated with aluminum. In the Btg horizon, they are mainly associated with i r o n . The decrease i n the sugar to metal r a t i o with depth further i n d i -cated a greater degree of association with depth of p r o f i l e . The major associations i n the upper A horizons consist of calcium and i r o n with hexoses as compared to aluminum with pentoses i n the lower h o r i -zons . Stage B. 0.1N H 2S0 4 Extraction The r e s u l t s f o r the ir o n plus aluminum ex-tracted showed a general decrease with depth although some e l u v i a t i o n of the Aeg horizon and accumulation i n the Btg horizon i s in d i c a t e d . The calcium plus magnesium amounts extracted showed a general increase with depth and s i m i l a r e l u v i a t i o n and accumulation i n the Aeg and Btg horizons r e s p e c t i v e l y . The majority TABLE VI COMPARATIVE DrSTKTBlTnOlf OF HEXOSES AND PENTOSES WITH F e , A l , Ca AND Mg. Fe + A l + Hex OSes + Sugars Sugars H o r i z o n s Ca Mg Ca * Mg Fe A l Fe + A l C a • Mg P e n t o s e s (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ug/g) Fe + A l Total Metals Ap 70 - 70 - - 1 'Q 2 , 9 2 5 2 , 9 3 5 . 0 0 3111.10 Stage Ah 60 - 60 5 - 5 65 736 1 1 7 . 2 0 9.20 Aeg 10 - 10 150 311 191 501 398 0 . 8 1 O.SO A B t g - - - 320 50 370 370 113 0 . 3 0 0.30 Cg - - - 520 1 , 5 1 9 2 , 0 6 9 2 , 0 6 9 195 0 . 2 1 0.21 Ap 161 7 , 2 0 0 7 , 3 6 1 2 8 , 0 0 0 73,171 101 ,171 1 0 8 , 5 3 5 9 , 0 0 0 0 . 0 9 0.08 S t a g e A h 1,11(0 1 , 8 8 0 6 , 2 1 0 2 1 , 0 0 73,171 9 7 , 1 7 1 1 0 3 , 1 1 1 1 0 , 0 1 3 0 . 1 0 0.10 Aeg 760 1 3 , 2 0 0 1 3 , 9 6 0 1 5 , 0 0 0 2 1 , 3 9 0 3 9 , 3 9 0 5 3 , 3 5 0 2 , 8 8 0 0 . 0 7 0.05 9 B t g 960 2 0 , 1 0 0 2 1 , 3 6 0 2 6 , 0 0 0 31,707 5 7 , 7 0 7 7 9 , 0 6 7 3 , 3 3 9 0 . 0 6 0.01 Cg 1 ,710 1 5 , 6 0 0 1 7 , 3 1 0 2 0 , 5 0 0 3 0 , 1 8 7 5 0 , 9 8 7 6 8 , 3 2 7 3 , 8 7 0 0 . 0 8 0.06 Stage AP 21 21 7 , 8 0 0 3,122 1 0 , 9 2 2 1 0 , 9 1 6 1 2 , 3 7 5 1 . 1 3 1 .13 Ah 160 2 , 1 0 0 2 , 5 6 0 9 , 0 0 0 3 , 9 5 1 1 2 , 9 5 1 1 5 , 5 1 1 1 0 , 5 0 5 0 . 8 1 0 . 6 8 Aeg 260 1 , 8 0 0 5 , 0 8 0 190 366 556 7 , 3 1 6 159 0 . 2 0 0.06 D B t g SO 9 , 6 0 0 9 , 6 8 0 1 ,120 1 , 2 2 0 5 , 1 1 0 1 5 , 1 2 0 338 0 . 0 6 0.02 Cg - 8 1 , 0 0 0 8 1 , 0 0 0 2 , 6 6 0 7 ,317 9 , 9 7 7 9 3 , 7 7 7 1 , 2 9 3 0 . 1 3 0 .01 Ap _ 21 21 1 8 , 0 0 0 1 0 , 8 2 9 2 8 , 8 2 5 2 8 , 8 5 3 9 , 6 6 0 0 . 3 1 0.33 " t a g e Ah - - - 9 , 0 0 0 3 , 9 5 0 1 2 , 9 5 0 1 2 , 9 5 1 9 , 0 1 0 0.7O 0.70 Aeg 10 3 , 1 2 0 3 , 1 6 0 190 366 556 3 , 7 1 6 799 1 . 1 2 0 .21 DO B t g '10 8 , 1 6 0 8 , 2 0 0 1 , 2 2 0 1 , 2 2 0 5 , 1 1 0 1 3 , 6 1 0 712 0 . 1 1 0.0:, Cg - 1 , 8 0 0 1 , 8 0 0 2 , 6 6 0 7 , 3 1 0 9 , 9 7 0 1 9 , 7 7 7 1 , 1 2 5 0 . 1 1 0.88 •3tage Ap 10 2 , 1 0 0 2 , 1 0 0 2 , 1 6 0 1 1 , 6 3 1 1 6 , 7 9 1 1 9 , 2 3 1 11 ,015 0 , 6 6 0.57 Ah 10 2 , 1 0 0 2,110 2 , 0 0 0 2 1 , 3 9 0 2 6 , 3 9 0 2 8 , 8 3 0 1 1 , 8 2 5 0 . 1 9 0.15 DS Aeg 110 1 , 8 0 0 1 , 9 1 0 30 1 , 8 7 8 1 , 9 0 8 9 , 8 0 8 1 , 0 0 8 0 . 2 1 0.10 B t g 200 6 ,000 6 , 2 0 0 80 2 , 1 3 9 2 , 5 1 9 8,719 2,115 0 . 81 0.21 Cg 100 1 , 8 0 0 1 , 9 0 0 860 1 0 , 9 5 6 11 ,816 1 6 , 7 1 6 3 , 0 6 0 0 . 2 6 0.18 Ap _ 510 512 1 , 0 2 2 1 , 0 2 2 1 , 3 6 2 1 . 3 ? 1 .33 S t a g e Ah - - - 775 683 1 , 1 5 8 1 , 1 5 8 1 , 6 5 6 1 . 1 1 1.11 Aeg - - - 5 61 66 66 698 1 0 . 5 7 10.57 :w B t g - - - 220 293 513 513 302 0 . 5 9 0.59 Cg - - - 1 , 1 9 0 1 ,707 2 , 8 9 7 2 , 8 9 7 652 0 . 2 3 C.23 1IATZIC Ap 300 60 360 50 19 99 159 186 0.90 1,06 Stage Bg 10 - 10 65 11 175 215 170 0.97 0.79 A Cg 20 600 620 310 79 119 1 , 0 3 9 225 0 .51 C.22 Stage Ap 920 1 , 8 0 0 5,720 2 5 , 0 0 0 1 8 , 7 8 0 7 3 , 7 8 0 7 9 , 5 0 0 1 3 , 8 2 1 0 . 0 5 0.C5 Bg 1 , 6 0 0 9 , 6 0 0 U , 2 0 0 3 2 , 0 0 3 6 , 3 8 5 6 8 , 5 8 5 79 , 7 8 5 3 , 1 6 5 Q.05 0.01 B Cg 1 , 6 1 0 1 0 , 8 0 0 12,110 2 0 , 0 0 0 2 5 , 6 1 0 1 5 , 6 1 0 58 ,050 3 , 3 9 8 0.08 0.05 Stage Ap - 5 , 1 0 0 5 , 1 0 0 3 , 6 0 0 1 , 1 2 7 5 , 0 2 7 10 , 177 1 , 0 2 8 0 . 8 0 0.3:1 Bg 180 1 , 8 0 0 1 , 9 8 0 1 , 7 5 5 1 ,127 3 , 1 8 2 5 , 1 6 2 1 , 6 0 6 0.50 C.31 D Cg 390 3 , 9 0 0 1 , 2 9 0 280 780 1 , 0 6 0 5 , 3 5 0 1,755 1 . 6 6 0.33 Stage Ap - 900 900 6 , 1 5 0 6 , 0 0 0 1 2 , 6 0 0 1 3 , 5 0 0 1 , 0 2 8 0 . 3 2 0.30 Bg - 1 ,170 1 ,170 6 , 1 5 0 11 ,780 1 7 , 9 3 0 19 , 1 0 0 972 0 . 0 5 0.05 DD Cg - 720 720 5 , 9 0 0 13 ,111 1 9 , 3 1 1 2 0 , 0 3 1 1 ,170 0 . 0 6 0.06 Ap 30 1 ,170 1 , 2 0 0 870 7 ,317 8 , 1 8 7 9 , 3 8 7 3 , 5 3 5 0 . 1 3 0.38 Bg 60 1 , 8 0 0 1 , 8 6 0 795 10 , 9 7 5 11 ,770 1 3 , 6 3 0 2 ,115 0 .18 0. Ii" Cg 2 , 1 0 0 2,180 1 , 1 5 0 1 1 , 6 3 1 1 5 , 7 8 1 1 8 , 2 6 1 1,050 0.07 0.06 Stage Ap - - - 1 , 3 0 0 2 , 0 1 2 3 , 3 1 2 3 , 3 1 2 2J205 0 . 5 7 0.57 Bg - - - 870 2 , 2 0 7 3,077 3,077 317 0 . 1 0 0.10 DDD Cg - - - 65 159 221 2 , 2 3 0 105 0 . 1 8 0.18 HAZELWOD A h , 180 180 5 _ 5 185 630 1 2 6 . 0 0 3 .11 Stage 1 Bg 9C - 90 20 50 70 160 698 9 , 9 6 1.36 A A h 2 30 - 30 160 390 550 580 725 1 . 3 2 1.25 Cg 10 - 10 370 732 1 , 1 0 2 1 , 1 1 2 585 0 . 5 3 0.53 Stage A h x 1 , 0 1 0 1 , 5 6 0 2 , 6 0 0 2 2 , 0 0 0 11: ,163 6 3 , 1 6 3 7 3 , 1 0 8 5 , 3 1 9 0 . 0 8 0.07 Bg 800 3 , 6 0 0 1 , 1 0 0 3 0 , 0 0 0 31,707 6 1 , 7 0 7 6 6 , 1 0 7 3 , 1 1 0 0 . 0 5 0.05 B A h , 161 7 , 2 0 0 7 , 3 6 1 6 0 , 0 0 0 29 ,268 8 9 , 2 6 8 9 6 , 6 3 2 3 , 5 2 8 0.O1 0.01 Cg 1 , 1 8 0 1 2 , 6 0 0 1 1 , 0 8 0 6 0 , 0 0 0 21, ,951 8 1 , 9 5 1 9 6 , 0 3 1 3 , 2 8 5 0 . 0 1 0.01 A h 1 360 900 1 , 2 6 0 1 , 0 9 5 139 1 , 5 3 1 2 , 7 9 1 3 , 2 5 0 2 . 1 2 1.10 Stage Bg 270 630 1 , 0 0 0 1 , 2 0 0 622 1 , 8 2 2 2 , 8 2 2 2,187 1 .20 0.80 D A h 2 120 360 180 300 1 , 0 2 1 1 , 3 2 1 1 , 8 0 1 1 , 1 2 0 0 . 8 5 0.62 Cg 30 900 930 2 , 0 8 5 ,519 5 , 6 3 1 6 , 5 6 1 2,115 0 . 3 8 0 ,32 A h x 30 150 180 5 , 1 0 0 3 ,366 8 , 7 6 6 9 , 2 1 6 5 , 1 6 8 0 . 6 ? 0.5? Stage Bg - 510 510 5 , 2 5 0 6: ,000 1 1 , 2 5 0 1 1 , 7 9 0 2 , 1 9 0 0 .22 0.21 DD A h 2 - 180 180 3 , 3 0 0 It, ,610 7 , 9 1 0 8 , 0 9 0 2 , 5 2 6 0 .32 0.31 Cg - 510 510 1 , 5 0 0 1 ,683 9.183 9 , 7 2 3 1 , 9 5 8 0 . 21 0.20 Stage A h 1 300 150 750 1 ,710 10, ,980 1 2 , 6 9 0 1 3 , 1 1 0 2 , 8 7 5 0 . 2 3 0.21 Bg 300 150 750 1 , 2 0 0 10 ,980 1 2 , 1 8 0 1 2 , 9 3 0 1 , 8 9 0 0 . 1 6 0.15 DS A h 2 300 180 180 1 , 2 7 5 7, ,317 8 , 5 9 2 9 , 0 7 2 1 , 6 1 1 0 . 1 9 11.13 Cg 300 900 1 , 2 0 0 900 9, ,150 1 0 , 0 5 0 1 1 , 2 5 0 1 , 9 9 0 0 . 2 0 0.1? A h j _ 30 30 1 , 6 1 0 2 ,512 1 , 1 5 2 1 , 1 8 2 1 , 6 8 5 0.11 0.13 Stage Bg - 210 210 3 , 1 5 0 12 ,801 1 6 , 2 5 1 1 6 , 1 6 1 1 , 2 1 5 0.08 l l . C " 60 60 2 , 2 2 5 7 , ,927 1 0 , 1 5 2 1 0 , 2 1 2 950 0 .09 0.00 DDD A h 2 0.10 Cg - 30 30 2 , 1 7 5 1 , ,390 6 , 8 6 5 6 . 8 9 5 675 0 . 1 0 of sugars to metals r a t i o s are below 1. This may in d i c a t e a closer association between the sugars and metals. The Btg horizon shows the most association while the Ah and Ap horizons show the l e a s t . Although the pentoses:, show cl o s e r r e l a t i o n -ships throughout the p r o f i l e i n the upper horizons, magnesium and aluminum were c l o s e l y associated with hexoses. Throughout the p r o f i l e , aluminum and i r o n were c l o s e l y associated with pentoses, though aluminum was associated to a greater extent. Stage D. 0.5M Na^O., + IN K2SC>4 (pH 7.0) Extraction The y i e l d s of i r o n plus aluminum i n the Ap and Ah horizons were the highest with lower values i n the Aeg, Btg and Cg horizons which increased r e s p e c t i v e l y . The increase of calcium and magnesium values with depth were again demonstrated. Magnesium and i r o n were high i n the Ap and Ah horizons while magnesium and aluminum were high i n the others. The high values of hexoses i n the Ap and Ah horizons along with high values of i r o n and aluminum indicated a c l o s e r r e l a t i o n -ship of these constituents. In the Aeg, Btg and Cg horizons, the c l o s e s t r e l a t i o n s h i p s were shown between magnesium and pentoses and to a l e s s e r extent, pentoses and aluminum. Stage DD. 0.05M Na 4P 20 7 (pH 7.0) Extraction Although the values and trends were quite 70. s i m i l a r f o r aluminum and i r o n , those f o r calcium and magnesium were d i f f e r e n t from those of Stage D. The values were neither as high nor was the continuous decrease s t i l l present. The Ah and Cg horizons show the most prominent decreases i n calcium plus magnesium amounts extracted. However, the magnesium remained high i n comparison with calcium. The r e s u l t was a general decrease i n hexose values but an increase i n pentose values i n the Aeg, Btg and Cg horizons. A further look indicated that the c l o s e r r e l a t i o n s h i p s i n the Ap and Ah horizons were also between i r o n and hexoses whereas the Aeg, Btg and Cg horizons showed considerably c l o s e r r e l a t i o n s h i p between magnesium and pentoses. However, i n the Cg horizon considerable association between aluminum and pentoses was observed and the Aeg horizon between . hexoses and magnesium. Also, the potassium sulphate i n stage D r e -leased more magnesium and pentoses than the pyrophos-phate alone. Stage DS,. IN K 2 S 0 4 Extraction This extract released more aluminum and less i r o n than i t did i n the presence of pyrophosphate, except i n the Btg horizon where the aluminum released was l e s s . I t also released greater amounts of calcium i n the Ap, Cg.and Ah horizons, greater amounts of magnesium only i n the Ap horizon, and l e s s e r amounts 71. i n the Btg and Cg horizons, than i t did i n the pre-sence of pyrophosphate. The r e s u l t s indicated that there were close r e l a t i o n s h i p s between pentoses and aluminum i n the Ap, Ah and Cg horizons, and s i m i l a r l y close associations between pentoses and aluminum and magnesium i n the Aeg horizon. However, pentoses and magnesium were c l o s e l y r e l a t e d i n the Btg horizon. Also, there was considerable association between pentoses and magnesium i n the Cg horizon. Stage DDD. Chelex-100 (Na + Form) Extraction Similar trends as i n stage D and stage DD were demonstrated except that i r o n and aluminum were ex-tracted to the same extents. In the Cg horizon, more aluminum than i r o n was extracted and throughout the p r o f i l e , neither calcium nor magnesium was extracted. These r e s u l t s were deceiving because the Chelex-100 i s a s o l i d , so i t may have removed a l l the calcium and magnesium out of the s o l u t i o n and there-fore could not be analyzed. A l l of the Chelex-100 extracts showed t h i s feature, therefore, i t i s most l i k e l y that t h i s occurred. Further, t h i s extract was probably not as complete as the pyrophosphate because of the l i m i t e d penetrating a b i l i t y of the extractant. Another i n t e r e s t i n g feature was that although the hexose/pentose r a t i o s f o r the Ap and Ah horizons were quite s i m i l a r , s i m i l a r amounts of i r o n and aluminum were extracted from both horizons. HATZIC SERIES Stage A. Water Extraction There was a general decrease i n calcium and an increase of magnesium, ir o n and aluminum amounts extracted with depth of p r o f i l e . The most aluminum and the l e a s t magnesium were released from the Btg horizon. The c l o s e s t r e l a t i o n s h i p s observed were hexoses with calcium i n the Ap horizon, both hexoses and pentoses with aluminum i n the Bg horizon, and p r i m a r i l y pentoses with magnesium i n the Cg horizon. Also, there was some association between pentoses and aluminum i n the Cg horizon. B a s i c a l l y , the same trend was seen with calcium and hexoses being associated i n the Ap horizon while pentoses, were associated with magnesium and aluminum i n the lower horizons. Also, there i s a general increase of association of t o t a l extractable sugars with metals i n d i c a t i n g an increase of r e t e n t i o n with depth. Stage B„ 0.1N H2SC>4 Extraction A s i m i l a r pattern of the sugar to metal r a t i o s , a l l of which were below 0.1, indicated close assoc-i a t i o n s between the sugars and the metals, with the Bg horizon showing the c l o s e s t . In an o v e r a l l decreas-ing trend with depth, the Ap horizon released con-sid e r a b l y more aluminum than i r o n , whereas there were s i m i l a r values f o r the Bg and Cg horizons r e s p e c t i v e l y . 73. Both c a l c i u m and magnesium y i e l d s showed a. general i n c r e a s e w i t h depth, though magnesium values were c o n s i d e r a b l y g r e a t e r . The i n c r e a s i n g closeness of pentose a s s o c i a t i o n s w i t h aluminum and magnesium wi t h depth d i d not overshadow the a s s o c i a t i o n w i t h i r o n . These r e s u l t s were q u i t e s i m i l a r f o r the Langley h o r i z o n s . Stage D. 0.05M N a 4 P 2 0 7 + IN K 2 S 0 4 (pH 7.0) E x t r a c t i o n High y i e l d s of magnesium, i r o n and aluminum r e s p e c t i v e l y , throughout the p r o f i l e d i d not f o l l o w the same p a t t e r n as the Langley s e r i e s , i r o n p l u s aluminum e x t r a c t e d decreased w i t h depth. The lower magnesium value f o r the Btg h o r i z o n and the high magnesium value f o r the Ap h o r i z o n were conspicuous. However, magnesium and i r o n were s t i l l c l o s e l y assoc-i a t e d , mostly w i t h hexoses, i n the Ap h o r i z o n . The Bg h o r i z o n showed a. r e l a t i v e accumulation of hexoses. a s s o c i a t e d w i t h magnesium, i r o n and aluminum to a s i m i l a r e x t e n t . This was opposite to the Langley s e r i e s f o r the Btg h o r i z o n . However, the Cg h o r i z o n showed a s i m i l a r accumulation of pentoses, as d i d the Langley s e r i e s , being p r i m a r i l y a s s o c i a t e d w i t h mag-nesium. A uniform sugar to metal r a t i o between 0.3 and 0.4 i n d i c a t e d some e q u i l i b r i u m common t o a l l of the h o r i z o n s . 74. Stage DD. 0.05M N a 4 P 2 0 7 (pH 7.0) E x t r a c t i o n A very s l i g h t decrease w i t h depth i n the aluminum y i e l d s and a much g r e a t e r i n c r e a s e f o r y i e l d s of aluminum plus i r o n were observed. High values of aluminum and i r o n were seen throughout the p r o f i l e but a sm a l l amount of magnesium and the absence of ca l c i u m were conspicuous. There was a c l o s e r r e l a -t i o n s h i p between hexoses and aluminum than e i t h e r pentoses w i t h aluminum or hexoses w i t h i r o n , espec-i a l l y i n the lower h o r i z o n s . Magnesium values d i d not i n d i c a t e a c o n s i d e r a b l e degree of a s s o c i a t i o n w i t h the sugars. However, there was a s l i g h t accumulation of magnesium i n the Bg h o r i z o n . Stage DS. IN K 2 S 0 4 E x t r a c t i o n There was an i n c r e a s e of e x t r a c t a b l e i r o n , magnesium and c a l c i u m w i t h depth, although c a l c i u m values were very low. Although aluminum values were f a r h i g h e r than i r o n v a l u e s , they a l s o showed an i n c r e a s e w i t h depth. The Ap h o r i z o n showed a c l o s e r e l a t i o n s h i p between hexoses and aluminum, however t h i s r e l a t i o n s h i p was shown to a l e s s e r extent i n the Bg and Cg h o r i z o n s . Magnesium and i r o n a s s o c i a t i o n s were a l s o s u b s t a n t i a l . No e x p l a n a t i o n i s given f o r the completely d i f f e r e n t trend shown i n t h i s e x t r a c t i o n . Stage DDD. Chelex-100 (Na + Form) E x t r a c t i o n The absence of ca l c i u m and magnesium was s t i l l e v i d e n t . There was a decrease of e x t r a c t a b l e aluminum and i r o n with depth. This was d i f f e r e n t from the pyrophosphate buffer extraction i n that although a s l i g h t accumulation was seen f o r aluminum i n the Bg horizon, the d e f i n i t e increase with depth was not evident. The hexoses and aluminum r e l a t i o n s h i p was the c l o s e s t throughout the p r o f i l e . The sugar to metal r a t i o s showed a s i m i l a r trend, though much higher values were obtained than f o r the pyrophosphate ex-traction. HAZELWOOD SERIES Stage A. Water Extraction A decrease i n extractable calcium with depth and the complete absence of extractable magnesium were observed. An increase of extractable aluminum and ir o n with depth was also seen. The decrease of sugar to metal r a t i o s indicated a greater degree of assoc-i a t i o n between the sugars and aluminum than with i r o n associations with depth. However, hexoses and pentoses appeared equally c l o s e l y r e l a t e d with the metals i n the Ah^ horizon. Pentoses and aluminum showed closer r e l a t i o n s h i p s i n the lower horizons, e s p e c i a l l y i n the Cg. The association between pentoses and aluminum was always prominent i n the lower horizons. Stage B. 0.1N H 2 S 0 4 Extraction There was a decrease of the extractable c a l -cium values from the Ah, to the Ah_ horizon, whereas there was an increase of extractable magnesium values with depth down to the Cg horizon. However, calcium plus magnesium y i e l d s showed an increase with depth. The aluminum values showed a decrease but i r o n values showed an increase r e s p e c t i v e l y with depth. The Ah horizons showed a s l i g h t l y greater i r o n plus aluminum y i e l d s than the immediately underlying horizons. There was a decrease i n the sugar to metal r a t i o s with depth, i n d i c a t i n g that, although the Ah horizons yielded higher amounts of extractable sugars than the immediately underlying horizons, there was a c l o s e r association with depth. The Ah^ horizon showed c l o s e s t association between pentoses and alum-inum, and the Ah 2, Bg and Cg horizons showed close associations between pentoses and i r o n . The c l o s e s t a s sociation throughout the s o i l was between pentoses and i r o n which was much greater than between pentoses and aluminum. Stage D. 0.05M Na 4P 20 7 + IN K 2S0 4 (pH 7.0) Extraction A.decrease of extractable calcium with depth and of extractable magnesium down to the Ah 2 horizon was observed. However, the calcium plus magnesium y i e l d s showed a decrease down to the Ah 2 horizon. The Ah horizons yielded lower values than the underlying horizons f o r i r o n plus aluminum y i e l d s . However, the metals showed a decrease down to the Ah„ horizon. Iron and pentoses i n the Ah^ and Bg horizons and aluminum with pentoses i n the Ah 2 and Cg horizons were the dominant associations. A decrease of sugar to metal r a t i o s with depth indicated that there was an increasing association, e s p e c i a l l y between aluminum and pentoses with depth. Stage DD. 0.05M Na 4P 20 7 (pH 7.0) Extraction The increase of extractable magnesium values, though le s s than i n the presence of K 2S0 4, was sim i -l a r l y observed down to the Ah 2 horizon. Calcium y i e l d s were conspicuously low. Iron values decreased down to the Ah 2 horizon, while aluminum values showed an accumulation i n the Bg horizon within a s l i g h t increasing pattern with depth. However, as with the pyrophosphate plus K2SC>4 extraction, the Ah horizons showed lower values than the immediately underlying horizons. A s i m i l a r trend of accumulated metals was evident. The Ah horizons showed higher sugar to metal r a t i o s and indicated r e l a t i o n s h i p s of less closeness than underlying horizons. Stage DS. IN K 2S0 4 Extraction Equal y i e l d s of calcium were observed through-out the p r o f i l e and a decrease of extractable magnesium down to the Ah 2 horizon. Calcium plus magnesium y i e l d s were equal f o r the Ah^ and Bg horizons with a decrease i n the Ah„ horizon and the greatest amount was i n the 78. Cg horizon. Aluminum values decreased down to the Ah^ horizon while s i m i l a r values f o r the Bg and Ah^ horizons were seen i n the generally decreasing trend with depth. The i r o n plus aluminum y i e l d s showed a decrease down to the Ah^ horizon. Again the sugar to metal r a t i o s showed greater values i n the Ah horizons i n d i c a t i n g greater degrees of association i n the underlying horizons. Pentoses, and aluminum were associated to the greatest extent throughout the pro-f i l e . Stage DDD. Chelex-100 (Na + Form) Extraction Again no calcium was extracted but unlike the other s e r i e s , a small amount of magnesium was observed. The aluminum values f o r the Ah horizons were less than the underlying horizons. These patterns do not co i n -cide with those of the pyrophosphate buffer s o l u t i o n . Again, aluminum and hexoses were most c l o s e l y related i n the Ah^ horizon but aluminum and pentoses were c l o s e l y associated i n the lower horizons. A s i m i l a r trend f o r the sugar to metal r a t i o s indicated assoc-i a t i o n to a greater extent i n the lower horizons except i n the Cg horizon. SUMMARY AND CONCLUSIONS Three G l e y s o l s were s e l e c t e d , y i e l d i n g samples of twelve h o r i z o n s , which were used to develop the e x t r a c t i o n procedure and to study the d i s t r i b u t i o n of hexoses and pentoses and t h e i r a s s o c i a t i o n s w i t h i r o n , aluminum, c a l c i u m and magnesium. A summary of the stages of e x t r a c t i o n i s as f o l l o w s : A. Water S o l u b l e E x t r a c t i o n Percentages of t o t a l e x t r a c t a b l e hexoses and hexose values showed a general decrease w i t h depth i n the Langley and H a t z i c s e r i e s . Hazelwood s e r i e s showed an i n c r e a s e from the Ah^ to Ah^ h o r i z o n s , then de-creased i n the Cg h o r i z o n . No c l e a r o v e r a l l trend was shown by t o t a l pentoses. However, percentages of t o t a l e x t r a c t a b l e pentoses show a general i n c r e a s e w i t h depth. B. 0 . 1 N H 2 S 0 4 E x t r a c t i o n Y i e l d s of hexoses were g r e a t e r than those f o r Stage A. Ap and Ah horizons y i e l d e d very h i g h values i n a de c r e a s i n g trend w h i l e percentages of t o t a l ex-t r a c t a b l e hexoses tended to i n c r e a s e w i t h depth. Y i e l d s of pentoses were g r e a t e r than those of Stage A. Although there were accumulations and d e p l e t i o n s w i t h i n the p r o f i l e , there was an o v e r a l l , though sometimes s l i g h t , decrease of e x t r a c t e d pentoses w i t h depth w h i l e 80. percentages of t o t a l extractable pentoses showed an increase. D. 0.05M Na 4P 20 7 + IN K 2S0 4 (pH 7.0) Extraction Although the values f o r the Ap and Ah horizons were generally higher, percentages of the t o t a l ex-tr a c t a b l e hexoses were higher i n the Bg horizon than i n the Btg horizon. There appeared to be a general decrease i n y i e l d s with depth, and accumulations i n the Bg and Cg horizons were indicated by the percen-tage values. Both the y i e l d s of pentoses and percen-tage values showed a decrease to the B horizons, then an increase to the Cg horizons. DD. 0.05M Na 4P 20 7 (pH 7.0) Extraction This stage displayed greater dispersion than any of the other p a r a l l e l stages. According to the y i e l d s of hexoses obtained f o r the Langley s e r i e s , the D extr a c t i o n was more e f f i c i e n t f o r the Ap and Ah horizons while the DD extraction was more e f f i c i e n t i n the lower horizons. Generally, there was a decrease of extractable hexoses with depth of p r o f i l e but percentages of t o t a l extractable hexoses did not reveal a d e f i n i t e pattern. According to the y i e l d s of pentoses, s i m i l a r amounts or less pentoses were extracted generally except f o r the Btg horizon. DS. IN K 2S0 4 Extraction This stage always yielded the most c l e a r s o l u t i o n of the p a r a l l e l stages. The y i e l d s of hexoses 81. were high i n the Ap and Ah horizons of the Langley s e r i e s but g r e a t e r i n the Ap h o r i z o n of the H a t z i c s e r i e s . The p a t t e r n s were a l l unique to each s e r i e s and d i d not show a d e f i n i t e d i f f e r e n c e between stages D and DD., A general decrease of amounts of pentoses and an i n c r e a s e of percentages of t o t a l e x t r a c t a b l e pentoses w i t h depth was observed. The p a t t e r n s were again unique f o r the e x t r a c t i o n and again d i d not show a d e f i n i t e d i f f e r e n c e between stages D and DD, DDD. Chelex-100 (Na + Form) E x t r a c t i o n With r e s p e c t to c h e l a t i n g p r o p e r t i e s , both hexoses and pentoses e x t r a c t e d were only able to i n d i c a t e , at b e s t , o n l y p a r t l y s i m i l a r c h e l a t i n g p r o p e r t i e s . F. 0.05N NaOH E x t r a c t i o n There was a general decrease i n hexose y i e l d s and percentages of t o t a l e x t r a c t a b l e hexoses w i t h depth of p r o f i l e w i t h i n d i c a t i o n s of d e p l e t i o n s and accumulations w i t h depth. There were no new p a t t e r n s of y i e l d s of pentoses and percentages of t o t a l e x t r a c t -able pentoses f o r the h o r i z o n s . G. F i n a l H y d r o l y s i s Y i e l d s of hexoses showed a general decrease w i t h depth but the percentages of t o t a l e x t r a c t a b l e hexoses i n d i c a t e d t h a t the Bg, Btg and Aeg horizons had l a r g e amounts of hexoses f i x e d . The y i e l d s of pentoses showed a s i m i l a r p a t t e r n , though there were 82. marked d i f f e r e n c e s . The t o t a l e x t r a c t a b l e hexoses, comprising stages A, B, D, F and G showed t h a t the organic A hor i z o n s contained the l a r g e s t amounts of hexoses, w h i l e the lower h o r i z o n s although having l e s s e r amounts, had most of t h e i r hexoses f i x e d . The t o t a l e x t r a c t a b l e pentoses showed t h a t the o r g a n i c A ho r i z o n s contained the l a r g e s t amounts, wi t h a pentose ' s i n k ' i n the B h o r i z o n s , i n a general d e c r e a s i n g p a t t e r n w i t h depth. The hexose/pentose d i s t r i b u t i o n showed a g r e a t e r accumulation of hexoses than pentoses i n the upper A. h o r i z o n s but the re v e r s e i n the lower h o r i z o n s . Of note, i s the c o n s i s t e n t r a t i o of l e s s than one f o r the d i l u t e a c i d treatment. The general i n d i c a t i o n i s t h a t there i s g r e a t e r r e t e n t i o n of pentoses than hex-oses w i t h i n c r e a s e i n depth of p r o f i l e . The comparative d i s t r i b u t i o n of sugars w i t h ions showed the f o l l o w i n g : Stage A The water s o l u b l e e x t r a c t i o n showed ( i f v a l i d a s s o c i a t i o n s can be made) t h a t hexoses and c a l c i u m were a s s o c i a t e d i n Ap and Ah h o r i z o n s , and the pentoses w i t h i r o n , aluminum and magnesium i n order of de-c r e a s i n g importance, formed the c l o s e s t a s s o c i a t i o n s 83. i n the lower h o r i z o n s . Stage B The d i l u t e a c i d e x t r a c t i o n showed a r e l a t i o n -s h i p of pentoses w i t h aluminum and to a l e s s e r extent, i r o n , throughout the p r o f i l e . Stage D The pyrophosphate and potassium sulphate e x t r a c t i o n showed t h a t pentoses or hexoses formed c l o s e a s s o c i a t i o n s w i t h i r o n and aluminum i n the Ap and Ah h o r i z o n s . Pentoses appeared to be a s s o c i a t e d w i t h i r o n , magnesium and aluminum i n the lower h o r i -zons . Stage DP The pyrophosphate e x t r a c t i o n showed c l o s e r e l a t i o n s h i p s of hexoses w i t h i r o n and aluminum i n the upper Ah and Ap h o r i z o n s w h i l e pentoses were a s s o c i a t e d w i t h magnesium and aluminum i n the lower h o r i z o n s . Stage PS The potassium sulphate e x t r a c t i o n showed t h a t pentoses or hexoses were c l o s e l y a s s o c i a t e d w i t h aluminum i n the Ap, Ah and Cg h o r i z o n s w h i l e pentoses were c l o s e l y r e l a t e d w i t h magnesium and aluminum i n the other h o r i z o n s . Stage PPP The Chelex - 1 0 0 e x t r a c t i o n showed t h a t hexoses were a s s o c i a t e d w i t h aluminum throughout the s o i l . 84. Neither calcium nor magnesium was measureable. The sequential procedure of extraction might have achieved desired purposes of s e l e c t i v e l y and progressively extracting organic matter and assoc-iated ions i n order that the d i s t r i b u t i o n of carbohy-drates and i o n i c constituents can demonstrate p r o f i l e d i f f e r e n t i a t i o n . The s i g n i f i c a n c e of various d i s -t r i b u t i o n s l i e s i n the trends which show character-i s t i c patterns. No pretense i s given to the exact meaning or implications of these trends but various suggestions have been made i n the pertinent sections. As an example, the trends of carbohydrate depletion i n the Aeg horizon and f i x a t i o n of carbohydrates i n the B horizons are i n d i c a t i v e of a c h a r a c t e r i s t i c process which does not n e c e s s a r i l y include only carbo-hydrate and i o n i c materials but possibly other con-s t i t u e n t s . The extraction procedure i s biased towards the progressive removal of constituents by s o l u b i l i z -ation of material i n the outer locations with the help of mild mechanical d i s p e r s i o n . I t can be argued that complete dispersion f a c i l i t a t e s the complete extraction of s i m i l a r constituents simultaneously. However, t h i s excludes most relevant information concerning the proximity of constituents and possibly information concerning the formation of associations. The greatest 85. d i f f i c u l t y l i e s i n p r e c i s e l y l o c a t i n g these c o n s t i t -uents. However, f o r the present, an approximation provided by gradual dispersion can s u f f i c e . A study of a l l compounds, organic and i n o r -ganic, remaining a f t e r various stages of extraction can be made by completely dispersing each residue and studying f o r p e r s i s t i n g organo-metallic complexation. Leaching studies without d i s p e r s i o n can also provide information as to the processes involved i n r e d i s t r i -bution of organic and inorganic constituents i n the s o i l by using various s o l u b i l i z i n g agents. Of some s i g n i f i c a n c e i s the i n d i c a t i o n by p a r t i a l study of the d i s t r i b u t i o n of i n d i v i d u a l sugars, that there are marked differences between extracts. 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