UBC Theses and Dissertations

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UBC Theses and Dissertations

Forest soil phosphorus availabilty to seedlings of pinus patula and cupressus lusitanica Gaitho, Charles Waweru 1978

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FOREST SOIL PHOSPHORUS A V A I L A B I L I T Y TO SEEDLINGS OF PINUS PATULA AND CUPRESSUS LUSITANICA by CHARLES WAWERU GAITHO B . S c . F o r e s t r y , M a k e r e r e U n i v e r s i t y , K a m p a l a , 1974 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES D e p a r t m e n t o f S o i l S c i e n c e We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF B R I T I S H COLUMBIA D e c e m b e r , 1978 © C h a r l e s Waweru G a i t h o , 1978 In p r e s e n t i n g t h i s t h e s i s • I n ' p a r t i a l , f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e H e a d o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f S o i l S c i e n c e  The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook Place Vancouver, Canada V6T 1W5 D a t e D e c e m b e r 2 1 , 1978 - i i -ABSTRACT I n a p r e l i m i n a r y s t u d y , d i f f e r e n t a m o u n t s o f i r o n and a l u m i n u m p h o s p h a t e s w e r e a d d e d t o B f and Ah h o r i z o n m a t e r i a l s , a n d p o t a s s i u m p h o s -p h a t e was a d d e d t o a m i x e d L - F - H h o r i z o n m a t e r i a l . The s o i l m a t e r i a l s w e r e t h e n i n c u b a t e d f o r 16 d a y s and a n a l y s e d f o r e x t r a c t a b l e A l , Fe a n d P ( O l s e n ' s m e t h o d ) . R e s u l t s a f t e r i n c u b a t i o n showed t h a t t h e B f and Ah h o r i z o n m a t e r i a l had more e x t r a c t a b l e Fe a n d A l t h a n t h e L - F - H m a t e r i a l . E x t r a c t a b l e P s u g g e s t e d a P d e f i c i e n c y i n B f s o i l m a t e r i a l a n d a r e l a -t i v e l y h i g h l e v e l o f a v a i l a b l e P i n L - F - H m a t e r i a l . A d d i t i o n o f l a r g e a m o u n t s o f i r o n and a l u m i n u m p h o s p h a t e s t o t h e B f a n d Ah m a t e r i a l y i e l d e d o n l y s l i g h t i n c r e a s e s i n e x t r a c t a b l e P. H o w e v e r , t h e a m o u n t s o f e x t r a c t -a b l e P i n d i c a t e d t h a t t h e p h o s p h a t e f o r m s a d d e d t o t h e s e s o i l m a t e r i a l s c o u l d r e m a i n p a r t i a l l y e x t r a c t a b l e f o r some t i m e a n d i t was i n f e r r e d t h a t t h e y r e s e m b l e d n a t i v e s o i l p h o s p h a t e s r a t h e r t h a n f e r t i l i z e r p h o s p h a t e s . N e x t , t h e a v a i l a b i l i t y o f p h o s p h o r u s t o two c o n i f e r s p e c i e s ( P i n u s p a t u l a a n d C u p r e s s u s 1 u s i t a n i c a ) was t e s t e d f o r t h e same t h r e e f o r e s t s o i l m a t e r i a l s . D i f f e r e n t a m o u n t s o f p h o s p h o r u s w e r e a d d e d t o t h e s e m a t e r i a l s , a s b e f o r e , a n d s e e d l i n g s o f t h e t w o p l a n t s p e c i e s w e r e grown f o r 178 d a y s . P h o s p h o r u s u p t a k e by t h e s e e d l i n g s was m e a s u r e d a n d c o r r e l a t e d w i t h t h e c o n c e n t r a t i o n o f s o i l p h o s p h o r u s e x t r a c t e d by f i v e m e t h o d s ( B r a y P - l , m o d i f i e d B r a y P - l , O l s e n , T r u o g a n d M e h l i c h ) , i n o r d e r t o i d e n t i f y t h e m o s t s u i t a b l e e x t r a c t i o n m e t h o d t o s e r v e a s an i n d e x o f s o i l p h o s p h o r u s a v a i l a b i l i t y t o t h e t r e e s e e d l i n g s . S e e d l i n g g r o w t h ( h e i g h t , d i a m e t e r , a n d b i o m a s s ) was l e a s t f o r s e e d l i n g s grown i n B f a n d g r e a t e s t f o r t h o s e grown i n L - F - H m a t e r i a l s . S e e d l i n g s g r o w n i n B f s o i l m a t e r i a l s h o w e d , g e n e r a l l y , g r e a t e r b i o m a s s f o r r o o t s t h a n f o r f o l i a g e o r s t e m , b u t t h o s e grown i n t h e l e a s t P - d e f i c i e n t i ( L - F - H ) m a t e r i a l had g r e a t e r b i o m a s s f o r f o l i a g e t h a n s t e m o r - i i i -r o o t s . A n a l y s i s o f P u p t a k e by s e e d l i n g s i n d i c a t e d s l i g h t l y h i g h e r P c o n c e n t r a t i o n i n r o o t s t h a n i n s t e m o r f o l i a g e . T o t a l P u p t a k e was l e a s t f r o m B f a n d h i g h e s t f r o m L - F - H m a t e r i a l s . P h o s p h a t e s a d d e d t o m i n e r a l s o i l g a v e a s u b s t a n t i a l r e l a t i v e i n c r e a s e i n t o t a l P u p t a k e , e s p e c i a l l y f o r B f m a t e r i a l s . H o w e v e r , f o r L - F - H m a t e r i a l , a d d e d p h o s p h a t e s c a u s e d i n c r e a s e s i n u p t a k e w h i c h w e r e m o s t l y l a r g e i n a b s o l u t e v a l u e , b u t s m a l l r e l a t i v e t o u p t a k e f r o m unamended s o i l . C u p r e s s u s l u s i t a n i c a s e e d l i n g s a c c u m u l a t e d more p h o s p h o r u s t h a n P i n u s p a t u l a s e e d l i n g s w i t h t h e l o w P l e v e l s , w h i l e t h e o p p o s i t e was u s u a l l y t h e c a s e w i t h t h e h i g h P l e v e l s . E x t r a c t a b l e P a f t e r s e e d l i n g g r o w t h was l o w e s t i n B f a n d h i g h e s t i n L - F - H m a t e r i a l s a n d i t i n c r e a s e d w i t h i n c r e a s e i n t h e amount o f p h o s -p h a t e s a d d e d . 01 s e n ' s m e t h o d e x t r a c t e d more P f r o m t h e t h r e e s o i l m a t e r -i a l s t h a n a n y o f t h e o t h e r e x t r a c t i o n m e t h o d s . T h e r e w e r e s l i g h t , i n c o n -s i s t e n t d i f f e r e n c e s i n t h e a m o u n t s o f P e x t r a c t e d by t h e B r a y P - l and m o d i f i e d B r a y P - l m e t h o d s . W h i l e p h o s p h o r u s c o n c e n t r a t i o n i n s o i l e x t r a c -t e d by t h e f i v e m e t h o d s f r o m t h e t h r e e s o i l m a t e r i a l s w h e r e P i n u s p a t u l a s e e d l i n g s w e r e grown c o r r e l a t e d w i t h e a c h o t h e r , P e x t r a c t e d by M e h l i c h m e t h o d f r o m t h e Ah s o i l m a t e r i a l f a i l e d t o c o r r e l a t e w i t h t h e o t h e r m e t h o d s e x c e p t t h e O l s e n m e t h o d . F o r p i n e , c o n c e n t r a t i o n o f P e x t r a c t e d by a l l t h e m e t h o d s f r o m t h e t h r e e s o i l m a t e r i a l s y i e l d e d s i g n i f i c a n t ( P < _ 0 . 0 5 a n d P 5 0 . 1 0 , r e s p e c -t i v e l y ) c o r r e l a t i o n w i t h P u p t a k e f r o m t h e P - d e f i c i e n t B f , b u t f a i l e d t o y i e l d s i g n i f i c a n t ( P < 0 . 1 0 ) c o r r e l a t i o n w i t h P u p t a k e f r o m Ah m a t e r i a l . The O l s e n , T r u o g and B r a y P - l m e t h o d s y i e l d e d v e r y s i g n i f i c a n t ( P 5 0 . 0 1 ) c o r r e l a t i o n w i t h P u p t a k e by c y p r e s s f r o m Ah m a t e r i a l . C o r r e l a t i o n a n a l y s i s o f f o l i a t P c o n c e n t r a t i o n w i t h e x t r a c t a b l e P c o n c e n t r a t i o n i n s o i l showed s i g n i f i c a n t ( P < 0 . 0 5 ) c o r r e l a t i o n f o r P i n u s - i v -p a t u l a . w i t h a l l m e t h o d s . A l l b u t t h e T r u o g m e t h o d y i e l d e d s i g n i f i c a n c e ' a t P<0.01. F o r C u p r e s s u s 1 u s i t a n i c a , c o r r e l a t i o n s w e r e b e t t e r w i t h B f t h a n w i t h Ah and L - F - H m a t e r i a l s , and o n l y t h e O l s e n m e t h o d y i e l d e d s i g -n i f i c a n c e (P<0.10) w i t h a l l t h r e e m a t e r i a l s . O v e r a l l , c o n s i d e r i n g a l l s o i l m a t e r i a l s and b o t h s p e c i e s , t h e O l s e n m e t h o d y i e l d e d t h e m o s t s a t i s f a c t o r y r e l a t i o n s h i p s w i t h P u p t a k e by t h e s e e d l i n g s a n d w i t h f o l i a r P c o n c e n t r a t i o n . - V -TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS v LIST OF TABLES vii LIST OF FIGURES viii ACKNOWLEDGEMENTS x INTRODUCTION 1 LITERATURE REVIEW 3 MATERIALS AND METHODS 11 1. Soil Materials 11 2. Phosphorus Extraction and Analysis 11 a. Bray P-l Method 11 b. Modified Bray P-l Method 11 c. Olsen Bicarbonate Extraction Method 13 d. Mehlich Double-acid Method 13 e. Truog Method 13 3. Iron and Aluminum Phosphate Preparation 14 4. Soil Incubation 14 5. Al, Fe and P Extraction and Analysis 15 6. Seed-bed Preparation and Seed Sowing 15 7. Soil Potting and Seedling Transplanting 16 8. Plant Materials, Digestion and Analysis 17 9. Caro's Acid Digestion of Plant Tissue 18 RESULTS AND DISCUSSION 20 1. Preliminary Study: Extractable Fe, Al and P 20 2. Seedling Growth 22 3. Extraction Methods 2 8 - v i -4 . P h o s p h o r u s C o n c e n t r a t i o n a n d U p t a k e by S e e d l i n g s 30 5 . C o r r e l a t i o n B e t w e e n E x t r a c t i o n M e t h o d s 34 6 . C o r r e l a t i o n B e t w e e n S o i l P E x t r a c t i o n M e t h o d s a n d S e e d l i n g P U p t a k e 36 SUMMARY AND CONCLUSION 41 BIBLIOGRAPHY 42 APPENDICES 45 1 . B r i e f D e s c r i p t i o n o f P i n u s p a t u l a and C u p r e s s u s l u s i t a n i c a 2 . R e g r e s s i o n s a n d C o r r e l a t i o n s B e t w e e n P h o s p h o r u s U p t a k e a n d E x t r a c t a b l e P h o s p h o r u s - v i i -L I S T OF TABLES T a b l e P a g e 1 Some p r o p e r t i e s o f t h e s o i l m a t e r i a l s b e f o r e s e e d ! i n g g r o w t h 12 2 S o i l e x t r a c t a b l e A l , Fe a n d P b e f o r e i n c u b a t i o n 21 3 S o i l e x t r a c t a b l e A l , F e , a n d P ( a v e r a g e s o f 3 r e p l i c a t e s ) a f t e r 16 d a y s i n c u b a t i o n a t 25 t o 27 C a n d a t f i e l d , c a p a c i t y 21 4 S e e d l i n g growth, o v e r 178 d a y s : d i a m e t e r a t b a s e and h e i g h t ( a v e r a g e s o f 5 s e e d l i n g s ) 26 5 B i o m a s s ( o v e n - d r y ) o f p l a n t p a r t s ( a v e r a g e s o f 10 s e e d l i n g s ) 27 6 E x t r a c t a b l e P (ppm) a f t e r 178 d a y s o f s e e d l i n g g r o w t h ( E a c h v a l u e i s t h e a v e r a g e o f 5 r e p l i c a t e s ) 29 7 C o n c e n t r a t i o n o f P i n p l a n t t i s s u e ( e a c h v a l u e i s t h e a v e r a g e o f 5 r e p l i c a t e s ) 32 8 P i n p l a n t t i s s u e o f 1 7 8 - d a y - o l d s e e d l i n g s ( a v e r a g e s o f 10 s e e d l i n g s ) 33 9 C o e f f i c i e n t s o f c o r r e l a t i o n ( r ) b e t w e e n s o i l P a m o u n t s e x t r a c t e d by v a r i o u s m e t h o d s 35 10 C o e f f i c i e n t s o f c o r r e l a t i o n ( r ) b e t w e e n P u p t a k e b y s e e d l i n g s a n d c o n c e n t r a t i o n o f s o i l P e x t r a c t e d by v a r i o u s m e t h o d s 37 11 R e g r e s s i o n c o n s t a n t s ( a ) a n d c o e f f i c i e n t s ( b ) b e t w e e n s e e d l i n g P u p t a k e and c o n c e n t r a t i o n o f s o i l P e x t r a c t e d by v a r i o u s m e t h o d s ( y =a+bx, w h e r e y i s P u p t a k e a n d x i s e x t r a c -t a b l e s o i l c o n c e n t r a t i o n ) 39 12 C o e f f i c i e n t s o f c o r r e l a t i o n ( r ) b e t w e e n s e e d -l i n g f o l i a r P c o n c e n t r a t i o n and c o n c e n t r a t i o n o f s o i l P e x t r a c t e d by v a r i o u s m e t h o d s 40 - v i i i -L I S T OF FIGURES F i g u r e P a g e 1 X - r a y d i f f r a c t i o n o f i r o n p h o s p h a t e 23 2 X - r a y d i f f r a c t i o n o f a l u m i n u m p h o s p h a t e 24 3 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d B r a y ' s P - l e x t r a c t a b l e P i n s o i l f o r B f h o r i z o n m a t e r i a l s 47 4 R e l a t i o n s h i p b e t w e e n P u p t a k e by f_. p a t u l a a n d m o d i f i e d B r a y P - l e x t r a c t a b l e P i n s o i l f o r B f h o r i z o n m a t e r i a l s 49 5 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d 01 s e n ' s e x t r a c t a b l e P i n s o i l f o r B f h o r i z o n m a t e r i a l s 51 6 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d T r u o g 1 s e x t r a c t a b l e P i n s o i l f o r B f h o r i z o n m a t e r i a l s 53 7 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d M e h l i c h ' s e x t r a c t a b l e P i n s o i l f o r B f h o r i z o n m a t e r i a l s 55 8 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d B r a y ' s P - l e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 57 9 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a and m o d i f i e d B r a y P - l e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 59 10 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d 01 s e n ' s e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 61 11 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d T r u o g 1 s e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 63 12 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a a n d M e h l i c h ' s e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 65 13 R e l a t i o n s h i p b e t w e e n P u p t a k e by IP. p a t u l a and B r a y ' s P - l e x t r a c t a b l e P i n s o i l f o r L - F - H h o r i z o n m a t e r i a l s 67 14 R e l a t i o n s h i p b e t w e e n P u p t a k e by IP. p a t u l a a n d m o d i f i e d B r a y P - l e x t r a c t a b l e P i n s o i l f o r L - F - H h o r i z o n m a t e r i a l s 69 - i x -15 R e l a t i o n s h i p b e t w e e n P u p t a k e by P_. p a t u l a and O l s e n ' s e x t r a c t a b l e P i n s o i l f o r L - F - H h o r i z o n m a t e r i a l s 71 16 R e l a t i o n s h i p b e t w e e n P u p t a k e by IP. p a t u l a a n d T r u o g ' s e x t r a c t a b l e P i n s o i l f o r L - F - H h o r i z o n m a t e r i a l s 73 17 R e l a t i o n s h i p b e t w e e n P u p t a k e and M e h l i c h ' s e x t r a c t a b l e P i n s o i l f o r L - F - H h o r i z o n m a t e r i a l s 75 18 R e l a t i o n s h i p b e t w e e n P u p t a k e by C_. l u s i t a n i c a a n d M e h l i c h ' s e x t r a c t a b l e P i n s o i l f o r B f h o r i z o n m a t e r i a l s 77 19 R e l a t i o n s h i p b e t w e e n P u p t a k e by C_. 1 u s i t a n i c a a n d B r a y ' s P - l e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 79 20 R e l a t i o n s h i p b e t w e e n P u p t a k e by C_. 1 u s i t a n i c a a n d m o d i f i e d B r a y P - l e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 81 21 R e l a t i o n s h i p b e t w e e n P u p t a k e by C_. 1 u s i t a n i c a a n d O l s e n ' s e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 83 22 R e l a t i o n s h i p b e t w e e n P u p t a k e by C_. 1 u s i t a n i c a a n d T r u o g ' s e x t r a c t a b l e P i n s o i l f o r Ah h o r i z o n m a t e r i a l s 85 23 R e l a t i o n s h i p b e t w e e n P u p t a k e by C_. 1 u s i t a n i c a a n d M e h l i c h ' s e x t r a c t a b l e P i n s o i l f o r L - F - H h o r i z o n m a t e r i a l s 87 ACKNOWLEDGEMENTS I am g r a t e f u l t o t h e G o v e r n m e n t o f K e n y a f o r s p o n s o r i n g me t o s t u d y i n C a n a d a , a n d t o t h e G o v e r n m e n t o f C a n a d a f o r f i n a n c i n g my s t u d y a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a t h r o u g h t h e C a n a d i a n I n t e r n a t i o n a l D e v e l o p m e n t A g e n c y . I w i s h t o e x p r e s s my s p e c i a l t h a n k s and a p p r e c i a t i o n t o my s u p e r v i s o r , D r . T . M . B a l l a r d ( A s s o c i a t e P r o f e s s o r , D e p a r t m e n t o f S o i l S c i e n c e and F a c u l t y o f F o r e s t r y ) , who g a v e v a l u a b l e g u i d a n c e a t a l l s t a g e s o f t h e s t u d y and p r e s e n t a t i o n o f t h i s t h e s i s . T h a n k s a r e e x t e n d e d t o o t h e r members o f my t h e s i s c o m m i t t e e ; - D r . C A . R o w l e s ( P r o f e s s o r a n d C h a i r m a n o f t h e S o i l S c i e n c e D e p a r t m e n t ) , D r . L . M . L a v k u l i c h ( P r o f e s s o r , S o i l S c i e n c e D e p a r t m e n t ) , a n d D r . A . A . Bomke ( A s s i s t a n t P r o f e s s o r , S o i l S c i e n c e D e p a r t m e n t ) , f o r t h e i r a d v i c e a n d r e c o m m e n d a t i o n s . T h e a s s i s t a n c e o f D r . J . O t c h e r e - B o a t e n g d u r i n g l a b o r a t o r y a n a l y s i s i s g r a t e f u l l y a c k n o w l e d g e d . I e x t e n d my d e e p e s t a p p r e c i a t i o n t o my f a m i l y f o r t h e i r c o n s t a n t p a t i e n c e a n d e n c o u r a g e m e n t t h r o u g h o u t t h e p e r i o d o f my s t u d y away f r o m home. - 1 -INTRODUCTION F r a c t i o n a t i o n s t u d i e s i n a c i d f o r e s t s o i l s h a v e i n d i c a t e d t h a t a c o n s i d e r a b l e p o r t i o n o f s o i l p h o s p h o r u s i s f r e q u e n t l y p r e s e n t a s i r o n -and a l u m i n u m - b o u n d p h o s p h a t e s . Much o f t h e w e a t h e r e d i n o r g a n i c p h o s p h a t e i s u n a v a i l a b l e t o p l a n t s b e c a u s e o f p r e c i p i t a t i o n w i t h a m o r p h o u s o x i d e s a n d h y d r o x i d e s o f i r o n and a l u m i n u m . P h o s p h a t e a v a i l a b i l i t y t o t r e e s i s e n h a n c e d by t h e m y c o r r h i z a l f u n g i n o r m a l l y a s s o c i a t e d w i t h t r e e r o o t s y s -t e m s . A g r i c u l t u r a l m e t h o d s f o r e v a l u a t i n g s o i l p h o s p h o r u s a v a i l a b i l i t y h a v e been d e v e l o p e d p r i n c i p a l l y f o r l e s s a c i d s o i l s and ( p r e d o m i n a n t l y ) n o n - m y c o r r h i z a l c r o p s . The B r a y P - l m e t h o d ( 1 - m i n u t e e x t r a c t i o n w i t h d i -l u t e H C l - N H ^ F ) i s o f t e n a p p l i e d t o a c i d f o r e s t s o i l s , b u t s o m e t i m e s g i v e s v a r i a b l e r e s u l t s , e s p e c i a l l y w i t h h y d r o p h o b i c s o i l s a m p l e s . P i n u s p a t u l a a n d C u p r e s s u s 1 u s i t a n i c a a r e two e x o t i c s p e c i e s w h i c h h a v e been g r o w n i n l a r g e q u a n t i t y i n K e n y a . T h e s e two s p e c i e s h a v e been g r o w n p r e d o m i n a n t l y i n t h e h i g h l a n d s ( o v e r 1700m a b o v e s e a l e v e l ) w h i c h w e r e f o r m e r l y u n d e r i n d i g e n o u s f o r e s t s . The s o i l s i n t h e s e a r e a s a r e r e l a t i v e l y f e r t i l e and d e e p . H o w e v e r , due t o g r e a t e r n e e d o f t h i s l a n d f o r a g r i c u l t u r e , t h e r e c e n t t e n d e n c y h a s b e e n t o a f f o r e s t a r e a s a t l o w e r e l e v a t i o n , b o t h f o r p r o v i s i o n o f wood a n d t o r e d u c e s o i l e r o s i o n . F e r t i l i z e r t r i a l s a n d p o t t e s t s i n g r e e n h o u s e s on s o i l s f r o m t h e s e l a t t e r a r e a s h a v e shown t h a t p h o s p h o r u s i s t h e m o s t i m p o r t a n t n u t r i e n t l i m i t i n g g r o w t h and y i e l d o f a g r i c u l t u r a l c r o p s . The l o w a v a i l a b i l i t y o f p h o s p h o r u s i n t h e s e a r e a s i s a t t r i b u t e d t o t h e p r e s e n c e o f h i g h c o n c e n t r a t i o n s o f i r o n and a l u m i n u m o x i d e s and h y d r o x i d e s . T h e s e f i n d i n g s p e r t a i n t o a g r i -c u l t u r a l c r o p s and more i n f o r m a t i o n i s r e q u i r e d f o r f o r e s t p l a n t s . The o b j e c t i v e o f t h i s s t u d y i s t o e v a l u a t e s o i l t e s t m e t h o d s f o r e s t i m a t i n g a v a i l a b l e p h o s p h o r u s , u s i n g s e e d l i n g s o f P_. p a t u l a and C_. 1 u s i t a n i c a grown i n s o i l m a t e r i a l s w h i c h d i f f e r i n s e s q u i o x i d e c o n t e n t and p h o s p h o r u s a v a i l a b i l - 3 -LITERATURE REVIEW A v a i l a b i l i t y t o p l a n t s o f s c a r c e l y s o l u b l e i r o n a n d a l u m i n u m p h o s p h a t e s has b e e n c o n s i d e r e d by many w o r k e r s . The m o s t commonly u s e d a p p r o a c h i s t o r e l a t e t h e a v a i l a b i l i t y o f t h e s e p h o s p h a t e s t o t h e i r e x -t r a c t a b i l i t y , f r o m s o i l s , by s o l u t i o n s . S o l u b i l i t y o f i r o n and a l u m i n u m p h o s p h a t e s d e p e n d s on t h e i r f o r m ( c o l l o i d a l , a m o r p h o u s , c r y s t a l l i n e ) , p a r -t i c l e s i z e , h y d r a t i o n , e t c . a n d s u c h s o i l f a c t o r s a s m o i s t u r e c o n t e n t , t e m p e r a t u r e , t e x t u r e , a n d p H . P l a n t s t o o h a v e v a r i e d a b i l i t y t o t a k e up t h e s e s p a r i n g l y s o l u b l e p h o s p h a t e s , d e p e n d i n g o n s u c h f a c t o r s a s s p e c i e s , r o o t d e v e l o p m e n t , a n d m y c o r r h i z a l d e v e l o p m e n t . A l t h o u g h a l o t o f l i t e r a t u r e on t h e a v a i l a b i l i t y o f i r o n a n d a l u m i n u m p h o s p h a t e s i s a v a i l a b l e , m o s t o f t h e p l a n t s u s e d a r e a g r i c u l t u r a l c r o p s , a n d v e r y l i t t l e l i t e r a t u r e e x i s t s on t h e a v a i l a b i l i t y o f t h e s e c o m -p o u n d s t o f o r e s t t r e e s . A n o t h e r c o m p l i c a t i o n i s t h a t many w o r k e r s h a v e n o t i d e n t i f i e d t h e f o r m o r d e g r e e o f h y d r a t i o n o f t h e i r o n o r a l u m i n u m p h o s p h a t e s u s e d i n t h e i r s t u d i e s . S e v e r a l t y p e s o f i r o n and a l u m i n u m compounds h a v e been p r e p a r e d i n t h e l a b o r a t o r y , ( C h a n g and J a c k s o n 1 9 5 7 ; F u j i w a r a 1 9 5 0 ; T a y l o r e t a l . 1 9 6 0 ; L i n d s a y a n d Dement 1 9 6 1 ) , a n d s e v e r a l h a v e been f o u n d i n s o i l s ( L i n d s a y a n d T a y l o r 1 9 6 0 ; T a y l o r e t a l . 1 9 6 0 ; L i n d s a y a n d V l e k 1 9 7 7 ; N o v o z a m s k y a n d Beek 1 9 7 6 ) . F i x a t i o n o f s o l u b l e f e r t i l i z e r p h o s p h a t e s h a s b e e n e x t e n s i v e l y r e c o g n i z e d i n s o i l s h i g h i n i r o n o r a l u m i n u m o r t h e i r compounds u n d e r a c i d c o n d i t i o n s . A t pH a b o v e n e u t r a l , t h e p r e s e n c e o f c a l c i u m p l a y s a r o l e i n p h o s p h a t e f i x a t i o n . C o l l o i d a l a n d a m o r p h o u s i r o n a n d a l u m i n u m p h o s p h a t e s a r e r e l a -t i v e l y more a v a i l a b l e t o p l a n t s t h a n t h e c r y s t a l l i n e f o r m . L i n d s a y a n d T a y l o r ( 1 9 6 0 ) f o u n d t h a t c o l l o i d a l i r o n a n d a l u m i n u m p h o s p h a t e s a r e r e l a -t i v e l y g o o d s o u r c e s o f p h o s p h o r u s i n n e u t r a l s o i l s , b u t t h e i r a v a i l a b i l i t y - 4 -i s much l e s s u n d e r more a c i d c o n d i t i o n s . T h e s e c o l l o i d a l p h o s p h a t e s w e r e f o u n d t o be t h e r m o d y n a m i c a l l y u n s t a b l e w i t h r e s p e c t t o c r y s t a l 1 i n e f o r m s s u c h a s s t r e n g i t e ( F e P C v 2 H 2 0 ) a n d v a r i s c i t e ( A l P C v 2 H 2 0 ) . I r o n a n d a l u m i n u m p h o s p h a t e s a l s o d i f f e r i n t h e i r a v a i l a b i l i t y t o p l a n t s . S e v e r a l w o r k e r s h a v e f o u n d a l u m i n u m p h o s p h a t e s more a v a i l a b l e t h a n t h e c o r r e s p o n d i n g f e r r i c p h o s p h a t e s ( F u j i w a r a 1 9 5 0 ; L i n d s a y a n d DeMent 1 9 6 1 ; L i n d s a y a n d T a y l o r 1 9 6 0 ) . T h e s e d i f f e r e n c e s i n a v a i l a b i l i t y h a v e b e e n a t t r i b u t e d t o t h e d i f f e r e n c e s i n s o l u b i l i t y o f i r o n and a l u m i n u m p h o s p h a t e s . C h a n g and J a c k s o n ( 1 9 5 7 ) h a v e g i v e n t h e s o l u b i l i t y p r o d u c t s o f d i f f e r e n t i r o n and a l u m i n u m p h o s p h a t e c o m p o u n d s . A l u m i n u m p h o s p h a t e s a r e shown t o be more s o l u b l e t h a n i r o n p h o s p h a t e s o f t h e same s p e c i e s a t t h e same pH v a l u e . The c o n c e n t r a t i o n o f p h o s p h a t e i o n i s l o w e s t a t pH 3 t o 5 i n t h e c a s e o f i r o n s a l t s , a n d a t pH 4 t o 6 i n t h e c a s e o f a l u m i n u m s a l t s ( F u j i w a r a 1 9 5 0 ) . A g e i n g o f i r o n a n d a l u m i n u m p h o s p h a t e s h a s b e e n f o u n d t o d e c r e a s e t h e i r s o l u b i l i t y . F u j i w a r a ( 1 9 5 0 ) f o u n d t h a t a m o r p h o u s i r o n a n d a l u m i n u m p h o s p h a t e s , a d e q u a t e l y h y d r a t e d , c r y s t a l l i z e d u r i n g s t o r a g e o v e r a l o n g p e r i o d o f t i m e , a n d t h e a v a i l a b i l i t y o f t h e c r y s t a l -l i n e s a l t s becomes f a r l e s s t h a n a m o r p h o u s s a l t s . I n c u b a t i o n e x p e r i m e n t s h a v e shown d i f f e r e n c e s i n a v a i l a b i l i t y o f a d d e d p h o s p h a t e s t o s o i l s v a r y i n g i n p h y s i c a l p r o p e r t i e s . T a y l o r e t a l . ( 1 9 6 0 ) a d d e d c o l l o i d a l f e r r i c p h o s p h a t e s a n d c o l l o i d a l a l u m i n u m p h o s -p h a t e t o f i n e s a n d y l o a m d e f i c i e n t i n p h o s p h o r u s . T h e y i n c u b a t e d t h e s o i l i n t h e g r e e n h o u s e a n d grew c o r n o v e r v a r y i n g p e r i o d s o f 5 0 , 5 6 and 6 0 d a y s . T h e i r r e s u l t s showed t h a t i n c u b a t i o n d e c r e a s e d t h e u p t a k e o f p h o s p h o r u s i n t h e u n l i m e d a c i d s o i l (pH 4 . 8 ) . P o o r r o o t d e v e l o p m e n t was a l s o n o t i c e d . A c q u a y e ( 1 9 6 3 ) , w o r k i n g i n t h e t r o p i c s , i n c u b a t e d s o i l s a t v a r y i n g t e m p e r a t u r e s , a n d f o u n d t h a t P - m i n e r a l i z a t i o n was s l o w f o r 1 4 d a y s , b u t i n c r e a s e d a f t e r t h a t . E n w e z o r ( 1 9 6 6 ) f o u n d c o m p a r a b l e r e s u l t s when - 5 -he i n c u b a t e d l i g h t - t e x t u r e d s o i l s a t 30°C f o r a p e r i o d o f t w e l v e weeks. He r e p o r t e d t h a t i n c r e a s i n g l e v e l s o f added i n o r g a n i c phosphorus i n c r e a -sed t h e m i n e r a l i z a t i o n o f s o i l o r g a n i c phosphorus. In a p r e l i m i n a r y e x p e r i m e n t u s i n g t h e same s o i l w i t h added s o l u b l e i n o r g a n i c phosphorus, he found t h a t n e t phosphorus m i n e r a l i z a t i o n s e t i n a f t e r t h r e e weeks. In s t u d i e s aimed a t e v a l u a t i n g t h e e x t r a c t a b l e i r o n and alum-inum from s o i l s , and t h e i r e f f e c t s on p l a n t n u t r i e n t s a v a i l a b i l i t y , p y r o -phosphate and o x a l a t e e x t r a c t i n g s o l u t i o n s have been used. D i t h i o n i t e s o l u t i o n , which e x t r a c t s i r o n and aluminum from c r y s t a l l i n e f orms, i s a l s o sometimes used f o r t h i s purpose. McKeague (1967) e v a l u a t e d t h e use o f 0.1 M N a-pyrophosphate and a c i d ammonium o x a l a t e as e x t r a c t a n t s o f t h e a c c u m u l a t i o n p r o d u c t s i n p o d z o l s and some o t h e r s o i l s . He found t h a t the p y r o p h o s p h a t e s o l u t i o n e x t r a c t e d some o f t h e o r g a n i c forms o f Fe and A l from samples o f Podzol B and some A c i d Brown Wooded B h o r i z o n s . I t d i d not d i s s o l v e i n o r g a n i c amorphous (aged) o r c r y s t a l l i n e Fe and Al s u b s t a n -ces t e s t e d . The a c i d o x a l a t e s o l u t i o n e x t r a c t e d Fe and Al from some amorphous i n o r g a n i c s u b s t a n c e s as w e l l as from o r g a n i c complexes but d i d not d i s s o l v e c r y s t a l l i n e Fe o x i d e s . McKeague e t a l . (1971) showed t h a t t h e i r o n e x t r a c t e d by 0.1M Na i tP 20 7 was l a r g e l y o r g a n i c Fe. The d i f f e r e n c e between o x a l a t e and p y r o p h o s p h a t e - e x t r a c t a b l e Fe g i v e s a measure o f amorphous i n o r g a n i c (aged) Fe. They found a l s o t h a t s p o d i c h o r i z o n s c o n t a i n e d much more pyrophos-p h a t e - e x t r a c t a b l e Fe and A l than o t h e r s o i l m a t e r i a l s t e s t e d . D u r i n g r e c e n t y e a r s a v e r y l a r g e amount o f r e s e a r c h has been done and p u b l i s h e d , comparing e x t r a c t a n t s and a n a l y t i c a l p r o c e d u r e s f o r t e s t i n g a v a i l a b l e s o i l phosphorus ( N e l s o n e t a l . 1953). The i n f e r r e d con-c e n t r a t i o n o f a v a i l a b l e phosphorus i n s o i l can v a r y g r e a t l y w i t h t h e ex-t r a c t i o n method used. - 6 -A c i d i c e x t r a c t i n g s o l u t i o n s h a v e b e e n p r o p o s e d b e c a u s e i t was a s s u m e d t h a t t h e p l a n t r o o t s e x c r e t e a c i d s a n d t h e s e m i g h t a c t a s s o l v e n t s . Ammonium f l u o r i d e s o l u t i o n was p r o p o s e d ( K u r t z e t a l . 1 9 4 6 ) a s an e x t r a c t -i n g a g e n t b e c a u s e t h e f l u o r i d e i o n seemed t o r e p l a c e s o r b e d p h o s p h o r u s . T h e u s e o f a s o d i u m b i c a r b o n a t e s o l u t i o n h a s a l s o b e e n p r o p o s e d ( O l s e n e t a l . 1 9 5 4 ) , t h e t h e o r y b e i n g t h a t t h e b i c a r b o n a t e i o n r e d u c e s t h e a c t i v i t y o f C a 2 + i o n i n c a l c a r e o u s s o i l s a n d t h e r e b y i n c r e a s e s t h e s o l u b i l i t y o f p h o s p h o r u s . G e n e r a l l y t h e amount o f e x t r a c t a b l e p h o s p h o r u s d e t e r m i n e d w i t h t h e u s e o f s t r o n g e r a c i d s was h i g h e r t h a n w i t h w e a k e r a c i d s . The B r a y P - l M e t h o d T h i s m e t h o d was d e v e l o p e d by B r a y a n d K u r t z ( 1 9 4 5 ) , a n d a p p e a r s t o h a v e b e e n p r i m a r i l y d e s i g n e d f o r n o n - c a l c a r e o u s s o i l s . T h e e x t r a c t i n g s o l u t i o n i s 0 . 0 3 N NH^F a n d 0 . 0 2 5 N HC1. The s o i l . t o s o l u t i o n r a t i o i s 1 : 7 . 3 + 3 + The f l u o r i d e i o n h a s t h e p r o p e r t y o f c o m p l e x i n g Fe a n d A l i o n s . I t t h u s c a n r e l e a s e some o f t h e p h o s p h a t e f r o m f e r r i c and a l u m i n u m p h o s p h a t e s . I n c l u s i o n o f HC1 i n t h e e x t r a c t a n t r e s u l t s i n s o l u t i o n o f t h e more a c t i v e c a l c i u m p h o s p h a t e s . I t a l s o p r e v e n t s t h e c a l c i u m r e l e a s e d by t h e f l u o r i d e b e i n g p r e c i p i t a t e d a s c a l c i u m p h o s p h a t e . T u r n e r a n d R i c e ( 1 9 5 2 ) f o u n d t h a t a f l u o r i d e : a l u m i n u m m o l e r a t i o i n e x c e s s o f 6 : 1 p r e v e n t e d p r e c i p i t a -t i o n o f p h o s p h a t e by a l u m i n u m , b u t w i t h f e r r i c i o n s u c h a f l u o r i d e e f f e c t was v e r y s l i g h t . A l u m i n u m f l u o r i d e c o m p l e x e s , t o o , w e r e f o u n d more s t a b l e t h a n w e r e f e r r i c f l u o r i d e c o m p l e x e s . W a t a n a b e e t a l . ( 1 9 6 5 ) r e p o r t e d t h a t w i t h t h e B r a y P - l m e t h o d a s o u r c e o f e r r o r a p p e a r s t o be a s s o c i a t e d w i t h o r g a n i c m a t t e r w h i c h i n c r e a -s e s t h e c o l o u r i n t e n s i t y o f t h e a q u e o u s s o l u t i o n ( e x t r a c t a b l e P was d e t e r -m i n e d c o l o r i m e t r i c a l l y ) . The l o w s o i l : s o l u t i o n r a t i o o f t h e e x t r a c t i o n p r o c e d u r e c o u l d i n c r e a s e t h e i n t e r f e r e n c e o f o t h e r e l e m e n t s s u c h a s i r o n . - 7 -The v e r y s h o r t e x t r a c t i o n t i m e (1 m i n u t e ) g i v e n f o r t h i s m e t h o d may be t o o s h o r t f o r good s o l u t i o n - s o i l c o n t a c t , i n t h e c a s e o f h y d r o p h o b i c s o i l s a m p l e s . O l s e n b i c a r b o n a t e m e t h o d The O l s e n m e t h o d o f p h o s p h o r u s e x t r a c t i o n ( O l s e n e t a l . 1 9 5 4 ) e m p l o y s a 0 . 5 M s o d i u m b i c a r b o n a t e s o l u t i o n a d j u s t e d w i t h s o d i u m h y d r o x i d e t o a pH o f e x a c t l y 8 . 5 . A s a m p l e o f s o i l i n t h e r a t i o o f s o i l : s o l u t i o n o f 1 : 2 0 , i s s h a k e n f o r 3 0 m i n u t e s . T h i s m e t h o d was p r i m a r i l y d e s i g n e d f o r u s e i n c a l c a r e o u s s o i l s b u t i t has s i n c e b e e n u s e d f o r b o t h a c i d a n d c a l c a r e o u s s o i l s . T h e m a i n e f f e c t o f t h e b i c a r b o n a t e o r c a r b o n a t e i n c a l c a r e o u s 2 + s o i l s i s t o d e c r e a s e t h e Ca a c t i v i t y , w h i c h i n t u r n i n c r e a s e s t h e s o l u -b i l i t y o f p h o s p h o r u s . The m a i n e f f e c t o f t h e b i c a r b o n a t e on a c i d a n d n e u t r a l s o i l s p r o b a b l y w o u l d be t h r o u g h i o n i c c o m p e t i t i o n o f HCO3", CO3 and 0H~ i o n s f o r p h o s p h a t e a d s o r b e d on t h e s u r f a c e o f s o i l p a r t i c l e s . K u r t z e t a l . ( 1 9 4 6 ) f o u n d t h a t t h e r e p l a c i n g a b i l i t y o f HC03~ f o r p h o s -p h a t e was g r e a t e r t h a n t h e r e p l a c i n g a b i l i t y o f a c e t a t e o r s u l p h a t e i o n s o n a c i d s o i l s . C h a i a n d C a l d w e l l ( 1 9 5 9 ) f o u n d t h a t t h e N a H C 0 3 m e t h o d g a v e a h i g h e r c o r r e l a t i o n w i t h i r o n a n d a l u m i n u m p h o s p h a t e s t h a n a c i d i c e x t r a c t i n g s o l u t i o n s , s u g g e s t i n g t h a t t h e b a s i c n a t u r e o f t h e s o l v e n t f a v o u r e d t h e e x t r a c t i o n o f i r o n a n d a l u m i n u m p h o s p h a t e s . I n a c i d i c s o i l s c o n t a i n i n g i r o n a n d a l u m i n u m p h o s p h a t e s , p h o s p h o r u s i s r e l e a s e d a s t h e pH r i s e s ( O l s e n e t a l . 1 9 5 4 ) . B i n g h a m ( 1 9 6 6 ) r e p o r t e d t h e d r a w b a c k o f t h e m e t h o d was t h a t s o d i u m b i c a r b o n a t e s o l u b i l i z e s o r g a n i c m a t t e r f r o m s o d i c s o i l s a n d s o i l s h i g h i n o r g a n i c m a t t e r may p r e s e n t a c o l o u r p r o b l e m . T h e c h a r c o a l o r c a r b o n - b l a c k u s e d f o r a b s o r b i n g t h e c o l o u r e d o r g a n i c m a t e r i a l s a l s o r e l e a s e s o r a b s o r b s some p h o s p h o r u s . - 8 -T r u o g m e t h o d T r u o g ( 1 9 3 0 ) p r o p o s e d t h e u s e o f weak a c i d a s an e x t r a c t a n t o f a v a i l a b l e p h o s p h o r u s . T h e e x t r a c t i n g s o l u t i o n i s 0 . 0 0 2 N H2S0^ b u f f e r e d by a d d i n g 3 g o f p o t a s s i u m o r ammonium s u l p h a t e p e r l i t r e so a s t o p r o d u c e a pH o f a b o u t 3 . 0 . T h e s o i l t o e x t r a c t i n g s o l u t i o n r a t i o i s 1 : 2 0 0 a n d s h a k i n g t i m e i s 30 m i n u t e s . T h i s l o w r a t i o o f s o i l t o e x t r a c t i n g s o l u -t i o n i s s u g g e s t e d t o l e s s e n t h e r e f i x a t i o n o f d i s s o l v e d p h o s p h o r u s w h i c h may o c c u r w i t h h i g h i o n c o n c e n t r a t i o n . S h e r r e l l ( 1 9 7 0 ) m e n t i o n e d t h a t t h e l a r g e amount o f e x t r a c t a n t n e c e s s a r y becomes a d i s a d v a n t a g e w i t h a l a r g e number o f s o i l s a m p l e s . M e h l i c h m e t h o d T h e M e h l i c h m e t h o d i s a m o d i f i c a t i o n o f t h a t d e v e l o p e d i n N o r t h C a r o l i n a by N e l s o n e t a l . ( 1 9 5 3 ) t o e x t r a c t p h o s p h o r u s f r o m some N o r t h C a r o l i n a s o i l s w h i c h f i x p h o s p h a t e s t r o n g l y . T h e m e t h o d was i n t r o d u c e d by N o r t h C a r o l i n a s o i l s c i e n t i s t s i n t o p a r t s o f S o u t h A m e r i c a , a n d was i n t r o d u c e d i n t o Kenya by M e h l i c h when w o r k i n g a t t h e N a t i o n a l A g r i c u l t u r a l L a b o r a t o r i e s , N a i r o b i . T h e e x t r a c t a n t i s a g e n e r a l - p u r p o s e o n e d e s i g n e d t o e x t r a c t a number o f n u t r i e n t e l e m e n t s i n a s i n g l e s h a k i n g , so t h a t e x -t r a c t a b l e P , C a , M g , N a , K a n d Mn c a n be d e t e r m i n e d . , T h e e x t r a c t i n g s o l u t i o n recommended by M e h l i c h f o r u s e i n Kenya i s a m i x t u r e o f 0 . 1 N HC1 and 0 . 0 2 5 N H 2 S ( V ' ( t h a t u s e d i n N o r t h C a r o l i n a i s 0 . 0 5 N HC1 a n d 0 . 0 2 5 N H 2 S 0 4 ) . I t has b e e n f o u n d ( N e l s o n e t a l . 1 9 5 3 ) t h a t m i x e d a c i d s a r e more e f f e c t i v e t h a n HC1 a l o n e a s a p h o s p h o r u s e x t r a c -t a n t f o r s o i l s f i x i n g p h o s p h o r u s a s i r o n and a l u m i n u m p h o s p h a t e s . The s o i l : s o l u t i o n r a t i o u s e d i s 1 : 5 , w i t h a s h a k i n g t i m e o f 10 m i n u t e s . P h o s p h o r u s - f r e e c a r b o n b l a c k o r c h a r c o a l i s u s e d t o a b s o r b t h e c o l o u r e d c o n s t i t u e n t s . - 9 -A c o m p a r i s o n o f a l l t h e m e t h o d s d e s c r i b e d a b o v e shows t h a t no o n e e x t r a c t i o n c a n be e x p e c t e d t o p r o d u c e r e s u l t s c o r r e l a t i n g w e l l w i t h a v a i l a b l e p h o s p h o r u s u n d e r a l l c o n d i t i o n s . B i s h o p and B a r b e r ( 1 9 5 8 ) r e p o r t e d t h a t s o l u b i l i t y c u r v e s o f c a l c i u m p h y t a t e a n d o t h e r o r g a n i c p h o s -p h o r u s compounds i n d i c a t e d t h e y a r e p a r t i a l l y a c i d - s o l u b l e , s u g g e s t i n g t h a t an a c i d e x t r a c t c o n t a i n s some p h o s p h o r u s f r o m o r g a n i c s o u r c e s . The d i f f e r e n t p r o c e d u r e s f o r e s t i m a t i n g a v a i l a b l e p h o s p h o r u s a r e b e s t c o m p a r e d a n d t h e i r r e l a t i v e e f f i c i e n c y j u d g e d by t h e d e g r e e o f c o r r e l a t i o n o b t a i n e d w i t h p h o s p h o r u s u p t a k e by p l a n t s . S o i l t e s t s u s e d i n s o i l - p l a n t r e l a t i o n s h i p s t u d i e s a r e u s u a l l y t h o s e d e v e l o p e d f o r a g r o n o m i c c r o p s and o n l y i n a f e w c a s e s h a v e t h e y been e v a l u a t e d f o r t r e e s . I n many a g r o n o m i c s t u d i e s t h e r e s u l t s o f t h e e x t r a c t i o n m e t h o d s w e r e w e l l c o r r e l a t e d , a l t h o u g h t h e amount o f p h o s p h o r u s e x t r a c t e d by t h e d i f f e r e n t m e t h o d s v a r i e d . P a c k a n d Gomez ( 1 9 5 6 ) f o u n d t h a t many e x t r a c t i o n m e t h o d s w e r e s i g n i f i c a n t l y r e l a t e d t o f o l i a g e - P l e v e l s o f c o t t o n and a l f a l f a i n s o i l s v a r y i n g i n t e x t u r e and p H . Humphreys and P r i t c h e t t ( 1 9 7 2 ) f o u n d many e x t r a c t i o n m e t h o d s w e r e s i g n i f i c a n t l y r e -l a t e d t o f o l i a g e - P l e v e l s i n P i n u s e l l i o t t i i ' ( s l a s h p i n e ) g r o w n i n a c i d , p o d z o l i c s o i l s . V o i g t ( 1 9 6 6 ) f o u n d t h e same when he c o m p a r e d T r u o g and B r a y P - l m e t h o d s w i t h y o u n g P i n u s r i g i d a ( p i t c h p i n e ) g r o w n i n an i n f e r -t i l e , s a n d y s o i l . D i f f e r e n c e s , h o w e v e r , h a v e b e e n e n c o u n t e r e d i n c o m p a r i s o n s o f P u p t a k e by p l a n t s a n d s o i l t e s t s f o r a v a i l a b l e p h o s p h o r u s . H a u s e r ( 1 9 7 3 ) r e p o r t e d a b e t t e r c o r r e l a t i o n o f t h e O l s e n m e t h o d w i t h p l a n t u p t a k e f r o m s e v e r a l t r i a l s . The O l s e n m e t h o d was f o u n d u s e f u l f o r b o t h a c i d a n d a l k a l i n e s o i l s i n b o t h t r o p i c a l a n d t e m p e r a t e c l i m a t e s . I t a l s o p e r f o r m e d s a t i s -f a c t o r i l y f o r p a d d y s o i l s . W e l l s ( 1 9 6 5 ) f o u n d a h i g h l y s i g n i f i c a n t - 10 -c o r r e l a t i o n b e t w e e n t h e amount o f p h o s p h o r u s e x t r a c t e d f r o m Ap a n d B 2 h o r i z o n s by t h e T r u o g m e t h o d and t h e u p t a k e o f P by P i n u s t a e d a ( l o b l o l l y p i n e ) i n S o u t h C a r o l i n a . K a d e b a a n d B o y l e ( 1 9 7 8 ) , w h i l e e v a l u a t i n g p h o s -p h o r u s i n f o r e s t s o i l s i n W i s c o n s i n , f o u n d t h a t t h e B r a y m e t h o d e x t r a c t e d t h e h i g h e s t amount o f P , e x c e p t i n some f i n e - t e x t u r e d s o i l s h a v i n g pH a b o v e 6 . H o w e v e r , t h e T r u o g m e t h o d had a b e t t e r (more s i g n i f i c a n t ) c o r r e l a t i o n w i t h p h o s p h o r u s u p t a k e by P i n u s r e s i n o s a ( r e d p i n e ) i n t h e g r e e n h o u s e . P r i t c h e t t a n d L l e w e l l y n ( 1 9 6 6 ) r e p o r t e d d i f f e r e n t r e s u l t s . T h e y f o u n d t h a t t h e B r a y m e t h o d c o r r e l a t e d b e t t e r w i t h P u p t a k e by P i n u s e l l i o t t i i ( s l a s h p i n e ) i n s a n d y s o i l s o f pH 4 . 5 t o 5 . 5 . I n a number o f c a s e s , s o i l s w h i c h g i v e a p o o r c o r r e l a t i o n a r e h i g h i n e x t r a c t a b l e p h o s p h o r u s and show l i t t l e o r no r e s p o n s e t o p h o s p h a t e a p p l i c a t i o n ( A n d e r s o n 1 9 6 0 ) . - 11 -MATERIALS AND METHODS 1 . S o i l M a t e r i a l s T h r e e s o i l m a t e r i a l s , B f , A h , a n d a m i x e d f o r e s t f l o o r ( L , F , a n d H) h o r i z o n m a t e r i a l f r o m a p o d z o l a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a R e s e a r c h F o r e s t a t Haney w e r e u s e d . T h e p a r e n t m a t e r i a l a t t h e c o l l e c t i o n s i t e i s g l a c i a l d r i f t d e r i v e d p r e d o m i n a n t l y f r o m a c i d i g n e o u s r o c k s , b u t a l s o c o n t a i n i n g some v o l c a n i c a n d n o n - c a l c a r e o u s s e d i m e n t a r y r o c k f r a g m e n t s ( O t c h e r e - B o a t e n g a n d B a l l a r d 1 9 7 8 ) . The p a r e n t m a t e r i a l s a r e w e l l - d r a i n e d s a n d y l o a m t o l o a m y s a n d , a n d t h e f o r e s t f l o o r i s a 1 9 -c m - t h i c k m o r . The s a m p l e s w e r e p a r t i a l l y a i r - d r i e d and t h e n s i e v e d t h r o u g h 0 . 5 cm mesh a n d s t o r e d i n p l a s t i c c a n s . S o i l m o i s t u r e c o n t e n t , pH a n d o t h e r p r o p e r t i e s w e r e d e t e r m i n e d a f t e r a i r - d r y i n g a n d s i e v i n g . T h e r e -s u l t s a r e shown i n T a b l e 1 . 2 . P h o s p h o r u s E x t r a c t i o n a n d A n a l y s i s F i v e m e t h o d s w e r e u s e d f o r t h e e x t r a c t i o n o f a v a i l a b l e p h o s p h o r u s f r o m s o i l s . W i t h a l l e x t r a c t i o n m e t h o d s , P was d e t e r m i n e d c o l o r i m e t r i c a l l y a t 700 nm, a f t e r t r e a t m e n t o f t h e e x t r a c t w i t h ammonium m o l y b d a t e a n d r e -d u c t i o n w i t h a s c o r b i c a c i d t o f o r m t h e b l u e c o m p l e x ( W a t a n a b e a n d O l s e n 1 9 6 5 ) . a ) . B r a y P - l M e t h o d To 2 . 8 5 g ofc2mm s o i l i n a 125 ml e x t r a c t i o n b o t t l e was a d d e d 2 0 . 0 ml o f t h e e x t r a c t i n g s o l u t i o n ( 0 . 0 3 N NH^F, 0 . 0 2 5 4 N H C I ) a n d t h e m i x -t u r e was s h a k e n f o r one m i n u t e . T h e s o i l was f i l t e r e d i m m e d i a t e l y a f t e r s h a k i n g , u s i n g m o i s t Whatman No. 4 2 f i l t e r p a p e r . b) . M o d i f i e d B r a y P - l M e t h o d Due t o t h e h y d r o p h o b i c ! ' t y o f some a i r - d r y s o i l s , e . g . some Ah - 12 -T a b l e 1 . Some p r o p e r t i e s o f t h e t h r e e s o i l m a t e r i a l s b e f o r e s e e d l i n g g r o w t h . _ _ _ _ _ _ _ _ S o i l M a t e r i a l E x c h a n g e a b l e C a t i o n s 9 K j e l d a h l E x t r a c t a b l e Na K Ca Mg C E C b N m e / l O O g - % ppm B f 0 . 0 5 5 0 . 1 0 0 . 1 7 0 . 0 5 2 4 . 5 0 . 0 7 4 . 6 4 . 8 Ah 0 . 0 8 5 0 . 2 5 0 . 5 7 0 . 2 0 4 3 . 0 0 . 4 4 1 3 . 7 4 . 5 LFH 1 . 1 2 1 . 5 9 1 6 . 4 9 2 . 5 8 1 1 8 . 8 1 . 0 3 6 8 . 9 3 . 9 a , by e x c h a n g e w i t h 1 . 0 N KC1 f o r N a , C a , and M g , a n d 1 . 0 N NaCL f o r K. b , by s a t u r a t i o n w i t h 1 . 0 N K C 1 , w a s h i n g w i t h i s o p r o p y l - a l c o h o l , a n d d e -s o r p t i o n w i t h 1 . 0 N N a C l . c , P by O l s e n 1 s ( 0 . 5 M NaHCOs) e x t r a c t i o n m e t h o d . d , pH m e a s u r e d i n 1 : 2 s o i l : H 2 0 f o r t h e m i n e r a l h o r i z o n m a t e r i a l , a n d 1 : 5 ; s 6 i l : H 2 0 f o r t h e o r g a n i c h o r i z o n m a t e r i a l . - 13 -and L - F - H m a t e r i a l s , t h e o n e - m i n u t e e x t r a c t i o n o f t h e B r a y P - l m e t h o d d o e s n o t e n a b l e c o m p l e t e w e t t i n g o f t h e s o i l s a m p l e . T h e r e f o r e , t h e B r a y P - l m e t h o d was m o d i f i e d a s f o l l o w s : 10 ml d i s t i l l e d w a t e r was a d d e d t o 2 . 8 5 g o f s o i l i n an e x t r a c t i o n b o t t l e , a n d t h e s a m p l e was a l l o w e d t o s t a n d o v e r -n i g h t . T h e n 10 ml o f 0 . 0 6 N NH^F s o l u t i o n i n 0 . 0 5 N HCL was a d d e d a n d t h e m i x t u r e was s h a k e n f o r o n e m i n u t e , and f i l t e r e d f o r a n a l y s i s . c ) O l s e n B i c a r b o n a t e E x t r a c t i o n M e t h o d T h e m e t h o d o f O l s e n e t a l . ( 1 9 5 4 ) was u s e d . To 5 . 0 g o f s o i l was a d d e d a b o u t 1 t e a s p o o n f u l o f R e a g e n t G r a d e P - f r e e c h a r c o a l a n d 100 ml o f t h e e x t r a c t i n g s o l u t i o n ( 0 . 5 M NaHC0 3 a d j u s t e d t o pH 8 . 5 u s i n g IN NaOH s o l u t i o n ) . T h e c o n t a i n e r s w e r e s h a k e n f o r 30 m i n u t e s w i t h a m e c h a n i c a l s h a k e r and t h e s u s p e n s i o n was f i l t e r e d t h r o u g h t h e Whatman N o . 42 f i l t e r p a p e r s h a k i n g i m m e d i a t e l y b e f o r e p o u r i n g t h e s u s p e n s i o n i n t o a B u c h n e r f u n n e l f o r f i l t r a t i o n a n d s u b s e q u e n t a n a l y s i s . d) M e h l i c h D o u b l e - A c i d M e t h o d T h e m e t h o d o f M e h l i c h e t a l . ( 1 9 5 3 ) was a d o p t e d w i t h t h e m o d i -f i c a t i o n s u s e d by t h e S o i l S c i e n c e D i v i s i o n , U n i v e r s i t y o f N a i r o b i , K e n y a . The e x t r a c t i n g s o l u t i o n i s 0.1N HCL a n d 0 . 0 2 5 N H 2 S0i f . To 5 g s o i l i n an e x t r a c t i n g b o t t l e was a d d e d a b o u t 2 0 0 mg P - f r e e c h a r c o a l a n d 25ml e x t r a c t i n g s o l u t i o n . The s u s p e n s i o n was m i x e d w e l l a n d a l l o w e d t o s t a n d f o r o n e h o u r . T h e s u s p e n s i o n was t h e n s h a k e n f o r 10 m i n -u t e s , a n d f i l t e r e d u s i n g Whatman N o . 42 f i l t e r p a p e r . e ) T r u o g M e t h o d The m e t h o d o f T r u o g ( 1 9 3 0 ) was u s e d w i t h some m o d i f i c a t i o n s . To 0 . 5 g o f s o i l i n an e x t r a c t i n g b o t t l e was a d d e d 100 ml e x t r a c -t i n g s o l u t i o n ( 0 . 0 0 2 N H2S0tt c o n t a i n i n g 3 g o f K 2 S O 4 p e r l i t r e ) . T h e m i x -t u r e was s h a k e n i n a m e c h a n i c a l s h a k e r f o r 30 m i n u t e s , b e f o r e f i l t r a t i o n f o r a n a l y s i s . - 14 -3 . I r o n a n d A l u m i n u m P h o s p h a t e P r e p a r a t i o n I r o n a n d a l u m i n u m p h o s p h a t e s w e r e p r e p a r e d . F e - p h o s p h a t e was p r e p a r e d u s i n g t h e m e t h o d o f C h a n g a n d J a c k s o n ( 1 9 5 7 ) m a i n t a i n i n g pH a t 3 . 2 d u r i n g t h e p r e c i p i t a t i o n p e r i o d . A l u m i n u m p h o s p h a t e was p r e p a r e d by t h e m e t h o d o f T a y l o r e t a l . ( 1 9 6 0 ) , w i t h t h e m o d i f i c a t i o n t h a t A 1 C 1 3 - 6 H 2 0 was d i s s o l v e d i n N a h ^ P O ^ , a s i n t h e m e t h o d o f C h a n g and J a c k s o n ( 1 9 5 7 ) . T h e pH was m a i n t a i n e d a t 3 . 2 d u r i n g p r e c i p i t a t i o n . X - r a y d i f f r a c t i o n a n a l y s i s showed t h a t t h e i r o n p h o s p h a t e was c r y s t a l l i n e w i t h a s u g g e s t e d f o r m u l a o f FePO^. 2 H 2 0 . F u r t h e r a n a l y s i s showed t h a t t h e compound c o n t a i n e d 1 6 . 4 1 % P , w h i c h c o m p a r e d c l o s e l y w i t h t h e 1 6 . 5 % f o u n d by C h a n g a n d J a c k s o n ( 1 9 5 7 ) . X - r a y d i f f r a c t i o n a n a l y s i s showed t h a t t h e a l u m i n u m p h o s p h a t e was c o l l o i d a l a n d a m o r p h o u s . C h e m i c a l a n a l y s i s s h o w e d t h a t t h e compound c o n t a i n e d 1 6 . 0 5 % . P . F i g u r e s 1 and 2 show t h e x - r a y d i f f r a c t i o n a n a l y s i s o f t h e two p h o s p h a t e c o m p o u n d s . 4 . P r e l i m i n a r y S t u d y : S o i l I n c u b a t i o n To d e t e r m i n e e x t r a c t a b i l i t y o f Fe and A l - p h o s p h a t e s a f t e r t h e y h a v e been a d d e d t o s o i l a n d i n c u b a t e d o v e r a p e r i o d o f t i m e , s o i l i n c u b a -t i o n e x p e r i m e n t s w e r e c a r r i e d o u t . To B f and Ah m a t e r i a l s , p h o s p h a t e s w e r e a d d e d i n t h e f o r m o f i r o n a n d a l u m i n u m p h o s p h a t e s d e s c r i b e d a b o v e . To t h e m i x e d L - F - H m a t e r i a l , p h o s p h a t e was a d d e d i n t h e f o r m o f s o l i d KH2P0i+. The a d d e d p h o s p h a t e s a n d s o i l w e r e m i x e d w e l l a n d w e i g h e d i n t o p l a s t i c p o t s . I n c u b a t i o n was c a r r i e d o u t i n t h e g r e e n h o u s e . D u r i n g t h e i n c u -b a t i o n p e r i o d , s o i l m o i s t u r e c o n t e n t was m a i n t a i n e d n e a r f i e l d c a p a c i t y by d a i l y a d d i n g e n o u g h d i s t i l l e d w a t e r t o r e s t o r e t h e i n i t i a l w e i g h t o f t h e s o i l . T e m p e r a t u r e was m a i n t a i n e d b e t w e e n 25 a n d 2 7 ° C . A f t e r 16 d a y s ' - 15 -i n c u b a t i o n , t h e s o i l m a t e r i a l s w e r e r e m o v e d f r o m t h e p o t s , a i r - d r i e d a n d s t o r e d b e f o r e a n a l y s i s o f e x t r a c t a b l e A l , F e , and P . 5 . A l , F e , and P E x t r a c t i o n a n d A n a l y s i s S o i l s w e r e a i r - d r i e d a n d s i e v e d t h r o u g h 100 mesh ( 0 . 1 4 9 mm s i e v e ) a s recommended by M c K e a g u e a n d Day ( 1 9 6 6 ) . A l a n d Fe w e r e e x t r a c -t e d by s o d i u m p y r o p h o s p h a t e and a c i d ammonium o x a l a t e e x t r a c t i o n s o l u t i o n s as d e s c r i b e d by McKeague ( 1 9 6 7 ) . a n d M c K e a g u e and Day ( 1 9 6 6 ) . A l a n d Fe w e r e d e t e r m i n e d u s i n g an a t o m i c a b s o r p t i o n s p e c t r o p h o t o m e t e r . F o r a v a i l -a b l e p h o s p h o r u s e x t r a c t i o n , t h e s o d i u m b i c a r b o n a t e m e t h o d o f O l s e n e t a l . ( 1 9 5 4 ) was u s e d . 6 . S e e d - b e d P r e p a r a t i o n a n d S e e d S o w i n g S e e d s w e r e f i r s t sown i n a s e e d b e d w h i c h c o n t a i n e d a l l t h e t h r e e s o i l m a t e r i a l s u s e d i n t h i s e x p e r i m e n t . I n c l u s i o n o f t h e f o r e s t f l o o r ma-t e r i a l was c o n s i d e r e d n e c e s s a r y t o e n s u r e s e e d l i n g i n o c u l a t i o n by m y c o r r h i z a -f o r m i n g f u n g i . T h i s m e t h o d o f m y c o r r h i z a l i n o c u l a t i o n o f c o n i f e r s e e d l i n g s has b e e n s u c c e s s f u l i n E a s t A f r i c a a n d h a s b e e n e x t e n s i v e l y u s e d e l s e w h e r e . To i n c r e a s e t h e g e r m i n a t i o n p e r c e n t o f t h e s e e d s , t h e s e e d s w e r e p r e t r e a t e d b e f o r e s o w i n g i n t o t h e s e e d - b e d . P i n u s p a t u l a a n d C u p r e s s u s  l u s i t a n i c a s e e d s w e r e s o a k e d i n c o l d w a t e r f o r 8 d a y s and 10 m i n u t e s , r e s -p e c t i v e l y . F l o a t i n g s e e d s w e r e d i s c a r d e d . The p r e t r e a t e d s e e d s w e r e sown i n r o w s , e a c h s p e c i e s i n o n e o f t h e s e e d - b e d s . Enough w a t e r was a d d e d i n f o r m o f s h o w e r s . G r o w t h i n t h e s e e d - b e d t o o k 50 d a y s , d u r i n g w h i c h p e r i o d u s u a l w a t e r i n g was c a r r i e d o u t . ( I t was n e c e s s a r y t o k e e p t h e s e e d l i n g s i n t h e s e e d - b e d l o n g e n o u g h f o r m y c o r r h i z a l i n f e c t i o n , b u t n o t so l o n g a s t o h a v e s i g n i f i c a n t p h o s p h o r u s u p t a k e . ) - 16 -7. S o i l P o t t i n g a n d S e e d l i n g T r a n s p l a n t i n g T h e s o i l m a t e r i a l s w e r e w e i g h e d o u t s e p a r a t e l y i n t h r e e s e t s . To t h e B f and Ah s o i l m a t e r i a l s , known a m o u n t s o f p h o s p h o r u s w e r e a d d e d i n t h e f o r m o f i r o n a n d a l u m i n u m p h o s p h a t e s , and s o l i d K H 2 P O 4 was a d d e d t o t h e L - F - H m a t e r i a l . T h r e e p h o s p h a t e l e v e l s ( 0 , 2 0 , a n d 200 ppm P f o r B f a n d A h ; a n d 0 , 2 0 , and 100 ppm P f o r L - F - H ) w e r e r e p l i c a t e d f i v e t i m e s f o r e a c h p l a n t s p e c i e s . The p h o s p h a t e s w e r e m i x e d t h o r o u g h l y w i t h t h e s o i l m a t e r i a l s . The m i x t u r e s w e r e t h e n w e i g h e d o u t i n t o p l a s t i c p o t s ( 7 . 5 cm x 7 . 5 cm x 6 . 5 c m ) . The w e i g h t s o f t h e m i x t u r e p e r p o t w e r e B f , 200 g ; A h , 120 g ; and L - F - H , 40 g . T h e s e w e i g h t s w e r e c h o s e n b e c a u s e o f t h e d i f f e r e n c e s i n b u l k d e n s i t y o f t h e t h r e e s o i l m a t e r i a l s . Ah and L - F - H s o i l m a t e r i a l s showed some h y d r o p h o b i c p r o p e r t i e s . To o v e r c o m e t h i s , t h e s o i l m a t e r i a l s w e r e s o a k e d i n d i s t i l l e d w a t e r o v e r -n i g h t b e f o r e t r a n s p l a n t i n g t e s t s e e d l i n g s . Two s e e d l i n g s w e r e t r a n s p l a n t e d i n e a c h p o t and t h e p o t s a r r a n -ged r a n d o m l y o n a b e n c h . The e x p e r i m e n t a l d e s i g n a m o u n t e d t o 3 s o i l m a t e r i a l s x 3 P l e v e l s x 2 s p e c i e s x 5 r e p l i c a t e s , f o r a t o t a l o f 90 p o t s . A l l s u b s e q u e n t w a t e r i n g was d o n e e v e r y o t h e r d a y , a d d i n g j u s t e n o u g h w a t e r t o make s u r e t h a t no l e a c h i n g t o o k p l a c e . F o r a d d i t i o n o f e s s e n t i a l p l a n t n u t r i e n t e l e m e n t s , H o a g l a n d ' s s o l u t i o n m i n u s p h o s p h o r u s was p r e p a r e d ( H o a g l a n d a n d A r n o n 1 9 5 0 ) , s t o r e d i n p l a s t i c b o t t l e s , a n d d i l u t e d and a d d e d t o t h e s e e d l i n g s when n e c e s s a r y . A l t e r n a t i n g p e r i o d s o f t w e l v e h o u r s o f l i g h t a n d t w e l v e h o u r s o f d a r k n e s s w e r e m a i n t a i n e d d u r i n g t h e g r o w i n g p e r i o d by u s e o f s u p p l e m e n -t a r y ^ h i t e f l u o r e s c e n t ) l i g h t s . T h e t e m p e r a t u r e o f t h e g r e e n h o u s e was u s u a l l y b e t w e e n 25 a n d 2 7 ° C . T h e p o t s w e r e moved r a n d o m l y t o a v o i d b e n c h e f f e c t s . - 17 -The g r e e n h o u s e g r o w t h p e r i o d was t e r m i n a t e d a f t e r 178 d a y s . B e -f o r e p l a n t s w e r e r e m o v e d f r o m t h e g r e e n h o u s e , f i v e c o n s e c u t i v e h e i g h t m e a s u r e m e n t s a n d o n e d i a m e t e r m e a s u r e m e n t w e r e d o n e . V i s u a l symptoms o f c o l o u r , d e f o r m i t i e s , f o r m a n d g r o w t h o f f u n g i (on t h e s o i l s u r f a c e ) w e r e a l s o r e c o r d e d . The s e e d l i n g s w e r e r e m o v e d f r o m t h e s o i l m a t e r i a l s , r o o t s w e r e s e p a r a t e d f r o m s t e m a n d f o l i a g e , a n d a l l p a r t s w e r e o v e n - d r i e d a t 6 5 ° C f o r 36 h o u r s . T h e i r m a s s e s w e r e d e t e r m i n e d a n d f o l i a g e was s e p a r a t e d f r o m s t e m s a n d w e i g h e d . The f o l i a g e was g r o u n d u s i n g p e s t l e a n d m o r t a r ; s t e m and r o o t s w e r e g r o u n d i n a b l e n d e r , and t h e s a m p l e s w e r e s t o r e d f o r f u t u r e a n a l y s i s . S o i l m a t e r i a l s w e r e a i r - d r i e d , p a s s e d t h r o u g h 2-mm s i e v e s , a n d s t o r e d f o r f u t u r e a n a l y s i s . 8 . M a t e r i a l s , D i g e s t i o n , a n d A n a l y s i s P r e p a r a t i o n o f p l a n t m a t e r i a l s f o r a n a l y s i s h a s a l r e a d y b e e n d i s c u s s e d . S i n c e t h e w e i g h t s o f t h e s e p a r a t e d p l a n t m a t e r i a l p a r t s w e r e l o w , t h r e e p l a n t m a t e r i a l d i g e s t i o n m e t h o d s w e r e t r i e d on some o t h e r p l a n t m a -t e r i a l s a m p l e s . T h r e e m e t h o d s w e r e t r i e d t o t e s t f o r t h e more a p p r o p r i a t e m e t h o d t o be u s e d on t h e e x p e r i m e n t a l s a m p l e s . The m e t h o d s t r i e d w e r e d r y - a s h i n g m e t h o d o f Chapman a n d P r a t t ( 1 9 6 1 ) ; s e l e n i u m - s u l p h a t e a c i d d i -g e s t i o n o f H u t t o n and Nye ( 1 9 5 8 ) ; a n d C a r o ' s a c i d d i g e s t i o n o f L i n d n e r a n d H a r l e y ( 1 9 4 2 ) . F o r t h e s e l e n i u m - s u l p h u r i c a c i d a n d C a r o ' s a c i d m e t h o d s , d i g e s t i o n was c a r r i e d o u t i n d i g e s t t u b e s u s i n g a T e c h n i c o n B l o c k D i g e s t o r . Of t h e t h r e e m e t h o d s t r i e d , C a r o ' s m e t h o d was f o u n d m o s t a p p r o -p r i a t e . I t g a v e c o m p l e t e d i g e s t i o n o f t h e p l a n t t i s s u e s , g a v e a f a s t e r d i g e s t f i l t e r i n g r a t e ( s i n c e t h e r e w e r e a l m o s t no s o l i d p a r t i c l e s s u c h a s - 18 -t h o s e f o u n d i n t h e s e l e n i u m - a c i d d i g e s t ) a n d t h e ammonium m o l y b d a t e - a s c o r -b i c a c i d m e t h o d c o u l d be u s e d f o r P d e t e r m i n a t i o n c o l o r i m e t r i c a l l y . I t was l e s s t i m e - c o n s u m i n g t h a n d r y a s h i n g . P r o b l e m s w e r e e n c o u n t e r e d w i t h P d e t e r m i n a t i o n when s e l e n i u i r H a c i d d i g e s t was u s e d , b e c a u s e a y e l l o w -b r o w n c o l o u r was f o r m e d w i t h ammonium m o l y b d a t e a n d a s c o r b i c a c i d . T h e C a r o ' s a c i d m e t h o d i s t h e o n l y o n e d e s c r i b e d h e r e , s i n c e i t was u s e d i n d i g e s t i o n o f a l l p l a n t m a t e r i a l s . 9. C a r o ' s A c i d D i g e s t i o n o f P l a n t T i s s u e P r e p a r a t i o n o f s a m p l e : 1) . A u n i f o r m s a m p l e was g r o u n d i n a m o r t a r t o p a s s a 20-mesh s c r e e n . 2) . T h e s a m p l e was d r i e d a t 70°C f o r a t l e a s t 8 h o u r s and vacuum d e s i c a -t e d f o r 1 h o u r . 3) . 0.1 g o f s a m p l e was w e i g h e d ( t o t h e n e a r e s t mg) i n t o d i g e s t t u b e s . 4) . U n d e r t h e h o o d , 10 ml c o n e . H2S0^ was a d d e d a n d m i x e d w e l l . 5) . S a m p l e t u b e s w e r e p l a c e d i n t o a d i g e s t o r b l o c k f o r 30 s e c o n d s ( f o r c h a r r i n g o f d r y s a m p l e s ) a n d t h e n w e r e r e m o v e d t o c o o l ( f o r a b o u t 1 m i n u t e ) . 6) . 10 ml o f 30% H202 was a d d e d i n s m a l l i n c r e m e n t s (2.5 ml a t a t i m e on t h e s i d e s o f t u b e s ) u s i n g a s p e c i a l l y p r e p a r e d d i s p e n s e r ( m o d i f i e d o x f o r d d i s p e n s e r ) t o a v o i d e x c e s s r e a c t i o n . 7) . T u b e s w e r e t h e n h e l d i n t h e b l o c k d i g e s t e r f o r 45 m i n u t e s a t 425°C. 8) . The t u b e s w e r e r e m o v e d a n d a l l o w e d t o c o o l (10-15 m i n u t e s ) . A b o u t 20 ml H20 was a d d e d t o e a c h t u b e a n d t h e s o l u t i o n s w e r e f i l t e r e d i n t o 50 ml v o l u m e t r i c f l a s k s a n d made t o v o l u m e w i t h d i s t i l l e d w a t e r . 9) . N e u t r a l i z a t i o n o f t h e H202/H2S0if d i g e s t s o l u t i o n f o r P d e t e r m i n a t i o n . S i n c e c o n c e n t r a t e d a c i d d i g e s t i s t o o a c i d , p a r t i a l n e u t r a l i z a -t i o n i s r e q u i r e d b e f o r e P d e t e r m i n a t i o n c o l o r i m e t r i c a l l y ( L i n d n e r and - 19 -H a r l e y 1 9 4 2 ) . NaOH s o l u t i o n was u s e d f o r t h i s p u r p o s e a n d t h e p r o c e d u r e was c a r r i e d o u t a s f o l l o w s : 2 . 5 ml o f t h e d i g e s t s o l u t i o n was p i p e t t e d i n t o a 25 ml v o l u m e t r i c f l a s k . 10 ml o f 2 . 5 N NaOH s o l u t i o n was a d d e d t o p a r t i a l l y n e u t r a l i z e t h e a c i d . T h e s o l u t i o n was made t o v o l u m e a n d t r a n s f e r r e d t o a p l a s t i c b o t t l e . The f i n a l pH was a b o u t 3 . 8 . - 20 -RESULTS AND DISCUSSION 1 . P r e l i m i n a r y S t u d y : E x t r a c t a b l e F e , A l , a n d P E x t r a c t a b l e F e , A l , a n d P d a t a f o r t h e t h r e e u n i n c u b a t e d s o i l m a t e r i a l s a r e g i v e n i n T a b l e 2 . S i m i l a r d a t a f o r i n c u b a t e d s o i l m a t e r i -a l s , w i t h a n d w i t h o u t a d d e d p h o s p h a t e s , a r e g i v e n i n T a b l e 3 . As e x p e c -t e d , b o t h t a b l e s show a t e n d e n c y f o r more Fe a n d A l t o be e x t r a c t e d by o x a l a t e t h a n by p y r o p h o s p h a t e . The f o r m e r t e n d s t o e x t r a c t b o t h o r g a n i c a n d a m o r p h o u s i n o r g a n i c f o r m s , a n d t h e l a t t e r t e n d s t o e x t r a c t o n l y o r g a n -i c f o r m s , b u t s u c h d i f f e r e n t i a t i o n i s more e x a c t f o r Fe t h a n f o r A l ( M c K e a g u e e t a l . 1 9 7 1 ) . B o t h s o l u t i o n s e x t r a c t e d more A l t h a n Fe f r o m t h e t h r e e s o i l m a t e r i a l s . P y r o p h o s p h a t e - e x t r a c t a b l e A l was l o w e s t i n t h e m i x e d L-F^H m a -t e r i a l . I n u n i n c u b a t e d s o i l , i t was h i g h e s t i n B f m a t e r i a l , a l t h o u g h v a l u e s f o r Ah a n d B f w e r e s i m i l a r i n i n c u b a t e d m a t e r i a l s . P y r o p h o s p h a t e -e x t r a c t a b l e Fe was h i g h e s t i n Ah and l o w e s t i n L - F - H m a t e r i a l . F o r i r o n , t h e d i f f e r e n c e b e t w e e n o x a l a t e - a n d p y r o p h o s p h a t e - e x t r a c t a b l e c o n c e n t r a -t i o n s was h i g h e s t i n t h e B f a n d l o w e s t i n t h e L - F - H . F o r a l u m i n u m , t h e same t r e n d was n o t e d , b u t t h e d i f f e r e n c e a m o u n t e d t o a b o u t z e r o f o r i n c u -b a t e d L - F - H s a m p l e s . T h e s e r e s u l t s s u g g e s t t h a t o r g a n i c Fe and A l c o m -p o u n d s may be m o r e c o n c e n t r a t e d i n t h e m i n e r a l t h a n t h e o r g a n i c s o i l m a t e r i a l s , and t h a t a m o r p h o u s i n o r g a n i c Fe and A l c o m p o u n d s a r e more a b u n -d a n t i n t h e m i n e r a l s o i l m a t e r i a l s , e s p e c i a l l y t h e B f . Where t h e s o i l m a t e r i a l s a r e u s e d f o r p o t t i n g s e e d l i n g s , t h e a b s o l u t e a m o u n t s o f o r g a n i c a n d a m o r p h o u s i n o r g a n i c Fe a n d A l c o m p o u n d s a r e a f f e c t e d by t h e r e l a t i v e b u l k d e n s i t y o f o r g a n i c a n d m i n e r a l s o i l m a t e r i a l s , a n d t h u s a r e much l o w e r f o r L - F - H t h a n f o r t h e Ah and B f m a t e r i a l s . E x t r a c t a b l e P was l o w e s t f o r B f a n d h i g h e s t f o r L - F - H m a t e r i a l . L a r g e a m o u n t s o f i r o n a n d a l u m i n u m p h o s p h a t e s a d d e d t o t h e Ah and B f T a b l e 2 . S o i l E x t r a c t a b l e A l , F e , a n d P b e f o r e i n c u b a t i o n . S o i l A l Fe P M a t e r i a l O x a l a t e P y r o p h o s p h a t e O x a l a t e P y r o p h o s p h a t e E x t r a c t a b l e by E x t r a c t a b l e E x t r a c t a b l e E x t r a c t a b l e E x t r a c t a b l e O l s e n ' s m e t h o d p e r c e n t ppm B f 5 . 9 0 1 . 5 3 1 . 2 1 0 . 3 3 4 . 4 Ah 2 . 8 6 1 . 1 7 0 . 9 9 0 . 5 4 1 3 . 7 L , F , H ( m i x e d ) 0 . 3 6 0 . 2 9 0 . 3 0 0 . 1 6 6 8 . 9 T a b l e 3 . S o i l E x t r a c t a b l e A l , Fe a n d P ( a v e r a g e s o f 3 r e p l i c a t e s ) a f t e r 16 d a y s i n c u b a t i o n a t 25 t o 2 7 ° C a n d a t f i e l d c a p a c i t y .  S o i l A l l_ Fe P M a t e r i a l O x a l a t e P y r o p h o s p h a t e O x a l a t e P y r o p h o s p h a t e E x t r a c t a b l e by E x t r a c t a b l e E x t r a c t a b l e E x t r a c t a b l e E x t r a c t a b l e O l s e n ' s m e t h o d p e r c e n t ppm B f C o n t r o l 6 . 3 0 1 . 4 5 +53ppm P a 6 . 1 2 1 . 4 7 +530ppmP a 6 . 0 3 1 . 4 6 Ah C o n t r o l 2 . 1 5 1 . 4 4 +53ppm P& 2 . 0 2 1 . 4 1 +530ppmP a 2 . 0 1 1 . 4 5 L , F , H ( m i x e d ) C o n t r o l . 0 . 3 0 0 . 3 2 +25ppm P? 0 . 3 1 0 . 3 5 +100ppmP D 0 . 3 1 0 . 3 4 1 . 2 3 0 . 2 9 4 . 8 . 1 . 2 0 0 . 2 9 5 . 0 1 . 2 3 0 . 3 7 6 . 0 0 . 9 5 0 . 6 4 1 2 . 8 0 . 9 5 0 . 6 3 1 3 . 6 0 . 9 9 0 . 6 5 1 7 . 2 0 . 3 2 0 . 1 2 7 4 . 8 0 . 2 2 0 . 1 5 7 2 . 6 0 . 2 3 0 . 1 5 1 2 1 . 2 a , a d d e d a s 1:1 a l u m i n u m p h o s p h a t e - P : i r o n p h o s p h a t e - P . b , a d d e d a s s o l i d p o t a s s i u m p h o s p h a t e . - 22 -m a t e r i a l s y i e l d e d o n l y s l i g h t i n c r e a s e s i n e x t r a c t a b l e P . S o l u b l e p h o s -p h a t e s a d d e d t o t h e L - F - H m a t e r i a l c a u s e d no c h a n g e i n e x t r a c t a b l e P w h e r e 25 ppm P was a d d e d , b u t c o n s i d e r a b l e c h a n g e w h e r e 100 ppm P was a d d e d . I n t h e l a t t e r c a s e , t h e i n c r e a s e o f e x t r a c t a b l e P was o n l y a b o u t 50 ppm, i n d i c a t i n g some n e t i m m o b i l i z a t i o n . The l e s s e r a d d i t i o n was a p -p a r e n t l y c o m p l e t e l y i m m o b i l i z e d d u r i n g t h e i n c u b a t i o n . The a d d i t i o n o f A l a n d Fe as p h o s p h a t e s i n t h e m i n e r a l s o i l s r e s u l t e d i n no o b v i o u s a n d c o n s i s t e n t c h a n g e s i n e x t r a c t a b l e Fe and A l c o n c e n t r a t i o n s . X - r a y d i f f r a c -t i o n p a t t e r n s i n d i c a t e t h a t t h e a d d e d i r o n p h o s p h a t e s ( F i g u r e 1) a n d a l u m i n u m p h o s p h a t e s ( F i g u r e 2) w e r e s u b s t a n t i a l l y c r y s t a l l i n e a n d a m o r -p h o u s , r e s p e c t i v e l y . The r e s u l t s o f t h i s s h o r t - t e r m i n c u b a t i o n a r e n o t n e c e s s a r i l y i n d i c a t i v e o f l o n g - t e r m e x t r a c t a b i l i t y . A c q u a y e ( 1 9 6 3 ) a n d E n w e z o r ( 1 9 6 6 ) f o u n d c h a n g e s i n e x t r a c t a b i l i t y w i t h l o n g i n c u b a t i o n t i m e s . F u j i w a r a ( 1 9 5 0 ) f o u n d t h a t c r y s t a l l i z a t i o n o f h y d r a t e d a m o r p h o u s i r o n and a l u m i n u m p h o s p h a t e s o c c u r r e d o v e r t i m e , a n d t h a t t h e a v a i l a b i l i t y o f c r y s t a l l i n e f o r m s was l o w e r . H o w e v e r , t h e s h o r t - t e r m i n c u b a t i o n s t u d y i n d i c a t e s t h a t t h e p h o s p h a t e f o r m s a d d e d t o t h e s e s o i l m a t e r i a l s c a n r e m a i n p a r t i a l l y e x t r a c t a b l e f o r some t i m e , s o t h a t c o m p a r i s o n s o f p h o s p h a t e u p t a k e w i t h e x t r a c t a b l e p h o s p h o r u s c o n c e n t r a t i o n s c a n be made f o r s o i l m a t e r i a l s t o w h i c h p h o s p h a t e s h a v e b e e n a d d e d , w h e r e t h e a d d e d p h o s p h a t e s r e s e m b l e n a -t i v e s o i l p h o s p h a t e s r a t h e r t h a n f e r t i l i z e r p h o s p h a t e s . T h u s , t h e u s e f u l -n e s s o f v a r i o u s s o i l t e s t m e t h o d s f o r e v a l u a t i n g a v a i l a b i l i t y o f n a t i v e s o i l p h o s p h a t e s c a n be a s c e r t a i n e d . 2 . S e e d l i n g g r o w t h T h e s e e d l i n g g r o w t h i n h e i g h t , d i a m e t e r , a n d mass i s shown i n T a b l e s 4 a n d 5 . W h i l e c y p r e s s w e r e t a l l e r t h a n p i n e s e e d l i n g s grown i n - 23 -- 24 -..' M P :M • I •;• I M M M : s : :•: • - i • • • ! 1 > M . ! i- ! M M i l 1 • r . M . i ' M| i j 1 "ill .. M MM' _.MM Mt M : M ! ! _ M J£T j ' j i ! M l i i i ! •: • 1 ; I : M r ; M ! i i I M i i \ Hi' r 1 J _ ; r 7v i ; ; i : M ' ; ] M M 1 M j i i \ I M •' i i j ! ! ! f | ! i '! i i |;j ; • I : i M : i . M 1 ! ! 1 : • i ' • , j , ' i • ! ; ! ' : i : | I i M i M M 1 I i • 1 : i • . ! I I i. i . i ' i 1 ! ! : i M N i 1 • i : MM ! ! 1 ! M M 1 i ! .! i i! i ! ! M j : IM i •i i M!: t i i I ! ' i j •11 M .11 i j j I 1 M i l mi j i . i j ! M M illi ! M i i . i i 1 1 i i M l j i . • ir ! 1 i i i '•I-i 1 St-i I i 1 1 ! i I j M 1 M M i l ! 1 i ' i ] M M M M !!! i i i i 1 1 ! i i I M ! i 1 . 1 • ! I i ir i i i ! i M i j M M I M | ! M I Mil M i 1 M M ; 11 M ill-• 1. I .i. 1 i I ! ; l • i in M M i ! M M t ! i < M ! ill j j i i • i 1 M 1 1 i ^ r l "I 1 1 i - i • | i • i i ! 1 ! ! 1 ; ! ! ! i M M Ml i l l i i i j | M ! j 1 • | i i „ b *\ M i I j j. ! i : . i i l i i i -i i M M M i t M M | 1 M j | | | !• i ! i I 1 ! i M M 1 i ' 1 " i.i M !•! M ' 1 i ; ' : i • 1 i • I • M M -; j j " •. ; i 1 , : ! M 1 i M ! M M MM' t i i - i i -liM • • M i ! M ! M M i ! i 1 * ' M i l i M j j M ! I i . 1 * - -f j • i t J ; i • | ' : j i i | M M MM!: M i ! ' 1 J : : ! i i l . : t i i . '• i i , i , M !. i. M l M M ! i " ' j • - i • i ji ! i j I" ! M i l ih! M > i 1 i ^ PM -1 ! i ; HEM '• i i '! i ! ! ' '' MM' IM; i '•; i <.<£ 1 . I ; • i ; M M ; ! M M M i i * '• i ! I ! 1 i ' • i M i l M M i l l ! 1 i 1 : ! j i 1 | | • M M • 1 M-. • ! ; : I — I I j ; ; : n M MO M 1 ; 5: M \ ; i M M i l l 0 j i M M 0 M M ; i : • I i i <ZL - )Z\l I | M M'J j'i-. '• - i i . ~4. - l 1 ! ' • : M M i'M : M M M 1 i • M | j . L-U-M i i l j ' M M M " r > 1 1 1 .4- ! i jlilil i I M- • • •• : i M . . M i l «t M_. I • _ l • , I • : ' 1 M__'_M5 ' l u L 1 1 ; _ ' M [ U M i ' ' : '1 M ! t l MM'M.!; - j - < ; < M l ' ; | • M . < I M : • M M ; M : ; I . < - 25 -s i m i l a r m e d i a , t h e d i a m e t e r s o f t h e p i n e s e e d l i n g s t e n d e d t o be g r e a t e r t h a n t h o s e o f t h e c y p r e s s . H e i g h t s and d i a m e t e r s f o r t h e two s p e c i e s w e r e l e a s t f o r B f and g r e a t e s t f o r t h e L - F - H m a t e r i a l s . M o s t o f t h e s e e d l i n g s grown i n t h e B f h o r i z o n m a t e r i a l w i t h no a d d e d p h o s p h o r u s showed p u r p l i s h l o w e r n e e d l e s a n d w e r e w e a k e r t h a n t h o s e grown i n t h e same s o i l m a t e r i a l s w i t h a d d e d p h o s p h o r u s . H o w e v e r , g r o w t h d i f f e r e n c e s a t t r i -b u t a b l e t o a d d e d p h o s p h o r u s w e r e g e n e r a l l y s m a l l a n d i n c o n s i s t e n t , a n d t h e d i f f e r e n c e s b e t w e e n l a r g e r a n d s m a l l e r s e e d l i n g s w i t h i n a t r e a t m e n t o f t e n t e n d e d t o o b s c u r e d i f f e r e n c e s b e t w e e n t r e a t m e n t s . A common f e a t u r e i n some B f a n d Ah h o r i z o n m a t e r i a l s was f u n g u s g r o w t h . V i s u a l e x a m i n a t i o n o f r o o t s showed t h a t t h e p i n e s e e d l i n g s w e r e m y c o r r h i z a l . (As C u p r e s s u s d e v e l o p s e n d o m y c o r r h i z a e , m i c r o s c o p i c e x a m i n a -t i o n w o u l d h a v e b e e n n e c e s s a r y f o r c o n f i r m a t i o n o f a m y c o r r h i z a l c o n d i t i o n i n t h e c y p r e s s . ) I n a l l t h e s o i l m a t e r i a l s a n d t r e a t m e n t s , c y p r e s s r o o t s w e r e more a b u n d a n t t h a n p i n e r o o t s . H o o s e g o o d a n d H o w l a n d ( 1 9 6 6 ) , w o r k -i n g i n E a s t A f r i c a , f o u n d t h a t C u p r e s s u s l u s i t a n i c a a p p e a r e d t o h a v e more s u r f a c e f e e d e r r o o t s s p r e a d i n t h e 0 - 3 0 c m - l e v e l , w h i l e t h e r o o t s y s t e m o f P i n u s p a t u l a was s p a r s e . I t was i n t e r e s t i n g t o n o t e t h a t t h e r e was more r o o t d e v e l o p m e n t i n t h e c o n t r o l t h a n i n t h e P - t r e a t e d L - F - H . T r a c e s o f t h e p h o s p h a t e s a d d e d a t t h e s t a r t o f t h e g r o w t h e x p e r i m e n t c o u l d be v i s u a l l y d e t e c t e d i n b o t h B f a n d Ah s o i l m a t e r i a l s . T a y l o r e t a l . ( 1 9 6 0 ) f o u n d t h e same phenomenon when t h e y g r e w c o r n f o r 62 d a y s i n s o i l s w h e r e c o l l o i d a l f e r r i c p h o s p h a t e and c o l l o i d a l a l u m i n u m p h o s p h a t e s w e r e a d d e d . R e s u l t s i n T a b l e 5 show t h a t , i n m o s t c a s e s , t o t a l b i o m a s s o f c y p r e s s s e e d l i n g s was s l i g h t l y g r e a t e r t h a n t h a t o f t h e p i n e s e e d l i n g s , e s p e c i a l l y a t l o w P - l e v e l s . R o o t b i o m a s s , a n d s t e m b i o m a s s t e n d e d t o be g r e a t e r f o r c y p r e s s t h a n f o r p i n e s , w h i l e t h e f o l i a r b i o m a s s o f p i n e 26 T a b l e 4 . S e e d l i n g g r o w t h o v e r 178 d a y s : ( a v e r a g e s o f f i v e s e e d l i n g s ) . d i a m e t e r a t b a s e and h e i g h t S o i l M a t e r i a l S p e c i e s D i a m e t e r H e i g h t B f C o n t r o l +20ppm P c +200ppm P c Ah C o n t r o l +20ppm P c +200ppm Pc LFH C o n t r o l +20ppm P d +100ppm Pc 1 a r g e r * 3 smal 1 e r ' 3 l a r g e r 1 3 s m a l l e r * 3 mm cm p 1 . 2 1 . 2 4 . 6 3 . 6 c 1 . 4 1 . 0 9 . 7 5 . 5 p 1 . 5 1 . 3 6 . 1 5 . 1 c 1 . 4 1 .1 1 1 . 8 8 . 6 p 1 . 5 1 . 4 6 . 3 5 . 4 c 1 . 4 1 . 2 1 2 . 5 7 . 4 p 1 . 7 1 . 5 6 . 9 6 . 2 c 1 . 6 1 . 4 1 5 . 1 1 1 . 8 p 1 . 6 1 . 5 7 . 4 6 . 2 c 1 . 6 1 . 3 1 5 . 0 1 0 . 6 p 1 . 7 1 . 4 7 . 8 6 . 1 c 1 . 8 1 . 2 1 8 . 3 1 0 . 4 p 2 . 5 1 . 8 1 1 . 4 9 . 2 c 2 . 0 1 . 6 2 1 . 3 1 5 . 4 p 2 . 3 1 . 7 1 0 . 6 8 . 5 c 2 . 0 1 . 8 1 9 . 6 1 5 . 9 p 2 . 2 1 . 8 1 1 . 3 9 . 8 c 2 . 2 1 . 8 1 9 . 4 1 6 . 0 a , P : P i n u s p a t u l a s e e d l i n g s , C : C u p r e s s u s 1 u s i t a n i c a s e e d l i n g s b , o f t h e two s e e d l i n g s grown i n e a c h p o t c , a d d e d a s 1 : 1 a l u m i n u m p h o s p h a t e - P : i r o n p h o s p h a t e - P . d , a d d e d a s p o t a s s i u m p h o s p h a t e 27 T a b l e 5 . B i o m a s s ( o v e n - d r y ) o f p l a n t p a r t s , ( a v e r a g e s o f t e n s e e d l i n g s ) S o i l M a t e r i a l B f C o n t r o l +20ppm P +200ppm P l Ah C o n t r o l +20ppm P +200ppm P^ LFH C o n t r o l +20ppm P c +100ppm Pc S p e c i e s 3 F o l i a g e S t e m R o o t s T o t a l P 0 . 1 8 4 g 0 . 1 7 7 0 . 3 3 7 0 . 6 9 8 C 0 . 2 4 0 0 . 1 9 3 0 . 3 7 8 0 . 8 1 1 P 0 . 3 6 7 0 . 2 3 5 0 . 4 5 2 1 . 0 5 4 C 0 . 3 2 3 0 . 2 4 2 0 . 5 7 1 1 . 1 3 6 P 0 . 3 4 2 0 . 2 8 3 0 . 4 6 1 1 . 0 8 6 c 0 . 3 0 9 0 . 2 6 1 0 . 5 1 1 1 . 0 8 1 p 0 . 5 6 0 0 . 2 8 0 0 . 5 2 0 1 . 3 6 0 c 0 . 5 2 0 0 . 3 3 6 0 . 7 1 0 1 . 5 6 5 p 0 . 6 0 4 0 . 3 4 1 0 . 5 4 7 1 . 4 9 2 c 0 . 5 0 3 0 . 3 3 2 0 . 5 7 2 1 . 4 0 7 p 0 . 6 3 3 0 . 3 2 4 0 . 4 9 3 1 . 4 5 0 c 0 . 5 4 7 0 . 3 5 3 0 . 7 3 5 1 . 6 3 5 p 1 . 4 1 0 0 . 5 1 1 0 . 5 9 7 2 . 5 1 8 c 1 . 1 2 2 0 . 5 4 2 0 . 8 9 8 2 . 5 6 2 p 1 . 3 7 1 0 . 5 8 0 0 . 6 6 1 2 . 6 1 2 c 1 . 0 3 6 0 . 5 5 6 0 . 7 3 8 2 . 3 3 0 p 1 . 3 5 6 0 . 5 0 7 0 . 5 9 5 2 . 4 5 8 c 1 . 1 8 6 0 . 5 9 2 0 . 9 5 9 2 . 7 4 7 a , P , P i n u s p a t u l a s e e d l i n g s ; C , C u p r e s s u s 1 u s i t a n i c a s e e d l i n g s b , a d d e d a s 1:1 a l u m i n u m p h o s p h a t e - P : i r o n p h o s p h a t e - P c , a d d e d a s p o t a s s i u m p h o s p h a t e - 28 -s e e d l i n g s t e n d e d t o be g r e a t e r t h a n t h a t o f c y p r e s s s e e d l i n g s . T h e r e was g e n e r a l l y g r e a t e r b i o m a s s f o r r o o t s t h a n f o l i a g e o r s t e m o f s e e d l i n g s o f b o t h s p e c i e s g r o w n i n B f h o r i z o n m a t e r i a l a n d o f c y p r e s s s e e d l i n g s grown i n Ah h o r i z o n m a t e r i a l . F o l i a r b i o m a s s was g r e a -t e r t h a n r o o t o r s t e m b i o m a s s o f p i n e s e e d l i n g s grown i n Ah h o r i z o n m a t e r i a l s . S e e d l i n g s o f b o t h s p e c i e s g r o w n i n L - F - H m a t e r i a l s had g r e a -t e r b i o m a s s i n f o l i a g e t h a n i n s t e m o r r o o t s . T h e r e w e r e somewhat more c o n s i s t e n t d i f f e r e n c e s i n b i o m a s s b e t w e e n t h e P - l e v e l s f o r B f t h a n f o r Ah and L - F - H m a t e r i a l s . A r e a s o n f o r t h i s c o u l d be t h a t e x t r a c t a b l e P c o n c e n t r a t i o n was h i g h e r f o r t h e l a t t e r m a t e r i a l s , s u g g e s t i n g l e s s d e f i -c i e n c y a n d h e n c e l e s s l i k e l i h o o d o f r e s p o n s e t o P a d d i t i o n s . 3 . E x t r a c t i o n m e t h o d s T h e c o n c e n t r a t i o n o f s o i l p h o s p h o r u s e x t r a c t e d by t h e f i v e m e t h o d s a r e shown i n T a b l e 6 . T h e d a t a show t h a t e x t r a c t a b l e p h o s p h o r u s was l o w e s t i n B f a n d h i g h e s t i n L - F - H m a t e r i a l s , w i t h a l l f i v e s o i l p h o s -p h o r u s e x t r a c t i o n m e t h o d s . T h i s was i n a g r e e m e n t w i t h t h e r e s u l t s a t t h e s t a r t o f t h e g r o w t h e x p e r i m e n t , w h e r e t h e L - F - H had more e x t r a c t a b l e P t h a n t h e o t h e r two s o i l m a t e r i a l s . E x t r a c t a b l e p h o s p h o r u s c o n c e n t r a t i o n i n c r e a s e d w i t h t h e amount o f a d d e d p h o s p h a t e s . The d i f f e r e n c e i n e x t r a c t a b l e P b e t w e e n t h e c o n t r o l a n d t h e p l u s 2 0 ppm P l e v e l was s l i g h t ; i t was l a r g e r b e t w e e n t h e p l u s 2 0 ppm P l e v e l a n d t h e p l u s 100 ppm P o r 200 ppm P l e v e l . T h i s i n c r e a s e i n e x t r a c t a b l e P w i t h a d d i t i o n o f i r o n a n d a l u m i n u m p h o s p h a t e s c o u l d h a v e been d i r e c t o r i n d i r e c t , i . e . d i r e c t f r o m t h e s e c o m p o u n d s , o r i n d i r e c t , d u e t o i n c r e a s e d p h o s p h o r u s m i n e r a l i z a t i o n i n d u c e d by t h e a d d e d p h o s p h a t e s . The e f f e c t o f t h e l a t t e r h a s been r e p o r t e d by some w o r k e r s , a s n o t e d i n t h e l i t e r a t u r e r e v i e w s e c t i o n o f t h i s p a p e r . - 29 -T a b l e 6 . E x t r a c t a b l e P (ppm) a f t e r 178 d a y s o f s e e d l i n g g r o w t h . ( E a c h v a l u e i s t h e a v e r a g e o f f i v e r e p l i c a t e s )  S o i l M a t e r i a l S p e c i e s 3 E x t r a c t i o n M e t h o d  B r a y P - l M o d . B r a y P - l 01 s e n T r u o g M e h l i c h p p m  B f C o n t r o l P 2 . 65 3 . 93 6 . 7 4 . .2 2 . 66 C 3 . 78 3 . 99 7 . 4 4 . .8 2 . 73 +20ppm P P 2 . 85 4 . 93 8 . 6 5 . , 0 2 . .82 C 3 . 79 5 . 51 8 . 6 5 . , 6 3 . 41 +200ppm P P 5 . 00 7. 68 2 1 . 3 8 . , 4 5 . ,67 C 6 . 44 8 . 32 2 0 . .3 8 . , 4 6 . ,01 i C o n t r o l P 8 . 32 7. , 6 0 2 0 . 3 5 . . 8 17. , 3 C 8 . 49 7 . . 8 0 2 2 . .7 4 . . 6 1 8 . , 9 +20ppm P P 1 0 . 06 1 0 . , 7 2 2 4 . , 9 6. . 4 1 9 . , 0 C 1 0 . 72 8 . , 8 9 2 3 . , 9 5. . 6 18. , 9 +200ppm P P 1 5 . 12 1 2 . . 0 5 3 5 . , 5 10. . 0 1 9 . . 0 c 1 4 . 62 9. , 5 8 3 6 . , 0 11. . 6 1 9 . . 6 C o n t r o l p 4 7 . 01 5 0 . . 5 0 7 6 . , 0 5 0 . . 0 6 5 . . 0 c 5 2 . 72 4 9 . . 2 0 74. , 5 6 8 . . 0 6 3 . . 4 +20ppm P p 4 8 . 95 5 2 . . 6 0 8 4 . . 2 5 4 , .7 67. . 2 c 5 9 . 4 3 5 4 . . 2 0 8 9 . . 3 6 6 , . 4 67 , . 4 +100ppm P p 5 7 . 26 6 2 . . 2 0 114. . 0 8 5 , . 5 7 3 . . 2 c 6 5 . 66 6 2 . . 9 0 1 0 9 . . 6 91 . . 6 7 3 , . 0 3 , P , P i n u s p a t u l a ; C , C u p r e s s u s 1 u s i t a n i c a - 30 -In a l l , O l s e n ' s ( N a H C 0 3 ) m e t h o d e x t r a c t e d more p h o s p h o r u s t h a n a n y o f t h e o t h e r e x t r a c t i o n m e t h o d s u s e d . T r u o g ' s m e t h o d r a n k e d s e c o n d i n e x t r a c t i n g P f r o m t h e B f h o r i z o n m a t e r i a l s , a n d M e h l i c h ' s m e t h o d r a n k e d s e c o n d i n e x t r a c t i n g P f r o m Ah a n d , i n some c a s e s , L - F - H m a t e r i a l s , b u t r a n k e d l a s t i n e x t r a c t i n g P f r o m B f m a t e r i a l s . T h e r e was a v e r y s l i g h t d i f f e r e n c e i n t h e amount o f P e x t r a c t e d by B r a y P-l a n d t h e m o d i f i e d B r a y P - l m e t h o d s , w i t h t h e B r a y P - l m e t h o d e x t r a c t i n g s l i g h t l y more P f r o m B f m a t e r i a l s and t h e m o d i f i e d B r a y P - l e x t r a c t i n g more P f r o m Ah m a t e r i a l s . P e x t r a c t e d by t h e f i v e m e t h o d s showed somewhat d i f f e r e n t r e -s u l t s f o r p i n e - g r o w n a n d c y p r e s s - g r o w n s o i l m a t e r i a l s . T h e r e was some t e n d e n c y f o r l e s s P t o be e x t r a c t e d f r o m s o i l m a t e r i a l s w h e r e p i n e was grown t h a n w h e r e c y p r e s s was g r o w n . H o w e v e r , t h i s r e s u l t was i n c o n s i s t e n t , e s p e c i a l l y w i t h O l s e n ' s m e t h o d , a n d may n o t be s i g n i f i c a n t . B o t h t h e B r a y P-l a n d m o d i f i e d B r a y P-l may h a v e i n d i c a t e d s l i g h t l y e x c e s s i v e v a l u e s o f e x t r a c t a b l e P , e s p e c i a l l y f r o m B f h o r i z o n ma-t e r i a l s . A s l i g h t d e c r e a s e i n e x t r a c t a b l e P by t h e two m e t h o d s was n o t i -c e d when a s m a l l amount o f P - f r e e c h a r c o a l was a d d e d . W a t a n a b e e t a l . ( 1 9 6 5 ) i n d i c a t e d t h a t c o l o u r i n t e r f e r e n c e c o u l d be o n e o f t h e p r o b l e m s e n c o u n t e r e d when B r a y P - l m e t h o d i s u s e d . 4 . P h o s p h o r u s c o n c e n t r a t i o n a n d u p t a k e by s e e d l i n g s A v e r a g e p h o s p h o r u s c o n c e n t r a t i o n i n d i f f e r e n t p a r t s o f t h e s e e d l i n g s , e x p r e s s e d i n p e r c e n t a g e , i s shown i n T a b l e 7 . T h e r e s u l t s i n -d i c a t e a s l i g h t l y h i g h e r P c o n c e n t r a t i o n i n r o o t s t h a n i n s t e m o r f o l i a g e i n m o s t c a s e s f o r s e e d l i n g s grown i n a l l s o i l m a t e r i a l s . W h i l e P c o n c e n -t r a t i o n s i n s t e m a n d f o l i a g e o f s e e d l i n g s g r o w n i n B f m a t e r i a l showed i n -c o n s i s t e n t t r e n d s , t h e r e was a h i g h e r P c o n c e n t r a t i o n i n f o l i a g e t h a n i n t h e s t e m s o f s e e d l i n g s grown i n L - F - H m a t e r i a l . A t h i g h e r s o i l P l e v e l s , - 31 -p i n e s e e d l i n g s t e n d e d t o h a v e s l i g h t l y h i g h e r P c o n c e n t r a t i o n s t h a n t h e c y p r e s s s e e d l i n g s . T o t a l p h o s p h o r u s u p t a k e by s e e d l i n g s , e x p r e s s e d i n mg P , i s p r e -s e n t e d i n T a b l e 8 . In g e n e r a l , t o t a l p h o s p h o r u s u p t a k e by s e e d l i n g s o f b o t h s p e c i e s was l e a s t f r o m B f a n d h i g h e s t f r o m L - F - H m a t e r i a l s . T h e s e r e s u l t s f o l l o w t h e same t r e n d a s t h o s e o f e x t r a c t a b l e p h o s p h o r u s i n t h e s e m a t e r i a l s i n t h a t e x t r a c t a b l e P was l e a s t i n B f a n d g r e a t e s t i n L - F - H m a t e r i a l s . T h e r e was o n l y a s l i g h t i n c r e a s e i n P u p t a k e f r o m t h e c o n t r o l t o t h e p l u s 20ppm P - l e v e l s f o r t h e t h r e e s o i l m a t e r i a l s , b u t t h e r e was a l a r g e i n c r e a s e i n P u p t a k e f r o m c o n t r o l t o t h e p l u s 100 o r 200ppm P l e v e l . T h e i n c r e a s e s i n P u p t a k e w i t h P a d d i t i o n s show c l e a r l y t h a t some o f t h e a d d e d p h o s p h a t e s w e r e a v a i l a b l e t o t h e t r e e s e e d l i n g s . When r e l a t i v e a m o u n t s o f p h o s p h o r u s i n t h e t h r e e p o r t i o n s o f t h e s e e d l i n g s w e r e e x a m i n e d , d i f f e r e n c e s w e r e n o t i c e d . T o t a l p h o s p h o r u s was h i g h e s t i n r o o t s a n d l o w e s t i n f o l i a g e i n t h e c a s e o f s e e d l i n g s grown i n B f h o r i z o n m a t e r i a l . T h i s was i n a g r e e m e n t w i t h t h e f a c t t h a t b o t h b i o -mass and P c o n c e n t r a t i o n i n r o o t s w e r e f o u n d t o be g r e a t e r t h a n t h o s e o f t h e f o l i a g e . S e e d l i n g s grown i n Ah m a t e r i a l had t h e g r e a t e s t amount o f P i n t h e r o o t s a n d t h e l e a s t i n t h e s t e m . The t o t a l P i n s e e d l i n g s grown i n L - F - H m a t e r i a l s was h i g h e s t i n f o l i a g e ( w i t h o n e e x c e p t i o n ) , a n d l e a s t i n t h e s t e m . T h e m a i n f a c t o r h e r e was t h e g r e a t e r b i o m a s s o f f o l i a g e a s c o m p a r e d w i t h o t h e r s e e d l i n g p a r t s . T h e p r e c e d i n g r e s u l t s i n d i c a t e t h a t s e e d l i n g r o o t s o f b o t h s p e -c i e s h a d , i n m o s t c a s e s , t h e g r e a t e s t P c o n c e n t r a t i o n s , b u t t h a t w i t h h i g h p h o s p h o r u s a v a i l a b i l i t y , f o l i a g e b i o m a s s was h i g h , c o n t a i n i n g more p h o s p h o r u s t h a n t h e o t h e r p a r t s o f t h e s e e d l i n g . C u p r e s s u s 1 u s i t a n i c a seemed t o a c c u m u l a t e more p h o s p h o r u s t h a n - 32 -T a b l e 7 . C o n c e n t r a t i o n o f P i n p l a n t t i s s u e . ( E a c h v a l u e i s t h e a v e r a g e o f 5 r e p l i c a t e s . )  S o i l M a t e r i a l S p e c i e s 3 S e e d ! i n g p a r t s  F o l i a g e Stem R o o t s % B f C o n t r o l P 0 . 044 0 . 054 0 . 066 C 0 . 0 5 3 0 . 051 0 . 0 6 5 +20ppm P P 0 . 056 0 . 055 0 . 068 C 0 . 080 0 . 071 0 . 088 +200ppm P P 0 . 088 0 . 178 0 . 114 c 0 . 087 0 . 110 0 . 077 i C o n t r o l p 0 . 064 0 . 057 0 . 105 c 0 . 087 0 . 097 0 . 112 +20ppm P p 0 . 101 0 . , 0 9 6 0 . 125 c 0 . 102 0 . , 1 2 5 0 . 125 +200ppm P p 0 . 132 0 . 189 0 . 214 c 0 . 108 0 . 116 0 . 175 C o n t r o l p 0 . 101 0 . , 0 8 7 0 . 0 9 9 c 0 . 114 0 . , 0 8 2 0 . ,114 +20ppm P p 0 . 112 0 . , 1 0 5 0 . 125 c 0 . 115 0 . , 0 6 7 0 . , 1 1 8 +100ppm P p 0 . 136 0 . , 1 2 0 0 . 143 c 0 . 122 0 . , 0 9 2 0 . , 1 5 3 a , P , P i n u s p a t u l a s e e d l i n g s ; C , C u p r e s s u s 1 u s i t a n i c a . - 33 -T a b l e 8 . P i n p l a n t t i s s u e o f 1 7 8 - d a y - o l d s e e d l i n g s ( a v e r a g e s o f t e n s e e d ! i n g s ) .  S o i l M a t e r i a l S p e c i e s 9 F o l i a g e Stem R o o t s T o t a l —mg C o n t r o l P 0 . 0 8 3 1 . 786 2 . 163 4 . 752 C 1 . 251 1 . 9 5 0 2 . 562 5 . 7 6 3 +20ppm P P 1 . 8 5 0 2 . 580 2 . , 6 5 1 7 . 081 C 2 . 535 3 . 4 6 5 4 . 229 1 0 . 229 +200ppm P P 2 . 967 5 . 704 . 4 . , 9 7 1 1 3 . 642 C 2 . 656 3 . 524 3 . , 8 8 9 1 0 . 0 6 9 i C o n t r o l P 3 , 559 1 . 258 5 . , 4 7 9 1 0 . 296 C 4 . 4 6 3 3 . 2 2 3 7. , 9 2 0 1 5 . , 6 0 6 +20ppm P P 6 . 178 3 . 138 6 . , 8 4 2 16. , 1 5 8 C 5 . 131 4 . 110 8 . , 8 1 5 18. , 0 6 0 +200ppm P P 8 . 300 6 . 150 10. , 5 0 4 2 4 . , 9 5 4 C 5 . 907 3 . 925 12. , 9 4 3 2 2 . , 7 7 5 C o n t r o l P 1 4 . 0 9 3 4 . 4 5 4 5. . 9 8 2 2 4 . , 5 2 9 c 1 2 . 800 4 . 322 10, . 2 5 4 2 7 . , 3 7 6 +20ppm P p 1 5 . 2 9 3 6 . 045 8 . . 2 7 0 2 9 . . 6 0 8 c 1 1 . 8 8 8 3 . 6 6 3 8 . . 6 2 4 2 9 . . 6 0 8 +100ppm P p 1 8 . 359 6 . 165 8 , . 5 5 2 3 3 . , 0 7 6 c 1 4 . 295 5 . 4 3 8 14. . 7 0 4 3 4 . . 4 3 7 a , P , P i n u s p a t u l a ; C , C u p r e s s u s l u s i t a n i c a - 34 -P i n u s p a t u l a s e e d l i n g s grown a t l o w P l e v e l s , b u t t h e o p p o s i t e was o f t e n t h e c a s e f o r s e e d l i n g s grown i n m a t e r i a l s h i g h i n e x t r a c t a b l e p h o s p h o r u s . T h e s e r e s u l t s w o u l d s u g g e s t t h a t w i t h P - d e f i c i e n t s o i l m a t e r i a l s , C u p r e s s u s 1 u s i t a n i c a may be more e f f i c i e n t t h a n P i n u s p a t u l a i n P u p t a k e . I t was n o t e d t h a t i n m o s t c a s e s t h e r e was more e x t r a c t a b l e s o i l P i n s o i l m a t e r i a l s w h e r e C u p r e s s u s 1 u s i t a n i c a s e e d l i n g s w e r e g r o w n , e v e n a t v e r y l o w e x t r a c t a b l e P l e v e l s . T h i s m i g h t be e a s i l y e x p l a i n e d i f i n t h o s e c a s e s , t h e p i n e e x t r a c t e d more s o i l p h o s p h o r u s . ( G o o r ( 1 9 6 6 ) n o t e d t h a t P_. p a t u l a h a s a h i g h e r demand f o r some n u t r i e n t e l e m e n t s , s u c h a s p h o s p h o r u s , t h a n some o t h e r c o n i f e r s p e c i e s . ) H o w e v e r , t h e d a t a i n d i c a -t e d t h a t t h e c y p r e s s e x t r a c t e d more p h o s p h o r u s i n t h i s s t u d y . T h u s o n e m i g h t h y p o t h e s i z e some i n t e r a c t i o n b e t w e e n t h e c y p r e s s r o o t s a n d s o i l , i n c r e a s i n g t h e amount o f e x t r a c t a b l e P a n d f a c i l i t a t i n g P u p t a k e . 5 . C o r r e l a t i o n b e t w e e n e x t r a c t i o n m e t h o d s C o e f f i c i e n t s o f c o r r e l a t i o n b e t w e e n c o n c e n t r a t i o n s o f P e x t r a c -t e d by t h e f i v e m e t h o d s u s e d i n t h i s s t u d y a r e p r e s e n t e d i n T a b l e 9 . C o n -c e n t r a t i o n s o f s o i l P e x t r a c t e d by t h e v a r i o u s m e t h o d s w h e r e P i n u s p a t u l a s e e d l i n g s w e r e g r o w n c o r r e l a t e d s t r o n g l y w i t h e a c h o t h e r f o r a l l s o i l m a -t e r i a l s , e x c e p t t h a t P e x t r a c t e d by t h e M e h l i c h m e t h o d f r o m Ah h o r i z o n m a t e r i a l was n o t c o r r e l a t e d w i t h P e x t r a c t e d by o t h e r m e t h o d s . Where C u p r e s s u s 1 u s i t a n i c a s e e d l i n g s w e r e g r o w n , c o n c e n t r a t i o n o f P e x t r a c t e d by t h e f i v e m e t h o d s f r o m B f a n d L - F - H m a t e r i a l s c o r r e l a t e d s t r o n g l y w i t h e a c h o t h e r . The o n l y common s t r o n g c o r r e l a t i o n s f o r Ah m a t e r i a l s w e r e o f O l s e n ' s e x t r a c t e d P w i t h B r a y ' s P - l , T r u o g ' s a n d M e h l i c h ' s e x t r a c t e d P c o n c e n t r a t i o n s . T a b l e 9 . C o e f f i c i e n t s o f c o r r e l a t i o n ( r ) b e t w e e n s o i l p h o s p h o r u s a m o u n t s e x t r a c t e d by v a r i o u s m e t h o d s . E x t r a c t i o n Mod. B r a y P - l 01 s e n T r u o g M e h l i c h  M e t h o d B f Ah LFH B f Ah LFH B f Ah LFH B f Ah LFH S p e c i e s 9 B r a y P - l P 0 . 7 5 1 * * 0 . 6 6 8 * * 0 . 8 9 7 * * 0 . 8 2 0 * * 0 . 8 3 2 * * 0 . 8 9 9 * * 0 . 7 5 1 * * 0 . 7 2 9 * * 0 . 4 9 8 0 . 8 3 7 * * 0 . 2 6 5 0 . 9 0 6 * * C 0 . 7 3 0 * * 0 . 1 1 5 0 . 9 3 3 * * 0 . 8 7 9 * * 0 . 8 7 1 * * 0 . 8 7 3 * * 0 . 6 4 8 * * 0 . 5 6 2 * 0 . 8 1 9 * * 0 . 8 4 3 * * 0 . 4 0 1 0 . 9 3 7 * * Mod. B r a y P - l P 0 . 5 8 1 * 0 . 6 5 2 * * 0 . 9 3 8 * * 0 . 5 6 9 * 0 . 5 8 5 * 0 . 6 7 1 * * 0 . 7 7 8 * * 0 . 3 2 8 0 . 9 1 5 * * C 0 . 7 2 0 * * 0 . 2 2 7 0 . 9 4 2 * * 0 . 6 0 3 * 0 . 3 8 1 0 . 9 1 3 * * 0 . 6 1 6 * 0 . 0 2 3 0 . 9 4 2 * * O l s e n P 0 . 8 3 8 * * 0 . 7 3 6 * * 0 . 5 3 3 * 0 . 9 0 3 * * 0 . 5 5 3 * 0 . 9 3 4 * * ^ C 0 . 7 4 7 * * 0 . 5 6 4 * 0 . 8 5 4 * * 0 . 8 6 6 * * 0 . 5 3 5 * 0 . 8 6 3 * * ^ T r u o g P 0 . 7 8 4 * * 0 . 2 6 8 0 . 6 1 6 * C 0 . 6 6 6 * * 0 . 0 7 1 0 . 8 5 3 * * * * s i g n i f i c a n t a t P < 0 . 0 1 * s i g n i f i c a n t a t P ^ O . 0 5 a , P , P i n u s p a t u l a ; C , C u p r e s s u s 1 u s i t a n i c a - 36 -6 . C o r r e l a t i o n b e t w e e n s o i l P e x t r a c t i o n m e t h o d s a n d s e e d l i n g P u p t a k e A s i g n i f i c a n t r e l a t i o n s h i p b e t w e e n e x t r a c t a b l e P c o n c e n t r a t i o n i n t h e s o i l and t h e amount o f P t a k e n up by t h e p l a n t i s p r o b a b l y t h e b e s t v a l i d a t i o n o f a P e x t r a c t i o n m e t h o d f o r i n d i c a t i n g s o i l P a v a i l a b i l -i t y . T h r e e c o r r e l a t i o n m e t h o d s , n a m e l y , l i n e a r , s e m i - l o g a n d l o g - l o g w e r e t e s t e d t o d e t e r m i n e w h i c h o f t h e t h r e e p r o v i d e t h e b e s t c o r r e l a t i o n . The s e m i - l o g d i d n o t i m p r o v e t h e c o r r e l a t i o n o v e r t h a t o f t h e l i n e a r , w h i l e t h e l o g - l o g m e t h o d i m p r o v e d t h e c o r r e l a t i o n n o n - s i g n i f i c a n t l y , a n d o n l y f o r P u p t a k e by P i n u s p a t u l a s e e d l i n g s . T h e r e f o r e t h e l i n e a r c o r r e -l a t i o n m e t h o d was s e l e c t e d . T a b l e 10 g i v e s c o e f f i c i e n t s o f l i n e a r c o r r e -l a t i o n b e t w e e n c o n c e n t r a t i o n o f s o i l P e x t r a c t e d by t h e v a r i o u s m e t h o d s and t o t a l P u p t a k e by t h e s e e d l i n g s o f t h e two p l a n t s p e c i e s . T h e s e c o r r e l a t i o n c o e f f i c i e n t s show some d i f f e r e n c e s b e t w e e n P i n u s p a t u l a and C u p r e s s u s l u s i t a n i c a . F o r P i n u s p a t u l a , a l l e x t r a c t i o n m e t h o d s y i e l d e d s i g n i f i c a n t ( P f 0 . 0 5 ) c o r r e l a t i o n s b e t w e e n e x t r a c t a b l e P c o n c e n t r a t i o n i n t h e s o i l a n d t h e amount o f P t a k e n up by t h e p l a n t . O v e r a l l , O l s e n ' s m e t h o d y i e l d s t h e h i g h e s t c o r r e l a t i o n c o e f f i c i e n t s . T h o u g h i t y i e l d s t h e s e c o n d h i g h e s t ( n e x t t o T r u o g ' s m e t h o d ) f o r L - F - H m a t e r i a l , t h e l a t t e r i s t h e l e a s t P - d e f i c i e n t o f a l l t h e t h r e e m a t e r i a l s t e s t e d , a n d h e n c e a s t r o n g c o r r e l a t i o n i s o f l i m i t e d p r a c t i c a l s i g n i f i c a n -c e f o r t h a t m a t e r i a l . T h e B r a y P - l a n d T r u o g m e t h o d s y i e l d c o r r e l a t i o n s a b o u t a s s i g n i f i c a n t a s t h o s e o b t a i n e d w i t h O l s e n ' s m e t h o d . T h e M e h l i c h m e t h o d y i e l d s e x c e l l e n t c o r r e l a t i o n f o r t h e v e r y P - d e f i c i e n t B f m a t e r i a l b u t a p p e a r s somewhat l e s s u s e f u l f o r t h e Ah a n d L - F - H m a t e r i a l s . F o r C u p r e s s u s l u s i t a n i c a , o n l y t h e M e h l i c h e x t r a c t i o n m e t h o d y i e l d e d v e r y s i g n i f i c a n t ( P - 0 . 0 5 ) c o r r e l a t i o n s b e t w e e n e x t r a c t a b l e P c o n -c e n t r a t i o n i n t h e s o i l a n d t h e amount o f P t a k e n up by p l a n t f r o m t h e - 37 -T a b l e 1 0 . C o e f f i c i e n t s o f c o r r e l a t i o n ( r ) b e t w e e n t o t a l P u p t a k e by s e e d l i n g s and c o n c e n t r a t i o n o f s o i l P e x t r a c t e d by v a r i o u s m e t h o d s . E x t r a c t i o n M e t h o d s S o i l M a t e r i a l s c . a S p e c i e s B r a y P - l Mod. B r a y P - l 01 s e n T r u o g M e h l i c h B f P 0 . 8 0 5 1 * * * 0 . 6 2 8 0 * * 0 . 8 9 5 1 * * * 0 . 7 8 2 0 * * * 0 . 8 3 1 6 * * * C 0 . 3 1 0 6 0 . 4 0 3 1 0 . 4 0 6 0 0 . 4 7 3 6 * 0 . 6 0 4 7 * * Ah P ' 0 . 8 5 6 3 * * * 0 . 6 5 6 6 * * * 0 . 8 9 4 3 * * * 0 . 7 5 1 6 * * * 0 . 5 7 9 9 * * C 0 . 6 6 8 1 * * * 0 . 5 1 9 5 * * 0 . 7 5 2 9 * * * 0 . 6 5 1 6 * * * 0 . 3 4 8 0 LFH P 0 . 6 0 3 1 * * 0 . 5 2 6 7 * * 0 . 6 2 0 3 * * 0 . 6 3 4 1 * * 0 . 6 1 1 5 * * C 0 . 3 9 3 2 0 . 4 9 6 0 * 0 . 4 6 6 0 * 0 . 4 4 2 8 * 0 . 5 1 4 1 * * * * * s i g n i f i c a n t a t P ^ O . 0 1 * * s i g n i f i c a n t a t P 5 0 . 0 5 * s i g n i f i c a n t a t P f O . 1 0 a , P , P i n u s p a t u l a s e e d l i n g s ; C , C u p r e s s u s l u s i t a n i c a s e e d l i n g s . - 38 -v e r y P - d e f i c i e n t B f h o r i z o n m a t e r i a l . R e s u l t s o f t h e T r u o g method w e r e n e x t m o s t s i g n i f i c a n t ( P 5 0 . 1 0 ) . M e h l i c h ' s m e t h o d , h o w e v e r , f a i l e d t o y i e l d s i g n i f i c a n t ( P _ 0 . 1 0 ) c o r r e l a t i o n f o r t h e Ah m a t e r i a l , b u t t h e O l s e n , B r a y P - l a n d T r u o g m e t h o d s y i e l d e d v e r y s i g n i f i c a n t ( P f O . O l ) c o r r e l a t i o n s w i t h P u p t a k e by t h e c y p r e s s f o r t h e A h . F o r t h e L - F - H , M e h l i c h ' s m e t h o d y i e l d e d t h e b e s t c o r r e l a t i o n s ( P _ 0 . 0 5 ) , a n d o n l y t h e B r a y P - l f a i l e d t o y i e l d s i g n i f i c a n c e a t P < 0 . 1 0 . When r e g r e s s i o n . " e q u a t i o n s r e l a t i n g e x t r a c t a b l e P c o n c e n t r a t i o n i n s o i l and t h e amount o f P t a k e n up by t h e p l a n t ( T a b l e 11) w e r e c o n s i d -e r e d , t h e s i g n i f i c a n t r e l a t i o n s showed g r e a t e r v a l u e s o f r e g r e s s i o n l i n e Y - i n t e r c e p t (P u p t a k e by p l a n t was t a k e n a s t h e d e p e n d e n t v a r i a b l e ) f o r t h e - c y p r e s s t h a n f o r t h e p i n e . H o w e v e r , t h e s l o p e s o f t h e r e g r e s s i o n l i n e s showed h i g h e r v a l u e s f o r t h e p i n e t h a n f o r t h e c y p r e s s ( s e e F i g u r e s 3 - 2 3 ) . F o l i a r P c o n c e n t r a t i o n c a n be e x p e c t e d t o i n d i c a t e t h e d e g r e e o f P d e f i c i e n c y i n t h e p l a n t . Hence o n e c o u l d a n t i c i p a t e t h a t a v a i l a b l e P c o n c e n t r a t i o n i n . t h e s o i l s h o u l d be p o s i t i v e l y c o r r e l a t e d w i t h f o l i a r P c o n c e n t r a t i o n i n t h e p l a n t . I n T a b l e 1 2 , t h i s h y p o t h e s i s i s b o r n e o u t by a l l t h e d a t a e x c e p t t h e r e l a t i o n s h i p f o r c y p r e s s w h e r e a v a i l a b l e P i n Ah h o r i z o n m a t e r i a l was e v a l u a t e d by M e h l i c h ' s m e t h o d . O v e r a l l , t h e m o s t s i g n i f i c a n t r e l a t i o n s h i p s w e r e f o u n d w h e r e 01 s e n ' s m e t h o d was u s e d . The B r a y P - l m e t h o d y i e l d e d r e s u l t s n e a r l y a s g o o d . M e h l i c h ' s m e t h o d a l s o y i e l d e d v e r y s i g n i f i c a n t r e s u l t s f o r B f m a t e r i a l , f o r b o t h s p e c i e s ; h a v -i n g b e t t e r c o r r e l a t i o n i n t h i s r e s p e c t t h a n e i t h e r t h e T r u o g o r m o d i f i e d B r a y P - l m e t h o d s . The B r a y P - l , m o d i f i e d B r a y P - l , a n d O l s e n m e t h o d s •• y i e l d e d h i g h l y s i g n i f i c a n t r e s u l t s w i t h P_. p a t u l a , b u t w i t h C_. 1 u s i t a n i c a t h e y w e r e l e s s s a t i s f a c t o r y . I n m o s t c a s e s , t h e c o r r e l a t i o n r e s u l t s f o r t h e m o d i f i e d B r a y P - l m e t h o d r e s e m b l e d t h o s e f o r t h e T r u o g m e t h o d . T a b l e 11 . R e g r e s s i o n c o n s t a n t s ( a ) and c o e f f i c i e n t s (b) b e t w e e n s e e d l i n g P u p t a k e a n d c o n c e n t r a t i o n o f s o i l P e x t r a c t e d by v a r i o u s m e t h o d s , ( y = a + b x , w h e r e y i s P u p t a k e and x i s e x t r a c t a b l e s o i l P c o n c e n t r a t i o n ) .  E x t r a c t i o n m e t h o d s S o i l B r a y P-•1 M o d . B r a y P - l 01 s e n T r u o g M e h l i c h M a t e r i a l S p e c i e s a b a b a b a b a b B f P C - 1 . 6 0 6 7 0 2 . n ; s . n . 8 5 5 9 0 s . 3 . 8 1 9 8 5 0 . 8 1 3 9 9 n . s . n . s . 1. n , , 7 3 1 9 5 , s . 0 . 5 5 6 9 0 n . s . 1. n . , 5 3 1 5 7 1 . 0 4 1 3 3 , s . n : . s . 0 . 4 , 3 7 8 5 5 36397 2 . 2 3 3 7 3 1 . 0 6 7 1 0 Ah P C - 2 . 1 4 7 3 4 1. 1 0 . 2 1 4 5 3 0 . 7 2 6 2 0 79867 - 0 . 4 0 7 7 6 1 . 7 3 0 2 1 8 . 3 3 8 0 7 1 . 2 0 9 0 9 - 5 . 6. . 5 4 2 8 3 , 5 7 0 7 6 0 . 8 4 3 0 5 0 . 4 4 5 4 1 5 . 14. , 9 8 7 2 4 1 . 5 7 6 7 6 , 3 6 4 1 2 0 . 5 7 5 3 6 - 4 4 . n . 3 8 5 5 8 s . 3 . 3 4 5 6 4 n . s . LFH P 1 . 0 0 7 3 9 0 . n . s . n . 54708 s . 6 . 3 1 6 9 5 0 . 4 1 0 9 1 n . s . n . s . 15. n . , 1 2 0 1 6 , s . 0 . 1 5 1 3 1 n . s . 17. n . , 7 5 9 9 4 0 . 1 7 8 6 3 , s . n . s . - 2 5 . - 1 7 . 0 2 2 4 5 3 1 9 8 0 0 . 7 8 9 1 3 0 . 6 7 7 2 1 a , P , P i n u s p a t u l a s e e d l i n g s ; C , C u p r e s s u s l u s i t a n i c a s e e d l i n g s , n . s . , Not s i g n i f i c a n t a t P f 0 . 0 5 - 4 0 -T a b l e 1 2 . C o e f f i c i e n t s o f c o r r e l a t i o n ( r ) b e t w e e n s e e d l i n g f o l i a r P c o n -c e n t r a t i o n a n d c o n c e n t r a t i o n o f s o i l P e x t r a c t e d by v a r i o u s m e t h o d s . E x t r a c t i o n m e t h o d s S o i l S p e c i e s M o d . M a t e r i a l B r a y P - l B r a y P - l 01 s e n T r u o g M e h l i c h B f P 0 . 7 5 0 6 * * * 0 . 7 0 9 2 * * * 0 . 8 3 1 9 * * * 0 . 7 1 6 7 * * * 0 . 9 1 4 1 * * * C 0 . 7 3 2 7 * * * 0 . 5 6 4 8 * * 0 . 7 0 7 5 * * * 0 . 6 2 9 9 * * 0 . 7 0 7 3 * * * Ah P 0 . 8 5 0 5 * * * 0 . 8 0 9 8 * * * 0 . 8 6 0 9 * * * 0 . 7 9 3 2 * * * 0 . 5 6 5 5 * * C 0 . 4 7 2 6 * 0 . 4 6 1 4 * 0 . 4 7 5 4 * 0 . 4 4 3 7 * - 0 . 0 9 0 9 LFH P 0 . 8 7 7 0 * * * 0 . 8 0 4 6 * * * 0 . 8 3 6 8 * * * 0 . 5 7 4 8 * * 0 . 8 9 1 1 * * * C 0 . 2 5 7 1 0 . 2 9 4 5 0 . 5 1 9 0 * * 0 . 3 0 3 4 0 . 2 5 7 7 * * * s i g n i f i c a n t a t P 5 0 . 0 1 * * s i g n i f i c a n t a t P < 0 . 0 5 * s i g n i f i c a n t a t P < 0 . 1 0 a , P , P i n u s p a t u l a s e e d l i n g s ; C , C u p r e s s u s 1 u s i t a n i c a s e e d l i n g s . - 41 -SUMMARY AND CONCLUSIONS P u p t a k e by C u p r e s s u s l u s i t a n i c a s e e d l i n g s e x c e e d e d t h a t by P i n u s p a t u l a s e e d l i n g s , grown i n s o i l s v e r y l o w i n a v a i l a b l e P . H o w e v e r , t h e o p p o s i t e s o m e t i m e s o c c u r r e d w i t h s o i l s h i g h i n a v a i l a b l e P. F o r P i n u s p a t u l a a l l t h e e x t r a c t i o n m e t h o d s f o r a v a i l a b l e s o i l P y i e l d e d s t r o n g c o r r e l a t i o n s w i t h P u p t a k e by t h e p l a n t f r o m t h e t h r e e h o r i z o n m a t e r i a l s , s u g g e s t i n g t h a t a n y o f t h e m c o u l d be u s e d a s a s a t i s -f a c t o r y i n d e x o f a v a i l a b l e s o i l P f o r t h i s s p e c i e s . H o w e v e r , f o r C u p r e s s u s l u s i t a n i c a , o n l y t h e M e h l i c h , a n d T r u o g , m e t h o d s y i e l d e d s i g n i -f i c a n t c o r r e l a t i o n s w i t h P u p t a k e by t h e p l a n t f r o m t h e P - d e f i c i e n t B f h o r i z o n m a t e r i a l . The more s i g n i f i c a n t c o r r e l a t i o n o b t a i n e d f o r t h e M e h l i c h m e t h o d s u g g e s t s i t may be t h e b e s t i n d e x o f a v a i l a b l e P i n p o d -z o l i c B f h o r i z o n m a t e r i a l . H o w e v e r , w h i l e a l l t h e o t h e r m e t h o d s showed s i g n i f i c a n t c o r r e l a t i o n s w i t h P u p t a k e by C_. l u s i t a n i c a f r o m Ah h o r i z o n m a t e r i a l , M e h l i c h ' s m e t h o d d i d n o t . F o r fJ. l u s i t a n i c a g r o w n i n s o i l s v e r y h i g h i n a v a i l a b l e P , t h e M e h l i c h m e t h o d a p p e a r s b e s t , b u t o n l y t h e B r a y P - l m e t h o d y i e l d e d n o n - s i g n i f i c a n t c o r r e l a t i o n s . O v e r a l l , c o n s i d e r -i n g b o t h s p e c i e s and a l l s o i l m a t e r i a l s , O l s e n ' s m e t h o d y i e l d e d t h e b e s t r e s u l t s . M o d i f y i n g t h e B r a y P - l m e t h o d d i d n o t i m p r o v e c o r r e l a t i o n b e -t w e e n P u p t a k e by s e e d l i n g s and e x t r a c t a b l e P i n s o i l m a t e r i a l s . O v e r a l l , f o l i a r P c o n c e n t r a t i o n c o r r e l a t e d b e s t w i t h r e s u l t s o f t h e O l s e n m e t h o d , w h e r e b o t h s p e c i e s and a l l s o i l m a t e r i a l s w e r e c o n s i d -e r e d . - 42 -BIBLIOGRAPHY Aquaye, D. K. 1963. Some s i g n i f i c a n c e of s o i l organic phosphorus mineral-i z a t i o n i n the phosphorus n u t r i t i o n of cocoa i n Ghana. Plant and S o i l 19: 65-79. Anderson, M. S. 1960. Symposium on S o i l T e s t i n g . J. A g r i c . Food Chem. 8 (2): 84-104. Bingham, F. T. 1966. Phosphorus. J_n: Chapman, H.D. (ed.) Diagnostic c r i t e r i a f o r plants and s o i l . Univ. of C a l . , R i v e r s i d e , pp. 324-361. Bishop, W.D. and Barber, S.A. 1958. The e f f e c t of s o i l phosphorus com-pounds on s o i l t e s t c o r r e l a t i o n . S o i l S c i . Soc. Amer. Proc. 22: 435-439. Bray, R.H. and K u r t z , L.T. 1945. Determination of t o t a l organic and a v a i l a b l e forms of phosphorus i n s o i l s . J. S o i l S c i . 59: 39-45. Chai, M.C. and C a l d w e l l , A.C. 1959. Forms of phosphorus and f i x a t i o n i n s o i l s . S o i l S c i . Soc. Amer. Proc. 23: 458-267. Chapman, H.D. and P r a t t , P.F. 1961. Methods of a n a l y s i s f o r s o i l s , p l a n t s , and waters. Univ. of C a l . , R i v e r s i d e , pp. 172. Enwezor, W.O. 1966. The b i o l o g i c a l transformation of phosphorus during the incubation of a s o i l t r e a t e d with s o l u b l e inorganic phosphorus and with f r e s h and r o t t e d organic m a t e r i a l s . P l a n t and S o i l 25: 463-466. Fujiwara, A. 1950. Chemical c o n s t i t u t i o n and a v a i l a b i l i t y of i r o n and aluminum phosphates. 1. Studies on the c o n s t i t u t i o n s and manural ef-f e c t s o f s c a r c e l y s o l u b l e phosphates. Tohoku J. Agr. Research. 1: 129-141. Goor, A.Y. and Barney, C.W. 1976. Cupressus 1 u s i t a n i c a M i l l . In: Forest t r e e p l a n t i n g i n a r i d zones. 2nd Ed. The Ronald Press Company, New York. pp. 302-304. Goor, G.P. Van. 1966. The n u t r i t i o n of some t r o p i c a l pines. S i l v i c u l -t u ra em Sao Paulo. 4/5 (4): 313-340. G r i f f i t h , A.L. and Howland, P. 1961. Rate of growth of new roots and new mycorrhiza immediately a f t e r p l a n t i n g . East A f r i c a n A g r i c . and For. Research Org. 27: 84-85. Hauser, G.F. 1973. Guide to the c a l i b r a t i o n of s o i l t e s t s f o r f e r t i l i -zer recommendations. S o i l B u l l e t i n No. 18. F.A.0., Rome. Hoagland, D.R. and Arnon, D.I. 1950. Method f o r growing plants i n water-c u l t u r e without s o i l . C a l i f o r n i a Agr. Exp. S t a t i o n . C i r . 347 Hoosegood, P.H. and Howland, P. 1966. A p r e l i m i n a r y study of the root d i s t r i b u t i o n o f some e x o t i c t r e e crops, evaluated by a r a p i d sampling method. East A f r i c a n A g r i c . and For. Res. Org. 31: 16-18:' - 43 -H u m p h r e y s , F . R . a n d P r i t c h e t t , W . L . 1 9 7 2 . A s o i l - t e s t i n g p r o c e d u r e f o r p r e d i c t i n g p h o s p h o r u s s t a t u s o f P i n u s e l l i o t t i i p l a n t a t i o n s . P l a n t a n d S o i l 3 7 : 4 7 9 - 4 8 7 . H u t t o n , R . G . a n d N y e , P . H . 1 9 5 8 . The r a p i d d e t e r m i n a t i o n o f t h e m a j o r n u t r i e n t e l e m e n t s i n p l a n t s . J . S c i . Food A g r i c . 9 : 7 - 1 4 . K a d e b a , 0 . and B o y l e , J . R . 1 9 7 8 . E v a l u a t i o n o f p h o s p h o r u s i n f o r e s t s o i l s : c o m p a r i s o n o f p h o s p h o r u s u p t a k e , e x t r a c t i o n m e t h o d , a n d s o i l p r o p e r t i e s . P l a n t a n d S o i l . 4 9 : 2 8 5 - 2 9 7 . K u r t z , T . , D e T u r k , E . E . , a n d B r a y , R . H . 1 9 4 6 . P h o s p h a t e a d s o r p t i o n by I l l i n o i s s o i l s . S o i l S c i . 6 1 : 1 1 1 - 1 2 4 . L i n d n e r , R . C , a n d H a r l e y , C . P . 1 9 4 2 . A r a p i d m e t h o d f o r t h e d e t e r m i n a -t i o n o f n i t r o g e n i n p l a n t t i s s u e . S c i . 9 6 : 5 6 5 - 5 6 6 . L i n d s a y , W . L . and D e m e n t , J . D . 1 9 6 1 . E f f e c t i v e n e s s o f some i r o n p h o s -p h a t e s a s s o u r c e s o f p h o s p h o r u s f o r p l a n t s . P l a n t a n d S o i l 1 4 : 1 1 8 - 1 2 6 . ' L i n d s a y , W . L . , a n d T a y l o r , A . W . 1 9 6 0 . P h o s p h a t e r e a c t i o n p r o d u c t s i n s o i l and t h e i r a v a i l a b i l i t y t o p l a n t s . 7 t h I n t e r . C o n g r . S o i l S c i . 4 : 5 8 0 - 5 8 6 . L i n d s a y , W . L . , a n d V l e k , P . L . G . 1 9 7 7 . P h o s p h a t e m i n e r a l s . In_: D i x o n , J . B . and W e e d , S . B . ( e d s . ) M i n e r a l s i n S o i l E n v i r o n m e n t s . S o i l S c i . S o c . A m e r i c a , M a d i s o n , W i s c o n s i n , p p . 6 3 9 - 6 7 2 . M c K e a g u e , J . A . 1 9 6 7 . An e v a l u a t i o n o f 0 . 1 M p y r o p h o s p h a t e a n d p y r o p h o s -p h a t e - d i t h i o n i t e i n c o m p a r i s o n w i t h o x a l a t e a s e x t r a c t a n t s o f t h e a c c u m u -l a t i o n p r o d u c t s i n p o d z o l s a n d some o t h e r s o i l s . C a n . J . S o i l S c i . 4 7 : 9 5 - 9 9 . M c K e a g u e , J . A . , B r y d o n , J . E . , a n d M i l e s , N . M . 1 9 7 1 . D i f f e r e n t i a t i o n o f f o r m s o f e x t r a c t a b l e i r o n a n d a l u m i n u m i n s o i l s . S o i l S c i . S o c . A m e r . P r o c . 3 5 : 3 3 - 3 8 . M c K e a g u e , J . A . , a n d D a y , J . H . 1 9 6 6 . D i t h i o n i t e - a n d o x a l a t e - e x t r a c t a b l e Fe and A l a s a i d s i n d i f f e r e n t i a t i n g v a r i o u s c l a s s e s o f s o i l s . C a n . J . S o i l S c i . 4 6 : 1 3 - 2 2 . M e h l i c h , A . , P i n k e r t o n , A . , R o b e r t s o n , W . , a n d K e m p t o n , R. 1 9 5 3 . Mass a n a l y s i s m e t h o d s f o r s o i l f e r t i l i t y e v a l u a t i o n . N a t i o n a l A g r i c u l t u r a l L a b . , Kenya D e p t . o f A g r i c u l t u r e . N e l s o n , W . L . , M e h l i c h , A . , and W i n t e r s , E. 1 9 5 3 . The d e v e l o p m e n t , e v a l u -a t i o n , a n d u s e o f s o i l t e s t s f o r p h o s p h o r u s a v a i l a b i l i t y . A g r o n . 4 : 1 5 3 - 1 8 8 . N o v o z a m s k y , I . a n d B e e k , J . 1 9 7 6 . Common s o l u b i l i t y e q u i l i b r i a i n s o i l s . I n : B o l t , G . H . and B r u g g e n w e r t , M . G . M . ( e d s . ) S o i l C h e m i s t r y . P a r t A . E l s e v i e r , A m s t e r d a m , p p . 9 6 - 1 2 5 . - 44 -O l s e n , S . R . , C o l e , W . V . , W a t a n a b e , F . S . , and D e a n , L . A . 1 9 5 4 . E s t i m a t i o n o f a v a i l a b l e p h o s p h o r u s i n s o i l by e x t r a c t i o n w i t h s o d i u m b i c a r b o n a t e . C i r c u l a r No. 9 3 9 . U . S . D e p t . o f A g r i c . p p . 1 - 1 9 . O t c h e r e - B o a t e n g , J . , a n d B a l l a r d , T . M . 1 9 7 8 . U r e a f e r t i l i z e r e f f e c t s o n d i s s o l v e d n u t r i e n t c o n c e n t r a t i o n s i n some f o r e s t s o i l s . S o i l S c i . A m e r . P r o c . 4 2 : 5 0 3 - 5 0 8 . P a c k , M . R . , and G o m e z , S . 1 9 5 6 . C o r r e l a t i o n b e t w e e n P l a n t a n d s o i l t e s t s i n New M e x i c o . S o i l S c i . S o c . A m e r . P r o c . 2 0 : 5 2 9 - 5 3 1 . P e r e i r a , H . G . 1 9 5 2 . W a t e r u s e b y f o r e s t c o v e r s o n t h e A b e r d a r e s . E a s t A f r i c a n A g r i c . a n d F o r . R e s . O r g . A n n u a l R e p o r t . P e r e i r a , H . G . 1 9 5 5 . S o i l m o i s t u r e c r i t e r i a f o r p l a n t i n g d a t e s . Kenya F o r e s t D e p t . T e c h . N o t e 2 7 . P r i t c h e t t , W . L . , a n d L l e w e l l y n , W . R . 1 9 6 6 . R e s p o n s e o f s l a s h p i n e ( P i n u s  e l 1 i o t t i i ) t o p h o s p h o r u s i n s a n d y s o i l s . S o i l S c i . S o c . A m e r . P r o c . 3 0 : 5 0 9 - 5 1 2 . S h e r r e l l , C . G . 1 9 7 0 . C o m p a r i s o n o f c h e m i c a l e x t r a c t i o n m e t h o d s f o r t h e d e t e r m i n a t i o n o f a v a i l a b l e p h o s p h a t e i n s o i l s . New Z e a l a n d J . A g r i c . R e s . 1 3 : 4 8 1 - 4 9 3 . T a y l o r , A . W . , G u r n e y , E . W . , a n d L i n d s a y , W . L . 1 9 6 0 . E v a l u a t i o n o f some i r o n a n d a l u m i n u m p h o s p h a t e s a s s o u r c e s o f p h o s p h a t e s f o r p l a n t s . S o i l S c i . 9 0 : 2 5 - 3 1 . T r u o g , A . W . , 1930." D e t e r m i n a t i o n o f r e a d i l y a v a i l a b l e p h o s p h o r u s o f s o i l s . J . A m e r i c a n S o c . A g r o n . 2 2 : 8 7 4 - 8 8 2 . T u r n e r , R . C . , a n d R i c e , H . M . 1 9 5 2 . R o l e o f t h e f l u o r i d e i o n i n r e l e a s e o f p h o s p h a t e a d s o r b e d by a l u m i n u m a n d i r o n h y d r o x i d e s . S o i l S c i . 7 4 : 1 4 1 - 1 4 8 . V i o g t , G . K . 1 9 6 6 . P h o s p h o r u s u p t a k e i n y o u n g p i t c h p i n e ( P i n u s r i g i d a M i l l ) . S o i l S c i . S o c . A m e r . P r o c . 3 0 : 4 0 3 - 4 0 6 . W a t a n a b e , F . S . , L i n d s a y , W . L . , a n d O l s e n , S . R . 1 9 6 5 . N u t r i e n t b a l a n c e i n v o l v i n g p h o s p h o r u s , i r o n a n d z i n c . S o i l S c i . S o c . A m e r . P r o c . 2 9 : 5 6 2 - 5 6 5 . W a t a n a b e , F . S . , a n d O l s e n , S . R . 1 9 6 5 . T e s t s o f a s c o r b i c a c i d m e t h o d f o r d e t e r m i n i n g p h o s p h o r u s i n w a t e r a n d NaHC03 e x t r a c t s i n s o i l . S o i l S c i . S o c . A m e r . P r o c . 4 9 : 6 7 7 - 6 7 8 . W e l l s , C . G . 1 9 6 5 . N u t r i e n t r e l a t i o n s h i p b e t w e e n s o i l s and n e e d l e s o f l o b l o l l y p i n e ( P i n u s t a e d a ) . S o i l S c i . S o c . A m e r . P r o c . 2 9 : 6 2 1 - 6 2 4 . W o r m a l d , T . J . 1 9 7 5 . P i n u s p a t u l a . T r o p i c a l F o r e s t r y P a p e r s N o . 7 . Commonw. F o r . I n s t . , O x f o r d . - 4 5 -A p p e n d i x 1 . P i n u s p a t u l a i s now g r o w i n g on s u i t a b l e s i t e s f r o m t h e e q u a t o r t o 3 1 ° S o u t h i n A f r i c a a n d a s f a r a s 4 2 ° f r o m t h e e q u a t o r i n New Z e a l a n d . I n E a s t A f r i c a i t t h r i v e s i n t h e m o n s o o n a l t w o - p e a k - r a i n f a l l c l i m a t e i n w h i c h t h e m a j o r i t y o f t h e r a i n f a l l s i n t h e r e l a t i v e l y c o o l e r s e a s o n s . I t g r o w s a l o n g s i d e P i n u s r a d i a t a , a w i n t e r - r a i n f a l l s p e c i e s . I t a p p e a r s t o do w e l l on m o s t warm a r e a s w i t h a r a i n f a l l o v e r a b o u t 750 mm a y e a r . I t i s a f f e c t e d by w a t e r s t r e s s i n a l o n g d r y s e a s o n , e s p e c i a l l y on s h a l l o w s o i l s . P i n u s p a t u l a g r o w s on a w i d e r a n g e o f s o i l s . I n t h e h i g h l a n d s o f E a s t A f r i c a i t d o e s w e l l o n y o u n g f e r t i l e v o l c a n i c s o i l s , and a l s o t h r i v e s on m a t u r e , l e a c h e d , i n f e r t i l e s o i l s d e r i v e d f r o m t h e b a s e m e n t c o m -p l e x , e s p e c i a l l y i n some p a r t s o f S o u t h e r n A f r i c a . Van G o o r ( 1 9 6 6 ) n o t e d t h a t P_. p a t u l a was more e f f i c i e n t a t t a k i n g up n i t r o g e n , p h o s p h o r u s a n d b o r o n t h a n w e r e P_. e l 1 i o t t i i a n d P_. c a r i b a e a . The common f e a t u r e s o f t h e s o i l s o n s i t e s f a v o u r e d by P_. p a t u l a a r e t h a t t h e y a r e a c i d , and t h a t t h e y h a v e a good m o i s t u r e s u p p l y . Deep s o i l s w h i c h r e m a i n m o i s t t h r o u g h o u t t h e d r y s e a s o n f a v o u r P_. p a t u l a . P e r e i r a ( 1 9 5 2 , 1 9 5 5 ) f o u n d t h a t o n d e e p l o a m s o i l s i n K e n y a , P . p a t u l a c o u l d d r a w on a l l t h e m o i s t u r e f r o m t h e f i r s t 4 . 3 m o f s o i l . I t s r o o t i n g d e p t h i s more i m p o r t a n t t h a n s o i l d e p t h . I t c a n g r o w o n s h a l l o w s o i l s p r o v i d e d t h e r o o t s c a n p e n e t r a t e t o d e e p e r h o r i z o n s ( W o r m a l d 1 9 7 5 ) . C u p r e s s u s l u s i t a n i c a i s an e v e r g r e e n , c o n i f e r o u s t r e e . I t i s a n a t i v e o f M e x i c o , G u a t e m a l a , E l S a l v a d o r , a n d H o n d u r a s w h e r e i t g r o w s b e -t w e e n 1300 a n d 3 3 0 0 m a b o v e s e a l e v e l . I t h a s b e e n p l a n t e d i n E t h i o p i a , K e n y a , S o u t h A f r i c a , A u s t r a l i a , a n d C e n t r a l a n d S o u t h A m e r i c a . The s p e -c i e s g r o w s on m o i s t s l o p e s a n d n e a r s t r e a m s ( G o o r a n d B a r n e y 1 9 7 6 ) . - 46 -C l i m a t e o f i t s n a t u r a l h a b i t a t i s m i l d t o warm s u b h u m i d and h u m i d , a n d i t i s r e s i s t a n t t o m o d e r a t e l y r e s i s t a n t t o d r o u g h t and f r o s t . I t g r o w s on many d i f f e r e n t s o i l s and i s a b l e t o t h r i v e on v o l -c a n i c p u m i c e , w h e r e f e w o t h e r s p e c i e s s u c c e e d . I t i s t h e r e f o r e t r i e d f o r t h e a f f o r e s t a t i o n o f e r o d e d and d r y m o u n t a i n s i d e s i n t h e t r o p i c s . Low a v a i l a b i l i t y o f p h o s p h o r u s a n d n i t r o g e n a r e known t o l i m i t t h e g r o w t h o f p l a n t a t i o n s o f C u p r e s s u s l u s i t a n i c a on v o l c a n i c . a s h s o i l s . O b s e r v a t i o n s o f t h e p l a n t s o f P i n u s p a t u l a and C u p r e s s u s  l u s i t a n i c a p l a n t e d i n b o x e s w i t h a g l a s s - p l a t e showed t h a t new r o o t s a r e f o r m e d a s e a r l y a s t h e f i r s t week a f t e r p l a n t i n g a n d t h e f i r s t new m y c o r r h i -z a l d e v e l o p m e n t on s e e d l i n g s a l s o o c c u r r e d i n t h e f i r s t week ( G r i f f i t h a n d H o w l a n d 1 9 6 1 ) . - 47 -F i g u r e 3 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) a n d B r a y ' s P - l e x t r a c t a b l e P i n s o i l (ppm) ( A b s c i s s a ) , f o r B f h o r i z o n m a t e r -i a l s . R e g r e s s i o n e q u a t i o n i s Y = - 1 . 6 0 6 7 0 + 2 . 8 5 5 9 0 X and r = 0 . 8 5 0 1 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . 15.40 >y >'*" t.vc USED TO PLOT PP.FCICTEO VALUES: " * n IS USED WHERE"PREDICTED VALUES CCVFR DATA POINTS A PC!NT OUTSIDE GRAPH. 15.40 'in/1n1111/\i111iii11\iin1111i\iin11nI\Iii111iii\ uiinni\iuiiiiii\miiiiii\tiiiiriii\iitttiui\ 2 . 0 0 0 " 2 . 7 0 0 " 3 . ACQ • 4 . I P O - 4.800 5. n i STAMC? B C T*EE.N SLASHES ON THE X-AXIS IS 0.3500E-01 Bray's P -l Extractable P (ppm) \ ' ; 50C - 49 -F i g u r e 4. R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by IP. p a t u l a ( o r d i n a t e ) ai mod. B r a y P - l e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r B f h o r i z o n ma t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 3 . 8 1 9 8 5 + 0 . 8 1 3 9 9 X and r = 0 . 6 2 8 0 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o f p o i n t s f a l l i n g o n t h e r e g r e s s i o n l i n e . •pLnf OF Y £ YHA1!' VS VAKZ . V E R T I C A L A X I S I S V - A X l b . " .•gtr-.rrtf, n+w—i'Ki'o- AP. E USED TC PLOTPRECIT.TED' VALUES; "*" p = pq-SFN TS A PCIN T OUTSIDE GRAPH. 15.40 IS USED WHERE PREDICTED' VALUESCCVERDATAPCINTS 15.40 • 4 .20^ O.O'JU 3"=TK=FN SLASH'S CN TH? X-AXIS IS 0.1300 Figure MnrHflBri Br?.v P-1 ExtT-ant.ahlB P I'TITWIV . — 1 4 . 6 C DISTANCE 6 E O F i g u r e 5 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) a n d O l s e n ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r B f h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 1 . 7 3 1 9 5 + 0 . 5 5 6 9 0 X a n d r = 0 . 8 9 5 1 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g o n t h e r e g r e s s i o n l i n e . PLOV ftp V t YHA -' VAP 'J" I V S R t K A L A X I S I S V - A X l S r „ t „ ocpRPCFNTS ft P O X N T " U T S I D E G R A P H . 1 3.400 Figure 5-tzAlc? B F - W E E N . S L A S H E S ' O N THF X - A X I S IS 0 .1800 24. EC cn ro - 5 3 ' -F i g u r e 6 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) a n d T r u o g ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r B f h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 1 . 5 3 1 5 7 + 1 . 0 4 1 3 3 X a n d r = 0 . 7 8 2 0 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . P L O T C F V t V H A l V y V A M V . V E R T I C A L AXIS TS Y - A X I S . "THE n + n p f p o p s c , 1 5 . 4 0 A N D - * " ARE U S E O - T D PLOT PREDICTED V A L U E S ; I S USED W E R E PPFDICTEO VALUES CCVER DATA PCINTS NTS A POINT OUTSIDE GRAPH. j T 3 .^00 - ^ O O O 4 . 3 0 0 " " 6 . 4 0 3 B . 4 C O DISTAK'CF BETWEEN SLASHES ON THE X - A X I S IS 0 . 9 0 0 0 E - 0 1 ' 0.0 - 55 -F i g u r e 7 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by IP. p a t u l a ( o r d i n a t e ) and M e h l i c h ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r B f h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 0 . 3 7 8 5 5 + 2 . 2 3 3 7 3 X and r = 0 . 8 3 1 6 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g o n t h e r e g r e s s i o n l i n e . P L O T O F Y £ V H A T VS VASb . V E R T I C A L AXI5 I S Y - A X I S . - T f f e - T , T M 7 W S . - « - 4 N O - H - * - » - - « - r O S E D ~ T ' C P L O T P R E C I S E D VALUES; « • » I S USED WHERE PREDICTED VALUES COVER DATA POINTS" » ( » REPRESENTS A POINT OUTSIDE GRAPH. 15.40 - 1 T 3 . 4CC DISTANCE BETfcFEN SLASHES OK THE X-AXIS IS 0.4500E-01 Mehlich s Extractable P (pppV • : : '• • 3.400 .7 00 tn - 57 -F i g u r e 8 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by IP. p a t u l a ( o r d i n a t e ) and B r a y ' s P - l e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = - 2 . 1 4 7 3 4 + 1 . 7 2 6 2 0 X a n d r = 0 . 8 5 6 3 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g o n t h e r e g r e s s i o n l i n e . P L O T C £ Y & Y H A T V ? . V E R T I C A L A X I S I S Y - A X I S T " t H E - » . % " * " AMD>•*" ARE USED TC" PLOT PRE OI CT ED " V A L U E S ; » * » I S USED WHERE PREDICTED VALUES CCV „^- REPRESENTS A PCI NT GUTS IDE GRAPH. 25.10 ER DATA POINTS 100 Figure 8. 1 um ni 1111111 m Milium 1 iiiiiiiii\iiiiiiiii\imimi\iiiii piSTiNCP P'TV.'JEN SLASHES O N THE X-AXIS IS 0.1100 . Bray' s P-l-Extrautable-P (ppm___ / / / / I / / 15 II1111l\l11111111\ 40 17.60 co - 59 -F i g u r e 9 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P . p a t u l a ( o r d i n a t e ) a n d mod. B r a y P - l e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n ma-t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 0 . 4 0 7 7 6 + 1 . 7 3 0 2 1 X a n d r = 0 . 6 5 6 6 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g o n t h e r e g r e s s i o n l i n e . °LOt OF Y £ YHAt VS V A 0 7 .VERTICAL AXIS IS Y-AXlS "THE - "•""» "* " RE PASSES' , 28.10 AND »*" AO E USEO TC PLCT PRECICTEO VALUES": TS A POINT OUTSIDE GRAPH. ••*« IS USED WHERE PREDICTED VALUES CTVER DATA PCINTS 9. 10O Figure 9-01 ST < 1 \ t r 1111111 \ 1 r 111111 \ 111111111 \ 111111111 \ 111111111 \ 1111111 n 1111111111 \ 11 1 00 IIIIIIIII MICE 8FTWFEN SLASHES ON THE X-AXIS IS C.8500E-OI Modified Bray P-l Extractable P fppm). 11 IIIIIMIIIIIII r\ 30 15.CO C T l O - 61 -F i g u r e 1 0 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) and O l s e n ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n ma-t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 5 . 5 4 2 8 3 + 0 . 8 4 3 0 5 X a n d r = 0 . 8 9 4 3 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a -t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLOT OF Y t YHAT VS. V A » B VERTICAL AXIS IS Y-AXIS, -THE""".".""*" A'.'D "*" APE USED TO PLOT PREDICTED VALUES: n » n REPRESENTS A POINT OUTSIOE GRAPH. «*" IS USED HHER5PRECKTED'VALUES COVER DATA POINTS 28.10 28.10 / ll.U 27.34 / / .... 26.96 . _ r .... 2 4 # 5 8  •"""/" 1 26.20 / / 25.82 ~ ZT~. 44 / y 25.06 / / yS 24.68 y - - 24.30 "24.30 / ; / 23.92 1 23.54 ' 23.16 / 22.78 / / 22.40 ' "22.02 / 21.64 / / 21.26 ; 2u.aa / 20.50 2 0.50 / 1 20.12 "19.74" ' 7 19.36 P uptake(mg) 1 1 8.98 rsr 6 c / / / 1 18.22 17.84 ^ 17.46 " - " / ' ' 17.08 1 6. 70 / 1 y 16.70 — i t . 3 2 / 15.94 / / 1 y 1 15.56 — , £ •' Q " " ' / ' " " " ' .y 14.80 / 14.42 T5.04 / y l 13.66 f 1 13.28 "' 12.90 . 12.90 I 1 12.52 1 2. 1 4 11.76 11.38 11. CO " 10.62 10.24 S.860 9.4«TT !00 ~y : : r . 9.10c Flg'jre 10. OI^TfNCF PEThEEN SLASHES ON THE X-AXIS IS 0.2000 . Olsen s Extractable P (ppm). C O - 63 -F i g u r e 11 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) a n d T r u o g ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 5 . 9 8 7 2 4 + 1 . 5 7 6 7 6 X a n d r = 0 . 7 7 0 0 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . P L O T C F Y I Y H A V V S V A P 9 "VERTICAL A X I S IS Y-AXIS. —-f pc~ ' 1 7 * 7"V" "AH"0 &P F USED TC n + n ccpofSENTS A P O I N T OUTSIDE -> a 1 -"PLOT PREDICTED VALUES; ••*" IS USEO WHERE PREDICTED VALUES COVER OATA POINTS' GRAPH. 1 2 8 .10 _ 7 7 " / / / *r 2 7 . 3 4 / 2 6 . 9 6 . : y£- " ' " " 7 4 . 5 8 / / / I 1 / 2 6 . 2 0 / 2 5 . 8 2 / . . — 7 * " / / f / 2 5 . 0 6 / 2A. 6 8 ' . :J.._-.;... - - - • 2 4 . 3 0 " " ' - 2 " A V 3 0 " " f / / 2 3 . 9 2 , / 2 3 . 5 4 1 / _ . -ll I k 1 1 / / 2 2 . 7 8 / 2 2 . 4 0 ' . _ . / — — " ' — 2 2 . 0 2 : -1 f / 2 1 . 6 4 / * ' 2 1 . 2 6 / . 7T-.-RR 2 0 . 5 0 1 1 / . 2 0 . 5 0 / 2C. 1 2 / „ - " 1<J."7A~~ r ~ / / 1 / 1 9 . 3 6 / 1 8 . 9 8 / . — — i f l . f i n / / • 1 8 .22 1 / 1 7 . 8 4 / '. - - — 1 7 . 4 6 / / 1 7 . 0 8 / 1 6 . 7 0 \ / — / / z / 1 5 . 9 4 1 / 1 5 . 5 6 .y 1 L - - - - • 1 5 . 1 8 — /"" / z / " 1 4 . 8 0 ' • 1 4 . 4 2 _ • ''i.OA i / i / 1 1 3 . 6 6 1 3 . 2 8 _ _ - — • - " " " 1 2 . 9 0 1 2 . 9 0 i / t s " 1 2 . 5 2 1 2 . 1 4 l l "" is '/ l / l 1 1 . 3 8 1 1 . 0 0 • , - • '• - " """ 1 0 . 6 2 " 7 / 1 / 1 0 . 2 4 9 . 8 6 0 : • c- .-jrnn ; 7 - 1 — 9 . 1 0 0 , 4 - o n - A - - - 6 - . 4 o o " 8.eco i i . z o - T . - j f . r r . P = T V . E E N S L A S H E S O N T H E X - A X I S IS 0 . 1 2 C 0 Pi^ure 1 1 . Truck's Extractable P (ppm). „ — — — • - 65 -F i g u r e 1 2 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) a n d M e h l i c h ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 4 4 . 3 8 5 5 8 + 3 . 3 4 5 6 4 X and r = 0 . 5 7 9 9 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . " P L O T O F Y S Y M A T V * V A P . I O . V E R T I C A L AXIS l b V - A X I b. -Tpe_*T"7H*M~*'N0'"H"*'""'A^"F"U'S,:0~TC"''PC0T PR n 4.« REPRESENTS A POINT OUTSIDE GRAPH. 2 e . 10 E C I C T E D V A L U E S r TS~USED- HHERrP^ETJTCTED "VALUES COVER DATA POINTS 1 9.100 19.60 - ii i H . n n l o . o j 11111111 f i g u r e 12. , f 1 7 . 2 0 1 8 . 0 0 ntS-AMOE RETWEFN SLASHES ON THE X rAXIS IS _0.4000E-01 Mehlich's Extractable T (ppm). 20.4C C T l C T l - 6 7 -F i g u r e 1 3 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) a n d B r a y ' s P - l e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r L - F - H h o r i z o n ma-t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y - 1 . 0 0 7 3 9 + 0 . 5 4 7 0 X a n d r = 0 . 6 0 3 1 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . Y H A + V A Q i l .VERTICAL AXI5 IS Y-AXIS. PLOT OF Y & T H , — A - USFO TO P l O T P R E D I C T S VALUES; "*" IS USED WHERS" PREDICTED VALUES COVER DATA "POINTS n + ™ REPRESENTS A POINT OUTSIDE GRAPH. '36.40 36.40 20.40 Figure 13-- i 7 . f r ~ 4 6 . 1 0 5 0 . 1 0 5 4 . i u C1TS T*NCE PFTViF.EN SLASHES ON THE X-AXIS IS 0.2CCO • Rrav's P-l Extractable P ! PPm). — • • • ~ ~ 20.40 10 CT) CO - 69 -F i g u r e 1 4 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) and mod. B r a y P - l e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r L - F - H h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y - 6 . 3 1 6 9 5 + 0 . 4 1 0 9 1 X a n d r = 0 . 5 2 6 7 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLOT OP Y ft YHAT VS •*" AP e USED TO PLOT PR 4 POINT OUTS IDE GRAPH .VERTICAL AXIS 1 5 Y - A X I S . EDICTFD VALUES; "*»'IS USED WHERE PREC1CTED VALUES COVER DATA POINTS 26. 30 •7 — ' 2 6.4B 26.16 25.84 I 25.20 24.88 — — : 2"4T5~5: i 24.24 I / • , 23.92 " " 23.60 ' 23.60 • - — — - - ~ — ~ 1 . • • f 23.28 22.96 : : :  1 i / / „ _ _ _ .. - — - -22.32 22.00 — 21.68 "/ / / 21.36 • . 21.C4 — 2C. 12 ~ / 20.40 20.40 F1<nirf> 1*. 1 " / / i / 1 III HUM i niiiii\iiiiiini\iiiiiiiii\iiiniiii\ — • L . f . ^ . r - " 5C. 9C 54. SC DIS-ANCE BETWEEN SLASHES ON T H E X-AXIS IS 0.2000 Modified Bray P"1 l-Vt.ractable P (ppm).' / / / / / / / / / I 111111111\111111111\ 62.90 tk.'.C o - 71 -F i g u r e 1 5 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by IP. p a t u l a ( o r d i n a t e ) a n d O l s e n ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r L - F - H h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 1 5 . 1 2 0 1 6 + 0 . 1 5 1 3 1 X a n d , r = 0 . 6 2 0 3 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLC-T CF V f. V H A ? V S . V A R 1 3 — . V E R T I C A L A X I S I S Y - A X I S . "TH' ~"VWT"*M "AMD REPR CSEMTS A 36.40 M P U S E 0 " T 0 PLOT ' PREDICTED' VALUE S PCINT OUTSIDE GRAPH. IS USED WHERE PREDICTED VALUES COVER DATA POINTS 20.40 Figure 15. nsnnnnnnlnnnulnnnnnn,nninnlnn\nnnnn,unnu\nn,ununn LL .-JA P C . 0 0 « j « . n n . c. >7 STANCE B CTWEEN SLASH'S ON THE X-AXIS IS Olsen's Extractable P (ppm) S4.CC 0.7000 II UM HI II111\ 136; - 73 -F i g u r e 1 6 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) and T r u o g ' s e x t r a c t a b l e P i n s o i l (,ppm) ( a b s c i s s a ) , f o r L - F - H h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 1 7 . 7 5 9 9 4 + 0 . 1 7 8 6 3 X a n d r = 0 . 6 3 4 1 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLKI I'H V (• V HA' VS v.MK ' .VkHULAL AXIS IS H-ftXli,. B + n c r o R C ^ N - S A POTNT OUTSIDE GRAPH. 1 36.40 • - 75 -F i g u r e 17. R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by P_. p a t u l a ( o r d i n a t e ) a n d M e h l i c h ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r L - F - H h o r i z o n m a t e r -i a l s . R e g r e s s i o n e q u a t i o n i s Y = 2 5 . 0 2 2 4 5 + 0 . 7 8 9 1 3 X and r = 0 . 6 1 1 5 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g o n t h e r e g r e s s i o n l i n e . - 76 -t M O *> tO * • co p* oo u i * t -J" I f ^ pi (q M P> f l Ki CM rsj <\i INI Ki rsi c (M fsj CM Z o > u D > U J 6-X D a — < i a a ; XJ > • * U J D b t o t n H-P •-< c u.< O' > <1 L" c C J > a >- NT: U3 u.> t o >• U.l t • Cf- o J.. s Cl L J i o l i ' • " cr m U z - J X + LX s >: » ^ • W H ^ : f> >. i x m ; « £ — i i ^ • x ii ^ • -P •v . o o •v in i v -— itj -^ K ^ ^ > ' - 77 -F i g u r e 1 8 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by £ . 1 u s i t a n i c a ( o r d i n a t e ) and M e h l i c h ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r B f h o r i z o n ma-t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 4 . 3 6 3 9 7 + 1 . 0 6 7 1 0 X a n d r - 0 . 6 0 4 7 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLOT CP Y t Y UAT V.< VAR23 .VERTICAL AXIS IS Y-AXIS. " T H E - " c PR E SE N T S A .50 . n * n A 3 f USED T C PLOT- P R F C I C T E O V A L U E S ; " ' * « I S "USED "WHEREPREDICTED VALUES CCVER 0 ATA POINTS" POINT OUTSIDE GRAPH. Figure IS. / / / / / / / / / 1 / / / / / / / / / 1 ii n i ii n 11 IIII i ii 11 ii i III II 11 III ii m i \ i i i i i i i i i \ i i i i i i i i i \ i i i i i i i i i \ i i i m i u \ - i . o->i ^ . 0 0 0 " ~ 4 . 2 0 0 " 5 . ' 4 0 0 " 6 .600 7. D I S T A N C E BETWEEN SLASHES ON THE X - A X I S IS 0 . 6 0 0 0 E - 0 1 ; Mehlich s gytrant.ahla P fppm) ; _ _ . 4 .500 800 CO - 79 -F i g u r e 1 9 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by 1 u s i t a n i c a ( o r d i n a t e ) and B r a y ' s P - l e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 1 0 . 2 1 4 5 3 + 0 . 7 9 8 6 7 X a n d r = 0 . 6 6 8 1 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLOT OF Y & YHAT v ^ vft.K^ .VERTICAL A«l S IS T-Ani». ^ q e ^ ^ - * D - - ^ U S E D " WHERE" PPEDTCTED VALUES COVER DATA POINTS M t™ P R E S E N T S A OQTNT OUTSIOE GRAPH. ! 28.30 __ 13, «, - " - 8 . 5 0 0 " 1 0 . 4 0 1 ' " ' r ^ T ^ M C E BETWEEN SLASHES OM THE X-AXIS IS C350OE-01 10 C O o - 81 -F i g u r e 2 0 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by C_. 1 u s i t a n i c a ( o r d i n a t e ) a n d mod. B r a y P - l e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 8 . 3 3 8 0 7 + 1 . 2 0 9 0 9 X a n d r = 0 . 5 1 9 5 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . • P L O T C F Y C Y H A T VK V&k^ b i V E R T I C A L A X I S I S Y - A X I S , ; THE" AMD — A O F U S F O T C P L O ^ P R E C I C T E O V A L U E S ; — TS USED WHERE PREDICTED VALUES CCVFR DATA POINTS « + REPRESENTS A POINT OUTSIDE GRAPH. 28.30 28.30 13. 30 Figure 20. - c, * 7.A"0~ n.koa y.K.u nt S T A N C E BETWEEN SLASHES ON THE X-AXIS IS 0.6000E-01 20 00 ro Modified Brav P-l Extractable P (ppm). - 83 -F i g u r e 2 1 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by fJ. 1 u s i t a n i c a ( o r d i n a t e ) and O l s e n ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n m a t e r -i a l s . R e g r e s s i o n e q u a t i o n i s Y = 6 . 5 7 0 7 6 + 0 . 4 4 5 4 1 X a n d r = 0 . 7 5 2 9 The p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLOt OF Y £ YHAT VS VAPg 6 . V E R T I C A L A X I S I S Y - A X I S . - TH= -«7*7">-«-A'NO' AP FT U S E D T O PLOT PREDICTEDVALUES: "*" IS USED WHERE PREDICTED VALUES COVER DATA POINTS it + n RFPPESfNTS A PO!N T OUTSIDE GRAPH. 28.30 13.30 Figure 21. 'in i mi in i\in mi II I in n II 111/////////111 II i in i\Iimiiivi i II i II 11 i\iiu II i iiMi II 11 mM 11 I'II m\ - i q . ? 0 ? 2 . PC " 26.40" ' 3 0 . 0 0 " 33.60 -'• n u T n ; r i : BETWEEN SLASHES ON THE X-AXIS IS 0.18CO "' "Olsen's Extractable P (ppmjj . — _ _ _ , 13.30 20 CO - 8 5 -F i g u r e 2 2 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) b y C^ . 1 u s i t a n i c a ( o r d i n a t e ) a n d T r u o g 1 s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r Ah h o r i z o n m a t e r -i a l s . R e g r e s s i o n e q u a t i o n i s Y = 1 4 . 3 6 4 1 2 + 0 . 5 7 5 3 6 X a n d r = 0 . 6 5 1 6 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . CQ 00 GO ', . — — — •(uidoj _ axq'B'icrej^ xa s Honjj, ' . 0091*0 SI SIXV-X 3Hi N O SiHSVlS N3_Hia8 dDfcViSiU o e ° e i 0£'8Z •HdVXO gOISinO i N l o d V S l N i S 3 c d 3 d S.NI0d ,_VO i>iAQ3 S3IYIVA, Q313Iti3Hd .3d3HK ..0.3Sn .SI. »»» ^mvA.^i^i^ .lO.ld. 3 i ,QiSn..afl?_ «.»»-QNV. _ + H J M * » . - 87 -F i g u r e 2 3 . R e l a t i o n s h i p b e t w e e n P u p t a k e (mg) by C . 1 u s i t a n i c a ( o r d i n a t e ) and M e h l i c h ' s e x t r a c t a b l e P i n s o i l (ppm) ( a b s c i s s a ) , f o r L - F - H h o r i z o n m a t e r i a l s . R e g r e s s i o n e q u a t i o n i s Y = 1 7 . 3 1 9 8 0 + 0 . 6 7 7 2 1 X and r = 0 . 5 1 4 1 T h e p l o t t e d n u m e r a l s a r e d a t a p o i n t s ; t h e d o t s a r e c o m p u t e r a p p r o x i m a t i o n s o f p o i n t s f a l l i n g on t h e r e g r e s s i o n l i n e . PLOT OF Y f, YHAl VJ> VAH33 .VERTICAL AXIS !S Y-AXIS. T H » •.."."•» a W — « C U S - D T C PLOT p p . E r , C " D V A L U F S , - I S USED WHERE PREDICTED VALUES COVER DATA POINTS » + * pcpqcsENTS A PO^NT OUTSIDE GRAPH. A3.00 T 18.00 mm unit 11 n in i II \ n i iiiiinmiiiiii ]'"" ' " i \ / i n " " i \ \ " " " ' " \ u ? 0 • - -Ot^TANCF BETV>C!;N SLASHFS ON TH? X-AXIS IS .0.1400 Wehllch's Extractable .?•'(ppm ie. 00 74. CO CO 

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