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Some factors affecting the extraction of sulphate from selected Lower Fraser Valley and Vancouver Island… Bart, Aldwyn Louis 1969

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SOME FACTORS AFFECTING THE EXTRACTION OF SULPHATE FROM SELECTED LOWER FRASER VALLEY AND VANCOUVER ISLAND SOILS by ALDWYN L. BART B.Sc. (Agriculture) University of the West Indies, 1965 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in tfte Department of SOIL SCIENCE We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December 1969 - i v -I n 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 an a d v a n c e d d e g r e e a t 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 , 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 make 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 and 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 may be g r a n t e d by t h e Head o f t h e Department 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 . Department 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 V a n c o u v e r 16 8, B.C., Canada Date ABSTRACT A s t u d y was u n d e r t a k e n t o d e t e r m i n e some o f t h e f a c t o r s w h i c h a f f e c t e d t h e e x t r a c t i o n o f s u l p h u r f r o m seven s e l e c t e d s o i l s o f t h e Lower F r a s e r V a l l e y and V a n c o u v e r I s l a n d ; w i t h p a r t i c u l a r r e f e r e n c e t o t h e e f f e c t o f pH, c o n c e n t r a t i o n and c a t i o n o f p h o s p h a t e b u f f e r s . I n a l l c a s e s t h e p r e s e n c e o f p h o s p h a t e r e s u l t e d i n more s u l p h u r b e i n g e x t r a c t e d , t h a n e x t r a c t i o n w i t h w a t e r o n l y . I n e v e r y i n s t a n c e i n c r e a s i n g t h e c o n c e n t r a t i o n o f n e u t r a l s o d i u m p h o s p h a t e b u f f e r s f r o m 0.005M t o 0.5M r e s u l t e d i n i n c r e a s i n g s u l p h u r e x t r a c t i o n . U s i n g a 0.5H sodium p h o s p h a t e b u f f e r and i n c r e a s i n g t h e pH f r o m 4 t o 8 g e n e r a l l y r e s u l t e d i n maximum e x t r a c t i o n a t .pH 7, e x c e p t n o t a b l y i n t h e L a n g f o r d s o i l i n w h i c h t h e amount o f s u l p h u r e x t r a c t e d i n c r e a s e d as t h e pH was changed from 4 t o 8. The b e h a v i o u r o f f o u r s u r f a c e s o i l s when e x t r a c t e d w i t h 0.5M sodium p h o s p h a t e a t v a r y i n g pH l e v e l s was q u i t e s i m i l a r , t h e m i n e r a l o g y o f t h e <2u f r a c t i o n was a l s o s i m i l a r . G e l f i l t r a t i o n s t u d i e s o f t h e 0.5M p h o s p h a t e e x t r a c t s o f t h e L a n g f o r d showed t h a t a t pH 4 l i t t l e i n o r g a n i c s u l p h a t e was e x t r a c t e d , w h i l e f r o m pH 6 t o 8, t h e amount e x t r a c t e d r e m a i n e d a l m o s t c o n s t a n t , t h ough more t h a n t h r e e t i m e s t h a t e x t r a c t e d a t pH 4. The e x t r a c t e d o r g a n i c f r a c t i o n i n c r e a s e d as t h e pH v a r i e d f rom 4 t o 8. In s o i l s with a low carbon content and a high content of free iron and aluminum oxides, the water extr-actable sulphur was very low, as was the amount of phosphate extractable organic sulphate. The amount of sulphate extracted from the orig i n a l a i r dry samples by 0.5M phosphate was very much less than the sulphate adsorbed from a 50 ppm sulphur solution. It was found that a neutral 0.5M sodium phosphate solution extracted more sulphur in nearly a l l cases, than other extractants, and i n the s o i l s studied cold water did not seem suitable. The neutral 0.5M phosphate solution extracted inorganic and a portion of the organic sulphate and may be expected to be a suitable chemical extractant which w i l l be able to indicate the sulphur status of s o i l s of the Lower Fraser Valley. - v -ACKNOWLEDGMENTS The author wishes to express his thanks to Dr. L. E. Lowe, Assistant Professor, Department of Soil Science, for suggesting the study and for his constant interest, encouragement and advice. Thanks are also expressed to the members of the Department of Soi l Science for many useful suggestions and in particular to Miss P. Dairon and Dr. L. M. Lavkulich for their help i n the mineralogical study. The financial support obtained through the Faculty of Agricultural Sciences Research and Development Fund i s also acknowledged. - v i -TABLE OF CONTENTS Page INTRODUCTION 1 LITERATURE REVIEW 3 MATERIALS 41 EXPERIMENTAL METHODS 41 Determination of Total Sulphur i n S o i l 41 Determination of HI-Reducible Sulphur 4 2 Extraction Procedures Used in the Study of Soil Sulphate 42 Separation of Phosphate Extractable Sulphate into i t s Organic and Inorganic Fractions 4 3 Determination of Total Carbon 4 5 Free Alumina and Free Oxides of Iron 45 X-Ray Diffraction Analyses for the <2u Fraction 45 So i l pH 46 Adsorption Capacity 46 RESULTS AND DISCUSSION 47 Factors Affecting the Extraction of Soil Sulphate 47 Effect of Cation 5 6 Adsorption Capacity 6 6 The Separation of the Extracted Sulphur into Their Organic and Inorganic Fractions 71 Reduction in the Time of Analysis 76 SUMMARY AND CONCLUSIONS REFERENCES v x x i -LIST OF TABLES Table I II III IV VI VII VIII IX X XI XII XIII Some s o i l properties Mineral distribution in <2u f r a c t i o n Amounts o f sulphate extracted a t pH 7 with phosphate b u f f e r s of varying concentration (ppm S) Amounts of sulphate e x t r a c t e d w i t h 0.5M phosphate b u f f e r s a t v a r y i n g pH levels (ppm S) Amounts of sulphate extracted with 0.05M phosphate buffers at varying pH levels (ppm S) Amounts of sulphate extracted with 0.05M Ca(H 2P0 1 +) 2 at pH 3.5 (ppm S) Amounts of sulphate extracted w i t h 0.5M NH^F, pH 6 Extractable S as percent o f HI and tot a l S (ppm S) Cold water extraction for s u l p h a t e sulphur Adsorption capacities for the sulphate ion and free iron and aluminum oxides Desorption of adsorbed sulphate by a 0.5M sodium phosphate solution a t pH 7.0 (ppm S) Sulphate in water wash and 0.5M phosphate extract at pH 7.0 as a percentage of to t a l adsorbed The separation of 0.5M phosphate extracts at pH 7.0 into their organic and inorganic components. Inorganic SO. = Total extract -Organic S0 a (ppm S) Page '+8 49 53 54 55 57 58 6 1 65 67 69 70 74 - ix -Table XIV Page Fractions extracted with increasing pH for Langford 0"-6" (ppm S). Inorganic = Total e x t r a c t - Organic fraction 7 5 - X -L I S T OF FIGURES F i g u r e P a S e pH 7 . 0 C o n c e n t r a t i o n o f P h o s p h a t e V a r y i n g Between 0 . 0 0 5 M and 0 . 5 M 5 0 2 0 . 5 M Sodium P h o s p h a t e E x t r a c t a n t pH V a r y i n g f r o m 4 . 0 t o 8 . 0 5 2 INTRODUCTION Sulphur has been described as the nutrient element slighted in agricultural research (Alway, 1940); though i t s essentiality has been known from the time of Liebig (Coleman, 1966). Indeed, i t i s only recently that this element has been receiving the attention i t deserves. Sulphur affects not only the yield of crops, but in certain cases the quality also (Newton et a l . , 1959; Freid, 1948; Rendig and Weir, 1957; Walker, 1955). Sulphur i s a constituent of a number of plant compounds, most important of these are the plant proteins valuable in animal nutrition. The importance to human and animal nutrition cannot be over-emphasized and i t i s considered that the lack of sulphur-containing amino acids i s one of the factors that limits the biological value of proteins (Odelein, 1963). The general path of sulphur in the cycle of l i f e i s s o i l to plant to animal, hence the importance of under-standing the reactions of s o i l sulphur and the continuing attempt to determine the a v a i l a b i l i t y of sulphate in so i l s by chemical extraction. A number of extractants have been used to estimate the available sulphur fraction in s o i l and of these phosphate solutions appear to be the most promising. Their effectiveness - 2 -as a s u l p h a t e e x t r a c t a n t was r e p o r t e d by E n s m i n g e r ( 1 9 5 4 ) , who e x t r a c t e d c o m p a r a t i v e l y l a r g e amounts o f s u l p h u r w i t h a 500 ppm P s o l u t i o n , b u t l i t t l e o r none w i t h a 0.1 N HC1 s o l u t i o n . S p e n c e r and F r e n e y (1960) f o u n d t h a t o n l y h o t w a t e r s o l u b l e and h e a t s o l u b l e e x t r a c t i o n s removed more s u l p h u r f r o m s o i l s t h a n p h o s p h a t e s o l u t i o n s . Fox e t a l . , (1964) r e p o r t e d t h a t s o l u b l e s u l p h a t e p l u s a f r a c t i o n o f t h e a d s o r b e d was e x t r a c t e d by p h o s p h a t e s o l u t i o n s . The g e n e r a l , f a c t o r s a f f e c t i n g s u l p h u r e x t r a c t i o n w i t h p h o s p h a t e b u f f e r s a r e n o t w e l l known, a l s o , r e l a t i v e l y l i t t l e i s known o f t h e s u l p h u r s t a t u s o f B r i t i s h C o l u m b i a s o i l s . I n v i e w o f t h i s t h e o b j e c t i v e s o f t h i s i n v e s t i g a t i o n were: (a) To s t u d y t h e f a c t o r s w h i c h a f f e c t p h o s p h a t e e x t r a c t i o n and i n p a r t i c u l a r t h e c o n c e n t r a t i o n , pH and c a t i o n o f t h e p h o s p h a t e e x t r a c t a n t . (b) To s t u d y t h e forms o f s u l p h u r e x t r a c t e d and i n p a r t i c u l a r , s o l u b l e , a d s o r b e d , o r g a n i c and i n o r g a n i c f o r m s . - 3 -LITERATURE REVIEW T o t a l S u l p h u r o f S o i l s The t o t a l s u l p h u r c o n t e n t o f s o i l i s v a r i a b l e , b u t i m p o r t a n t s i n c e i t g i v e s an i n d i c a t i o n o f t h e e x i s t i n g r e s e r v e s w h i c h may be c o n v e r t e d by b a c t e r i a l o r c h e m i c a l a c t i o n i n t o t h e s u l p h a t e f o r m w h i c h p l a n t s can u t i l i z e . Lowe (1963) and a l s o W h i t e h e a d (1964) summarized t h e t o t a l s u l p h u r c o n t e n t o f s o i l s as r e p o r t e d by v a r i o u s w o r k e r s i n a number o f c o u n t r i e s . The v a l u e s r a n g e d f r o m 0.0010 p e r c e n t f o r c u l t i v a t e d m i n e r a l s o i l s i n Oklahoma t o 0.73 p e r c e n t f o r o r g a n i c s o i l s i n A l b e r t a . T o t a l s u l p h u r d e t e r m i n a t i o n i n some E a s t e r n C a n a d i a n s o i l s , c h i e f l y p o d z o l s w h i c h were sampled by h o r i z o n , gave v a l u e s o f 0.008 t o 0.207 p e r c e n t ( M a c K e n z i e e t a l . , 1967). These w o r k e r s f o u n d t h a t t h e r e was no r e l a t i o n between t o t a l s u l p h u r , g e o g r a p h i c l o c a t i o n and s o i l u s e . S o i l s u l p h u r o c c u r s i n many f o r m s , t h e s e a r e : o r g a n i c s u l p h u r , w a t e r - s o l u b l e s u l p h a t e , a d s o r b e d s u l p h a t e , i n s o l u b l e s u l p h a t e c o p r e c i p i t a t e d w i t h c a l c i u m c a r b o n a t e and r e d u c e d i n o r g a n i c s u l p h u r compounds (*Beaton , 1968 ) . O r g a n i c S u l p h u r B a r d s l e y and L a n c a s t e r (1960) s t a t e d t h a t t h e o r g a n i c s u l p h u r s h o u l d be t a k e n i n t o a c c o u n t when e v a l u a t i n g t h e s u l p h u r s t a t u s o f s o i l s . T h i s i s due t o i t s p o t e n t i a l as a s o u r c e o f n u t r i e n t f o r p l a n t s . * B e a t o n , J.D. 1968. U n p u b l i s h e d p a p e r ; P r e s e n t e d a t S o i l and P l a n t A n a l y s t s ' Workshop, C h i c a g o , I l l i n o i s . December 12, 1968. The major portion of the sulphur in well drained agricultural s o i l s of the humid region occurs in the surface layers. This fact has been shown by many workers. Hess, 1958, in studying the distribution of sulphur in the muds, water and vegetation of Lake Victoria found that the sulphur occurred in organic form up to 1.0 percent, in samples of mud of various thickness at 2-9 metres depth and deeper. Indications were that the muds were aerated, as i l l u s t r a t e d by the low sulphide content, less than 20.0 ppm. In well-drained grassland s o i l s most of the sulphur occurred in the organic matter (Walker, 1957). In a coarse and a fine sandy loam s o i l more of the sulphur occurred in the organic form (Kamprath, Nelson and F i t t s , 1957). In a meadow dark brown s o i l about 90 percent of the sulphur was in the ploughed layer (Shkonde, 1957) and was organic. The view that most of the s o i l sulphur in humid regions i s organic i s supported by Freney et a l . , 1962 ; Harward, Chao and Fang, 1962 ; Jordan, 1964; and Lowe, 1964 and 1965. Values for the organic sulphur fraction in soils ranged from 65-70 percent of the tot a l sulphur in chernozems and black prairie so i l s (Evans and Rost, 1945) 50 percent for chesnut and 7 5 percent for chernozems in Russia (Madanov, 1946) 60-70 percent for two podzols and 33 percent for a brown forest from Quebec (Lowe and Delong, 1961). Shkonde (1957) reported 90 percent in the ploughed layer of meadow dark brown s o i l s . - 5 -I n o r g a n i c Sulphur Except f o r s o i l s i n a r i d and semi a r i d r e g i o n s , which may accumulate s u l p h a t e s a l t s and i n which the behaviour of sulphate i s dominated by the s o l u b i l i t y of gypsum ( R e i t e m e i e r , 1946 ; Dutt and Anderson, 1964) , the i n o r g a n i c sulphate l e v e l i n most s o i l s i s g e n e r a l l y c o n s i d e r e d t o be l e s s than 2 5 percent of the t o t a l s u l p h u r (Burns, 1967) and i n s u r f a c e s o i l s the f i g u r e seems t o be l e s s than 10 percent (Harward and Reisenauer, 1965). In s u b s o i l s the i n o r g a n i c f r a c t i o n may r e p r e s e n t a s i g n i f i c a n t p o r t i o n of the t o t a l (Harward and Reisenauer, 1966). I t i s now thought t h a t the percentages of s u l p h a t e s u l p h u r based on e a r l i e r analyses may be low as r e l a t i v e l y l a r g e q u a n t i t i e s o f s u l p h a t e sulphur a s s o c i a t e d w i t h the s o i l o r g a n i c matter may have been excluded from the r e s u l t s of e a r l i e r s u l p h a t e determin-a t i o n s because of the nature of the e x t r a c t i o n procedures (Burns, 1967 ). Most s o i l s have some c a p a c i t y t o r e t a i n sulphate (Harward and Reisenauer, 1966 ) . Ensminger (1954) determined the sulphate content and a d s o r p t i o n c a p a c i t y o f 12 Alabama s o i l s . He found t h a t l e a c h i n g these s o i l s w i t h water or d i l u t e h y d r o c h l o r i c a c i d f a i l e d t o e x t r a c t any s u l p h a t e , whereas l e a c h i n g w i t h phosphate o r a c e t a t e s o l u t i o n s r e s u l t e d i n the e x t r a c t i o n of l a r g e amounts of s u l p h a t e . Thus, the adsorbed form should be d i s t i n g u i s h e d from the s o l u b l e form even though water e x t r a c t i o n may u l t i m a t e l y - 6 -r e s u l t i n t h e r e p l a c e m e n t o f a d s o r b e d s u l p h a t e ( R e i s e n a u e r , 1967), The h i g h l y weathered s o i l s , which o c c u r i n r e g i o n s o f h i g h r a i n f a l l i n t h e South E a s t e r n U n i t e d S t a t e s , P a c i f i c N o r t h West and C e n t r a l and South A m e r i c a , namely, the r e d -y e l l o w p o d z o l s ( u l t i s o l s ) and l a t o s o l s ( o x i s o l s ) , c o n t a i n a p p r e c i a b l e amounts o f a d s o r b e d s u l p h a t e o r have the a b i l i t y t o a d s o r b (Chao, Harward and Fand, 1962; Kamprath, 1968). Indeed, Kamprath i n 196 8 s t a t e d t h a t the forms and r e a c t i o n s o f s u l p h u r i n t h e s e h i g h l y weathered s o i l s were q u i t e d i f f e r e n t from s o i l s o f t h e sub-humid a r i d and s e m i - a r i d r e g i o n s and t h a t i f p o s i t i o n a l l y a v a i l a b l e ; t h i s s u l p h a t e i s an i m p o r t a n t s o u r c e o f a v a i l a b l e s u l p h u r . S u l p h u r Content o f S o i l s Any assessment o f t h e a v a i l a b l e s u l p h u r o f s o i l s i s c o m p l i c a t e d by the m u l t i p l i c i t y o f s o u r c e s o f s u l p h u r and t h e i r magnitude. The amount o f s u l p h u r i n a s o i l w i l l be d e t e r m i n e d by t h e f a c t o r s which add s u l p h u r and t h o s e which remove i t . The o r i g i n a l s o u r c e o f most s o i l s u l p h u r was d o u b t l e s s t h e s u l p h i d e s o f m e t a l s c o n t a i n e d i n p l u t o n i c r o c k s ( T i s d a l e and N e l s o n , S o i l F e r t i l i t y and F e r t i l i z e r s , 1966) . S u l p h u r i s b rought down i n r a i n water, however, i t i s not known what p r o p o r t i o n o f t h i s becomes a v a i l a b l e t o p l a n t s (Whitehead, 1964). In a s u r v e y o f some o f the d a t a f o r the amounts o f s u l p h u r i n p r e c i p i t a t i o n i n v a r i o u s p a r t s o f the w o r l d , the v a l u e s f o r s u l p h u r i n p r e c i p i t a t i o n _ 7 -ranged from 100 l b s u l p h u r per acre per year t o 1 l b or l e s s i n some i n l a n d areas o f A u s t r a l i a , New Zealand and A f r i c a , the h i g h e r values o c c u r r e d i n the immediate v i c i n i t y of i n d u s t r i a l c i t i e s . Seasonal t r e n d s i n the q u a n t i t y brought down have been noted (Jordan and Ensminger, 19 5 8) . The s u l p h u r i n r a i n water at I t h a c a , New York, averaged 3 7.63 l b acre f o r 6 months from November t o A p r i l and 11.23 l b f o r the s i x months from May t o October ( L e l a n d , 1952). The h i g h e r values f o r the w i n t e r months were a t t r i b u t e d t o the consumption of c o a l f o r home h e a t i n g ( L e l a n d , 1952 ). Sulphur i s a l s o added i n i r r i g a t i o n water. W e l l water used f o r i r r i g a t i o n i n Idaho added from about 25 l b per acre f o o t t o 700 l b (Jensen e t a l . , 1951). Data f o r r i v e r water per acr e f o o t was from 3 t o 1849 l b per acre f o o t (Thorne and P e t e r s o n , 1954) . S o i l s and p l a n t s absorb sulphur d i o x i d e and perhaps o t h e r sulphurous gases d i r e c t l y from the atmosphere (Coleman, 1966). Alway et a l . , i n 1937, compared the a b s o r p t i o n of sulphurous gases d i r e c t l y from the atmosphere by s o i l and le a d peroxide c y l i n d e r s of the same area. The values f o r a loam and a loamy sand were from 0.99 l b per acre t o 2.03 and r e p r e s e n t about 22.0 percent of the a b s o r p t i o n by the c y l i n d e r s . The work of Johansson (19 5-9) supported the e a r l i e r f i n d i n g s , indeed t h i s work confirms t h a t near to h i g h - 8 -i n d u s t r i a l a c t i v i t y the sulphur added d i r e c t l y from the a i r exceeds by a f a c t o r of 3 t o 5 the s u l p h u r added t o the s o i l through p r e c i p i t a t i o n . Sulphur may a l s o be added t o the s o i l supply from sea s p r a y , v o l a t i l e s u l p h i d e s from the sea, as found on the c o n t i n e n t a l s h e l f o f f the coast of I r e l a n d ( E r i k s o n , 1959 and 1960). Large amounts of s u l p h u r are s u p p l i e d t o the s o i l system i n c i d e n t a l l y by v a r i o u s a g r i c u l t u r a l p r a c t i c e s . The data f o r the s u l p h u r content of f e r t i l i z e r s , manures and s o i l amendments are summarized by Mehring and Bennett (1950). Sulphate of ammonia (23-24 percent s u l p h u r ) and superphosphate (12 percent average), both w i d e l y used f e r t i l i z e r s , can be expected t o supply the sulphur requirements of most cr o p s . The present t r e n d i s towards the use of h i g h e r a n a l y s i s and purer f e r t i l i z e r s which w i l l l i k e l y c o n t a i n l e s s s u l p h u r ,. (Jordan and Ensminger, 1958 ; Coleman, 1966 ) . Jensen (1963 ) i n d i c a t e d t h a t i t was not p o s s i b l e by use o f f e r t i l i z e r s t o i n c r e a s e the sulphur content of s o i l t o the plow depth by sulphur c o n t a i n i n g f e r t i l i z e r s and t h a t only by i n c r e a s i n g the o r g a n i c matter content c o u l d t h i s be a t t a i n e d . The use of f u n g i c i d e s e.g. Bordeaux, s u p p l i e d s u l p h u r t o the s o i l . Sulphur added i n t h i s manner f o r d i s e a s e c o n t r o l may amount to 50 t o 60 l b per acre (Jordan and Ensminger, 19 5 8 ) . Modern f u n g i c i d e s e.g. Zineb, w i l l add much s m a l l e r q u a n t i t i e s of sulphur and are a l s o a p p l i e d at much lower r a t e s (Whitehead, 1964) . - 9 -A g r i c u l t u r e as a whole accounts f o r 40 percent of the t o t a l annual world consumption o f s u l p h u r (Coleman, 1966). The a d d i t i o n s of su l p h u r t o the s o i l - p l a n t system tend t o be o f f s e t by the c o n t i n u a l l o s s e s which occur. P l a n t removal, l e a c h i n g and e r o s i o n are the p r i n c i p a l ways i n which s o i l s ulphur i s l o s t (Jordan and Ensminger, 1958) . In g e n e r a l , crops r e q u i r e about the same amount of sulphur as they do phosphorus. B r a s s i c a and L i l i a c e a e have u n u s u a l l y h i g h requirements and c o n t a i n 2 0 t o 40 l b per acre of the element i n t h e i r t o p s . Legumes remove about 15 t o 3 0 l b per acre and s m a l l g r a i n s , grasses and corn r e q u i r e about 15 l b per acre or l e s s (Jordan and Ensminger, 1958; Beaton, 1966; S t a n f o r d and Jordan , 1966; Relsenauer, 1967). Sulphur i s removed from s o i l by l e a c h i n g . This l o s s occurs c h i e f l y as s u l p h a t e s ; t h i s i s due t o i t s a n i o n i c nature and the s o l u b i l i t y of most of i t s common s a l t s . These l o s s e s may be q u i t e h i g h on f i n e t e x t u r e d s o i l s . However, the amount of sul p h a t e l o s t by l e a c h i n g v a r i e s w i d e l y ( T i s d a l e and Nelson, 1966). The movement of sulphate w i t h i n s o i l s determines the magnitude of l o s s e s of the element i n drainage waters (Harward and Reisenauer, 1966). Some values i l l u s t r a t i n g the magnitude of l e a c h i n g l o s s e s are given by a number of workers, f i g u r e s quoted by Jordan - 10 -and Ensminger (1958) are 35 to 55 lb of sulphur per acre per year in I l l i n o i s , 4 3 lb per acre in New York, 1 lb per acre from cropped s o i l and 3 lb for uncropped i n Wisconsin. The extremes of loss of sulphur by leaching are given as in s i g n i f i c a n t l y small amounts up to 285 lb per acre per annum (Harward and Reisenauer, 1966). The loss was found to be greatest from soils well supplied with sulphur (Harward and Reisenauer, 1966). The role of adsorption reactions in leaching was evidenced by the more rapid and complete removal of chloride than sulphate from acid s o i l s , greater losses of sulphur from s o i l s that had been limed or f e r t i l i z e d with phosphate and smaller losses of sulphur from banded than from broadcast application of sulphur f e r t i l i z e r s (Harward and Reisenauer, 1966) . Extraction of Available Sulphur from Soils A renewed interest in sulphur as a plant nutrient has followed numerous reports of crop responses (Freney, Barrow and Spencer, 1962). In fact, sulphur deficient areas are rather widespread and crop deficiencies have been reported in Central and South Afr i c a , India, B r a z i l , Argentina, Central America, Europe, Australia, New Zealand, Canada and the United States (Coleman, 1966; Freney, Barrow and Spencer, 1962) . - 11 -These sulphur deficiencies are occurring probably because of the increased use of sulphur free f e r t i l i z e r s , the decreased use of sulphur as a fungicide and insecticide and increased crop yields, which means increased requirements (Coleman, 1966). As a result of the increasingly important part now being played by sulphur i n l i m i t i n g crop yields, numerous investigations are now being made into the chemistry of s o i l sulphur and the factors governing the supply of sulphur to plants. The investigations have been directed to determining the mechanism of sulphate adsorption, the factors affecting adsorption and desorption, the fractions extracted by various procedures, the correlation between plant growth and extraction using a variety of chemical extractants, and f i n a l l y the determination of the extracted fractions. Reisenauer (196 7) states that the appraisal of available s o i l nutrients and particularly the nutrient anions, is complicated by the lack of complete understanding of the chemical forms of these elements in the s o i l and the absence of complete knowledge of the plant factors determining absorption and u t i l i z a t i o n of nutrient elements. A chemical extractant to determine available s o i l sulphur must be empirical i f the chemistry i s unknown, so that before an . extractant is used on a rational basis It i s imperative that the forms and reactions of the various fractions be understood either wholly or p a r t i a l l y . - 12 -The principal plant available forms of sulphur in agricultural s o i l s are those released i n the decomposition of s o i l organic matter; the readily soluble sulphate; t h e sulphate adsorbed by the mineral fraction; and that added from the atmosphere, or in i r r i g a t i o n waters or incidentally as a f e r t i l i z e r constituent or in disease and insect control chemicals (Reisenauer, 1967) . Some sulphate forms found are insoluble sulphate, that coprecipitated with calcium carbonate and reduced inorganic sulphur compounds (*Beaton, 1968). Bardsley and Lancaster (1965) stated that organic sulphur should be included in the evaluation of the sulphur status of s o i l s , because i t represents a potential supply of this nutrient for plant growth. Before organic sulphur becomes available to plants, conversion t o inorganic sulphate or small uncombined organic sulphur compounds such as cysteine or methionine i s necessary (Freney and Stevenson, 1966) . Very l i t t l e i s known about th e organic forms of sulphur in s o i l s and the constituent sulphur compounds in this fraction (Freney, Barrow and Spencer, 1962 ; Kononova, 1966). It is assumed that proteins, polypeptides and amino acids are present to some extent because plant, animal and microbial residues contain these forms, but i t i s unknown whether they '''Beaton, J.D. 1968. Unpublished paper; Presented at Soil and Plant Analysts' Workshop, Chicago , I l l i n o i s . December 12, 196 8. - 13 -persist for any appreciable time (Freney, Barrow and Spencer, 1962). The organic sulphur fraction can be conveniently divided into two fractions (a) the carbon-bonded fraction and (b) the HI reducible non-carbon-bonded fraction (Belong and Lowe, 1962 ; Lowe , 1964 , 1966 ) . The f i r s t fraction includes a l l forms of organic sulphur except covalent sulphate and alkyl sulphones; amino acids and p r o t e i n s are thought to belong to this fraction (Beaton et a l . , 1968). Starkey (1950) suggested that though a great variety of organic sulphur compounds are present in s o i l organic matter they a r e susceptible to decomposition and so do not accumulate and are not readily detected. Whitehead (1964) calculated that 11 to 16 percent of the total sulphur in 4 soils was present in amino acid form and suggested s t a b i l i z a t i o n of the sulphur during humus formation. Freney and Stevenson (1966) reported that somewhat more than half of the carbon-bonded sulphur in s o i l would occur in compounds other than cysteine, cystine or methionine. Lowe (196 9) reported that in nine Alberta s o i l s , 39 percent of the carbon-bonded sulphur in the humic acid fraction was recovered as amino acid sulphur after hydrolysis. The non-carbon-bonded sulphur fraction includes forms such as ester sulphates, where the sulphur is separated - 14 -from the carbon atom by an oxygen atom -C-0-S-; -C-N-S-linkages are also possible (Beaton et a l . , 1968). Freney (1961) t r i e d mild desulphation with methanolic hydrogen chloride, in an attempt to extract covalently bound sulphate from s o i l organic matter, by the formation of methyl sulphate and he suggested that this fraction can account for considerable amounts of sulphate. It is thought that this non-protein sulphur could include sulphated polysaccharides or sulphate esters of phenols. Polysaccharides may constitute up to 30 percent of the s o i l organic matter (Parsons and Tinsley, 1961). Small quantities of sulphated polysaccharides have been isolated from Alberta s o i l s (Lowe, 1968). The inorganic sulphate in surface soil s accounts for about 6 percent of tota l sulphur (Freney, 1961). Other inorganic forms with a lower oxidation state than sulphate, for example sulphides, sulphites, thiosulphate, elemental sulphur, and polysulphides may only be responsible for 1.0 percent of the tota l Sulphur (Freney, 1961). A figure of 10 percent for inorganic sulphur was given by Harward and Reisenauer (1966) for surface soil s though for subsoils these workers said that the inorganic fraction may represent a . significant fraction. Burns (1967) suggests that though i t has been the belief that most s o i l s , except in dry areas where sulphate may accumulate, contain less than 25 percent of their total sulphur in the inorganic sulphate form and many soils - 15 -considerably less, this figure may be an underestimation of to t a l sulphate as r e l a t i v e l y large quantities of organic sulphate sulphur may not have been included in the results of e a r l i e r sulphate determination due to inadequate extraction procedures. The inorganic sulphate consists of water-soluble sulphate, adsorbed sulphate, insoluble sulphate, insoluble coprecipitated with calcium carbonate and reduced inorganic sulphur compounds ("Beaton, 196 8). Soluble sulphate i s readily absorbed by plants and represents an immediately available supply for their growth. The movement, reactions and adsorption of sulphur by plants occur predominantly as sulphate (Harward and Reisenauer, 1966 ) . The sulphates of barium and strontium are extremely insoluble. Calcium sulphate has a low but significant s o l u b i l i t y and i s steadily removed by continuous leaching, the sulphates of magnesium, potassium and sodium are readily soluble (Whitehead, 1964). In humid areas with thorough leaching, a l l sulphate salts, except the infrequent barium and strontium sulphates, are subject to removal (Whitehead, 1964). In arid areas the behaviour of sulphate involves mainly solution and precipitation of gypsum. The main factors affecting s o l u b i l i t y are s o i l *Beaton, J.D. 1968 . Unpublished paper; Presented at Soil and Plant Analysts' Workshop, Chicago, I l l i n o i s . December 12, 1968. - 16 -moisture content, common ion effect and ionic strength. The sulphate i n solution increased on dil u t i o n for a l l s o i l s except one low in gypsum (Reitemeier, 1946). Insoluble sulphate coprecipitated with calcium carbonate may comprise an important fraction of s o i l sulphur and one s o i l contained 9 3 percent of i t s sulphur in this form (Williams and Steinbergs, 1962). This sulphate probably occurs as a cocrystallized impurity with calcium carbonate. Most surface soils contained only a l i t t l e sulphur in this form (Williams and Steinbergs, 1962). Harward and Reisenauer (1966) reviewed the chemical reactions of inorganic sulphur in solution. The factors affecting the loss of sulphur and the a b i l i t y of soils to adsorb sulphate received slight attention (Jordan and Ensminger, 1958). In 1927 Mattson demonstrated adsorption of sulphate by some s o i l colloids and the increasing adsorption capacity of a Norfolk s o i l c o l l o i d with increasing acidity. The adsorption capacity of iron and aluminium hydrogels and their a b i l i t y to adsorb sulphate was shown (Lichtenwalner et al_. , 1923). Ensminger (1954) determined some factors which affected the adsorption of sulphate by 12 Alabama s o i l s . He found no acetate extractable sulphate in the A horizon of any of the s o i l s , but some of the B and C horizons contained appreciable quantities of sulphate in - 17 -this form. The B and C horizons showed a capacity to adsorb sulphate as also did aluminium oxide. Kamprath et a l . ( 1 9 5 6 ) showed that sulphate adsorption decreased with Increasing pH and that very l i t t l e sulphate was adsorbed above pH 6 . 0 . This agrees with Ensminger's findings in 1 9 5 4 that lime reduced the extractable sulphate in the six to twelve inch layer of a Eutaw clay. Liming increased the outgo of sulphate in water collected in lysimeter studies (Maclntire et a l . , 1 9 4 5 ) . Ensminger ( 1 9 5 4 ) found that phosphate reduced the retention of sulphate of a Cecil sandy clay loam and that dilute phosphate solutions 500 ppm phosphorus was effective in extracting sulphate from s o i l s . Chao et a l . ( 1 9 6 2 ) found that phosphate increased the movement of sulphate in their column studies. The same conclusion was reached by Kamprath et a l . ( 1 9 5 6 ) when he found that phosphate was effective in reducing sulphate adsorption. The highly weathered red-yellow podzols and latosols which usually occur in regions of high r a i n f a l l and temperature contain appreciable amounts of adsorbed sulphate or are able to adsorb sulphate (Ensminger, 1 9 5 4; Jordan and Bardsley, 1 9 5 8 ; Chao et a l . , 1 9 6 2 ; Kamprath, 1 9 6 8 ) . The factors which influence sulphate sorption by so i l s are summarized by Harward and Reisenauer, 1966 , as follows: (a) Soil horizon. Most soils have some capacity to retain sulphate. The amounts of sulphate in surface - 18 -h o r i z o n s may be l o w and a r e o f t e n g r e a t e r i n l o w e r s o i l h o r i z o n s . (b) S o i l m i n e r a l . K a o l i n m i n e r a l s r e t a i n more s u l p h a t e t h a n t h e m o n t m o r i l l o n i t e g r oup o f c l a y s . ( c ) Hydrous o x i d e s . A l u m i n i u m and i r o n o x i d e s show a marked t e n d e n c y t o r e t a i n s u l p h a t e . (d) pH. R e t e n t i o n o f s u l p h a t e i n c r e a s e s as pH d e c r e a s e s . ( e ) S u l p h a t e c o n c e n t r a t i o n . The amount o f a d s o r p t i o n i s c o n c e n t r a t i o n d e p e n d e n t . A d s o r b e d s u l p h a t e i s i n k i n e t i c e q u i l i b r i u m w i t h s u l p h a t e i n s o l u t i o n . ( f ) P r e s e n c e o f a n i o n s . S u l p h a t e i s g e n e r a l l y c o n s i d e r e d t o be h e l d w i t h t h e s t r e n g t h o f r e t e n t i o n i n t h e o r d e r p h o s p h a t e > s u l p h a t e > n i t r a t e = c h l o r i d e . P h o s p h a t e w i l l d i s p l a c e o r reduce t h e a d s o r p t i o n o f s u l p h a t e b u t s u l p h a t e has l i t t l e o r no e f f e c t on p h o s p h a t e . From t h e s t u d i e s o f Chao e t a l . (1962 ) i t a p p e a r s t h a t e x t r a c t i o n w i t h w a t e r w i l l u l t i m a t e l y r e s u l t i n t h e r e p l a c e m e n t o f a d s o r b e d s u l p h a t e . F o u r s u c c e s s i v e w a t e r e x t r a c t i o n s removed 71 t o 80 p e r c e n t o f added a d s o r b e d s u l p h a t e f r o m two a c i d Oregon s o i l s . (g) The e f f e c t o f c a t i o n s . The amount o f s u l p h a t e r e t a i n e d i s a f f e c t e d by t h e a s s o c i a t e d c a t i o n o f t h e s a l t o r by t h e e x c h a n g e a b l e c a t i o n . T h i s e f f e c t f o l l o w s - 19 -the lyotropic series H > Sr > Ba > Ca > Mg > Rb > K > NH^  > Na > L i . The cation of the salt may be retained in addition to the sulphate, (h) Organic matter. Removal of organic matter from three so i l s with high adsorption capacities resulted in a marked reduction of this property (Chao et a l . , 1962). This i s d i f f i c u l t to explain since other soils containing similar amounts of organic matter had been found to adsorb only small amounts of sulphate (Whitehead, 1964 ) . Definite sulphate adsorption capacities were not found for soils studied by Chao et a l . (1962). This indicated that mechanisms other than simple anion exchange were involved. There are several mechanisms by which sulphate may be held (Whitehead, 1964). Some of these are given by Harvard and Reisenauer (1966). The main s o i l constituents participating in sulphate adsorption are hydrated aluminium and iron oxides. Red-yellow podzolic and l a t e r i t i c s o i l s were very effective in removing sulphate from solution (Mattson, 1927). Sulphate retention was much greater in soils containing large amounts of these constituents than in soils dominated by 3-layer clay minerals (Kamprath, Nelson and F i t t s , 1956; Berg and Thomas, 1959). Colloids with a high iron oxide content had a large adsorption - 20 -capacity (Kamprath, 1968). Soils with a much higher content of iron and aluminium had an appreciable a b i l i t y to hold sulphate against leaching. Removal of the hydrous oxides of iron and aluminium resulted in a marked reduction in their sulphate adsorption capacity (Chao et a l . , 1962 ). In acid soil s the hydrous iron and aluminium oxides tend to form co-ordination complexes due to the donor properties of oxygen. The complexes are polymeric with various proportions +++ --' OH of aquo (-M-0H2) , hydroxo (-M-0H) , o l ( - M ^ ^ M - ) , and oxo (-M'Q^M-) groups. The proportion of aquo to hydroxo and o l groups and consequently the charge i s determined by the equilibrium pH. The formation and composition of c o l l o i d a l l y dispersed hydrous oxides and precipitates may be explained on the basis of olation, oxolation and anion penetration (Rollinson, 1956 ). Anion penetration involves the rupture of the hydrous oxide surface by breaking of aquo, hydroxo or oxo linkages and replacement of the aquo, hydroxo or ol groups by anions such as sulphate (Harward and Reisenauer, 1966 ) and is directly related to the a b i l i t y of an anion to co-ordinate with the metal cation. Oxyanions like sulphate have donor properties and can replace aquo, hydroxo or ol groups in the co-ordination complex (Bailar, 1956 ) . Sulphate is a moderately strong - 21 -c o - o r d i n a t o r w i t h a l u m i n i u m ( M a r i o n and Thomas, 1 9 4 6 ) . P e n e t r a t i o n by s u l p h a t e a n i o n s r e s u l t s i n an i n c r e a s e i n pH due t o d i s p l a c e m e n t o f h y d r o x o o r o l g r o u p s ( R o l l i n s o n , 1956) . T h i s p e n e t r a t i o n o c c u r s upon t h e a d d i t i o n o f s u l p h a t e s a l t s t o a l u m i n i u m o x i d e s o l s , t h e d i s p l a c e d OH i o n s a r e n e u t r a l i z e d by r e a c t i o n w i t h t h e H i o n s f o r m e d by h y d r o l y s i s o f a l u m i n i u m i o n s i n t h e p r e s e n c e o f t h e s e s u l p h a t e s a l t s e.g. f e r t i l i z e r s a l t s ( K a m p r a t h , 1 9 6 8 ) . T h i s t y p e o f r e a c t i o n has been d e m o n s t r a t e d f o r s o i l s y s t e m s by measurement o f pH d i f f e r e n c e s i n K^SO^ and KC1 s a l t s o l u t i o n s (Chao e t a l . , 1 9 6 5 ) . S u l p h a t e gave h i g h e r pH v a l u e s t h a n c h l o r i d e w i t h d i f f e r e n c e s b e i n g g r e a t e s t i n s o i l s h i g h i n Fe and A l h y d r o u s o x i d e s . The a d s o r p t i o n o f s u l p h a t e by s o i l s may i n v o l v e two s t e p s . The f i r s t r a p i d c o n v e r s i o n i s p r o b a b l y due t o r e a c t i o n w i t h s u r f a c e g r o u p s , w h i l e t h e s l o w e r r e a c t i o n may be due t o a r a t e l i m i t i n g r u p t u r e o f o l and oxo l i n k a g e s and a n i o n p e n e t r a t i o n . T h i s i n c r e a s e d a d s o r p t i o n o f s u l p h a t e w i t h t i m e was shown by Chang and Thomas (196 3 ) . R e a c t i o n s o f a c i d w i t h h y d r o u s a l u m i n a a l s o o c c u r i n two s t e p s (Graham and Thomas, 194 7) . The i n t e r a c t i o n o f pH and h y d r o u s o x i d e s on s u l p h a t e a d s o r p t i o n has been d e m o n s t r a t e d (Kamprath e t a l . , 1956; Berg and Thomas, 1959; Chao e t a l . , 1 9 6 3 ) . S t r o n g l y a c i d c o n d i t i o n s a r e most f a v o u r a b l e t o a d s o r p t i o n . The amounts o f - 22 -s u l p h a t e r e t a i n e d above pH 6-7 a r e n o t s i g n i f i c a n t ( Harward and R e i s e n a u e r , 1 9 6 6 ) . The i n t e r a c t i o n between h y d r o x y i r o n and pH was shown by Chao e t a l . ( 1 9 6 3 ) . A r e c e n t a l l u v i u m d i d n o t show any marked c a p a c i t y t o a d s o r b s u l p h a t e t i l l i t was c o a t e d w i t h F e , w h i l e t h e r e m o v a l o f f r e e Fe compounds fr o m a r e d d i s h - b r o w n l a t e r i t e r e s u l t e d i n a marked d e c r e a s e i n i t s r e t e n t i o n c a p a c i t y . I n c r e a s i n g t h e pH r e s u l t s i n a d e c r e a s e o f t h e p o s i t i v e c h a r g e o f h y d r o u s o x i d e s o f i r o n and a l u m i n i u m and i n i n c r e a s e d a c t i v i t y o f t h e OH i o n w h i c h r e p l a c e s t h e a d s o r b e d s u l p h a t e ( K a m p r a t h , 1968)„ As a c i d i t y i s i n c r e a s e d t h e p o s i t i v e c h a r g e on t h e complex i n c r e a s e s , t h i s i s b a l a n c e d by c o u n t e r i n g a n i o n s . T h u s , l i m i n g d e c r e a s e s t h e amount o f s u l p h a t e a d s o r b e d by s u r f a c e s o i l s and s i n c e r e d - y e l l o w p o d z o l i c and l a t o s o l s a r e o f t e n f a i r l y a c i d , c o n d i t i o n s a r e f a v o u r a b l e f o r s u l p h a t e a d s o r p t i o n s ( K a m p r a t h , 1 9 6 8 ) . S u l p h a t e may be r e p l a c e d by o t h e r a n i o n s o f g r e a t e r c o - o r d i n a t i n g a b i l i t y ( Harward and R e i s e n a u e r , 1966) . T h i s i s why t h e d i s p l a c e m e n t o f s u l p h a t e by t h e use of p h o s p h a t e e x t r a c t i n g s o l u t i o n has much t o recommend i t . S o i l s w i t h p r e d o m i n a n t l y k a o l o n i t i c c l a y s have a much h i g h e r a d s o r p t i o n p o t e n t i a l t h a n s o i l s w i t h m o n t m o r i l l o n i t i c c l a y s (Kamprath e t a l . , 19 5 6 ) . I t i s " i m p o r t a n t t o r e a l i z e t h a t h y d r o u s o x i d e s a r e u s u a l l y a s s o c i a t e d w i t h k a o l i n - 23 -minerals and the sulphate adsorption may probably be due chiefly to the hydrated oxides of iron and aluminum, so that the contaminants i n the mineral sample may be more effective in sulphate adsorption than the clay minerals themselves (Harward and Reisenauer, 1966 ; Kamprath, 1968) . Incorporation into mineral structures may be included as an adsorption mechanism. Part of the inorganic sulphur may be in mineral forms of low or slight s o l u b i l i t y , e.g. elemental sulphur, sulphides under poor aeration and as sul-phates i n salt affected, calcareous and gypsiferous s o i l s (Harward and Reisenauer, 1966) . Insoluble sulphate is co-precipitated with calcium carbonate in calcareous s o i l s (Williams and Steinberg, 1962). Sulphate may be retained by some mechanism by which the cation i s also retained; this i s less understood than other mechanisms (Harward and Reisenauer, 1966). Jackson (1963) suggested the following type of reaction //0H\ yOE\ XA1 MX + KHSO ^ * XA1 A1X + H„0 \0H>^ H \SO,f" K Chang and Thomas (1963) suggested replacement of OH by SO^ and replacement of exchangeable Al by the added cation and + hydrolysis of the Al to form H which neutralized the displaced OH and so sent the reaction to completion. Salts - 24 -containing sulphate may be retained in s o i l pores or cavities and in pumice so i l s salt solutions retained in pores were d i f f i c u l t to displace and required two weeks shaking to equilibrate (Harward and Reisenauer, 1966). Chao et a l . (1962) suggested that organic matter may adsorb sulphate due to i t s amphoteric properties and the development of positive charges under certain conditions. The capacity of soils to adsorb sulphate from solution has received some study (Ensminger, 1954; Kamprath et a l . , 1956; Berg and Thomas, 1959 ; Barrow, 1959 ; Chao et a l . , 1960 ; Liu and Thomas, 1961; Chao et a l . , 1962 ; Chang and Thomas, 1963 ; Chao et a l . , 1963 ; Hogg, 1966 ; Barrow, 1967 ) . Many soils have l i t t l e reaction with the sulphate ion. In others, however, reactions do occur and sulphate ions are adsorbed (Barrow, 1967 ) . The measurement of a s o i l ' s a b i l i t y to adsorb sulphate involves many d i f f i c u l t i e s ; and Barrow (1967) suggests that for comparing soils i t i s convenient to characterize the sulphate adsorbing a b i l i t y of soils by a single value. One p o s s i b i l i t y proposed i s the t o t a l amount of adsorbed sulphate, which is the sum of i n i t i a l adsorbed sulphate and the amount removed from the equilibrating solution. Many factors play a part in sulphate adsorption. Barrow (1967) found that the s o i l solution ratio was not - 25 -important and that wide variations had l i t t l e effect on the realtionship between the amount of sulphate adsorbed and the equilibrium solution concentration. Though Chao et a l . (1962) found that equilibrium was reached with their s o i l s in four hours, Barrow (1967) found that adsorption equilibrium w a s not rapidly reached and not reached within 4 8 hours; he suggests an increase i n the number of adsorption sites with time. He also found that temperature affects the equilibrium and greatest adsorption occurs at 4°C. The past history of the s o i l can be important and Barrow (1967) found that s o i l s irrigated with s l i g h t l y saline water may have accumulated much adsorbed sulphate and that when the concentration of the equilibrium solution was low, sulphate may be desorbed from the s o i l s and as a result the adsorption capacity underestimated. The sulphate ion i s absorbed by plants and soluble sulphate represents an immediately available supply. Because of the importance of sulphate, chemical indices of available sulphur should include this form of the element. Some procedures for measuring available sulphur may correlate well with plant response, even though l i t t l e i s known about the nature of the sulphur measured (Beaton et al., 1968 ) . Many chemical extractants have been t r i e d , and a detailed l i s t i s in the Sulphur Inst. Tech. Bull. No. 14, 1968. Some - 26 -of those mentioned are cold water (Clark and Green, 1964; Bartlett and Neller, 1960 ), hot water (Spencer and Freney, 1960). Ammonium acetate 0.1 N was used by McClung and De Freitas (1959) and Spencer and Freney (1960). Ammonium acetate plus acetic acid has been t r i e d by J o r d a n (196 4) and Kittams and Attre (1965). Sodium acetate at pH 4.8 was used by Ensminger (1954) and at pH 7.0 in 1958. Morgan's solution (2% acetic acid plus sodium acetate) was t r i e d by many workers (Anderson and Webster, 1959 ; Jordan and Bardsley, 1958 ; Chesnin and Yien, 1950 ; Bartlett and Neller, 1960 ; Harward, Chao and Fang, 1962 ; Jordan, 1964). Ammonium carbonate 1.0 N was used by Puri and Ashgar (1938) , c a l c i u m carbonate by Williams and Steinberg (19 62, 1964) and sodium carbonate 0.25 M by Grant et a l . (1968). Bardsley and Kilmer (1963) tri e d 0.5 M sodium carbonate as also did B a r d s l e y and Lancaster in 196 5. Chlorides, phosphates, ammonium c i t r a t e , sodium hydroxide, hydrochloric acid , Bray's solution and anion exchange resins have a l l been tried. (S. Inst. Tech. Bull. No. 14 , 196 8) . The fractions of sulphur e x t r a c t e d may be s e p a r a t e d into the following (S. Inst. Tech. Bull. 14 , 1968). (a) Readily soluble sulphate and variable small amounts of organic sulphur. These forms are obtained from soils by water, lithium chloride - 27 -(0.1 M) c a l c i u m c h l o r i d e - d i l u t e and sodium c h l o r i d e . (b) R e a d i l y s o l u b l e s u l p h a t e and p o r t i o n s o f a d s o r b e d s u l p h a t e . E x t r a c t a n t s r e m o v i n g t h e s e f r a c t i o n s a r e p h o s p h a t e s o l u t i o n s , c a l c i u m c a r b o n a t e s u s p e n s i o n s , n e u t r a l n o r m a l ammonium a c e t a t e , a c i d ammonium a c e t a t e , and a c i d sodium a c e t a t e . A l l a d s o r b e d s u l p h a t e i s supposed t o be e x t r a c t e d by s o l u t i o n s c o n t a i n i n g 500 ppm p h o s p h o r u s ( B e a t o n e£ aJL. , 1 9 6 8 ) . Lowe i n 1963 f o u n d t h a t r a i s i n g t h e c o n c e n t r a t i o n o f t h e p h o s p h a t e s o l u t i o n f r o m 500 ppm P t o 15,000 ppm P r e s u l t e d I n a n i n e f o l d i n c r e a s e i n t h e s u l p h a t e e x t r a c t e d f r o m a p o d z o l . ( c ) R e a d i l y s o l u b l e s u l p h a t e and p o r t i o n s o f b o t h a d s o r b e d and o r g a n i c s u l p h u r a r e e x t r a c t e d by 0.5 M sodium b i c a r b o n a t e a t pH 8.5, n e u t r a l ammonium a c e t a t e and h e a t t r e a t m e n t f o l l o w e d by sodium c h l o r i d e e x t r a c t i o n . However, r e c e n t A u s t r a l i a n s t u d i e s seem t o i n d i c a t e t h a t a d s o r b e d s u l p h a t e i s n o t as r a p i d l y a v a i l a b l e as s o l u b l e .sulphate (Anonymous, S u l p h u r I n s t . J o u r n a l V o l . 5, No. 2, Summer, 1 9 6 9 ) . A l t h o u g h d e c r e a s e s i n ' a d s o r b e d s u l p h a t e f o l l o w i n g c r o p p i n g w i t h o a t s c o n f i r m e d t h a t a d s o r b e d s u l p h a t e was r e a d i l y a v a i l a b l e t o p l a n t s ( W i l l i a m s and S t e i n b e r g , 1 9 6 4 ) . - 28 -Lowe (1966) separated organic and inorganic sulphate in s o i l extracts by the use of gel f i l t r a t i o n . Differences in the amount of sulphur extracted from the s o i l s result both from the different extractants employed and s o i l properties. Profile variations displayed may be attributed to pH differences and the clay and l i m e contents of the v a r i o u s layers (Harward and Reisenauer, 1966). The different rates of mineralization of organic sulphur to plant available sulphate may be influenced by sulphatase a c t i v i t y (Tabatabai and Bremner, 1967 ) . This enzyme a c t i v i t y w i l l further i n c r e a s e a v a i l a b i l i t y of sulphate with time and make comparison of extractants for different soil s even more d i f f i c u l t . The Methylene Blue Method for Sulphate Determination The most sensitive and specific methods are based on Caro's reaction (Gustafsson, 1960a) i n which t h e solution containing hydrogen sulphide is mixed with an acidic solution of para-aminodimethylaniline (P.A.D.A.) and f e r r i c i r o n i s added; however, the c r i t i c a l c o n d i t i o n s r e q u i r e d for analytical determination of ug amounts of sulphur have n o t always been well understood and since studies of extractable sulphate must be based on reliable d e t e r m i n a t i o n s of small concentrations of sulphate a detailed r e v i e w of the important analytical considerations seems appropriate. Research programs involving sulphur metabolism in plants and biological systems - 2 9 -have frequently been hampered by the lack of sensitive, rapid and specific methods for the estimation of sulphur (Johnson and Nishita, 1 9 5 2 ) . Very often there i s need for a method capable of determining sulphate sulphur in the presence of a number of organic sulphur compounds. This need has l e d to attempts to reduce sulphate to hydrogen sulphide which can be determined by sensitive t i t r i m e t r i c or colorimetric methods. The methylene blue method i s entirely specific for hydrogen sulphide (Gustafsson, 1960a) and also sensitive (Fogo and Popowsky, 1 9 4 9 ) . Caro's methylene blue reaction was recommended by E m l l Fisher ( 1 8 8 3 ) (citing Gustafsson, 1960a) f o r the id e n t i f i c a t i o n of hydrogen sulphide. In t h i s reaction, the solution containing hydrogen sulphide i s mixed with an a c i d i c solution of P-aminodimethylaniline and f e r r i c iron is added. The solution f i r s t becomes red from an intermediate compound but changes to blue as methylene blue i s formed. St. Lorant in 1929 developed a method for the reduction of microgram amounts o f sulphate to hydrogen sulphide. He seems to have been the f i r s t to employ the reducing properties of hydriodic acid for the quantitative determination of sulphate. The reduction being performed by boiling the sulphate with a mixture of hydriodic acid, formic acid and red phosphorus. Johnson and Nishita (19 5 2) - 30 -a t f i r s t u s e d L o r a n t ' s r e d u c i n g m i x t u r e , b u t s u b s e q u e n t l y changed t o a m i x t u r e o f h y d r i o d i c , f o r m i c and h y p o p h o s p h o r o u s a c i d s i n t h e r a t i o o f 4:2:1; t h i s r e a g e n t was e a s i e r t o make and u s e . Luke (1949) u s e d h y d r i o d i c , h y d r o c h l o r i c and hypo-p h o s p h o r o u s a c i d s and R o t h (1951) h y d r i o d i c and f o r m i c a c i d s and h y p o p h o s p h i t e . G u s t a f s s o n (1960) i n v e s t i g a t e d t h e c o l o u r r e a c t i o n i n t h e m e t h y l e n e b l u e method u s e d f o r t h e d e t e r m i n a t i o n o f s u l p h a t e . A c c o r d i n g t o B e r n t h s e n (Ann. 18 85) ( C i t e d by G u s t a f s s o n ) f e r r i c i r o n t o g e t h e r w i t h P - a m i n o d i m e t h y l a n i l i n e g i v e s a r e d o x i d a t i o n p r o d u c t , W u r s t e r ' s r e d w h i c h r e a c t s i n s e v e r a l ways w i t h h y d r o g e n s u l p h i d e . Among o t h e r p r o d u c t s s u l p h i d e g r e e n , l e u c o m e t h y l e n e b l u e and m e t h y l e n e r e d a r e s a i d t o be formed. The f i r s t two a r e e a s i l y t r a n s f o r m e d t o m e t h y l e n e b l u e w h i l e m e t h y l e n e r e d i s n o t . L o r a n t (1929) assumes t h a t m e t h y l e n e r e d and m e t h y l e n e b l u e a r e formed i n t h e p r o p o r t i o n o f 1:50; t h u s , h y d r o g e n s u l p h i d e i s n o t q u a n t i t a t i v e l y t r a n s f o r m e d t o m e t h y l e n e b l u e , t h o u g h b o t h L o r a n t (1929) and Bethge (1953 ) r e p o r t q u a n t i t a t i v e y i e l d s i n t h e r e d u c t i o n o f p o t a s s i u m s u l p h a t e -U s i n g s t a n d a r d s u l p h i d e s o l u t i o n s p r e p a r e d f r o m N a 2 S . 9 H 2 0 , G u s t a f s s o n (1960a) s t u d i e d t h e e f f e c t o f s e v e r a l v a r i a b l e s t o d e t e r m i n e t h e i r e f f e c t ori t h e f o r m a t i o n o f m e t h y l e n e b l u e . She recommends g e n t l e m i x i n g w i t h o u t s h a k i n g b e f o r e t h e - 31 -addition of the f e r r i c solution, this decreases the transfer of hydrogen sulphide into the gas phase; while vigorous shaking after the addition of the f e r r i c solution f a c i l i t a t e s the quantitative reaction of any hydrogen sulphide in the gas phase. The reaction of the hydrogen sulphide occurs a short time after the addition of the f e r r i c solution and this was demonstrated by the recovery of 90 percent of added sulphide solution t h i r t y seconds after the addition of the f e r r i c solution. Insufficient mixing before the addition of the f e r r i c solution causes low results. A methylene blue absorption curve prepared using about 3 8 ug S, in a sulphide solution gave maximum absorption at 667 and 743 mu. The yi e l d of methylene blue increases with increasing acidity, but i t s extinction at 667 my decreases. The optimal sulphuric acid concentration in the f i n a l solution i s about 0.30 M. As acidity increases the extinction maximum i s s l i g h t l y displaced towards longer wavelengths. The absorption maximum at 743 my which i s absent i n solutions of methylene blue in d i s t i l l e d water increases with the acidity. This is suggested to be caused by the formation of another compound, possibly by the addition of a proton to the methylene blue cation. The use of hydrochloric acid instead of sulphuric acid for the 'amino' reagent resulted in a lower extinction even at the optimal concentration of the hydrochloric acid. - 32 -V a r y i n g t h e amounts o f 'amino' r e a g e n t s as w e l l as t h o s e o f z i n c a c e t a t e and f e r r i c s o l u t i o n s d i d n o t a f f e c t t h e f i n a l e x t i n c t i o n g r e a t l y , even o v e r f a i r l y l a r g e v a r i a t i o n s , p r o v i d e d t h a t t h e f i n a l a c i d i t y r e m a i n s c o n s t a n t ( G u s t a f s s o n , 1960 , p a p e r a ) . The e f f e c t o f t e m p e r a t u r e on t h e l i g h t a b s o r p t i o n was s t u d i e d by M e c k l e n b u r g and R o s e n k r a u z e r (19m) and t h e y r e p o r t e d a l a r g e r l i g h t a b s o r p t i o n when t h e r e a c t i o n i s p e r f o r m e d a t a l o w e r t e m p e r a t u r e . G u s t a f s s o n (1960a) s t u d i e d t h e e f f e c t s o f t e m p e r a t u r e on b o t h t h e y i e l d o f m e t h y l e n e b l u e and i t s a b s o r b a n c e . Her r e s u l t s i n d i c a t e two o p p o s i t e e f f e c t s . When t h e e x t i n c t i o n was d e t e r m i n e d a t v a r i o u s t e m p e r a t u r e s , she f o u n d t h a t t h e e x t i n c t i o n i n c r e a s e d w i t h t h e t e m p e r a t u r e a t w h i c h t h e measurement was c o n d u c t e d and t h a t t h e t e m p e r a t u r e c o e f f i c i e n t a r o u n d 20°C was f o u n d t o be ab o u t + 0.4 p e r c e n t p e r d e g r e e f o r 96 ug S p e r 100.0 ml and u s i n g a 1-cm c e l l ; a c o n c e n t r a t i o n o f 19 ug S p e r 100.0 ml gave a c o e f f i c i e n t o f +0.05 p e r c e n t p e r d e g r e e f o r each d e g r e e C above 20°C. These r e s u l t s a g r e e w i t h t h e f i n d i n g s o f R a b i n o w i t c h and E p s t e i n (1941) who used m e t h y l e n e b l u e s o l u t i o n s i n w a t e r a t pH 3.4. I n c r e a s i n g t h e t e m p e r a t u r e had t h e o p p o s i t e e f f e c t on t h e y i e l d o f m e t h y l e n e b l u e . G u s t a f s s o n f o u n d t h a t t h e y i e l d i s s t e a d i l y l o w e r e d w i t h i n c r e a s i n g t h e t e m p e r a t u r e a t t h e t i m e o f r e a c t i o n . No maximum a b s o r b a n c e w i t h r e a c t i o n - 33 -t e m p e r a t u r e was o b t a i n e d by G u s t a f s s o n (1960) who a t t r i b u t e d t h e l o w e r y i e l d t o t h e s t r o n g l y d e c r e a s i n g a b s o r p t i o n c o e f f i c i e n t o f h y d r o g e n s u l p h i d e w i t h i n c r e a s i n g temperature and a l s o t h a t t h e c a p a c i t y o f the r e a c t i o n m i x t u r e t o r e a c t w i t h f u r t h e r amounts o f s u l p h i d e added a f t e r t e n o r t h i r t y s e c onds was s t r o n g l y l o w e r e d w i t h i n c r e a s i n g t e m p e r a t u r e . G u s t a f s s o n (1960a) f o u n d t h e c o l o u r t o be f u l l y d e v e l o p e d a f t e r 15 m i n u t e s a t 20°C and t h e e x t i n c t i o n was t h e n c o n s t a n t f o r s e v e r a l h o u r s i f the s o l u t i o n was k e p t i n subdued l i g h t . J o h n s o n and N i s h l t a (.1952 ) s t a t e t h a t m e t h y l e n e b l u e s o l u t i o n s a r e s t a b l e a t l e a s t s e v e r a l days i f s t o r e d i n t h e d a r k ; b u t e x p o s u r e t o s u n l i g h t c a u s e s r a p i d f a d i n g . The s u s c e p t i b i l i t y o f s u l p h i d e , i n z i n c a c e t a t e s o l u t i o n , t o o x i d a t i o n was s t u d i e d by G u s t a f s s o n (19 6 0a) and she f o u n d t h a t s u l p h i d e i n the z i n c a c e t a t e s o l u t i o n was u n e x p e c t e d l y s t a b l e . She f o u n d t h a t b u b b l i n g a s t r e a m o f a i r a t t h e r a t e o f 50-100 ml p e r m i n u t e , f o r one. h o u r before c o l o u r d e v e l o p m e n t , i n a b o u t 22 ug s u l p h i d e - S i n two s o l u t i o n s r e s u l t e d i n l o s s e s o f 1.1 and 1.3 percent. U s i n g s t a n d a r d s u l p h a t e s o l u t i o n s , J o h n s o n and N i s h i t a (1952 ) o b t a i n e d a l i n e a r r e l a t i o n between t h e amounts o f s u l p h a t e and t h e a b s o r b a n c y o f t h e r e s u l t i n g methylene b l u e s o l u t i o n s . T h i s r e l a t i o n s h i p e x i s t e d between t h e r a n g e o f 1.0 and 50.0 micrograms o f s u l p h u r per 100 ml. G u s t a f s s o n o b t a i n e d a l i n e a r r e l a t i o n s h i p u s i n g d i f f e r e n t amounts o f - 34 -sulphide; but l i n e a r i t y existed between 1.0 and 25.0 ppm S per 10 0 ml. Johnson and Nishita (1952) obtained l i n e a r i t y by diluting solutions of concentration greater than 50.0 yg S per 100 ml with solutions containing the same concentrations of d i s t i l l e d water, P-aminodimethy1aniline (P.A.D.A.) and f e r r i c ammonium sulphate. The diluting solution must be of exactly the same acid concentration. This proves that there is a deviation from Beer's law and not a decrease in yield of methylene blue. Gustafsson (1960) confirmed this result. Dilution of concentrated methylene blue solution i s satisfactory for amounts of sulphur up to approximately 300 micrograms. Amounts in excess of 300 micrograms give low results due to limiting amounts of P.A.D.A. (Johnson and Nishita, 1952) . Solutions of methylene blue in water (pH 3.4) do not follow Beer's law even at very low concentrations (Rabinowitch and Epstein , 1941) . These workers found that this deviation is explained by the formation of dimeric ions 2 + (MB2) . The absorption maxima for this dimeric form occurs at 600 my. The monomeric ion which occurs in dilute solutions has an absorbance maximum at 656 my. Dissociation of methylene blue is increased by an increase in temperature, hence the reason for the increase in absorbance at 667 my with Increasing temperature. The absorption maximum f o r methylene blue i s rather sharp at 670 my and as a result deviations from Beer's law may be expected i f instruments of low spectral purity are used (Johnson and Nishita, 1952) . - 35 -Lorant (1929 cited by Gustafsson, 1960a) found that 6 3.7 percent of the added sulphide was transformed to methylene blue. Gustafsson (1960) calculated the reaction yield to be 66.7 percent. The reduction of sulphate to hydro-gen sulphide i s also subject to variation depending on the experimental conditions. The composition of the reducing reagent on the reduction was studied by Gustafsson (19 6 0 paper b). The mixtures she studied were: 1. HI + P 2. H I + P + HCOOH 3. HI + P + HAc 4. HI + P + H 3P0 2 5. HI + H 3P0 2 6. HI + H 3P0 2 + HCOOH 7. HI + NaH2P02 + HAc These mixtures were mixed in various proportions and before use were refluxed for one hour with a stream of nitrogen bubbling through to remove traces of sulphur. She found that a reducing solution consisting of HI + NaH2P02 + HAc gave the best precision and the lowest blanks. Johnson and Nishita (1952) used a mixture of HI + H(H 2P0 2) and HCOOH revised reducing solution. Roth (1951) obtained a constant yield only for reagents containing 43-53 percent of formic acid, and he recommends these proportions, although a higher y i e l d , as much as 2 0.0 percent, was o b t a i n e d w i t h reagents containing less formic acid. Reagents without formic or acetic acid sometimes fumed and gave large negative errors. In the presence of - 36 -e i t h e r f o r m i c o r a c e t i c l o w e r r a t i c r e s u l t s a r e n o t o b t a i n e d ( G u s t a f s s o n , 1 9 6 0 b ) . She i n d i c a t e d t h a t t h e r e d u c i n g m i x t u r e she recommends, o b t a i n e d by d i s s o l v i n g 2.5 grams NaH^PO^R^O i n 2 5 ml o f g l a c i a l a c e t i c a c i d and 100.0 ml o f h y d r i o d i c a c i d ( s p e c i f i c g r a v i t y 1.7) and r e f l u x e d f o r one h o u r w h i l e b u b b l i n g a s t r e a m o f n i t r o g e n t h r o u g h , i s s t a b l e f o r months i f p r o t e c t e d f r o m undue e x p o s u r e t o l i g h t and a i r . L o r a n t (1929) ( c i t e d by G u s t a f s s o n 1960b) s t a t e s t h a t s u l p h a t e i s r e d u c e d even a t room t e m p e r a t u r e t h o u g h s l o w l y . J o h n s o n and N i s h i t a (1952) r e p o r t t h a t t h e r a t e o f h e a t i n g o f t h e d i g e s t i o n f l a s k i s n o t e x t r e m e l y c r i t i c a l . G u s t a f s s o n (1960b) s t a t e s t h a t t o p r e v e n t l o s s e s , p r e s u m a b l y , as s u l p h u r d i o x i d e a t l o w e r t e m p e r a t u r e s , t h e r e d u c i n g m i x t u r e s h o u l d be h e a t e d f a i r l y r a p i d l y . The d i s t i l l a t i o n t i m e recommended by G u s t a f s s o n (1960b) u n d e r h e r p r o c e d u r e i s t e n m i n u t e s . J o h n s o n and N i s h i t a (1952) recommend one h o u r f o r t h e i r samples ( p l a n t m a t e r i a l s , s o i l s and i r r i g a t i o n w a t e r s ) . D i l u t i n g t h e sample w i t h w a t e r c a u s e s c o n s i d e r a b l e l o s s e s , t h e a d d i t i o n o f 0.5 ml o f w a t e r t o e v a p o r a t e d s u l p h a t e samples c a u s e a 6.0 p e r c e n t d e c r e a s e i n y i e l d w h i l e a 2.0 ml a d d i t i o n c a u s e d a 35.0 p e r c e n t r e d u c t i o n ( G u s t a f s s o n , 1960b) . Joh n s o n and N i s h i t a (1952 ) s u g g e s t a 2.0 ml s o l u t i o n sample b u t i n d i c a t e t h a t t h e use o f l a r g e r volumes r e q u i r e e v a p o r a t i o n t o n e a r d r y n e s s . The apparatus must also be conditioned b e f o r e samples can be d i s t i l l e d . This i s done by making a preliminary run with either a sample or standard containing a small amount o f reducible sulphur. This is necessary t o e q u i l i b r a t e the d i g e s t i o n - d i s t i l l a t i o n apparatus and wash solution w i t h r e s p e c t to hydrogen sulphide. J o h n s o n and Nishita (19 5 2) obtained values that were 5.0 percent low, i . e . about 1.0 microgram of sulphur was not recovered for the f i r s t run only. Gustafsson (1960 paper b) o b t a i n e d results t o o low by 0.1 -0.2 microgram of sulphur. The y i e l d of reduction was found to be within t h e limits of experimental error (Gustaffson, 1961, II) . The precision i s most encouraging. Johnson and N i s h i t a (1952) using water samples and s o i l extracts i n which the sulphate contents ranged from 94.4 to 842 ppm, obtained a precision better than 5 percent (95 percent confidence l i m i t s ) . Interferences Heavy metals interfere with the method„ and result in low results due to low yields of methylene blue. Johnson and Arkley (1954) report that copper in the water used for the wash and absorbing solutions c a u s e s precipitation of copper sulphide and the s u l p h i d e is not available t o form methylene blue. Gustafsson (19 6 0b) confirmed that 30-50 micrograms of Cu per l i t r e were responsible for certain - 38 -a n o m a l i e s i n t h e y i e l d o f m e t h y l e n e b l u e . A d d i t i o n o f c o p p e r t o t h e f e r r i c s o l u t i o n had no e f f e c t t h u s e x c l u d i n g t h e a s s u m p t i o n t h a t c o p p e r may s e r v e as a c a t a l y s t f o r some h a r m f u l s i d e - r e a c t i o n a p p e a r i n g a t t h e c o l o u r d e v e l o p m e n t ( G u s t a f s s o n , 1 9 6 0 b ) . I n t e r f e r e n c e f r o m Pb, when l e a d was added as l e a d n i t r a t e i n c o n c e n t r a t i o n s o f 10-20 m i c r o g r a m s o f l e a d , was n o n e x i s t a n t . M e r c u r y c a u s e d i n t e r f e r e n c e w h e t h e r added i n t h e z i n c a c e t a t e a b s o r b i n g s o l u t i o n o r t o the f e r r i c ammonium s u l p h a t e ( G u s t a f s s o n , 1960, p a p e r I I ) . T h i s was e x p l a i n e d by t h e f a c t t h a t m e r c u r y forms complexes o f g r e a t e r s t a b i l i t y 2-w i t h S and SH t h a n c o p p e r . J o h n s o n and N i s h i t a (1952) f o u n d t h a t more t h a n 6.0 m i l l i g r a m s o f n i t r a t e i n the sample c a u s e d low a p p a r e n t s u l p h u r v a l u e s . E v i d e n c e o f n i t r a t e i n t e r f e r e n c e was a r a p i d and p r o n o u n c e d d a r k e n i n g o f t h e s odium p h o s p h a t e - p y r o g a l l o l wash s o l u t i o n . V o l a t i l e compounds g e n e r a t e d by t h e r e a c t i o n o f n i t r a t e w i t h t h e r e d u c i n g s o l u t i o n were i n c o m p l e t e l y t r a p p e d i n t h e wash s o l u t i o n and p r e v e n t e d t h e s y n t h e s i s o f m e t h y l e n e b l u e . S e v e r a l o r g a n i c s u l p h u r compounds were d i g e s t e d by J o h n s o n and N i s h i t a (1952 ) t o d e t e r m i n e the e x t e n t o f i n t e r f e r e n c e when s u l p h a t e s u l p h u r i s d e t e r m i n e d by t h e d i r e c t d i g e s t i o n method, f o r e x a m p l e , on p l a n t t i s s u e s . Most o f t h e compounds t r i e d y i e l d e d no a p p a r a n t s u l p h a t e s u l p h u r , however, h e a t i n g w i t h 90 p e r c e n t f o r m i c a c i d o r i n t h e p r e s e n c e o f 30 m i l l i g r a m s o f n i t r a t e r e s u l t e d i n v a r i a b l e amounts o f s u l p h a t e s u l p h u r . There i s no e x p l a n a t i o n why t h e f o r m i c a c i d i n t h e r e d u c i n g m i x t u r e does n o t l a b i l i z e t h e s u l p h u r o f t h e compounds. J o h n s o n and N i s h i t a (1952) do n o t recommend t h e use o f h y d r o g e n p e r o x i d e i n t h e wet a s h i n g p r o c e d u r e as b o t h h y d r o g e n p e r o x i d e and p e r c h l o r i c a c i d seem t o o x i d i z e i o d i d e t o i o d i n e and r e s u l t e d i n l o w e r y i e l d s o f H^S and m e t h y l e n e b l u e . The f o r m s o f H l - r e d u c i b l e s u l p h u r were enumerated by A r k l e y (1961) and a r e t h o u g h t t o c o n s i s t o f : 1. I n o r g a n i c s u l p h i d e s and p o l y s u l p h i d e s (FeS and F e S2 2. E l e m e n t a l S and o t h e r i n s o l u b l e i n o r g a n i c s u l p h u r compounds o f o x i d a t i o n s t a t e l e s s t h a n p l u s s i x 3. I n s o l u b l e o r s p a r i n g l y s o l u b l e s u l p h a t e compounds s u c h a s b a r i u m s u l p h a t e , o r s t r o n t i u m s u l p h a t e , and s u l p h a t e c o n t a i n i n g m i n e r a l s e . g . a l u n i t e . 4. S u l p h a t e p r e c i p i t a t e d i n amorphous i r o n and a l u m i n i u m h y d r o u s o x i d e s 5. S u l p h a t e s u b s t i t u t e d i n p h o s p h a t e m i n e r a l s e . g . a p a t i t e 6. S u l 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 m i n e r a l s 7. R e d u c i b l e o r g a n i c s u l p h u r s u c h as o r g a n i c e s t e r -s u l p h a t e compounds. - 40 -The C-S c o v a l e n t bond i n o r g a n i c compounds i s n o t d i s r u p t e d by t h i s r e d u c i n g m i x t u r e ; h owever, t h e N - s u l p h a t e and O - s u l p h a t e g r o u p s i n s o i l s h o u l d be i n c l u d e d i n t h i s f r a c t i o n as F r e n e y (1961) f o u n d t h a t t h e N - s u l p h a t e and 0-s u l p h a t e g roups i n h e p a r i n and O - s u l p h a t e g r o u p s o f a g a r were HI r e d u c i b l e . Most o f t h e i n o r g a n i c s u l p h u r compounds t e s t e d by F r e n e y (1958) were e i t h e r w h o l l y o r p a r t i a l l y HI r e d u c i b l e e x c e p t t h i o c y a n a t e . The r e s u l t o b t a i n e d by t h e HI r e d u c i b l e method as a measure o f t h e s u l p h a t e c o n t e n t ought t o be b o t h r e a s o n a b l y a c c u r a t e and p r e c i s e as the i n o r -g a n i c forms o f s u l p h u r , w i t h l o w e r o x i d a t i o n s t a t e s t h a n s u l p h a t e have been fo u n d t o a c c o u n t f o r a b o u t 1.0 p e r c e n t o f t h e t o t a l s u l p h u r i n w e l l d r a i n e d m i n e r a l s o i l s ( F r e n e y , 1961) . T h i s f r a c t i o n i n c l u d e d s u l p h i d e , s u l p h i t e , t h i o s u l p h a t e e l e m e n t a l s u l p h u r and p o l y s u l p h i d e s . - 41 -MATERIALS The s o i l s amples used i n t h e s t u d y were a l l f r o m t h e P r o v i n c e o f B r i t i s h C o l u m b i a . The two c o n c r e t i o n a r y brown samples b e l o n g e d t o t h e A b b o t s f o r d and N i c h o l s o n s e r i e s , t h e o r t h i c humic g l e y s o l t o t h e Hazlewood s e r i e s and t h e a c i d brown wooded was fr o m t h e Whatcom s e r i e s . These s o i l s have been d e s c r i b e d by L u t t m e r d i n g and S p r o u t ( 1 9 6 6 ) . A d e o r c i c r e g o s o l f r o m t h e Monroe s e r i e s was a l s o i n c l u d e d ( L u t t m e r d i n g and S p r o u t , 1 9 6 7 ) . Two s o i l s were f r o m V a n c o u v e r I s l a n d , an a c i d d a r k brown f o r e s t f r o m t h e S a a n i c h t o n s e r i e s and a b l a c k s o i l f r o m t h e L a n g f o r d s e r i e s (Day, F a r s t a d and L a i r d , 1 9 5 9 ) . Some p r o p e r t i e s o f t h e s e s o i l s a r e summarized i n T a b l e I . A l l s o i l s were a i r d r i e d and ground w i t h a wooden r o l l e r t o pas s t h r o u g h a 2 mm s i e v e . The d e x t r a n g e l us e d i n t h e f r a c t i o n a t i o n s t u d i e s t o s e p a r a t e o r g a n i c and i n o r g a n i c s u l p h a t e i n s o i l e x t r a c t s was o b t a i n e d f r o m P h a r m a c i a Company, u n d e r t h e t r a d e name Sephadex. The G-50 medium and G-2 5 medium t y p e s were u s e d . E x p e r i m e n t a l Methods D e t e r m i n a t i o n o f T o t a l S u l p h u r i n S o i l T o t a l s u l p h u r was e s t i m a t e d by use o f t h e Leco . i n d u c t i o n f u r n a c e and s u l p h u r d e t e r m i n a t o r , model 517 ( L a b o r a t o r y Equipment C o r p . , S t . J o s e p h , M i c h i g a n ) . I n most s o i l s a \ gram sample was used e x c e p t i n one o r two where - 42 -\ gram was n e c e s s a r y due t o low t o t a l s u l p h u r c o n t e n t s . N i t r o g e n s and h a l o g e n s a r e t h o u g h t t o i n t e r f e r e ( B e a t o n e t a l . , 1 9 6 8 ) . D e t e r m i n a t i o n o f H i - R e d u c i b l e S u l p h u r The H l - r e d u c i b l e s u l p h u r was d e t e r m i n e d by t h e a p p l i c a t i o n o f J o h n s o n and N i s h i t a ' s r e d u c t i o n method d i r e c t l y t o 0.1 - 0.2 5 gm s a m p l e s , w h i c h were gro u n d t o p a s s a 6 0 mesh s i e v e . T h i s method ought t o r e c o v e r o r g a n i c s u l p h a t e s and i n o r g a n i c forms o f s u l p h u r o f w h i c h s u l p h a t e i s n o r m a l l y t h e dominant f o r m ( J o h n s o n and N i s h i t a , 1952; F r e n e y , 1 9 5 8 ) . The t i m e o f d i s t i l l a t i o n was f o r t y m i n u t e s , a v a r i a b l e t r a n s f o r m e r 750 w a t t e l e c t r i c h e a t e r was u s e d a t t h e 7 0 s e t t i n g . I n o r d e r t o f a c i l i t a t e r a p i d h e a t i n g t h e b u r n e r was m a i n t a i n e d a t t h i s s e t t i n g and c a r e must be e x e r c i s e d i n r e m o v i n g t h e h o t d i s t i l l a t i o n f l a s k s . The r e c e i v i n g f l a s k i s g e n t l y shaken b e f o r e t h e a d d i t i o n o f t h e f e r r i c s o l u t i o n and v i g o r o u s l y f o r about two m i n u t e s a f t e r t h e f e r r i c i o n i s added. E x t r a c t i o n P r o c e d u r e s Used i n t h e S t u d y o f S o i l S u l p h a t e The a d s o r b e d p l u s s o l u b l e s u l p h a t e was e x t r a c t e d by p l a c i n g 5.0 gram samples o f s o i l i n a 100 ml c e n t r i f u g e t u b e and a d d i n g 50.0 ml o f e x t r a c t i n g s o l u t i o n . The sample was shaken f o r 30 m i n u t e s , c e n t r i f u g e d a t 1,400 RCF f o r t w e n t y m i n u t e s and f i l t e r e d t h r o u g h a Whatman No. 1 f i l t e r p a p e r . A 2.0 ml a l i q u o t was u s e d t o d e t e r m i n e t h e H l - r e d u c i b l e s u l p h u r i n t h e e x t r a c t ( J o h n s o n and N i s h i t a , 1 9 5 2 ) . The e x t r a c t i n g s o l u t i o n s were p r e p a r e d by m i x i n g s o l u t i o n s o f t h e same m o l a r i t y o f sodium d i h y d r o g e n p h o s p h a t e and d i s o d i u m h y d r o g e n p h o s p h a t e , i n s u i t a b l e p r o p o r t i o n s t i l l t h e r e q u i r e d pH was o b t a i n e d . I n t h e p r e l i m i n a r y s t u d i e s t h e pH a f t e r e x t r a c t i o n was d e t e r m i n e d u s i n g a C o r n i n g M odel 12 pH m e t e r . B o t h 0.5 M ammonium f l u o r i d e pH 6.0 ( F i s h e r a l k a c i d t e s t r i b b o n ) and 0.05 M C a d ^ P O ^ .H 20 pH 3.5 were u s e d t o e x t r a c t a few s e l e c t e d s a m p l e s . The p r o c e d u r e was i d e n t i c a l w i t h t h a t u s e d f o r t h e p h o s p h a t e b u f f e r s . Water e x t r a c t a b l e s u l p h u r was a l s o e s t i m a t e d . I n a l l a n a l y s e s d e i o n i z e d d i s t i l l e d w a t e r was u s e d , and t h e s u l p h u r v a l u e s were b a s e d on a t l e a s t two d e t e r m i n a t i o n s . S e p a r a t i o n o f P h o s p h a t e E x t r a c t a b l e S u l p h a t e i n t o i t s O r g a n i c and I n o r g a n i c F r a c t i o n s The e x t r a c t e d s u l p h a t e i n t h e p h o s p h a t e b u f f e r s was s e p a r a t e d i n t o t h e o r g a n i c and i n o r g a n i c forms by g e l f i l t r a t i o n on Sephadex d e x t r a n g e l s . T h i s w i l l p e r m i t s e p a r a t i o n and s e p a r a t e d e t e r m i n a t i o n of o r g a n i c and i n o r g a n i c s u l p h a t e . Sephadex G-25 and G-50 medium g e l s were u s e d and compared. Lowe i n 1966 u s e d a G-2 5 f i n e gel t o p e r f o r m t h i s s e p a r a t i o n . The p r o c e d u r e employed a l a b o r a t o r y c olumn, w h i c h - 44 -has a u n i f o r m i n t e r n a l d i a m e t e r (0.85 cm) v e r y l i t t l e v o i d s p a c e a t t h e b o t t o m o f t h e c o l u m n , w h i c h m i n i m i z e s zone r e - m i x i n g , and an a d j u s t a b l e o u t l e t t o g i v e some c o n t r o l o f t h e f l o w r a t e . W i t h t h e G-50 medium g e l t h e f l o w r a t e was 1.7 ml p e r m i n u t e , w h i l e w i t h t h e G-25 medium i t was 1.46 ml m i n u t e . The h e i g h t o f t h e Sephadex i n t h e column was 35.0 cm w h i l e t h e column i t s e l f i s 40.0 cm. The Sephadex was f i r s t e q u i l i b r a t e d w i t h 0.02 M s o d i u m t e t r a b o r a t e b u f f e r and p a c k e d i n t o t h e column. The v o i d volume was 9.0 ml f o r t h e G-50 medium g e l and 10.0 ml f o r t h e G-25, and was d e t e r m i n e d w i t h B l u e D e x t r a n 2000 s u p p l i e d by P h a r m a c i a , U p p s a l a Sweden. S e p a r a t i o n s on t h e G-50 were a f f e c t e d by a p p l y i n g 4.0 ml o f s o i l e x t r a c t t o t h e column and e l u t i n g w i t h t h e b o r a t e b u f f e r o r g a n i c s u l p h a t e was e l u t e d between 9.0 ml and 16.2 ml and i n o r g a n i c f r o m 18.3 ml t o 24.0 m l . A f t e r e v a p o r a t i o n t h e s u l p h a t e was d e t e r m i n e d by t h e J o h n s o n and N i s h i t a (1952 ) c o l o r i m e t r i c p r o c e d u r e . W i t h t h e G-25 t h e o r g a n i c s u l p h a t e was e l u t e d f r o m 10.0 ml t o 12.0 ml w h i l e t h e i n o r g a n i c f r a c t i was f r o m 12.5 ml t o 16.0 m l . Lowe i n 1966 o b t a i n e d c o m p l e t e r e c o v e r y u s i n g s t a n d a r d p o t a s s i u m s u l p h a t e s o l u t i o n s and f o u n d t h a t r e c o v e r y o f t o t a l s u l p h a t e r a n g e d f r o m 93 t o 98 . p e r c e n t f o r a v a r i e t y o f s o i l e x t r a c t s t e s t e d . He d i d n o t o b t a i n s a t i s f a c t o r y r e s u l t s when t h e s u l p h a t e - s u l p h u r i n t h e e x t r a c t was l e s s t h a n 10.0 ppm. - 45 -Determination of Total Carbon Total carbon was determined by the use of the Leco induction furnace and carbon analyzer, model 572-200 (Labor-atory Equipment Corporation, St. Joseph, Michigan). Samples of 0.25 - 0.50 grams, depending on the carbon content, were mixed with one scoop each of iron and t i n accelerator. Free Alumina and Free Oxides of Iron The free alumina was determined by boiling the s o i l sample for only 2.5 minutes in a large excess of 0, 5 N NaOH (Jackson, 196 5). The aluminum was measured by the colorimetric method using aluminon. A Bausch and Lomb Sprectronic 2 0 spectrophotometer was used for the absorbance measurements. The iron oxide was extracted by the sodium dithionite (Na^S^O^) citrate-bicarbonate method on the residue from the free alumina extraction (Jackson, 19 6 5). The iron was measured by atomic absorption. X-Ray Diffraction Analyses for the <2u Fraction 50.0 gram samples of <2 mm a i r dry s o i l were segregated for x-ray analysis, using a quick method (Jackson, 195 6, a modified procedure). The separated <2u fraction was then saturated with magnesium and potassium (Whittig, Methods of Soil Analysis, Black, Editor, Am. Society of Agronomy, Inc. Publisher, 1965) . Solvation with 10 percent glycerol was also carried out on the <2u fraction (Whittig, 1965) . - 46 -Slides were prepared from the saturated suspensions and then x-rayed using copper Kal radiation. The x-ray diffractograms were interpreted in order to determine the mineralogy of the s o i l samples. Soil pH Soil pH was determined using a soil:water ratio of 1:2.5 (Jackson, 1958) ; and a Corning Model 12 pH meter. Adsorption Capacity This was essentially the method of Chao et a l . (1962). 5 gm of s o i l and 2 5 ml of K^SO^ solution containing 50 ppm S in a 5 0 ml centrifuge were shaken for one hour, l e f t over overnight with slow shaking and centrifuged for 10 minutes at 6,000 rpm the following day. The supernatant solution was f i l t e r e d through a Whatman No. 1 f i l t e r paper and the sulphur in the solution estimated by the methylene blue method. - 47 -RESULTS AND DISCUSSION Factors A f f e c t i n g the E x t r a c t i o n of S o i l Sulphate Phosphate has been much used as an extractant f o r s o i l sulphate. Ensminger (1954) was one of t h e f i r s t w o r k e r s to report i t s e f f i c i e n c y . He used a 500 ppm P s o l u t i o n . Freney (1968) suggested that phosphate s o l u t i o n s of t h i s concentration ought to remove a l l adsorbed sulphate though a few s u b s o i l s r e q u i r e 2000.0 ppm P. Lowe (1964) reported a nine f o l d increase i n the sulphate extracted from a podzol when the concentration of t h e phosphate s o l u t i o n was i n c r e a s e d from 500 ppm P to 15 ,000 ppm P (0.5 M). As a r e s u l t a study was made to determine the e f f e c t of concentration of phosphate buffers on sulphate e x t r a c t i o n (Table I I I ) . These r e s u l t s i n d i c a t e that i n c r e a s i n g the phosphate concentration increases the sulphate e x t r a c t i o n (Figure 1). The extracts obtained at the higher phosphate concentrations were darker i n colour than those of the more d i l u t e extractants i n d i c a t i n g the removal of s u b s t a n t i a l amounts of organic matter. Lowe (1968) extracted sulphated-polysaccharide materials i n phosphate extracts from A l b e r t a s o i l s , The pH of the extracts f o r the 0.5 M, 0.2 M, and 0.1 M, e x t r a c t i n g solutions d i d not vary by more than 0.4 of a pH u n i t f r o m the o r i g i n a l e x t r a c t i n g s o l u t i o n s . However, the extracts from the 0.005 M s o l u t i o n s were almost one pH u n i t lower f o r most T a b l e I . Some S o i l P r o p e r t i e s G r e a t Group S e r i e s S a m p l i n g Depth P r o f i l e T e x t u r e V e g e t a t i o n E£ T o t a l % C B l a c k L a n g f o r d 0' 6' •-6" '-12" Ac A l l i A 1 2 ( 3 "-13") Loam Loam g r a s s l a n d p r e s u m a b l y u n d i s t r u b e d 5.9 5.9 12.21 5.21 R e g o s o l Monroe 0' 6' •~6" *-12" Ah C l C °2 0"-4" 4"-10" 10"-18" S i l t l o a m p a s t u r e s h r u b , d i s t u r b e d 5.8 5.9 1.96 1.09 A c i d Brown Wooded Whatcom 0' 2' 10' i _ 2 " '-12" '-27? Ap B f BC S i l t l o a m Maple and some A l d e r 5.5 6.0 6.1 7.98 2.00 1.01 A c i d Dark Brown F o r e s t S a a n i c h t o n 0' 6' '-6" '-12" A B l B 2 0"-2" 2"-6" 6 " - l l " C l a y loam p a s t u r e p r o b a b l y u n i m p r o v e d 5.8 6.4 2 .75 1.20 C o n c r e t i o n a r y Brown N i c h o l s o n 0' 6' »_6" '-12" B f h c c Bf cc 0"-4" 4"-13" S i l t loam p a s t u r e d i s t u r b e d 5.9 6.1 3.54 0.71 G l e y s o l i c Hazlewood 0 ! ' _7 " '-18" Ah B t g S i l t y c l a y loam p a s t u r e d i s t u r b e d 5.8 5.9 4.68 2.26 C o n c r e t i o n a r y Brown A b b o t s f o r d 0' 8' '-6" '-12" B f c c 1 B f c c 2 0"-5" 5 " - l l " Loam p a s t u r e d i s t u r b e d s i t e 5.9 5.9 2.37 1.17 T a b l e T. Some s o i l p r o p e r t i e s C.S.S.C. Sampling T o t a l C Great Group- 19 68 C l a s s ! f i c a t i o n Depth S o i l Type V e g e t a t i o n pH % La n g f o r d B l a c k Sombric B r u n i s o l 0" -6" Loam g r a s s l a n d 5 . 9 12 . 21 6" -12" Loan presumably 0 . 9 5 .21 u n d i s t u r b e d Monroe Regosol Degraded D i s t r i e 0" -6'-' S i l t p a s t u r e 5 . 8 1 .96 B r u n i s o l loam 6" -12" s h r u b , 5 . 9 1 . 09 d i s t u r b e d v/hatcom A c i d Brown B i s e q u a M i n i Humo 0" -2" S i l t Maple and 5 . 5 7 .98 Wooded F e r r i c P o d z o l 2 " -12" loam some A l d e r 6 . 0 2 .00 10" -27" 6 . 1 1 . 01 Sa a n i c h t o n A c i d Dark Sombric B r u n i s o l 0" -6" C l a y p a s t u r e 5 . 8 2 .75 Brown 6'' -12" loam p r o b a b l y 6 .4 T _L .20 F o r e s t unimproved N i c h o l s o n C o n c r e t i o n a r y M i n i Humo F e r r i c 0" -6" S i l t p a s t u r e 5 . 9 3 . 54 Brown P o d z o l 6" -12" loam d i s t u r b e d 6 .1 0 .71 Hazlewood G l e y s o l i c O r t h i c Humic 0" -7" S l l t y p a s t u r e 5 . 8 4 .68 G l e y s o l 7" -18" c l a y d i s t u r b e d 5 . 9 2 .26 loam A b b o t s f o r d C o n c r e t i o n a r y M i n i Humo F e r r i c 0" -6" Loam p a s t u r e 5 .9 2 . 37 Brown P o d z o l 6" -12" d i s t u r b e d 5 .9 1 .17 s i t e " Taken from S o i l Survey R e p o r t s Table II. Mineral distribution in <2u fraction Soil -M •rl ft o H CO +•> •H C o •H o 6 c o CO +-> •H H O CO > o o < cy CO CO H o o •H bO rd rH o •ri ft I w H CO ft CD >> t3 CO X S 1 <D £^  0) 4-> •rl U O r-i O Remarks Langford 0"-6" 2 0 3 1-2 2 0 1 1-2 0 0 Langford 6"-12" 1-2 0 3 0 1 0-1 0 0 0 0 Monroe 0"-6" 2 2 2 1 1 1 0 0 1-2 0 Mixed Mont. Monroe 6"-12" 3 2 2 1-2 1 1 0 0 1 0 Mont. Mixed Whatcom 0f,-2" 3 0 1-2 0 1-2 1 0-1 0 0 0 Whatcom 2"-10" 3-4 0 1-2 0 1-2 1 0 0 0 0 Whatcom 10"-27" 2 0 3 1-2 2 1 1 0 0 0 Saanichton 0"-6" 2-3 0 3 0 1 1 0 0 0 0 Saanichton 6"-12" 0 0 3 1 1-2 1 0 0 0 2 Nicholson 0"-6" 2 0 3 0 1-2 1 0 0 0 0 Nicholson 6"-12" 2-3 0 2-3 0 1-2 0-1 0 0 0 0 Hazlewood 0"-7" 2 1-2 2 1-2 1 1 0 0 1 0 Mont-Hazlewood 7"-18" 2 0 3 1 1-2 1 0 0 0 0 Abbotsford 0"-6" 2 0 3 0 1-2 0-1 0 0 0 0 Abbotsford 6"-12" 2 0 3 1-2 1 0-1 0 0 0 0 0 = none; 1-0 = 10%; 2 = 10 -35%; 3 = 35-6 5%; 4 = >65%, Numbers are Vm-illite estimates. FIGURE 1: pH 7.0 CONCENTRATION OF PHOSPHATE VARYING BETWEEN 0 . 0 0 5 M AND 0.5 M - 51 -of the s o i l samples. Part of the extracted sulphate at the lower concentration levels might be influenced by pH variation. The water extracts for a l l s o i l s were lower in sulphur than the lowest phosphate le v e l . The mere presence of phosphate results in greater sulphur extraction. For some surface horizons e.g. Abbotsford, Nicholson, Saanichton and Langford 0"-6" a 0.5 M extracting solution does not remove any sign i f i c a n t l y layer amounts of sulphate than a 0.2 M. The same can also be said for the Abbotsford 6"-12". The effect of pH on the extraction of sulphate was then studied in order to determine whether pH had any effect on sulphate extraction (Table IV). The results for the sub-surface horizons follow the same pattern as for the three soils given. The data shows that the soils do not behave in the same way when the pH of the extracting phosphate solution i s varied. The surface soils and the subsoils have one common property, this i s a drop in extracted sulphur at pH 8.0, from a maximum at pH 7.0 (Figure 2). The Langford 0"-6" and the Nicholson 0"-6" were exceptions in that increased sulphur extraction resulted with increasing the pH levels when the pH was increased from 4.0 to 8.0. Generally the following trends can be observed: (a) An increase in sulphate extraction with r i s i n g pH, this i s shown by Langford 0"-6" and Nicholson 0"-6". 70 .0 4.0 5.0 6.0 7.0 8.0 pH FIGURE 2: 0 5 M SODIUM PHOSPHATE EXTRACTANT pH VARYING FROM 4.0 TO 8.0 - 53 -T a b l e I I I . Amounts o f s u l p h a t e e x t r a c t e d a t pH 7 w i t h p h o s p h a t e b u f f e r s o f v a r y i n g c o n c e n t r a t i o n (ppm S) S o i l 0. 5M 0 . 2M L a n g f o r d 0"-6" 73 .0 70 .0 Monroe 0"-6" 37 .5 20 .0 Whatcom 2"-10" 37 .0 12 .0 Whatcom 0"-2" 45 .0 27 .5 S a a n i c h t o n 0"-6" 20 .0 15 .0 N i c h o l s o n 0"-6" 34 .0 32 .0 Hazlewood 0"-7" 67 .0 50 .0 A b b o t s f o r d 0"-6" 33 .5 35 .0 Hazlewood 7"-18" 45 .0 36 .2 A b b o t s f o r d 6"-12" 40 .0 47 .5 L a n g f o r d 6"-12" 124 .0 73 .5 0.1M 0.05M 0.005M Water 50.0 45. 0 19.0 8.5 12.50 5. 0 5.0 4.0 15.0 14. 0 10.0 0 . 0 30.0 24. 0 8.0 6.0 20.0 12. 0 8.0 2.5 32.0 20 . 0 10.0 4.0 26.0 26 . 0 16.0 6.0 30.0 30. 0 24.0 0.0 21.0 19. 0 19.0 0.0 32.0 29. 0 26.0 5.0 48.0 36 . 0 20.0 6 . 0 - 54 -Table IV. Amounts of sulphate extracted with 0.5M phosphate buffers at varying pH levels (ppm S) Soil pH Soil pH 4.0 pH 5.0 pH 6.0 pH 7.0 pH 8.0 1:2.5 Langford 0"-6" 28.0 43.0 67.0 73.0 95.0 5.9 Monroe 0"-6" 21.0 20.0 12.0 37.5 26.0 5.8 Whatcom 2"-10" 25.0 15.0 12.0 37.0 27.0 6.0 Whatcom 0"-2" 27.0 22.0 19.0 45.0 35.0 5.5 Saanichton 0"-6" 12.0 8.0 10.0 20.0 7.0 5.8 Nicholson 0"-6" 14.0 20.0 23.0 34.0 45.0 5.9 Hazlewood 0"-7" 41.0 43.0 50.0 67.0 32.0 5.8 Abbotsford 0"-6" 32.0 30.0 26.0 33.5 32.0 5.9 Hazlewood 7"-18" 28.0 16.0 26.0 45.0 30.0 6.8 Abbotsford 6"-12" 41.0 43.0 45.0 40.0 40.0 6.1 Langford 6"-12" 64.0 84.0 96.0 124.0 81.0 5.9 - 55 -(b) pH d i d not have any s i g n i f i c a n t e f f e c t on e x t r a c t i o n , A b b o t s f o r d 0"-6" and 6"-12" i l l u s t r a t e s t h i s p r o p e r t y . ( c ) A d e c r e a s e i n s u l p h a t e e x t r a c t i o n a t pH 8.0; f o r example, Monroe 0"-5" and Whatcom 0"-2", 2"-10". The most common p a t t e r n was maximum e x t r a c t i o n a t pH 7. The e f f e c t s o f pH c o u l d be due t o d i f f e r e n t f r a c t i o n s o f the s o i l s u l p h u r b e i n g a f f e c t e d by pH; p e r h a p s , e x t r a c t i o n o f d i f f e r e n t forms b e i n g more o r l e s s f a v o u r e d a t d i f f e r e n t pH v a l u e s . The s i m i l a r i t y o f t h e e f f e c t o f pH on most o f the s u r f a c e s o i l s c o u l d q u i t e p o s s i b l y be i n f l u e n c e d by t h e i r m i n e r a l o g y which i s q u i t e s i m i l a r ( T a b l e I I ) . The i n t e r a c t i o n between pH and c o n c e n t r a t i o n w a s s t u d i e d t o d e t e r m i n e whether a h i g h c o n c e n t r a t i o n o f phosphate b u f f e r 0.5 M i s j u s t i f i e d , o r can the same e f f e c t be a t t a i n e d u s i n g a h i g h pH and e x t r a c t i n g s o l u t i o n s o f lower c o n c e n t r a t i o n . A s t u d y was c a r r i e d out on L a n g f o r d 0"-6", S a a n i c h t o n 0"-6" and A b b o t s f o r d 6"-12" ( T a b l e V). T a b l e V. Amounts o f s u l p h a t e e x t r a c t e d w i t h 0.05M phosphate b u f f e r s a t v a r y i n g pH l e v e l s (ppm S) S o i l pH 4.0 pH 5.0 pH 6.0 pH 7.0 pH 8.0 B l a c k L a n g f o r d 0"-6" 26.0 26.0 34.0 45.0 56.0 A c i d Dark Brown F o r e s t S a a n i c h t o n 0"-6" 8.0 5.0 8.0 12.0 8.0 C o n c r e t i o n a r y Brown A b b o t s f o r d 6"-12" 34.0 34.0 36.0 29.0 34.0 - 56 -At t h e 0.05M l e v e l o f phosphate c o n c e n t r a t i o n t h e L a n g f o r d 0"-6" a g a i n shows i n c r e a s i n g amounts o f s u l p h a t e e x t r a c t e d w i t h i n c r e a s i n g pH, though t h e q u a n t i t y e x t r a c t e d i s a t a lower l e v e l . The S a a n i c h t o n 0"-6" show a s i g n i f i c a n t d i f f e r e n c e i n e x t r a c t i o n o n l y a t pH 7.0, but t h e d e c r e a s e i n e x t r a c t i o n a t pH 8.0 i s a g a i n n o t i c e d . The A b b o t s f o r d 6"-12" does not appear t o be much a f f e c t e d by pH; i n t h a t e s s e n t i a l l y the same amount o f s u l p h a t e i s e x t r a c t e d a t a l l pH l e v e l s i n v e s t i g a t e d ; though s l i g h t l y more s u l p h a t e i s e x t r a c t e d w i t h 0.5M s o l u t i o n s . I t t h u s seems t h a t pH and c o n c e n t r a t i o n b o t h a f f e c t e x t r a c t i o n , and t h e aim must be e x t r a c t i o n a t t h e r i g h t m o l a r i t y and optimum pH, i f i n d e e d , a l l t h e s u l p h a t e which i s e x t r a c t e d i s a c t u a l l y p l a n t a v a i l a b l e . T h i s i s a problem which remains t o be e x p l o r e d more f u l l y ; t h a t o f t h e a v a i l a b i l i t y o f t h e e x t r a c t e d s u l p h a t e . E f f e c t o f C a t i o n The e f f e c t o f c a t i o n has been s t u d i e d by Chao e t a l . (1963) who found t h a t a d s o r p t i o n o f s u l p h a t e from s o l u t i o n s r a n g i n g from 5 t o 100.0 ppm s u l p h u r f o l l o w e d the o r d e r : CaS0 4 > K 2S0 l | > (NH ! +) 2S0 [ 4 > Na^O^. These workers a l s o found t h a t i n s o i l s s a t u r a t e d w i t h K, Ca o r A l , a d s o r p t i o n o f s u l p h a t e i n c r e a s e d w i t h the v a l e n c y o f the s a t u r a t i n g c a t i o n , a l s o t h e y showed t h a t a d s o r p t i o n o f s u l p h a t e d e c r e a s e d n e a r n e u t r a l i t y i r r e s p e c t i v e o f the c a t i o n p r e s e n t , and t h a t the - 57 -pH e f f e c t was g r e a t e s t i n s o i l s c o n t a i n i n g much R^O^, exchangeable A l and/or amorphous m a t e r i a l s . The p a r t p l a y e d by t h e m i n e r a l s i n t h e s o i l s w i l l be d i s c u s s e d s u b s e q u e n t l y . Hence, the p r e s e n c e o f sodium m i n i m i z e s t h e a d s o r p t i o n o f s u l p h a t e . Thus, t h e r a t i o n a l e b e h i n d t h e use o f sodium phosphate b u f f e r s . To d e t e r m i n e whether any d i f f e r e n c e d i d i n f a c t e x i s t , a 0.05M C a ( H 2 P O | + ) 2 .H 20 e x t r a c t i n g s o l u t i o n a t pH 3.5 was u s e d . The r e s u l t s a r e t a b u l a t e d i n T a b l e V I . T a b l e V I . Amounts o f s u l p h a t e e x t r a c t e d w i t h 0.05M C a ( H 2 P O l | ) 2 a t pH 3.5 (ppm S) S o i l ppm S L a n g f o r d 0"-6" 26.0 S a a n i c h t o n 0"-6" 12.0 A b b o t s f o r d 6"-12" 38.0 Thus, comparing T a b l e s V and VI i t can be c o n c l u d e d t h a t t h e c a t i o n had v e r y l i t t l e i f any e f f e c t on t h e e x t r a c t i o n o f s u l p h a t e under the c o n d i t i o n s o f e x t r a c t i o n . The i n c r e a s e i n e x t r a c t i o n f o r t h e S a a n i c h t o n can be due t o the pH d i f f e r e n c e as e x t r a c t i o n i s i n c r e a s i n g w i t h lower pH ( T a b l e V) f o r t h i s s o i l . As f a r as l a b o r a t o r y r o u t i n e i s c o n c e r n e d , i t i s f a r e a s i e r t o p r e p a r e sodium phosphate s o l u t i o n s t h an t h o s e o f c a l c i u m phosphate. Thus, the c a l c i u m i s not more e f f i c i e n t . The c a l c i u m e x t r a c t s were much c l e a r e r and can be used by t u r b i d i m e t r y w h i l e the sodium e x t r a c t s - 58 -were q u i t e dark c o l o u r e d , however, the e x t r a c t c o l o u r does not e f f e c t the methylene b l u e c o l o r i m e t r i c method as used i n t h i s s t u d y . Chao (1964) found t h a t phosphate, molybdate (Mo0^~) and f l u o r i d e caused 44.0, 34.0 and 30.0 p e r c e n t d e p r e s s i o n on s u l p h a t e a d s o r p t i o n . Thus, phosphate and f l u o r i d e ought t o e x t r a c t the g r e a t e s t amount o f ads o r b e d s u l p h a t e . Out o f c u r i o s i t y e x t r a c t i o n w i t h f l u o r i d e was compared w i t h phosphate. 0.5M ammonium f l u o r i d e pH 6.0 was used t o e x t r a c t s u l p h a t e from L a n g f o r d 0"-6", S a a n i c h t o n 0"-6", Whatcom 0"-2", 2"-10", Hazlewood 0"-7" and A b b o t s f o r d 6"-12". These r e s u l t s a r e g i v e n i n T a b l e VII. T a b l e VII. Amounts o f s u l p h a t e e x t r a c t e d w i t h 0.5M NH 4F, pH 6. S o i l ppm S L a n g f o r d 0"-6" 135.0 S a a n i c h t o n 0"-6" 10 . 0 Whatcom 0"-2" 29.0 Whatcom 2"-10" 14.5 Hazlewood 0"-7" 24.0 A b b o t s f o r d 6"-12" 36.0 The r e s u l t s u s i n g 0.5M sodium phosphate b u f f e r a t pH 6.0 were 67 .0 , 10 . 0 , 19.0 , 12.0 , 50.0 , and 45.0 ppm s u l p h u r f o r the s o i l s i n the o r d e r g i v e n i n T a b l e VII. Thus, the f l u o r i d e e x t r a c t e d t w i c e as much HI r e d u c i b l e s u l p h u r as d i d - 59 -the phosphate f o r t h e L a n g f o r d sample. In t h e Whatcom 0"-2" more s u l p h u r was e x t r a c t e d w i t h NH^F t h a n w i t h t h e phosphate, however, i n t h e 2"-10" d e p t h , t h e phosphate was a b e t t e r e x t r a c t a n t . The r e s u l t was t h e same f o r t h e S a a n i c h t o n and s l i g h t l y l o w e r f o r A b b o t s f o r d . Phosphate proved t o have b e t t e r e x t r a c t i n g power f o r t h e Hazlewood 0"-7". The g r e a t e r f l u o r i d e f o r the L a n g f o r d 0"-6" and Whatcom 0"-2" can q u i t e e a s i l y be due t o t h e g r e a t e r e x t r a c t i o n o f o r g a n i c m a t t e r and c o n s e q u e n t l y t h e r e l e a s e o f more o r g a n i c s u l p h a t e , which i s n o t d i r e c t l y bound t o ca r b o n . The a b i l i t y o f the f l u o r i d e i o n t o e x t r a c t o r g a n i c m a t t e r has been demonstrated by S c h n i t z e r e t a l . (1958). In s o i l s w i t h a low ca r b o n c o n t e n t ( T a b l e I) and a r e s u l t i n g low o r g a n i c m a t t e r l e v e l and low o r g a n i c s u l p h a t e , the phosphate o r f l u o r i d e e x h i b i t e q u a l e x t r a c t i n g a b i l i t y w i t h t h e phosphate b e i n g more e f f i c i e n t . The e x p l a n a t i o n t h a t t h e g r e a t e r e x t r a c t e d s u l p h a t e i n t h e f l u o r i d e e x t r a c t i o n was due t o i t s g r e a t e r e x t r a c t i o n e f f i c i e n c y o f o r g a n i c m a t t e r i s s u p p o r t e d by t h e f a c t t h a t t h e L a n g f o r d 0"-6" and Whatcom 0"-2" had f a r more carbon ( T a b l e I) t h a n the o t h e r s o i l s o f T a b l e V I I , e x c e p t perhaps t h e Hazlewood 0"-7" but as w i l l be shown l a t e r t h i s s o i l had the h i g h e s t p e r c e n t a g e o f f r e e i r o n f o r the s u r f a c e s o i l s ; hence c o n t r i b u t i n g t o the phosphate e f f i c i e n c y . - 60 -A n e u t r a l 0.5M phosphate e x t r a c t i n g s o l u t i o n i s b e s t f o r most s o i l s , though i t s e f f i c i e n c y i s s t i l l unknown. T h i s w i l l be judged by t h e p r o p o r t i o n o f t o t a l s o i l s u l p h a t e (HI r e d u c i b l e ) and t o t a l s o i l s u l p h u r t h a t w i l l be e x t r a c t e d by t h i s e x t r a c t a n t . These f i g u r e s a r e p r e s e n t e d i n T a b l e V I I I . The Whatcom and Hazlewood were the two s o i l s sampled by h o r i z o n and i n b o t h s o i l s t h e t o t a l s u l p h u r d e c r e a s e s w i t h depth. The o t h e r s o i l s sampled on the 0"-6" and 6"-12" b a s i s a l s o i l l u s t r a t e t h i s d e c r e a s e i n t o t a l s u l p h u r w i t h d e p t h . A comparison o f t o t a l s u l p h u r w i t h t o t a l c a r b o n ( T a b l e I ) ought t o g i v e some i n d i c a t i o n as t o the p o s s i b i l i t y o f the o r g a n i c f r a c t i o n c o n t r i b u t i n g t o the i n c r e a s e d s u l p h u r c o n t e n t o f t h e s u r f a c e h o r i z o n s . I t i s an a c c e p t e d f a c t t h a t i n w e l l d r a i n e d a g r i c u l t u r a l s o i l s o f the humid r e g i o n s , most o f t h e s u l p h u r i s a s s o c i a t e d w i t h o r g a n i c compounds, e s p e c i a l l y i n s u r f a c e s o i l s ( B u rns, 196 8; Freney and Stevenson, 19 66 ; N e l s o n , 1964). S u l p h a t e i s supposed t o predominate i n the lower h o r i z o n s ( R e i s e n a u e r , 1967). Phosphate s o l u t i o n s a r e supposed t o remove r e a d i l y s o l u b l e s u l p h a t e and p o r t i o n s o f adsorbed s u l p h a t e (Beaton e t a l . , 19 6 8 ) . From T a b l e V I I I i t can be c o n c l u d e d t h a t the h i g h e r p e r c e n t a g e o f the phosphate e x t r a c t a b l e s u l p h u r i n the lower h o r i z o n s i n d i c a t e s t h a t a g r e a t e r p e r c e n t a g e o f t h e t o t a l s u l p h u r i s i n the r e a d i l y s o l u b l e and adsorbed forms. The e x t r a c t a b l e s u l p h u r a c c o u n t s f o r 5.8 t o almost 25.0 p e r c e n t T a b l e V I I I . S o i l T o t a l S HI S L a n g f o r d 0"-6" 1250 .0 468 .0 L a n g f o r d 6"-12" 1140 .0 608 .0 Monroe 0"-6" 220 .0 75 .2 Monroe 6"-12" 100 .0 75 .2 Whatcom 0"-2" 460 .0 100 .0 Whatcom 2"-10" 150 .0 57 .6 Whatcom 10"-27" 130 .0 72 .0 S a a n i c h t o n 0"-6" 170 .0 48 .0 S a a n i c h t o n 6"-12" 110 .0 51 .2 N i c h o l s o n 0"-6" 190 . 0 62 .0 N i c h o l s o n 6"-12" 80 .0 67 .2 Hazlewood 0"-7" 370 .0 244 .0 Hazlewood 7"-18" 200 .0 120 .0 A b b o t s f o r d 0"-6" 310 .0 76 .8 A b b o t s f o r d 6"-12" 100 .0 68 .8 E x t r a c t a b l e S as p e r c e n t o f HI and t o t a l S (ppm S) N e u t r a l 0.5M P O , - e x t r a c t a b l e 73.0 124.0 37.5 27.0 45.0 37.0 60.0 20.0 20.0 34.0 45.0 67 .0 45.0 33.5 40.0 E x t r a c t a b l e as % o f HI 15.0 20.0 50.0 35.0 45.0 64.0 83.0 42 .0 39.0 55 . 0 67 .0 27.0 37.0 44.0 58.0 E x t r a c t a b l e as % o f t o t a l S 6.0 11.0 17.0 27.0 10.0 25.0 46.0 12.0 18.0 18.0 56.0 18 .0 22.0 11.0 40.0 - 62 -o f t h e t o t a l s u l p h u r i n t h e s u r f a c e h o r i z o n s and from 10.8 t o 46.0 p e r c e n t f o r t h e 6" t o 12" d e p t h . A g r e a t e r p e r c e n t a g e o f t h e HI r e d u c i b l e s u l p h u r i s e x t r a c t e d by t h e phosphate b u f f e r . V a l u e s ranged from 15.5 t o 64 p e r c e n t f o r the s u r f a c e h o r i z o n s and from 20.3 t o 83.0 p e r c e n t f o r the 6" t o 12" d e p t h . Thus, i n most s o i l s a l a r g e p e r c e n t a g e o f t h e HI r e d u c i b l e , non c arbon bonded s u l p h u r i s not e x t r a c t e d under the c o n d i t i o n s used. T h i s f r a c t i o n which was not e x t r a c t e d c o u l d q u i t e p o s s i b l y be o r g a n i c s u l p h a t e and the more s t r o n g l y h e l d s u l p h a t e a n i o n which can r e p l a c e hydroxo o r o l groups i n c o - o r d i n a t i o n complexes w i t h i r o n and aluminum. Hence, t h i s s u l p h a t e which has p e n e t r a t e d the c o - o r d i n a t i o n complex by b r e a k i n g o l and oxo l i n k a g e s and so become c o - o r d i n a t e d t o aluminum and i r o n , can be r e d u c e d t o hydrogen s u l p h i d e by t h e p o w e r f u l r e d u c i n g m i x t u r e o f h y d r i o d i c f o r m i c and by hypophosphorous a c i d s , but cannot be r e p l a c e d by t h e phosphate i o n though p r e s e n t i n h i g h c o n c e n t r a t i o n i n an e x t r a c t i o n time o f h a l f an hour. However, i t i s q u i t e l i k e l y t h a t i f a h i g h c o n c e n t r a t i o n o f phosphate i o n s cannot r e p l a c e t h i s s u l p h a t e , the p l a n t r o o t s may a l s o be unable t o e x t r a c t i t . The o n l y way t o determine t h i s q u e s t i o n i s t h r o u g h p l a n t growth and e x t r a c t i o n s t u d i e s t o d etermine how much o f the e x t r a c t a b l e f r a c t i o n i s a c t u a l l y u t i l i z e d by p l a n t s o v e r a growing p e r i o d and whether the e x t r a c t i n g s o l u t i o n removes more than the p l a n t u t i l i z e s o r may be l e s s and attempt t o a s c e r t a i n whether a d e f i n i t e - 63 -p e r c e n t a g e o f t h e e x t r a c t a b l e s u l p h u r i s a v a i l a b l e t o p l a n t s o v e r a growing p e r i o d ; and i f p o s s i b l e t o d e f i n e what p e r c e n t a g e o f t h e e x t r a c t a b l e s u l p h u r r e p r e s e n t s a d e f i c i e n c y , o r a s u f f i c i e n c y o f s u l p h u r f o r optimum p l a n t growth. I f phosphate e x t r a c t i n g s o l u t i o n s remove t h e r e a d i l y s o l u b l e and a dsorbed s u l p h a t e , and water e x t r a c t s t h e r e a d i l y s o l u b l e and v a r i a b l e s m a l l amounts o f o r g a n i c s u l p h u r , t h e n the d i f f e r e n c e between t h e s u l p h u r e x t r a c t e d i n t h e s e two p r o c e s s e s ought t o i n d i c a t e how much i s a c t u a l l y a d s o r b e d . T h i s assumption however, t h a t s o l u b l e and a f r a c t i o n o f adsorbed s u l p h a t e i s e x t r a c t e d by phosphate s o l u t i o n s CBeaton e t a l . , 1968) i s open t o some doubt as subsequent d i s c u s s i o n on t h e s e p a r a t i o n o f t h e e x t r a c t e d f r a c t i o n s w i l l attempt t o show. However, t h e s u b t r a c t i o n p r o c e d u r e w i l l s t i l l be perfor m e d , though i t i s n e c e s s a r y t o emphasize t h a t a c e r t a i n amount o f t h e 0.5 M phosphate e x t r a c t can be o r g a n i c i n n a t u r e , f o r example s u l p h a t e d p o l y s a c c h a r i d e s and s u l p h a t e e s t e r s o f p h e n o l s (Lowe, 1968; Freney e t a l . , 1962) and need not have been adsorbed by t h e m i n e r a l f r a c t i o n o f t h e s o i l . T a b l e IX i n d i c a t e s t h e r e s u l t s o b t a i n e d f o r some s o i l s and i l l u s t r a t e s t h e p o s s i b l e maximum v a l u e f o r the s u l p h a t e which i s i n t h e adsorbed s t a t e . T a b l e IX shows t h a t a l l t h e s o i l s have some c a p a c i t y t o adsorb s u l p h a t e s u l p h u r . The lower h o r i z o n s o f - 64 -a l l t h e samples e x c e p t t h e r e g o s o l - M o n r o e , e x h i b i t h i g h e r l e v e l s o f a p p a r e n t adsorbed s u l p h a t e , t h a n t h e s u r f a c e h o r i z o n s , t h i s can q u i t e e a s i l y be due t o s u l p h a t e l e a c h i n g i n t h e upper h o r i z o n s and i t s subsequent a c c u m u l a t i o n i n t h e lower ones. Whether t h i s a c c u m u l a t i o n i s due t o i n c o m p l e t e l e a c h i n g , a d s o r p t i o n by hydrous o x i d e s o r e l e c t r o l y t i c i m b i b i t i o n (Thomas, 1960) remains open t o q u e s t i o n . Q u i t e p o s s i b l y many f a c t o r s c o n t r i b u t e t o s u l p h a t e a d s o r p t i o n and d i f f e r e n t f a c t o r s predominate under d i f f e r e n t e n v i r o n m e n t a l c o n d i t i o n s . In t h e s e p a r t i c u l a r s o i l s X-ray d i f f r a c t i o n s t u d i e s o f t h e <2u f r a c t i o n ( T a b l e I I ) f a i l e d t o r e v e a l the p r e s e n c e o f 1:1 c l a y m i n e r a l s o f t h e k a o l i n group. The p e r c e n t a g e o f f r e e i r o n and aluminum however were q u i t e h i g h ( T a b l e X). Thus , the c a p a c i t y o f t h e s e s o i l s t o adsorb s u l p h a t e can p r o b a b l y be a t t r i b u t e d l a r g e l y t o t h e f r e e hydrous o x i d e s o f i r o n and aluminum. T h i s a s p e c t w i l l be r e c o n s i d e r e d when the a d s o r p t i o n c a p a c i t i e s o f t h e s o i l s f o r s u l p h a t e w i l l be compared. C o l d water i s not a good e x t r a c t a n t f o r some s o i l s . The adsorbed f r a c t i o n i s more than t h e water s o l u b l e . On t h e whole t h e adsorbed form i s g r e a t e r i n t h e sub s o i l . I t w i l l be i n t e r e s t i n g t o see how much o f t h i s a p p arent adsorbed s u l p h a t e i s a c t u a l l y i n t h e a n i o n i c form, when the s e p a r a t i o n , o f t h e 0.5M e x t r a c t e d s u l p h a t e , i s performed on Sephadex columns by g e l f i l t r a t i o n . At t h a t s t a g e t h e q u e s t i o n o f the adsorbed s u l p h a t e ought t o be g r e a t l y c l a r i f i e d . - 65 -T a b l e IX. C o l d w ater e x t r a c t i o n f o r s u l p h a t e s u l p h u r S o i l L a n g f o r d 0"-6" L a n g f o r d 6"-12" Monroe 0"-6" Monroe 6"-12" Whatcom 0"-2" Whatcom 2"-10" Whatcom 10"-27" S a a n i c h t o n 0"-6" S a a n i c h t o n 6"-12" N i c h o l s o n 0"-6" N i c h o l s o n 6"-12" Hazlewood 0"-7" Hazlewood 7"-18" A b b o t s f o r d 0"-6" A b b o t s f o r d 6"-12" N e u t r a l 0.5M POii e x t r a c t Water e x t r a c t ppm S ppm S 73.0 124.0 37.5 27.0 45.0 37.0 60.0 20.0 20.0 34.0 45 .0 67.0 60.0 33.5 40.0 18.0 12.0 8.0 8.0 12.0 0.0 12.0 5.0 3.0 8.0 8.0 23.0 12.0 0.0 10.0 App a r e n t a d s o r b e d s u l p h a t e ppm S 55.0 112.0 29.5 19.0 33.0 37 .0 48.0 15.0 17.0 26.0 37.0 44.0 48.0 33.5 30.0 - 67 -T a b l e X. A d s o r p t i o n c a p a c i t i e s f o r t h e s u l p h a t e i o n and f r e e i r o n and aluminum o x i d e s S o i l S u l p h a t e a d s o r b e d % " f r e e " ppm S A l 1 % " f r e e ' Fe L a n g f o r d 0 "-6" 270 , .0 0 .4 0 .66 L a n g f o r d 6 "-12" 690. ,0 0 .91 0 .60 Monroe 0"- 6" 290, .0 0. .21 1 .08 Monroe 6"- 12" 510. .0 0 .33 0 .90 Whatcom 0" -2" 430, .0 0 , .10 1. .14 Whatcom 2" -10" 470. ,0 0 , .38 1. . 35 Whatcom 10 "_27" 830, . 0 0, .91 0, .96 S a a n i c h t o n 0"-6" 330, ,0 0 , .22 1, .08 S a a n i c h t o n 6"-12" 210 , .0 0, .40 0, .66 N i c h o l s o n 0"-6" 650 , . 0 0 , .27 1, .02 N i c h o l s o n 6"-12" 950. ,0 0 . . 82 0 . ,66 Hazlewood 0"-7" 350, ,0 0. .12 1. ,51 Hazlewood 7"-18" 570. .0 0. .73 2 . ,66 A b b o t s f o r d 0"-6" 7 30 . 0 0. ,25 1. .14 A b b o t s f o r d 6"-12" 750. .0 0. ,96 1. 27 - 68 -p e r c e n t c a r b o n i s much low e r i n t h e 6"-12" as shown i n T a b l e I . The f r e e i r o n o x i d e s were a t a h i g h l e v e l , 0.60 p e r c e n t f o r L a n g f o r d 6"-12" b e i n g the lowest l e v e l . The e v i d e n c e seems t o i n d i c a t e t h a t t h e f r e e aluminum e x e r t s a c o n s i d e r a b l e e f f e c t on a d s o r p t i o n c a p a c i t y . I f t h e L a n g f o r d 0"-6", t h e S a a n i c h t o n 6"-12" and the Nicholson 6"-12" a r e compared, the f o l l o w i n g points s t a n d o u t , t h e p e r c e n t a g e f r e e i r o n i s 0.66 f o r t h e t h r e e , The p e r c e n t a g e f r e e aluminum i s 0.4 f o r t h e L a n g f o r d and S a a n i c h t o n , t h e y b o t h a d s o r b comparable amounts o f s u l p h a t e , t h e f a r g r e a t e r o r g a n i c m a t t e r c o n t e n t o f t h e L a n g f o r d c o u l d perhaps e x e r t some i n f l u e n c e . The S a a n i c h t o n and the N i c h o l s o n however b o t h have a low o r g a n i c m a t t e r c o n t e n t but the N i c h o l s o n a l s o has a f a r g r e a t e r amount o f f r e e aluminum and a l s o a g r e a t e r a b i l i t y to adsorb s u l p h a t e . These r e s u l t s i m p l i c a t e i r o n and aluminum i n t h e s u l p h a t e a d s o r p t i o n o f t h e s e B r i t i s h Columbia s o i l s and indicate t h a t the s o i l s s h o u l d be a b l e t o r e t a i n s u l p h a t e f e r t i l i z e r . Chao e t a l . i n 1962 found t h a t f r e e i r o n and aluminum o x i d e s were a l s o i m p o r t a n t i n s u l p h a t e a d s o r p t i o n i n Oregon s o i l s which they s t u d i e d . The f o l l o w i n g s o i l s L a n g f o r d 0"-6" and 6"-12", A b b o t s f o r d 0"-6" and 6"-12" and Hazlewood 0"-7" and 7"-18 M were s u b j e c t e d t o e x t r a c t i o n w i t h 0 .-5M sodium phosphate at pH 7.0 as e x p l a i n e d i n t h e s e c t i o n on methods; b e f o r e t h i s - 69 -extraction was performed the s o i l s were washed with 10.0 ml of deionized water by shaking the s o i l s with the water- for five minutes, centrifuging for ten minutes and carefully pouring off the water. The water was c o l l e c t e d and i t s sulphate content determined. This procedure performed on a l l six samples was to minimize the amount of sulphate which may be carried o v e r from the sulphate adsorption e q u i l i b r a t i o n study. The results obtained are shown i n Table X I , Table XI. Desorption of adsorbed s u l p h a t e by a 0.5 M sodium phosphate s o l u t i o n at pH 7.0 (ppm S) S o i l Water wash 0^M^h£sph^te Q"-6" Black - L a n g f o r d 36.3 100.0 Gleysolic orthic humic ~ Hazlewood Q"-7" 0.8 64,0 C o n c r e t i o n a r y brown -Abbotsford 23.6 92,, 0 6"-12" B l a c k - L a n g f o r d 30.4 136,0 Gleysolic orthic humic -Hazlewood 7"-18" B t g 12.0 40.0 Concretionary brown -A b b o t s f o r d 2.4 84,0 These f i g u r e s show t h a t the percentage of sulphur i n t h e w a t e r wash was n e g l i g i b l e except i n the Langford 0"-6" where i t a c c o u n t s f o r 13,6 percent of the. t o t a l - 70 -a d s o r b e d . The 0.5M phosphate e x t r a c t f o r t h e s e s o i l s a r e : 73.0, 67.0 and 33.5 ppm S f o r t h e 0"-6" r e s p e c t i v e l y ; and 124.0, 45.0 and 40.0 f o r the 6"-12" group.. When the t o t a l amount o f s u l p h a t e which i s adsorbed i s compared t o t h e amount d e s o r b e d i t i s found t h a t o n l y 37.0, 18.2 and 12.6 p e r c e n t i s removed f o r the th r e e s o i l s o f the 0"-6" group and 19.7, 7.0 and 11.2 f o r the 6"-12" group. In a l l t h e samples d e s o r b e d , e x c e p t the Langford, l e s s than twenty p e r c e n t was removed; f u r t h e r the amount of sulphate desorbed f o r the L a n g f o r d and Hazlewood i s not much d i f f e r e n t from the s u l p h a t e e x t r a c t e d from t h e o r i g i n a l s o i l . The d i f f e r e n c e i s somewhat g r e a t e r f o r t h e A b b o t s f o r d ; though t h e percent d e s o r b e d i n t h i s case i s 12.6 and 11.2. These f i g u r e s are shown i n T a b l e X I I . Table X I I . Sulphate i n w a t e r wash and 0.5M phosphate e x t r a c t a t pH 7.0 as a p e r c e n t a g e o f t o t a l adsorbed S o i l 0"-6" B l a c k - L a n g f o r d G l e y s o l i c o r t h i c humic -Hazlewood 0"-7" C o n c r e t i o n a r y brown -A b b o t s f o r d 6"-12" B l a c k - L a n g f o r d G l e y s o l i c o r t h i c humic -Hazlewood 7"-18" C o n c r e t i o n a r y brown -A b b o t s f o r d Water wash as % o f t o t a l adsorbed 13.62 0.23 3.23 4.34 2.10 0.32 Phosphate 0.5M - pH 7.0 as % o f t o t a l a dsorbed 3 7.03 18.28 12.60 19.71 7.01 1 1 . 2 0 - 71 -The similarity in the amounts of sulphate extracted by the 0.5M phosphate, both i n the o r i g i n a l s o i l and in the samples saturated with sulphate can possibly indicate that the same fraction, some organic s u l p h a t e and perhaps the sulphate adsorbed by surface groups was desorbed while that held in o l and oxo linkages were not d e s o r b e d when the extraction time was limited to only t h i r t y minutes shaking. The percentage desorbed from t h e Abbotsford both 0"-6" and 6"-12" is quite close 12.60 and 11.20 percent respectively, this c a n also indicate desorption o f perhaps the same fraction, the surface h e l d groups. These surface held sulphate ions ought to be more readily plant available, while the more tigh t l y co-ordinated fraction may become available with time, or due to replacement by o t h e r more strongly co-ordination anions, organic and i n o r g a n i c in s o i l solutions. If this i s the case then t h e use of 0.5M phosphate buffers at pH 7.0 and extracted as suggested ought to g i v e a reasonable estimate of the available sulphate i n the soils studied and at least i n d i c a t e whether any response to sulphate f e r t i l i z e r s can be expected. The separation of the extracted sulphur into their o r g a n i c and inorganic fractions In 1966 Lowe separated the sulphate in s o i l extracts into the organic and inorganic fractions by gel - 72 -f i l t r a t i o n . I n t h i s s t u d y use was made o f Sephadex t o e f f e c t s uch a s e p a r a t i o n . A G-25 medium g e l was f i r s t u s e d t o attempt t h e s e p a r a t i o n o f the o r g a n i c from the i n o r g a n i c s u l p h a t e b u t a good s e p a r a t i o n was not obtained„ A G-50 medium g e l was t h e n used. T h i s ought t o r e t a r d t h e i n o r g a n i c f r a c t i o n more than t h e G-25 and so a l l o w a b e t t e r s e p a r a t i o n . U s i n g t h e G-50 g e l r e s u l t e d i n complete s e p a r a t i o n o f t h e o r g a n i c f r o m t h e i n o r g a n i c s u l p h a t e , From T a b l e X I I I we see t h a t s o i l s w i t h h i g h e r c a r b o n c o n t e n t s ( T a b l e I ) show a h i g h e r p e r c e n t a g e o f t h e i r e x t r a c t a b l e s u l p h a t e t o be a s s o c i a t e d w i t h the h i g h e r m o l e c u l a r w e ight f r a c t i o n , which must be the o r g a n i c s u l p h a t e ; and a c c o r d i n g l y a lower p e r c e n t a g e o f I n o r g a n i c s u l p h a t e , which i s t h e low m o l e c u l a r weight f r a c t i o n . In the Whatcom as t h e c a r b o n c o n t e n t d e c r e a s e s , t h e importance o f the o r g a n i c f r a c t i o n a l s o d e c r e a s e s . Indeed i n the lower h o r i z o n s o f the N i c h o l s o n and A b b o t s f o r d , a l l the s u l p h a t e appears t o be i n t h e i n o r g a n i c form. These two s o i l s a l s o have, a v e r y low carbon c o n t e n t i n t h e i r lower h o r i z o n s , The ca r b o n c o n t e n t does i n f l u e n c e the e x t r a c t a b l e o r g a n i c s u l p h a t e and the o r g a n i c s u l p h a t e can c o n t r i b u t e s u b s t a n t i a l l y t o the 0.5M phosphate e x t r a c t . Thus, t h i s e x t r a c t i o n p r o c e d u r e removes a p a r t o f the o r g a n i c s u l p h a t e c o n t a i n e d i n t h e s o i l s under s t u d y . I t i s p e r t i n e n t a t t h i s s t a g e t o c o n s i d e r how - 73 -much i n o r g a n i c and o r g a n i c i s e x t r a c t e d a t v a r y i n g pH l e v e l s . The L a n g f o r d s o i l which shows a marked r e s p o n s e t o the amount o f s u l p h a t e e x t r a c t e d a t v a r y i n g pH l e v e l s was c hosen. The r e s u l t s a r e g i v e n i n T a b l e XIV. I t i s c l e a r from th e above f i g u r e s t h a t at pH 4.0 l i t t l e i n o r g a n i c s u l p h a t e i s e x t r a c t e d and 71.5 p e r c e n t i s o r g a n i c . At pH 5.0 the s i t u a t i o n i s changed but l i t t l e and o r g a n i c s u l p h a t e s t i l l p r e d o m i n a t e s , At pH 6,0 and 7.0 t h e p e r c e n t a g e o f o r g a n i c s u l p h a t e i s steady a t about 6 0.0 p e r c e n t and t h e i n o r g a n i c f r a c t i o n has i n c r e a s e d from almost 25 t o 28 p e r c e n t t o almost f o r t y . Above pH 7.0 the p o s i t i o n i s a g a i n r e v e r s e d i n t h a t the p e r c e n t a g e o f the i n o r g a n i c f r a c t i o n d e c r e a s e s i n importance and i t i s the o r g a n i c s u l p h a t e e x t r a c t e d at the h i g h pH l e v e l . Between pH 6.0 and 8.0 t h e i n o r g a n i c s u l p h a t e i s a l m o s t c o n s t a n t 9 v a l u e s v a r y i n g between 26.0 and 30.0 ppm s u l p h u r . These v a l u e s a r e i n agreement w i t h a d s o r p t i o n s t u d i e s performed by s e v e r a l workers (Chao e t a l . , 1962 and 196 3; Kamprath, N e l s o n and F i t t s , 1956 ; Ensminger, 1954). They found t h a t more s u l p h a t e was adsorbed a t the lower pH l e v e l s . T h i s means t h a t the l e a s t amount o f s u l p h a t e w i l l be e x t r a c t e d at t h e low pH l e v e l s . At pH 7.0 w i t h a 0.5M phosphate e x t r a c t i n g s o l u t i o n almost i f not a l l o f the i n o r g a n i c a v a i l a b l e f r a c t i o n should be e x t r a c t e d . T h i s ought t o l e n d much support t o 0.5M sodium phosphate a t pH 7.0 as a s u i t a b l e e x t r a c t a n t f o r the a v a i l a b l e s u l p h a t e i n the s o i l s o f B r i t i s h Columbia. _ 74 _ T a b l e X I I I . The s e p a r a t i o n o f Q.SM phosphate e x t r a c t s a t pH 7.0 i n t o t h e i r o r g a n i c and i n o r g a n i c components. I n o r g a n i c SO = T o t a l e x t r a c t - Organic SO (ppm S) o r g . SO T o t a l extract i n o r g . as % o f S o i l 0.5M P0„ Org. SO, so, t o t a l L a n g f o r d 0" -6" 73, 0 44 2 28* 8 60 8 L a n g f o r d 6" -12 n 124. 0 80 0 44, 0 64 5 Whatcom 0"-2" 45 0 10 0 35. 0 2 2 6 Whatcom 2"-10" 37 0 8 0 29 0 21 6 Whatcom 10" -27 I! 60 .0 2 ,2 57 8 3 ,6 N i c h o l s o n 0 "-6 n 34 .0 7 . 5 26 5 22 ,0 N i c h o l s o n 6 "-12" 45 .0 0 ,0 4 5 0 0 .0 A b b o t s f o r d 0"- 6" 33 .5 0 ,5 33 0 1 .5 A b b o t s f o r d 6"- 12" 40 .0 0 ,0 40 ,0 0 .0 - 75 -T a b l e XIV. F r a c t i o n s e x t r a c t e d w i t h i n c r e a s i n g pH f o r Langford 0"-6" (ppm S ) . I n o r g a n i c -T o t a l e x t r a c t -- o r g a n i c f r a c t i o n 2 1 4.0 0.5M P 0 U a t pH 7.0 T o t a l e x t r a c t O r g a n i c I n o r g a n i c Organic as % o f t o t a l I n o r g a n i c as % o f t o t a l 28.0 20.0 8.0 71.5 28.5 5.0 43.0 32.0 11.0 74.5 25.5 6.0 67.0 41.0 26.0 61.2 38.8 7.0 73.0 44.2 28.9 60.5 39.5 8.0 95.0 65.0 30.0 68.5 31,5 ] - 76 -Reduction in the Time of Analysis I n the colorimetric methylene b l u e method f o r the determination of s u l p h a t e as p r o posed by Johnson and Nishita in 1952, a d i s t i l l a t i o n time o f one hour was suggested. T h i s long period o f d i s t i l l a t i o n i s t h e c h i e f disadvantage o f this method. G u s t a f s s o n i n 1960 s u g g e s t e d that ten minutes was s u f f i c i e n t . A time o f f o r t y minutes was t r i e d for these s o i l extracts and no d i f f e r e n c e i n absorbance was detected. In t h e d e t e r m i n a t i o n o f the HI reducible s u l p h u r , no d e t e c t a b l e d i f f e r e n c e i n absorbance was f o u n d between twenty and f o r t y minutes d i s t i l l a t i o n . Further in the estimation o f s u l p h u r in p l a n t t i s s u e a n a l y s i s , a d i s t i l l a t i o n time of forty minutes gave no d e t e c t a b l e difference in the absorbance value (*Herath, p e r s o n a l communication). The reduction i n d i s t i l l a t i o n time means that three runs can be made every two hours i n s t e a d o f two. In six hours of d i s t i l l a t i o n using six d i s t i l l a t i o n units , on a routine basis, f i f t y four samples can be a n a l y z e d instead of t h i r t y six, this means a f i f t y percent i n c r e a s e in analysis. *Herath, W. 196 9 . Personal communication, - 77 -SUMMARY AND CONCLUSIONS Increasing the concentration of phosphate buffers resulted in an increase i n the amount o f sulphate e x t r a c t e d . This was attributed to the high concentration of phosphate replacing chiefly t h e s u r f a c e adsorbed s u l p h a t e and perhaps some of the more strongly held f r a c t i o n ; though the po s s i b i l i t y o f varying amounts o f o r g a n i c s u l p h u r b e i n g extracted must a l s o be recognized, The pH of the extracting solution played a part in the quantity of sulphate extracted. In the Langford 0"-6" there was a marked increase in the amount of s u l p h a t e extracted with increase in pH, while the Abbotsford showed an almost constant amount extractable regardless o f pHI T h i s difference was a t t r i b u t e d t o the i n c r e a s e d amounts of organic sulphate extracted at pK 8.0 from the Langford 0"-6" w h i l e nearly a l l the extractable sulphate I n the Abbotsford 0"~6" was in the adsorbed form and the h i g h phosphate concentration was able t o replace t h i s e s s e n t i a l l y adsorbed sulphate. pH 7.0 was the l e v e l at which maximum e x t r a c t i o n occurred in most s o i l s . A 0.05M calcium phosphate extracting s o l u t i o n at pH 3.5 extracted similar amounts of sulphate as 0„05M sodium phosphate at pH 4.0. The calcium was not a more e f f i c i e n t - 78 -extractor; due to the i n s o l u b i l i t y o f calcium phosphate a 0.5M solution at pH 7.0 cannot be obtained, and as increasing the concentration of the phosphate extracting solution resulted in greater sulphur extraction this is a d i s t i n c t disadvantage preventing the use of calcium phosphate as a routine laboratory extractant. A 0.5M ammonium fluoride solution pH 6.0 did extract more sulphur in s o i l s with higher c a r b o n c o n t e n t s . In other samples the phosphate was more e f f i c i e n t , especially where the carbon content was of a low value. G e n e r a l l y , for the s o i l s of the Lower Fraser Valley phosphate should prove a better extractant. The amount of sulphate extracted by 0,5M phosphate buffers at pH 7.0 varied between 5.8 and 56.2 percent of the total sulphur. The lower values 5.8 p e r c e n t f o r the 0"-6" and 10.8 for the 6"-12" are for the Langford. G r e a t e r percent-ages of sulphate were removed from the Nicholson and the Whatcom Bf 2"-10" and 10"-27" than for t h e other s o i l s . The HI reducible sulphur being essentially the organic and inorganic sulphate and can thus be taken as an estimate of the maximum quantity of the sulphate present, varied between 15.5 and 8 3.3 percent o f the total sulphur. The mineral soils having the higher value and the Black-Langford the lower percentage, in both t h e 0"-6" and 6"-12" depths. - 79 -The a d s o r b e d s u l p h a t e i n t h e s o i l s was c a l c u l a t e d by s u b t r a c t i n g t h e amount o f s u l p h a t e e x t r a c t e d by t h e 0.5M sodium p h o s p h a t e a t pH 7.0 f r o m t h e d e m i n e r a l i z e d w a t e r e x t r a c t s . T h i s measure g i v e s t h e a p p a r e n t a d s o r b e d s u l p h a t e as some o r g a n i c s u l p h a t e was e x t r a c t e d by t h e p h o s p h a t e e x t r a c t a n t . The s o i l s had an a d s o r p t i o n c a p a c i t y f a r i n e x c e s s o f t h e amounts o f s u l p h a t e w h i c h was e x t r a c t e d , t h u s i n d i c a t i n t h e y were n o t a t t h e i r a d s o r p t i o n c a p a c i t y . T h i s a d s o r p t i o n was due p e r h a p s a l m o s t c o m p l e t e l y t o t h e amorphous i r o n and aluminum o x i d e s , as X - r a y d i f f r a c t i o n o f t h e <2u f r a c t i o n r e v e a l e d no k a o l i n c l a y m i n e r a l s . The a d s o r p t i o n c a p a c i t i e s r a n g e d f r o m 270.0 ppm s u l p h u r f o r t h e L a n g f o r d 0"-6" t o 950.0 ppm f o r N i c h o l s o n 6"-12". The amount o f o r g a n i c s u l p h a t e s e p a r a t e d by g e l f i l t r a t i o n was h i g h e r i n s o i l s w i t h a g r e a t e r c a r b o n c o n t e n t and c o n s e q u e n t l y a g r e a t e r amount o f o r g a n i c m a t t e r . Three o f t h e s o i l s o f t h e l o w e r d e p t h had n e g l i g i b l e amounts o f o r g a n i c s u l p h a t e 2.2 ppm s u l p h u r f o r t h e Whatcom 10"-27" and 0.0 ppm f o r t h e N i c h o l s o n and A b b o t s f o r d 6"-12". T h i s may e x p l a i n t h e l a c k o f s i g n i f i c a n t i n c r e a s e o f s u l p h a t e e x t r a c t e d a t d i f f e r e n t pH l e v e l s f o r t h e A b b o t s f o r d . The c o n c e n t r a t i o n o f phosphate b e i n g h i g h enough t o remove t h e a d s o r b e d s u l p h a t e a t t h e pH v a l u e s from 4.0 t o 8.0. - 80 -I n the L a n g f o r d from which the amounts o f s u l p h a t e e x t r a c t e d by 0.5M p hosphate, i n c r e a s e d w i t h i n c r e a s i n g pH, s e p a r a t i o n o f t h e o r g a n i c from th e i n o r g a n i c f r a c t i o n s showed t h a t a t pH 4.0 and 5.0 t h e o r g a n i c f r a c t i o n predominated. A t 6.0 and 7.0 t h e importance o f t h e i n o r g a n i c f r a c t i o n i n c r e a s e d t o almost 40.0 p e r c e n t o f t h e t o t a l e x t r a c t compared t o 25.0 t o 2 8.0 f o r t h e lower v a l u e s . A t pH 8.0 the f r a c t i o n e x t r a c t e d was p r e d o m i n a n t l y o r g a n i c . The time o f d i s t i l l a t i o n was r e d u c e d t o 40 minutes from 60 m i n u t e s , t h i s r e s u l t e d i n a 50.0 p e r c e n t i n c r e a s e i n a n a l y s e s d u r i n g a s i x hour p e r i o d . I n g e n e r a l i t was c o n c l u d e d t h a t a 0.5M sodium phosphate s o l u t i o n a t pH 7.0 was t h e most s u i t a b l e e x t r a c t a n t f o r the s u l p h a t e o f t h e s o i l s s t u d i e d and seemed t o g i v e a good i n d i c a t i o n o f the amount a v a i l a b l e and w i l l d e f i n i t e l y i n d i c a t e whether a r e s p o n s e t o s u l p h a t e f e r t i l i z e r a p p l i c a t i o n can be e x p e c t e d . F i r s t i t w i l l be n e c e s s a r y t o c o r r e l a t e p l a n t uptake w i t h s o i l e x t r a c t i o n b e f o r e any recommendations f o r s u l p h u r a p p l i c a t i o n s can be based on the r e s u l t s o b t a i n e d , u s i n g n e u t r a l 0.5M sodium phosphate t o e v a l u a t e the a v a i l a b l e s u l p h u r f o r f i e l d c r o p s grown on s o i l s of the Lower F r a s e r V a l l e y . - 81 -REFERENCES Alway, F . J . , Marsh, A.W. and M e t h l y , W.J. 1937. S u f f i c i e n c y o f a t m o s p h e r i c s u l p h u r f o r maximum c r o p y i e l d s . S o i l S c i . Soc. Am. P r o c . 2: 229-238. Alway, F . J . 1940. A n u t r i e n t element s l i g h t e d i n a g r i c u l t u r a l r e s e a r c h . J . Am. Soc. Agro n . 32: 913-921. A r k l e y , T.H. 1961. S u l p h u r compounds o f s o i l systems. Ph . D . T h e s i s , C a l i f o r n i a U n i v e r s i t y , B e r k e l e y . B a i l a r , J.C., J r . , and Busch, D . H . 19 56. G e n e r a l s u r v e y o f t h e c o o r d i n a t i o n compounds. ( I n "Ch e m i s t r y o f t h e C o o r d i n a t i o n Compounds", pp. 1-99. John C. B a i l a r , J r . , E d i t o r . R e i n h o l d P u b l i s h i n g Corp., New Y o r k ) . B a r d s l e y , C.E. and L a n c a s t e r , J . D . 1960. D e t e r m i n a t i o n o f r e s e r v e s u l p h u r and s o l u b l e s u l p h a t e s i n s o i l s . S o i l S c i . Soc. Am. P r o c . 24: 265-268. Barrow, N.J. 1967. S t u d i e s on t h e a d s o r p t i o n o f s u l p h a t e by s o i l s . S o i l S c i . 104: 342-349 . Beaton, J.D. 1966. S u l p h u r r e q u i r e m e n t s o f c e r e a l s , t r e e f r u i t s , v e g e t a b l e s , and o t h e r c r o p s . S o i l S c i . 101, No. 4 267-282. Beaton, J.D., Burns, G.R. and P l a t o u , J . 196 8. D e t e r m i n a t i o n o f s u l p h u r i n s o i l s and p l a n t m a t e r i a l . T e c h n i c a l B u l l e t i n No. 14. The S u l p h u r I n s t i t u t e . Beaton, J . D . 1968. S u l p h u r c h e m i s t r y i n t h e s o i l and the s t a t u s o f a v a i l a b l e s u l p h u r s o i l t e s t s . Unpub . Paper p r e s e n t e d a t S o i l and P l a n t A n a l y s t s ' Workshop , C h i c a g o , I l l i n o i s . B erg, W.A. and Thomas, G.W. 19 59. A n i o n e l u t i o n p a t t e r n s from s o i l s and s o i l c l a y s . S o i l S c i . Soc. Am. P r o c . 23: 348-350. Be r n t h s e n , A. 1885 . Ann 230 : 73 and i n 1889 , 251 : 1. ( C i t e d by G u s t a f s s o n , L. 1960(1)) . Bethge, P.O. 19 5 3 . On the v o l u m e t r i c d e t e r m i n a t i o n o f hydrogen s u l p h i d e and s o l u b l e s u l p h i d e s . A n a l y t . Chim. A c t a . 9: 129-139. - 82 -13. Burns, G.R. 1967. Oxidation of sulphur in s o i l s . Tech. B u l l . 13. The Sulphur Institute, Washington, D.C. 14. Chang, M.L. and Thomas, G.W. 1963. A suggested mechanism for sulphate adsorption by s o i l s . S o i l Sci. Soc. Am. Proc. 27: 281-283. 15. Chao, T.T., Harward, M.E. and Fang, S.C. 1962. Adsorption and desorption phenomena of s u l p h a t e ions in s o i l . S oil Sci. Soc. Am. Proc. 26: 234-237 . 16. Chao, T.T., Harward M.E. and Fang, S.C. 1962 . Movement of S35 tagged sulphate through s o i l columns. S o i l Sci. Soc. Am. Proc. 26: 27-3 2. 17. Chao, T.T., Harward, M.E. and Fang, S.C. 1962. Soil constituents and properties in the adsorption of sulphate ions. Soil Sci. 94: 276-283. 18. Chao, T.T., Harward, M.E. and Fang, S.C. 1963. Cationic effects on sulphate adsorption by s o i l s . Soil Sci. Soc. Am. Proc. 27 : 35-38 . 19. Chao, T.T. 1964. Anionic effects on sulphate adsorption by s o i l s . Soil Sci. Soc. Am. Proc. 28: 581-583. 20. Chao, T.T., Harward, M.E. and Fang, S.C. 1965. Exchange reactions between hydroxy1 and sulphate ions in s o i l s . Soil Sci. 99: 104-108. 21. Chapman, H.D. and Pratt, P.F. 1961. Methods of Analysis For Soils, Plants and Waters. U n i v e r s i t y of California, Division of Agricultural Sciences. 22. Coleman, R. 1966. The importance of sulphur as a plant nutrient in world crop production. Soil Sci. 101 (4): 230-239. 23. Day, J.H., Farstad, L. and Laird, D.G. 1959. Report Mo. 6 of the Br i t i s h Columbia Soil Survey. Research Branch, Canada Department of Agriculture in co-operation with The University of British Columbia and the Britis h Columbia Department of Agriculture. - 83 -24. B e l o n g , W.A. and Lowe, L.E. 1962. Note on ca r b o n bonded s u l p h u r i n s o i l . Can. J . S o i l S c i . 42: 223 . 25. D u t t , G.R. and Anderson, W.D. 1964. E f f e c t o f Ca-s a t u r a t e d s o i l s on t h e con d u c t a n c e and a c t i v i t y o f C l , S 0 4 ~ , and C a + + . S o i l S c i . 98: 377-382. 26. Ensminger, L.E. 1954. Some f a c t o r s a f f e c t i n g the a d s o r p t i o n o f s u l p h a t e by Alabama s o i l s . S o i l S c i . Soc. Am. P r o c . 18: 259-264. 27. E r i k s o n , E. 1959. T e l l u s , 11: 375. ( C i t e d by Whitehead, B.C. 1964). 28. E r i k s o n , E. 1960 . The y e a r l y c i r c u l a t i o n o f c h l o r i d e and s u l p h u r i n n a t u r e ; m e t e o r o l o g i c a l , g e o c h e m i c a l and p e d o l o g i c a l i m p l i c a t i o n s . P a r t I I . T e l l u s 12: 63-109. 29 . Evans , C. A. and R o s t , C O . 1945 . T o t a l o r g a n i c s u l p h u r and humus s u l p h u r o f Mi n n e s o t a s o i l s . S o i l S c i . 59 ( 2 ) : 125-137. 30. F i s h e r , E. 1883. Ber., 16: 2234. ( C i t e d by G u s t a f s s o n , L. , 196 0) . 31. Fogo, J.K. and Popowsky, M. 1949. S p e c t r o p h o t o m e t r i e D e t e r m i n a t i o n o f Hydrogen S u l p h i d e - - M e t h y l e n e B l u e Method. A n a l y t . Chem. 21: 732-734. 32. Fox, R.L., O l s o n , R.A. and Rhoades, H.F. 1964 . E v a l u a t i n g the s u l p h u r s t a t u s o f s o i l s by p l a n t and s o i l t e s t s . S o i l S c i . Soc. Am. P r o c . 28 ( 2 ) : 243-246 . 33. Freney, J.R. 1958 . D e t e r m i n a t i o n o f w a t e r - s o l u b l e s u l p h a t e i n s o i l . S o i l S c i . 86: 241-244 . 34. F r e n e y , J.R. 1961. Some o b s e r v a t i o n s on t h e n a t u r e o f o r g a n i c s u l p h u r compounds i n s o i l . A u s t r a l i a n J . Agr. Res. 12: 424-432. 35. F r e n e y , J.R., Barrow, N.J. and Spencer, K.A. 1962. A r e v i e w o f c e r t a i n a s p e c t s o f s u l p h u r as a s o i l c o n s t i t u e n t and p l a n t n u t r i e n t . P l a n t and S o i l 17: 295-308. - 84 -36. F r e n e y , J.R. and S t e v e n s o n , F . J . 1966. O r g a n i c s u l p h u r t r a n s f o r m a t i o n i n s o i l s . S o i l S c i . 101: 307-316. 37. Graham, R.P, and Thomas, A.W. 1947. The r e a c t i v i t y of hydrous a l u m i n a Towards a c i d s . Am. Chem. Soc. 69: 8 L 5 - 8 21.. 38. G u s t a f s s o n , L . 1960a. D e t e r m i n a t i o n o f u l t r a m i c r o amounts o f s u l p h a t e as methylene b i n e , 1: The c o l o u r r e a c t i o n . T a i a n t a <+: 2 27-2 35, 39. G u s t a f s s o n , L. 1960b. D e t e r m i n a t i o n o f u l t r a m i c r o amounts o f s u l p h a t e as methvlene b l u e . I I : The r e d u c t i o n . T a i a n t a 4: 236-243. 40. Harward, M. Eh , Chao, T.T. and Fane, S.C. 1962. The s u l p h u r s t a t u s and s u l p h u r eupoLvIng power of Oregon s o i l s . Anron. J . 54: i01-106. 41. Harward, M.E. and R e i s e n a u e r , H.M. 1966. R e a c t i o n s and movement of i n o r g a n i c s o i l s u l p h u r . S o i l S c i . 101 CM): 326-335. 42. Hesse, P.R. 1958. The d i s t r i b u t i o n of s u l p h u r in. the muds, water and v e g e t a t i o n o f Lake V i c t o r i a . H y d r o b i o l o g i a 11: 29-39. 4 3. Ho Kg, D.E. 196 6 . S t u d i e s on leachinp; l o s s e s o f s u l p h u r from pumice s o i l s , y e l l o w brown sands and loams. P r o c . N . Z . G r a s s l a n d Assoc. 1965, 123-128. 44. J a c k s o n , M . L . 1955. S o i l Chemical A n a l y s i s - A d v a n c e d Course. PubI. by the a u t h o r , Dept. of S o i l s , U niv. o f Wis., .Madison 6, Wis. 45. J a c k s o n , M . L . 1958. S o i l Chemical A n a l y s i s . pp. 38-54 C o n s t a b l e and Co. L t . d , Orange S t . , London W.C.2. 45. J a c k s o n , M . L . 196 3. Aluminum bonding and a n i o n retention by s o i l s . S o i l S c i . Soc. Am. P r o c . 27: .1 -10. 47. J a c k s o n , M.L. 1965. Free o x i d e s , h y d r o x i d e s and amorphous a l u r a i n o s i i i c a t e s . pp. 578-603. (In Methods o f S o i l A n a l y s i s " , F a r t 1 : Number 9 i n the s c r i e s agronomy, American S o c i e t y of Agronomy, Inc P u b l i s h e r Madison, W i s c o n s i n ) . - 85 -48. Jensen, M.C., Lewis, G.C. and Baker, G.0. 1951. Idaho Agr. Expt. Sta. Research Bull . 19. (Cited by Jordan, H.V., Ensminger, L.E. 1958). 49. Jensen, J. 1963. Some investigations on plant uptake of sulphur. Soil Sci. 95: 63-68. 50. Johansson, 0. 1959 . Sulphur problems in Swedish agriculture. K. Lantbr Hogsk. Ann. 25: 57-169 . (Cited by Coleman, R. , 1966),. 5 1 . Johnson, CM. and Nishita, H. 1952, Micro estimation of sulphur in plant materials, s o i l s and ir r i g a t i o n waters. Anal. Chem. 24: 736-742. 52. Jordan, H.V. and Ensminger, L. E. 1958 . The role o f sulphur i n s o i l f e r t i l i t y . Advanc. Agron. 10: 407-434 . 53. Jordan, H.V. and Bardsley, C.E. 19 5 8. Response o f crops to sulphur in Southeastern s o i l s . Soil Sci. Soc. Amer. Proc. 22: 254-256. 54. Jordan, H.V. 1964. Sulphur as a plant nutrient In the Southern United States. U.S.D.A. ARS Tech. Bull. 1297, 45 pp. 55. Kamprath, E.J. , Nelson, W.L. and F i t t s , J.W. 1956 . The effect of pH, sulphate and phosphate c o n c e n t r a t i o n on the adsorption of s u l p h a t e by s o i l s . S o i l S c i . Soc. Am. Proc. 20: 463-466. 56. Kamprath , E.J. , Nelson, W.L. and Fitt s , J.W. 1957 . Sulphur removal from soils by f i e l d crops. Agron. J. 49: 289-293. 57. Kamprath, E.J. 1968. Sulphur reactions and a v a i l a b i l i t y in highly weathered s o i l s . Sulphur Institute Journal Vol. 4 (3), The Sulphur Institute, Washington, D.C. pp 7-9. 58. Kononova, M.M. 1966 . S oil Organic Matter. 2nd English Edition. Pergamon Press Ltd., Headington H i l l H a l l , Oxford. 59. Leland, W.E. 1952. Nitrogen and sulphur in the precipitation at Ithaca, N.Y. Agron. J. 44: 172-175. - 86 -60. L i c h t e n w a l n e r , D.C., F l e u n e r , A.L. and Gordon, N.E. 192 3. A d s o r p t i o n and r e p l a c e m e n t o f p l a n t f o o d i n c o l l o i d a l o x i d e s o f i r o n and aluminum. S o i l S c i . 15: 151-165. 61. L i u , M. and Thomas, G.W. 1961. Nature o f s u l p h a t e r e t e n t i o n by a c i d s o i l s . Nature Lond. 192: 3 84. 62. Lowe, L.E. 1963. Ph.D. T h e s i s , M c G i l l U n i v e r s i t y , M o n t r e a l . 63. Lowe, L.E. 19 64. An approach t o t h e s t u d y o f t h e s u l p h u r s t a t u s o f s o i l s and i t s a p p l i c a t i o n t o s e l e c t e d Quebec s o i l s . Can. J . S o i l S c i . 44: 176-179. 64. Lowe, L.E. 1965. S u l p h u r f r a c t i o n s o f s e l e c t e d A l b e r t a s o i l p r o f i l e s o f the chernozemic and p o d z o l i c o r d e r s . Canadian J . S o i l S c i . 45: 297-303. 65. Lowe, L.E. 1966. The s e p a r a t i o n and d e t e r m i n a t i o n o f o r g a n i c and i n o r g a n i c s u l p h a t e i n s o i l e x t r a c t s . Can. J . S o i l S c i . 46: 92-93. 66. Lowe, L.E. 196 8. S o l u b l e p o l y s a c c h a r i d e f r a c t i o n s i n s e l e c t e d A l b e r t a s o i l s . Can. J . S o i l S c i . 48: 215-217. 67. Lowe, L.E. 1969. D i s t r i b u t i o n and p r o p e r t i e s o f o r g a n i c f r a c t i o n s i n s e l e c t e d A l b e r t a s o i l s . Can. J . S o i l S c i . 49: 129-141. 6 8. Luke, C L . 1949 . P h o t o m e t r i c D e t e r m i n a t i o n o f S u l p h u r i n M e t a l s and A l l o y s . A n a l . Chem. 21: 1369-1373. 69. L u t t m e r d i n g , H.A. and S p r o u t , P.N. 1966. P r e l i m i n a r y Report No. 7 o f The Lower F r a s e r V a l l e y S o i l S urvey. B r i t i s h Columbia Department o f A g r i c u l t u r e , Kelowna, B.C. 70. L u t t m e r d i n g , H.A. and S p r o u t , P.N. 1967. P r e l i m i n a r y Report No. 8 o f The Lower F r a s e r V a l l e y S o i l Survey. B r i t i s h Columbia Department o f A g r i c u l t u r e , Kelowna, B.C. M a c l n t i r e , W.H. , Shaw, W.M. and Robinson, B. 1945. The divergent behavior of KPO3 and K2SO4 i n s o i l s with and without limestone and dolomite. S o i l S c i . 59: 155-162. MacKenzie , A.F. , Delong, VI.A. and Ghanem, I.S. 1967 . T o t a l sulphur, acetate-extractable sulphur and i s o t o p i c a l l y exchangeable sulphate i n some Eastern Canadian s o i l s . Plant and S o i l 27 (3): 408-414. Madanov, P. 1946. The r a t i o of nitrogen and sulphur i n the organic matter of steppe s o i l s . Pedology 1946, p. 517. ( S o i l s and F e r t i l i z e r s 1 0 : 131, 1947). Marion, S.P. and Thomas, A.W. 1946. E f f e c t of diverse anions on the pH of maximum p r e c i p i t a t i o n of "aluminum hydroxide". C o l l o i d S c i . 1: 2 2.1-234. Mattson, • S. 1927. Anionic and c a t i o n i c adsorption by s o i l c o l l o i d a l materials of varying S I O 2 / A I 2 O 3 + Fe203 r a t i o s . Proc. Intern. Congr. S o i l Sox., 1st Congr. Comm. 11, pp. 199-211. (Cited by Chao, Harward and Fang, 1962). Mecklenburg, W. and Rosenkranzer, F. 1914. Z. anorg. Chem. 86: 143. (Cited by Gustafsson, L. 1960 (1)) Mehring, A.L. and Bennett, G.A. 1950. Sulphur i n f e r t i l i z e r s , manures and s o i l amendments. S o i l S c i . 70: 73-81. Nelson, L.E. 1964. Status and transformation of sulphur i n M i s s i s s i p p i s o i l s . S o i l S c i . 97: 300-306 . Newton, J.D., Bentley, C.F., Toogood, J.A. and Robertson, J.A. 1959. B u l l e t i n No. 21, F i f t h E d i t i o n , Revised. Department of Extension, U n i v e r s i t y of Al b e r t a . O d e l i e n , M. 1963. The e f f e c t of sulphur supply on the q u a l i t y of plant products. T i d s s k r . Norske. Land. 70: 35 (Cited by Coleman, R. 1966 . S o i l S c i . 101 (4): 230-239) . Parsons, J.W. and T i n s l e y . 1961. Chemical studies of polysaccharide material i n s o i l s and composts based on e x t r a c t i o n with anhydrous formic a c i d . S o i l S c i 92: 46-53. - 88 -12. R a b i n o w i t c h , E. and E p s t e i n , L.F. 1941. P o l y m e r i z a t i o n o f d y e s t u f f s i n s o l u t i o n . T h i o n i n e and Methylene B l u e . J . Amer. Chem. Soc. 63: 6 9-7 8. 13. R e i s e n a u e r , H.M. 1967 . A v a i l a b i l i t y a s s a y s f o r t h e se c o n d a r y and m i c r o n u t r i e n t a n i o n s . S o i l T e s t i n g and P l a n t A n a l y s i s . P a r t 1. S o i l T e s t i n g . S o i l S c i e n c e S o c i e t y o f A m e r i c a . S p e c i a l P u b l i c a t i o n No. 2. Madison, Wise. pp. 71-80 . 34. R e i t e m e i e r , R.F. 1946. E f f e c t o f m o i s t u r e c o n t e n t on t h e d i s s o l v e d and exchangeable i o n s o f s o i l s o f a r i d r e g i o n s . S o i l S c i . 61: 195-214. 85. R e n d i g , V.V. and Weir, W.C. 1957. E v a l u a t i o n by lamb f e e d i n g t e s t s o f a l f a l f a hay grown on a low-s u l p h u r s o i l . J . A n i m a l S c i . 16: 451-461. 86. R o l l i n s o n , C.L. 1956. O l a t i o n and r e l a t e d c h e m i c a l p r o c e s s e s . ( I n "Chemistry o f t h e C o o r d i n a t i o n Compounds," pp. 448-471. John C. B a i l a r , E d i t o r . R e i n h o l d P u b l i s h i n g C o r p o r a t i o n , New Y o r k ) . Roth, H. 19 51. Mikrochemie v e r Mikrochim. A c t a . 36/37: 379-393 . ( C i t e d by G u s t a f s s o n , L. 1960 C D ) . S c h n i t z e r , M. , W r i g h t , J.R. and D e s j a r d i n s , J.G. 1958 . A comparison o f the e f f e c t i v e n e s s o f v a r i o u s e x t r a c t -a n t s f o r o r g a n i c m a t t e r from two h o r i z o n s o f a p o d z o l p r o f i l e . Can. J . S o i l S c i . 38: 49-53. Shkonde, E . I . 1957. The r o l e o f s u l p h u r i n p l a n t n u t r i t i o n . D o k l . Akad. S-kh. Nauk. No. 2 : 22-25 . ( S o i l s and F e r t i l i z e r s 20: 785, 1957). Spencer, K. and Fre n e y , J.R. 196 0 . A comparison o f s e v e r a l p r o c e d u r e s f o r e s t i m a t i n g t h e s u l p h u r s t a t u s o f s o i l s . A u s t r a l i a n J . Agr. Res. 2 ( 6 ) : 948-959. 91. S t a n f o r d , G. and J o r d a n , H.V. 1966. S u l p h u r r e q u i r e -ments o f s u g a r , f i b e r and o i l c r o p s . S o i l S c i . 101 ( 4 ) : 258-266. 92. S t a r k e y , R.L. 1950. R e l a t i o n s o f micro-organisms t o t r a n s f o r m a t i o n s o f s u l p h u r i n s o i l s . S o i l S c i . 70: 55-65. 87 89, 90. - 89 -93. S t . L o r a n t , I . 1929. Z. P h y s i o l . Chem. 185: 245-266. ( C i t e d by G u s t a f s s o n , L. 1960). 94. S u l p h u r I n s t i t u t e J o u r n a l V o l . 5, No. 2, Summer, 1959. pp. 12. 95. S u l p h u r I n s t i t u t e T e c h n i c a l B u l l . No. 14. The S u l p h u r I n s t i t u t e , 1725 K S t . , N.W., Washington, D.C. 2 00 06;. 96. T a b a t a b a i , M.A. and Bremner, J M. 1967. S u l p h a t a s e enzymes i n s o i l s . 1: Use o f p - n i t r o p h e n y l s u l p h a t e f o r e s t i m a t i o n o^ a r y l s u l p h a t a s e a c t i v i t y . Agronomy A b s t r a c t s , Washington, D.C, p. 94. 97. Thomas, G.W. 1960. E f f e c t s o f e l e c t r o l y t e i m b i b i t i o n upon c a t i o n exchange b e h a v i o u r o f s o i l s . S o i l S c i . Soc. Am. P r o c . 24: 329-331. 98. Thorne, D.W. and P e t e r s o n , H.B. 1954. I r r i g a t e d S o i l s . p. 119. B l a k i s t o n , New York. ( C i t e d by J o r d a n , H.V., Ensminger, L.E. 1958). 99. T i s d a l e , S.L. and N e l s o n , W.L. 1966. S o i l f e r t i l i t y and f e r t i l i z e r s . The M a c m i l l a n Company, New Y ork. 100. Walker, T.W. 1955. S u l p h u r r e s p o n s e s i n A u s t r a l a s i a . World Crops 7: 441-444. 101. Walker, T.W. 1957. The s u l p h u r c y c l e i n g r a s s l a n d s o i l s J . B r i t i s h G r a s s l a n d Soc. 12: 10-18. 102. Whitehead, D.C. 1964. S o i l and p l a n t - n u t r i t i o n a s p e c t s o f t h e s u l p h u r c y c l e . S o i l s f e r t i l i z e r s ( 1 ) : 1-8. 103. W h i t t i g , L.D. 1965. X-ray d i f f r a c t i o n t e c h n i q u e s f o r m i n e r a l i d e n t i f i c a t i o n and m i n e r a l o g i c a l c o m p o s i t i o n pp. 671-698. ( I n Methods o f S o i l A n a l y s i s . P a r t 1: Number 9 i n the s e r i e s agronomy. American S o c i e t y o f Agronomy, I n c . P u b l i s h e r Madison, W i s c o n s i n . 104. W i l l i a m s , C.H. and S t e i n b e r g s , A. 1962. The e v a l u a t i o n o f p l a n t - a v a i l a b l e s u l p h u r i n s o i l s . I : The c h e m i c a l n a t u r e o f s u l p h a t e i n some A u s t r a l i a n s o i l s . P l a n t and S o i l 17: 279-294. 

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