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Evaluation of extraction and pretreatment of soil manganese and associated elements Bin Mohamed Ali, Zulkifli 1975

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EVALUATION OF EXTRACTION AND PRETREATMENT OF SOIL MANGANESE AND ASSOCIATED ELEMENTS '•by ZTJLKIPLI BIN MOHAMED ALI B.Sc. ( A g r i c ) , Univers i ty of B r i t i s h Columbia, 1973 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of SOIL SCIENCE We accept th is thesis as conforming to the. required standard THE UNIVERSITY OF BRITISH COLUMBIA September, 1975 In presenting this thesis in p a r t i a l f u l f i l m e n t of the require-ments for an advanced degree at The Universi ty of B r i t i s h Columbia, I agree that the Library sha l l make i t f ree ly avai lable for reference and study. I further agree that permission for extensive copying of th is thesis for scholar ly purposes may be granted by the Head of my Department or by his representatives. I t i s understood that copying or publ icat ion of th is thesis for f i n a n c i a l gain sha l l not be allowed without my writ ten permission. Department of S o i l Science Faculty of A g r i c u l t u r e , The Universi ty of B r i t i s h Columbia Vancouver, Canada V6T 1W5 ABSTRACT The manganese content of s o i l s from the Lower Fraser Valley hhas been previously invest igated. The studies conducted were con-f l i c t i n g in the to ta l amounts of manganese i n the s o i l s . Also there was no attempt in the e a r l i e r studies to relate manganese to some of the other oxides i n the s o i l s . This study was undertaken to elucidate further the chemistry of manganese in the s o i l s of the Lower Fraser Val ley and to evaluate extractants and effects of s o i l pretreatment on the amount of manganese extracted. I ron, aluminum and s i l i c o n , which are commonly associated with s o i l manganese, were also included in the study. The to ta l manganese concentrations obtained were higher than previously reported, even though the s o i l s were derived from the same area. The d i s t r i b u t i o n of to ta l i ron within the s o i l pedon was c lose ly related to that of manganese. Conventional extractants for amorphous inorganic and organic oxides were evaluated with reducing and chelating agents, for t h e i r a b i l i t y to extract manganese, together with aluminum, i ron and s i l i c o n . The extractants used were sodium pyrophosphate, acid ammonium oxalate , disodiumEDTA, hydroxy!amine hydrochloride and hydroquinone. Hydroquinone was only e f fec t ive in extract ing manganese, while sodium pyrophosphate, disodiumEDTA, acid ammonium oxalate and hydroxylamine hydrochloride extracted larger amounts of manganese, i ron and aluminum. Only hydroxyl-amine hydrochloride and ac id ammonium oxalate extracted s i l i c o n from i i i i i the samples. A l l ex t rac tants , with the exception of sodium pyrophos-phate, were consis tent with each other i n showing s i m i l a r d i s t r i b u t i o n s of the d i f f e r e n t elements w i t h i n the s o i l pedon. Successive ex t rac t ion a n a l y s i s i n d i c a t e d that the elements extracted by hydroxylamine hydrochloride were those der ived from the organic and inorganic complexed forms. This study a lso showed that the preceding extractants may a l t e r the s o i l system, thus quest ioning the r e l i a b i l i t y of successive ex t rac t ion a n a l y s i s . The e f f e c t of s o i l pretreatments on the e x t r a c t a b i 1 i t y of man-ganese, i r o n , aluminum and s i l i c o n was a lso i n v e s t i g a t e d . Some d i f -ferences were observed between i n - s i t u e x t r a c t i o n and a i r - d r y i n g t r e a t -ments. Freezing and s t o r i n g moist , contr ibuted to s i g n i f i c a n t l y high r e s u l t s . There was no consistency f o r the e f f e c t of the pretreatments on the d i f f e r e n t s o i l s . TABLE OF CONTENTS ABSTRACT . . . Page ABSTRACT . . . . i i LIST OF TABLES vi LIST OF FIGURES . . . . . . . . . . . v i i i ACKNOWLEDGEMENTS xi INTRODUCTION 1 CHEMISTRY OF MANGANESE, IRON, ALUMINUM AND SILICON 6 Li terature Cited 20 CHARTER 1 SELECTED PHYSICAL AND CHEMICAL PROPERTIES OF THE SOILS STUDIED 22 Introduction 22 Material and Methods 25 Results and Discussion 28 Conclusions 34 Li terature Cited 35 2 EVALUATION OF FIVE EXTRACTANTS FOR THE EXTRACTION OF MANGANESE, IRON, ALUMINUM AND SILICON 36 Introduction 36 Material and Methods 45 Results and Discussion 47 Conclusions 64 Li terature Cited 67 i v V CHAPTER Page 3 SUCCESSIVE EXTRACTION OF MANGANESE, IRON, ALUMINUM AND SILICON 69 Introduction 69 Material and Methods 72 Results and Discussions 74 Conclusion 92 L i t e r a t u r e Cited 94 4 THE EFFECT OF SOIL PRETREATMENTS ON THE EXTRACTION OF MANGANESE, IRON, ALUMINUM, AND SILICON USING HYDROXYLAMINE HYDROCHLORIDE AS THE EXTRACTANT 95 Introduction 95 Material and Methods 99 Results and Discussion 102 Concl usi on . . . . . 134 Li terature Ci ted . . . . . . . . . . . . . . . . . . . . . . . 137 SUMMARY • . • 139 APPENDIX . ' 143 LIST OF TABLES Table Page 1 Selected Basic Properties of Manganese, I ron, Aluminum and S i l i c o n 19 1.1 Selected Physical and Chemical Properties of the S o i l 29 1.2 Total Manganese, Iron and Aluminum in Relation to pH of the S o i l 30 1.3 Ex 1.3 Exchangeable Manganese, Aluminum, and Iron and Organic Matter Content of the S o i l 31 2.1 Correlat ion Matrix Among Extractants and S o i l Properties 62 3.1 Comparison between Sodium Pyrophosphate Extract ion and Comb.(im.afc<iibnoYi-of Hydroxylamine Hydrochloride and Sodium Pyrophosphate Extractions 75 3.2 Comparison between Sodium Pyrophosphate Extract ion and Sodium Pyrophosphate a f ter Hydroxylamine Hydro-chloride Extraction 76 3.3 Comparison between Acid Ammonium Oxalate Extract ion and a Combination of Hydroxylamine Hydrochloride and Acid Ammonium Oxalate Extractions 77 3.4 Comparison between Acid Ammonium Oxalate Extract ion and Acid Ammonium Oxalate a f ter Hydroxylamine Hydro-chloride Extract ion 80 3.5 Comparison between DisodiumEDTA Extract ion and Combination of Hydroxylamine Hydrochloride and DisodiumEDTA Extractions 81 3.6 Comparison between DisodiumEDTA Extraction and DisodiumEDTA af ter Hydroxylamine Hydrochloride Extract ion 83 3.7 Comparison between Hydroquinone Extraction and a Combination of Hydroxylamine Hydrochloride and Hydroquinone Extract ions . . . ; 84 vi vi i Table Page 3.8 Comparison between Hydroquinone Extract ion and Hydroquinone a f ter Hydroxylamine Hydrochloride Extraction 85 3.9 Comparison between Hydroxylamine Hydrochloride Extraction and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Dif ferent Extractants. Element - Manganese 87 3.10 Comparison between Hydroxylamine Hydrochloride Extract ion and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Dif ferent Extractants. Element - Iron 88 3.11 Comparison between Hydroxylamine Hydrochloride Extraction and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Dif ferent Extractants. Element - Iron 89 3.12 Comparison between Hydroxylamine Hydrochloride Extract ion and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Dif ferent Extractants. Element - S i l i c o n 90 LIST OF FIGURES Figure Page 1 Interrelat ionships between the i ron oxides and some c l o s e l y - r e l a t e d compounds 10 2 S i l i c o n in minerals and i t s reaction products . . . . 17 2.1 E x t r a c t a b i l i t y of d i f fe rent compounds of i ron by d i f f e r e n t extractants 38 2.2 Relative concentration of manganese extracted by the extractants in Tsawwassen, Blundell and Cloverdale series 48 2.3 Relative concentration of manganese extracted by the extractants i n G r e v e l l , Monroe and Sunshine series 50 2.4 Relative concentration of iron extracted by the extractants in Tsawwassen, Blundell and Cloverdale series 52 2.5 Relative concentration of i ron extracted by the extractants in G r e v e l l , Monroe and Sunshine series . . 55 2.6 Relat ive concentration of aluminum extracted by the extractants in Tsawwassen, Blundell and Clover-dale series 56 2.7 Relat ive concentration of aluminum extracted by the extractants in G r e v e l l , Monroe and Sunshine series 58 2.8 Concentration' of s i l i c o n extracted by the extrac-tants in Tsawwassen, Blundell and Cloverdale series . . 50 2.9 Concentration of s i l i c o n extracted by the extrac-tants in G r e v e l l , Monroe and Sunshine series 61 4.1 Tsawwassen - Concentration of hydroxylamine hydros chlor ide manganese extracted i n r e l a t i o n to the d i f f e r e n t pretreatments 103 4.2 Tsawwassen - Concentration of hydroxylamine hydro-chloride iron extracted in r e l a t i o n to the d i f f e r e n t pretreatments 104 vi i i i x Figure Page 4.3 Tsawwassen - Concentration of hydroxylamine hydro-chloride aluminum in r e l a t i o n to the d i f f e r e n t pretreatments 106 4.4 Tsawwassen - Concentration of hydroxylamine hydro-chloride s i1 icon in r e l a t i o n to the d i f f e r e n t pretreatments 107 4.5 Grevell - Concentration of hydroxylamine hydro-chlor ide manganese in r e l a t i o n to the d i f f e r e n t pretreatments 109 4.6 Grevell - Concentration of hydroxylamine hydro-chloride iron in r e l a t i o n to the d i f f e r e n t pretreatments •. I l l 4.7 Grevell - Concentration of hydroxylamine hydro-chlor ide aluminum in r e l a t i o n to the d i f f e r e n t pretreatments 113 4.8 Grevell - Concentration of hydroxylamine hydro-chlor ide s i l i c o n in r e l a t i o n to the d i f f e r e n t pretreatments 114 4.9 Blundell - Concentration of hydroxylamine hydro-chlor ide manganese in re la t ion to the d i f f e r e n t pretreatments 115 4.10 Blundell - Concentration of hydroxylamine hydro-chlor ide iron i n r e l a t i o n to the d i f f e r e n t pretreatments 117 4.11 Blundell - Concentration of hydroxylamine hydro-chlor ide aluminum i n r e l a t i o n to the d i f f e r e n t pretreatments 119 4.12 Blundell - Concentration of hydroxylamine hydro-chlor ide s i l i c o n in r e l a t i o n to the d i f f e r e n t pretreatments 120 4.13 Cloverdale - Concentration of hydroxylamine hydro-chloride manganese i n r e l a t i o n to the d i f f e r e n t pretreatments 122 4.14 Cloverdale - Concentration of hydroxylamine hydro-chloride iron in r e l a t i o n to the d i f f e r e n t pretreatments 123 X Figure Page 4.15 Cloverdale - Concentration of hydroxylamine hydro-chlor ide aluminum in re la t ion to the d i f f e r e n t pretreatments 125 4.16 Cloverdale - Concentration of hydroxylamine hydro-chloride s i1 icon in re la t ion to the d i f f e r e n t pretreatments 126 4.17 Sunshine - Concentration of hydroxylamine hydro-chloride manganese in re la t ion to the d i f f e r e n t pretreatments 128 4.18 Sunshine - Concentration of hydroxylamine hydro-chlor ide iron in r e l a t i o n to the d i f f e r e n t pretreatments 130 4.19 Sunshine - Concentration of hydroxylamine hydro-chlor ide aluminum in r e l a t i o n to the d i f f e r e n t pretreatments 131 4.20 Sunshine - Concentration of hydroxylamine hydro-chloride s i l i c o n in r e l a t i o n to the d i f f e r e n t pretreatments 133 ACKNOWLEDGEMENTS The author wishes to express many thanks to Prof . L. M. Lavkulich for his supervision throughout the research project . Sincere gratitude i s also extended to the Canadian and Malaysian government for sponsoring his studies i n Canada. Special thanks are also given to Dr. John Wiensffor helping with the Computer program. Suggestions made by the committee members i n w r i t i n g up this thesis are highly appreciated. The assistance given by the technicians with the atomic absorption spectrophotometer and dra f t ing the f igures i s highly appreciated. To my wife Susan, I convey deepest appreciation for her under-standing and patience during the pro ject . i x i INTRODUCTION The chemistry of manganese in s o i l i s s t i l l vague. Recently more attention has been directed to the study of manganese in s o i l . This i s par t ly the r e s u l t of the r e a l i z a t i o n that manganese plays a greater ro le than was assumed previously , both as plant nutr ient and in s o i l formation. The manganese status of the Lower Fraser Valley s o i l s has been studied by Baker (1950) and Safo (1970). Results for the tota l con-centration of manganese obtained by Baker were s i g n i f i c a n t l y higher than those obtained by Safo. Instrumentation, experimental procedure, sampling and treatment of samples before ex t rac t ion , are some of the factors that could contribute to th is difference in observations. The objective of th is study was to understand fur ther : i ) the chemistry of manganese in those Lower Fraser Val ley s o i l s which are derived from a l l u v i a l and marine parent mater ia ls , and i i ) the ef fects of various pretreatments on the e x t r a c t i o n f o f manganese from these s o i l s . I ron, aluminum and s i l i c o n were also included in the study because they are associated with manganese. The simultaneous occurrence of manganese, aluminum, iron and s i l i c o n in s o i l has been c i ted in s o i l s research. They have some common physical and chemical properties which is explained by the respective pos i t ion of these elements in the periodic table . 1 2 The compounds and complexes formed by these elements are important in s o i l genesis. The var iable valencies exhibited by manganese and iron o f fer numerous p o s s i b i l i t i e s for coordination compounds with or -ganic matter in the s o i l . The formation of these compounds has been c i t e d as one of the important mechanisms for the transport of these elements down the p r o f i l e , during s o i l formation. The conventional extract ion procedure for manganese has been based on Leeper's (1947) d i f f e r e n t i a t i o n : i ) water soluble form - extracted with d i s t i l l e d water, i i ) exchangeable form - extracted by neutral normal ammonium acetate, i i i ) eas i ly reducible forms - extracted by 0.2 percent hydro-quinone in neutral normal ammonium acetate, iv ) tota l amount - perchlor ic - hydrof luoric ac id d iges t ion . The f i r s t three of these d i f f e r e n t i a t i o n s are biased more towards the d i f f e r e n t oxidation states of manganese, and t h e i r r e d u c i b i l i t y rather than the actual form present in the s o i l . I t was, therefore, deemed necessary to evaluate the manganese by other extractants that are corre-lated with the forms ac tual ly present in the s o i l . The various forms of manganese in the s o i l can be categorized as: 1. w e l l - c r y s t a l l i z e d 2. amorphous inorganic oxides (which include both aged and r e l a t i v e l y recent forms), and 3. the organica l ly complexed forms (ei ther with humic or f u l v i c ac ids ) . 3 Each or a combination of these forms may be extracted by various ex-t ractants . In f a c t , the concentration and pH of each extractant has been evaluated for routine analysis in various l i t e r a t u r e s . Limitat ions such as the overlapping of forms extracted should be r e a l i z e d . The w e l l - c r y s t a l l i z e d form of manganese oxide i s known to be r e l a t i v e l y i n e r t . In this paper the amorphous as well as the organically-complexed forms w i l l be the h ighl ight of the invest igat ions . The amorphous oxides have not reached an equi l ibr ium state and have a r e l a t i v e l y large sur-face area compared to the c r y s t a l l i n e form. They ~are,,more.dice.ac'tivari and w i l l , therefore, influence s o i l properties to a greater extent. Five extractants were used to extract amorphous oxides and the organica l ly complexed forms. These were: 1) 0.2 M acid ammonium oxalate at pH 3.0, which extracts the amorphous organic and inorganic oxides; 2) 0.1 M hydroxylamine hydrochloride (NH20H.HC1) in 0.01 M n i t r i c acid at pH 2.0. This i s a strong reducing agent and i s also capable of complexing organica l ly bonded elements; 3) 0.02 M disodiumEDTA at pH 4.5 which extracts the organica l ly complexed forms by chelation as well as d ispers ion ; 4) 0.1 M sodium pyrophosphate at pH 10.0 which peptizes organic matter and extracts the amorphous organic oxides; and 5) 0.2 percent hydroquinone i n neutral normal ammonium acetate s o l u t i o n . This i s a reducing agent, r e l a t i v e l y weaker than hydroxylamine hydrochloride. 4 Dissolution brought about by these extractants often makes i t possible to analyze a l l four elements simultaneously with the atomic absorption spectrophotometer. This thesis attempts to evaluate the effectiveness of these extractants in extract ing manganese, i r o n , aluminum and s i l i c o n . An attempt i s also made to determine the corre-l a t i o n among extractants as well as between extractants and s o i l propert ies . The sequential extract ion of these elements by hydroxylamine hydrochloride (NH20H.HC1) followed by one of the other extractants and then again by hydroxylamine hydrochloride was also carr ied out. A comparison was made between the concentration of the elements extracted by the extractants i n d i v i d u a l l y and with the combination of hydroxyl-amine hydrochloride. The resul ts obtained should allow the evaluation of the s igni f i cance of using sequential analysis in s o i l extract ion studies . Moisture content, aerat ion , temperature and duration of s o i l sample storage are some of the factors that a f fec t the e x t r a c t a b i l i t y of a p a r t i c u l a r element. These factors control the decomposition of organic matter, microbial a c t i v i t y and the oxidation-reduction of the oxides in s o i l s . The e f fec t of d i f f e r e n t s o i l treatments on the con-centration of water-soluble and exchangeable manganese extracted, has often been mentioned. Studies were conducted to evaluate the e f fec t of s o i l treatments on the amorphous oxides and organically-complexed manganese, i r o n , aluminum and s i l i c o n . As stressed e a r l i e r these are more important, r e l a t i v e to the other forms. The s o i l treatments 5 involved were: A. I n - s i t u e x t r a c t i o n , B. A i r - d r y i n g for one week, C. Oven-drying at 50°C for one week, D. Oven-drying at 100°C for one week, E. Stored moist in p l a s t i c containers for three months, F. A i r - d r y i n g for four months, G. Frozen for one month. I t i s hoped that the resul ts obtained w i l l help to explain the differences in values reported by previous workers. These treatments should also make i t possible to evaluate the e f fec t of sampling at d i f fe rent seasons of the year on the e x t r a c t a b i l i t y of manganese, alumi-num, i ron and s i l i c o n . CHEMISTRY OF MANGANESE, IRON, ALUMINUM AND SILICON MANGANESE General properties Manganese constitutes about 0.085 percent of the earth's crust (Cotton and Wilkinson, 1972). Theoret ica l ly i t can exhib i t valencies of 1 to 7 (Remy, 1966), but in the s o i l only valencies of 2, 3, and 4 are common. The manganous (Mn 2 + ) and manganic (Mn 3 + ) ions are bas ic , while tetravalent manganese (Mn 4 + ) i s amphoteric. The conversion of manganese from one oxidation state to another i s dependent on the redox potential and pH, which are i n d i r e c t l y related to microbiological a c t i v i t y (Mann and Quastel , 1946). The presenee of unsat is f ied d-o r b i t a l s , which i s a charac ter i s t i c of a l l t r a n s i t i o n elements, makes i t possible for manganese to form numerous complex compounds. Manganese in s o i l Manganese i s thought to occur as the divalent ion i n so lut ion and on the exchange s i t e s ; in t r a n s i t i o n between c r y s t a l l i z e d and amor-phous form such as pyrolus i te and manganite (Dion et a l_ . , 1947); as a w e l l - c r y s t a l l i z e d mineral , e .g . hausmanite and h o l l a n d i t e ; in combination with amorphous Hydrous oxides of iron and aluminum; in associat ion with c lay structure (Hemstock and Low, 1953); and complexed with or-ganic matter. The presence of manganese in the s o i l can also be 6 7 categorized according to the d i f f e r e n t extractable states (Leeper, 1947; Serdobolski , 1950). They postulated that there was a dynamic equi l ibr ium between these forms: Water soluble manganese (' ' Exchangeable manganese (Mn 2 + ) (Mn 2 + ) Relat ive ly i n e r t manganese oxides* - " Eas i ly reducible man-ganese The conventional methods of extract ing manganese from s o i l are based on these forms. According to Geering (1969), to ta l d ivalent manganese i n ac id and neutral s o i l ranges from IO" 4 to 10~6 M and lower in calcareous s o i l . He also found that 85 to 99 percent of th is divalent manganese was organically-complexed. The reduction of the higher oxides into the d iva lent state depended on microbiological a c t i v i t y and on the presence of t h i o l s and ferrous ions (Jones, 1957). The presence of amorphous hydrous oxides of manganese in asso-c i a t i o n with the sesquioxides was f i r s t noted by Mitchel l et al_. (1964). These oxides provide a good source of cementation in s o i l . Manganese concretions in s o i l are the resu l t of the presence of microcrys ta l l ine structures (Taylor et a]_., 1964). These microcrysta l l ine forms are merely "aged" amorphous inorganic oxides and have been analyzed and found to be: B i r n e s s i t e : M.Mn 2 + Mn t f + ( 0 . 0H) 2 , M i s an a l k a l i n e earth metal ; 8 L i t h i o p h o r i t e : L i 2 A l 8 r V + 0 3 5 14H 20, M i s M n 2 + , C o 2 + or N i 2 + ; Ho i landi te : B a ( F e 3 W + ) 8 0 i 6 Pyrol u s i t e : Mn02 The manganese present ranges from +2 to +4 oxidation s tates . The f i r s t three forms contained 35 to 60 percent manganese, 3 to 9 percent barium, 0.5 to 1.5 percent cobalt and variable amounts of i r o n , aluminum, s i l i -con and other elements. Russell (1973) showed that humic acid i s able to complex d i v a -lent manganese. The strength of these complexes i s weaker than other meta l l i c cations such as divalent zinc and copper, and t r i v a l e n t alumi-num and i r o n . No statement was made with regard to the bond strength between t r i v a l e n t or tetravalent manganese, wari:di humic polymers. The greater e l e c t r o p o s i t i v i t y and smaller i o n i c r a d i i would tend to make i t stronger. Further studies need to be done on this aspect, considering the r e l a t i v e abundance of these forms in the s o i l . General properties Iron is the second most abundant metal a f ter aluminum, and i s the fourth most abundant element in the earth's crust (Cotton and W i l k i n -son, 1972). I t i s the 26th element in the per iodic table having the e lec tronic configuration of [Ar]3d 6 4S 2 . The p a r t i a l l y f i l l e d 3 d-IRON 9 o r b i t a l , puts i t i n the category of a t r a n s i t i o n element, and also accounts for the various complexes formed. The oxides FeO, Y -Fe 2 0 3 and Fe 3 0 4 are c lose ly related s t ruc-t u r a l l y , the oxygen atoms having a cubic close packing arrangement. Fe 3 0 4 i s made up of a combination of FeO and F e 2 0 3 , the proportion of which depends on the redox p o t e n t i a l . A summary of the various oxides and conditions that lead to t h e i r formation, is given in Figure 1. Complexes of iron with organic radicals are known. These complexes account for some of the mechanisms involved in iron removal and de-posi t ion in the s o i l system. The e lec t ronic configuration of i ron i s very s i m i l a r to that of manganese ( [Ar ]3d 5 4S 2 ) , the 25th element. Indeed iron and manganese have many physical and chemical properties in common. The occurrence of ferro-manganese nodules i n the s o i l , often in associat ion with cobal t , n i c k e l , and zinc has been c i ted in the l i t e r a t u r e (Taylor et aj_., 1966). Iron in s o i l In the s o i l , i ron i s thought to be present in s o l u t i o n , as primary and secondary minerals , as amorphous oxides and as ions attached on the cation exchange s i tes of both clay and organic c o l l o i d s . Iron has also been found associated in clay-organicvcomplexes. The primary minerals of iron include o l i v i n e , pyroxene, amphi-boles , micas and the various oxides of iron such as hematite, magnetite, l e p i d o c r i t e and goethite. Hematite (aFe 2 0 3 ) i s often found in the d r i e r and w e l l - o x i d i z e d s o i l . I t accounts for the dark-reddish tinge 10 F e 3 + Ox. Red. F e 3 + l Fez- Ox. Red. A1,0 Slow Pptn. Low pH aFeOOH 2U3 + Pptn. OH" ^ S i 0 2 I r o n - r i c h clay minerals Pptn. OH" Slow 'Oxidn. Aging Fe(0H)3 \ High pH, Temp \ Fe 3 0u I Pptn. OH" 1 -Fe£OH)2 ri;-! ' — S d o w oxidn. in presence C Q 3 2 -Dehydration Aging PH 4S7 Oxidn. pH Instant , 4-8 oxjidn. Oxidn. a * H l g h Y-FeOOH Aging in Hydrohematite d i l u t e a l k a l i Aging at high temp. Slow oxidn. H 2 0 2 at 100°c aFe 2 0 3 High temp: i f e a 0 3 Fe(OH)? C r y s t a l l i n e Oades, 1963 i * Figure 1 Igni t ion in presence of organic material 1 Alpha i ron oxides or amorphous iron oxides Interre lat ionships between the iron oxides and some c losely related compounds. 11 of s o i l s . Goethite (aFeOOH) i s commonly found in temperate s o i l s , often i n associat ion with r e l a t i v e l y wetter s o i l condit ions . Lepido-c r i t e (y-FeOOH), which i s an isomer of goethite , i s usually found in poorly-drained s o i l s . The orange brown mottles found in gley s o i l i s sa id to be l e p i d o c r i t e (Kamoshita and Iwasa, 1959). Magnetite (FeaO^) i s often present as dark sand s ize minerals. Oxidation of FesO^ y i e l d s the homogeneous Fe 2 0 3 (maghemite). These oxides and complex compounds of i ron are i n i t i a l l y i n the amorphous forms before aging gradually to the c r y s t a l l i z e d form. The associat ion of clay c o l l o i d s and iron (e i ther i n the i o n i c or oxide forms), par t ly accounts for the accumulation of i ron i n the subsurface horizons of mineral s o i l , t y p i c a l l y the Podzol. Barbier (1937) demonstrated the f i x a t i o n of f e r r i c hydrate with electronegative c l a y . A good X-ray analysis of most clay samples can only be achieved by destruction of the associated iron oxides (Mehra and Jackson, 1960). In wel l -dra ined s o i l s the d i s t r i b u t i o n of c l a y - i r o n oxide complexes, i s more even throughout the p r o f i l e . In s o i l s subjected to the f l u c -tuation of the water table there i s a d i s t i n c t layer of accumulation. Accumulation of i ron can also be observed in s o i l s in the form of concretions. Concretions are often found i n the zone of f luc tuat ing water-table s i g n i f y i n g a variable o x i d i z i n g and reducing condi t ion . Concretions i n the tubular form are observed around root channels often related to b i o l o g i c a l oxidation (Bloomfield, 1952). Most of these concretions are associated with other elements, namely manganese, cobal t , n i c k e l , copper and zinc (Taylor et a l_ . , 1966). 12 The movement of iron down the p r o f i l e i s preceded by reduction of the higher oxidation states to the ferrous forms, which are more soluble in water, or as organically-complexed i r o n . Leaf leachates have also been reported to s o l u b i l i z e iron (Oades, 1963). ALUMINUM General properties Aluminum i s the most abundant metal in the earth's crust . I t i s the 13th element in the per iodic table and has e lec t ronic configura-t ion of [Ne]3S 23P'. S i l i c o n , being adjacent to aluminum i n the per iodic tab le , has s i m i l a r chemical propert ies . Two kinds of anhydrous alumina, are present. S to ich iometr ica l ly they are the same. The hydrated form of alumina corresponds to the s toichiometr ic formula A10.0H and A1(0H) 3 . Two polymorphs of A10.0H occur, namely boehmite and diaspore. A l 3 + and S i 1 + + have i o n i c r a d i i of 0.50 A° and 0-^ 43 A 0 , respect ive ly . The closeness in the s ize of the r a d i i between these two elements allows the displacement of S i 4 + by A l 3 + in s i l i c a tetrahedra structures (Heslop and Robinson, 1960). The defic iency of pos i t ive charge i s made up by associat ing other cat ions . This i s the basis of the formation of num-erous a luminosi l i ca te minerals. Aluminum i n s o i l Aluminum mainly occurs as a luminosi l icate minerals s o i l s . This includes the fe ldspars , pyroxenes, amphiboles in tempercate and 13 p h y l l o s i l i c a t e s . Aluminum exhibi ts f o u r - f o l d coordination to oxygen in igneous rocks formed at high temperature, such as fe ldspars , but as weathering proceeds hydroxyl ions take over the oxygen p o s i t i o n s , and aluminum acquires octahedral coordination. The c r y s t a l l i n e mineral gibbsi te [A1(0H3 or A1 2 0 3 3H 2 0] i s the most abundant form of alumana in s o i l . I t occurs pr imar i ly in t rop ica l and subtropical s o i l s which have undergone intensive weathering and leaching of s i l i c o n . Gibbsite consists of paired sheets of hydroxyl ions , held together dioctahedral ly by aluminum ions. The series of paired sheets are held together by H-bonding. Gibbsite forms a very e f fec t ive cement for s o i l granules (Desphande, 1968). I t has also been shown that A1(0H) 3 i s more e f fec t ive than Fe(0H) 3 as a cementing agent. Gibbsite also has great a f f i n i t y for s i l i c a and reaction between these constituents lead to c r y s t a l l i z a t i o n of k a o l i n i t e or h a l l o y s i t e (Lough-nan, 1969). Amorphous hydrous oxides of aluminum, such as boehmite and i t s isomer diaspore, occur frequently with i ron oxides. These amorphous oxides of aluminum and iron are often p o s i t i v e l y charged. They are usually attached to the negatively-charged surface of c o l l o i d s . This associat ion of amorphous oxides with clay c o l l o i d s results in a net-pos i t ive charge instead of a negative charge i n certa in s o i l s (Sumner, 1967). 14 SILICON General properties S i l i c o n is the second most abundant element on the earth's c rus t , and has an atomic number of 14. I t i s in the same group as carbon and th is accounts for many s i m i l a r physical and chemical pro-perties between these elements. Carbon has an e lec t ronic configuration of 2S 2 2P 2 and s i l i c o n 3S 2 3P 2 . The a v a i l a b i l i t y of 3 d -orb i ta l s in the case of s i l i c o n makes i t possible to have variable valencies from 4 up to 40 (Heslop and Robinson, 1960). P r a c t i c a l l y , only the valency of four has been reported. S i l i c o n also has a lower i o n i z a t i o n poten-t i a l than carbon. Both factors explain the greater r e a c t i v i t y of s i l i -con. A look at the bond strengths of various s i l i c a diatomic molecules w i l l give an idea of the r e l a t i v e s t a b i l i t y of s i l i c o n compounds. * Bond Energies of S i l i c o n at 25°C Si Si 76 kcal/mole Si Cl 105 kcal/mole Si 0 188 kcal/mole Si H 71 kcal/mole Si C 104 kcal/mole * Rubber Company, Handbook of Physics and Chemistry, 1971/72. Chemi cal The values indicate the importance of e lec t ronegat iv i ty in bond strengths. Chlor ine , oxygen and carbon are more electronegative than s i l i c o n and hydrogen. The Si - C bond strength (104 kcal/mole) 15 i s r e l a t i v e l y lower than the C - C bonds. This i s due to the greater p o l a r i t y of the bond, Si - C " , allowing n u c l e o p h i l i c attack on s i l i c o n and e l e c t r o p h i l l i c attack on carbon. These values w i l l also be important in studying the various s i l i c a t e s , a luminosi l icates and clay-organiccoomplexes i n s o i l s . S i l i c o n l i e s adjacent to aluminum in the per iodic table . They ha«e some common physical and chemical propert ies . Aluminosi l i ca te compounds are important in a f fec t ing s o i l propert ies . S i l i c o n i n s o i l S i l i c o n in s o i l i s present in the form of s i l i c a , s i l i c a t e s and a luminos i l i ca tes . The soluble form being represented by monosi l i c i c acid [ S i ( 0 H ) 4 ] . The to ta l amount of s i l i c o n ranges from 50 to 70 per-cent, with sandy s o i l s having the upper l i m i t , and the r e l a t i v e concen-t ra t ion decreases with increasing organic matter content. Intensive weathering such as that prevalent i n t rop ica l s o i l s leads to depletion of s i l i c o n followed by negative enrichment of the sesquioxides (Bear, 1964). S i l i c a in s o i l i s present in the form of quartz , t r idymite and c r i s t o b a l i t e , each having low temperature (a) and high temperature (e) forms. The transformation into d i f f e r e n t forms takes place s l o w l y , since reforming and transforming of bonds i s necessary to bring th is about. S i l i c a i s also present as opal S iO^.nH 2 0 , often the decomposi-t ion product of organic matter. The s i l i c a t e s and a luminosi l i ca te forms of s i l i c o n are present as amorphous aggregations with the sesquioxides, in minerals such as 16 micas, feldspars and the p h y l l o s i l i c a t e s . The behaviour of s i l i c o n i n so lut ion does not seem to coincide with that in s o i l , in s o l u t i o n , s o l u b i l i t y of s i l i c a i s independent of pH from pH 2.0 to 9.0. There i s a rapid increase above pH 9.0 , because of the d i ssoc ia t ion of the monosi l i c i c acid [SiCOH)^] into s i l i -cate ions (Mckeague and C l i n e , 1963). In the s o i l , Beckwith and Reeve (1963) found that the concentration decreased from 70 ppm to 23 ppm as pH increased from 5.4 to 7Y2. The concentration reaches i t s minimum at pH 9.0 and s tar ts increasing again above pH 9.0. This c h a r a c t e r i s t i c behaviour of s i l i c i c acid in s o i l seems to coincide with the adsorption of monosi l i c ic acid on aluminum and iron oxides (Beckwith and Reeve, 1963; McKeague and C l i n e , 1963). I t has been concluded that s o l u b i l i t y of monosi l ic ic acid i n s o i l i s dependent on the sesquiioxiidesaandPpH. H-bonding i s thought to be responsible for th is adsorption - (0H ) 3 S i - 0 - H 0(Fe 2 0 [ + Hi + ) . A summary of the sources of s i l i c i c ac id i s i n d i -cated i n Figure 2. The f igure also shows the sources of aluminum and iron compounds discussed in the preceding sect ions. Relationship between the Basic Properties of Manganese, I ron , Aluminum  and S i l i c o n A further look into the basic chemistry of these elements helps to explain the numerous complexes of manganese, i r o n , aluminum, and s i l i c o n which add to the heterogeneity of s o i l . Manganese and i r o n , aluminum and s i l i c o n exhib i t closeness i n i o n i c r a d i i g iving them the p o s s i b i l i t y of d isplac ing each other in crysta l l a t t i c e s . The d i s -placement of S i 4 + (0.42 A°) by A l 3 + (0.51 A°) in the s i l i c a tetrahedra O l i v i n e , Augite, Hypersthene, Hornblende Volcanic glass (basic) Zeoli tes B i o t i t e Muscovite _». Amorphous hydrous oxides Ti Anatase /Goethite J Fe —-^TlHematite* Al LSI. /Gibbsite iBioehmite Kaol i n . t S i l i c i c acid .» Amorphous^ hydrous oxides r Tr ioc tahedra l ( i l l i t e ) J l i - S K K + 1 I H + V Clay v e r m i c u l l i t e H + 1 U + Dioctahedral ( i l l i t e ) Gibbsite *l-»Kaolin. —• S i l i c i c Allophanej acid Ca ++ H, Ca K Ca /• Montmorril lonite -Si0 2 ' J p+Si0 2 K a o l i n . - — ^ S i l i c i c acid K a o l i n . Volcanic glass (acid) 1 Amorphous hydrous / A l » Gibbsite 1 Feldspars oxides [ S i 1 S i l i c i c acid *Modif ied from Loughnan, 1969 Figure 2. S i l i c o n in minerals and i t s reaction products 18 has been mentioned in a previous sec t ion . Manganese, i ron and aluminum have the same coordination number of s i x (Table 1). Aluminum also has the coordination number of four , which i s the same as that of s i l i c o n . Ionizat ion potentials for iron and manganese are almost the same; th is adds s t a b i l i t y for the associat ion of these two elements i n the same compound. The e lec t ronic configuration of manganese, i r o n , aluminum and s i l i c o n have one thing in common; that i s an incompletely f i l l e d d -orb i ta l even though t h e i r r e a c t i v i t y var ies . This give the chance for these elements to form numerous common complexes with each other, with other cations and organic molecules. An extractant destined to extract one of these elements often brings into so lut ion the other elements too. The concentration extracted depends on the properties of the extractant and the procedure employed. 19 TABLE 1 Selected Basic Properties of Manganese. Iron, Aluminum and S i l i c o n Mn Fe Al Si Atomic Number 25 26 13 14 Atomic Radii (A?) 1.17 1.16 1.25 1.17 Ionic Radii M 2 + (A°) 0.80 0.74 Ionic Radii M 3 + (A°) 0.66 0.64 0.51 Ionic Radii M k + (A°) 0.60 - - 0.42 Coordination Number Mn 2 * = 6 Fe 2 * =6 A l 3 + = 4,6 S i 4 + = 4 with Oxygen Mn3 = 6 Fe 3 =6 Mn4 = 6 Ionizat ion Potent ia l 1. (eV) 7.43 7.90 5.95 8.15 2. (eV) 15.46 16.16 18.82 16.30 3. (eV) - - 28.44 33.50 4!. (eV) - - - 45.10 E h M / M 2 ! (V) -1.05 -0.44 n M / M 3 + (V) - - 1.67 M 2+?M 3 + (v) 1.51 0.77 Elec tronic Configuration [Ar]3d 5 4S 2 [Ar]3d 6 4S 2 [Ne]3S23P' [Ne]3S 23P 2 LITERATURE CITED Barbier , G. 1937. Conditions and modalities of the f i x a t i o n of c o l l o i d a l f e r r i c hydrate by s o i l c lay . Ann. Agron. 8: 34-43. Bear, F. E. 1964. Chemistry of the s o i l . 2nd E d i t i o n . A C S Mono-graph No. 160. Reinhold Publishing Corp. Beckwith, R. S . , and Reeve, R. 1963. Studies on soluble s i l i c a in s o i l s . I . The sorption of s i l i c i c acid by s o i l s and minerals. Aust. J . S o i l Res. 1: 157-68. Bloomfield, C. 1952. The d i s t r i b u t i o n of i ron and aluminum oxides in gley s o i l s . J . S o i l S c i . 3: 167-171. Cotton, F. A . , and Wilkinson, G. 1972. Advanced Inorganic Chemistry. Interscience Publ ishers . Desphande, T. L . , Greenland, D. J . , and Quirk, J . P. 1968. Changes in s o i l properties associated with the removal of iron and a l u -minum oxides. J . S o i l S c i . 19: 108-122. Dion, H. G . , Mann, P . J . G . , and Heintze, S. G. 1947. The e a s i l y - r e d u -c i b l e manganese of s o i l s . J . Agr. S c i . 37: 17-22. Geering, H. R. , Hodgson, J . F . , and Sdano, C. 1969. Micronutrient cation complexes in s o i l s o l u t i o n . IV. The chemical state of manganese in s o i l s o l u t i o n . S o i l S c i . Soc. Amer. Proc. 33: 81-85. Hemstock, G. G. and Low, P. F. 1953. Mechanism responsible for the retention of manganese in the c o l l o i d a l f rac t ion of s o i l . S o i l S c i . 76: 331-343. Heslop, R. B . , and Robinson, P. L. 1960. Inorganic Chemistry. A guide to advanced study. E lsevier Publishing Co. Inc. Jones, L . H . P . 1957. The e f fec t of l iming a neutral s o i l on the cycle of manganese. PI . and S o i l 8: 315-327. , and Handreck, K. A. 1967. S i l i c a i n s o i l s , plants and a n i -mals. Adv. Agron. 19: 107-149. Kamoshita, Y. and Iwasa, Y. 1959. On the rusty mottles in paddy f i e l d s o i l s . J . S c i . S o i l , Tokyo 30: 185-188. Leeper, G. W. 1947. The forms and reactions of manganese in the s o i l . S o i l S c i . 63: 79-94. 20 21 Loughnan, F. C. 1969. Chemical Weathering of the S i l i c a t e Minerals . E l sev ier Publishing Co. Inc. McKeague, J . A . , and C l i n e , M. G. 1963. S i l i c a in s o i l s . Adv. Agro. 15: 339-396. Mehra, 0/ P. and Jackson, M. L. 1958. Iron oxide removal from s o i l s and clays by a d i t h i o n i t e - c i t r a t e system buffered with sodium bicarbonate. Proc. 7th Nat. Conf. Clay and Clay Minerals 5: 317-327. M i t c h e l l , B. D . , Farmer, V. C . , and McHardy, W. J . 1964. Amorphous inorganic materials in s o i l s . Adv. Agron. 16: 327-383. Oades, J . M. 1963. The nature and d i s t r i b u t i o n of i ron compounds in s o i l s . S o i l s and F e r t i l i z e r s XXVI: 69-80 Remy, H. 1966. Treatise on inorganic chemistry. V o l . 2. E lsevier Publ ishing Co . , Amsterdam. Russe l l , E. W. 1973. S o i l conditions and plant growth. 10th E d i t i o n . Longman's Publ ishers . S e r d o b o l s k i i , E. P. 1950. The ef fects of s o i l conditions on the trans-formations of manganese compounds in the s o i l . Trudy Pochv. Inst . Dukuchaev 43: 192-216. Sumner, E. M. 1963. Ef fec t of i ron oxides on pos i t ive and negative charges in clays and s o i l s . Clay Minerals 5: 218-238. Taylor , R. M . , McKenzie, R. M . , and N o r r i s h , K. 1964. The mineralogy and chemistry of manganese i n some Austral ian s o i l s . Aust. J . S o i l Res. 2: 235=248. , and . 1966. The associat ion of trace elements with manganese minerals in Austra l ian s o i l s . Aust. J . S o i l Res. 4: 29-39. Weast, R. C. 1971-72. Handbook of Chemistry and Physics. The Chemical Rubber Company. CHAPTER I SELECTED PHYSICAL AND CHEMICAL PROPERTIES OF THE SOlliS: STUDIED: INTRODUCTION Robinson (1929) c i ted the range of 0 to 0.31 percent manganese in the s o i l s of the United States. Bear (1946) working on Hawaiian so i l s reported concentrations of as high as 10.0 percent in highly leached s o i l s . Leeper (1947) reported a range of 0 to 0.1 percent of to ta l manganese in Austral ian s o i l s . The to ta l concentration of manganese in B r i t i s h Columbia so i l s ranges from 0.007 to 0.494 percent (Baker, 1950). He also stressed the r e l a t i v e l y high concentration of manganese in the Lower Fraser Valley compared to other areas in the province. Further studies by Safo (1970) showed that to ta l man-ganese in the Lower Fraser Valley s o i l s ranged from 82.0 to 957.5 ppm. The results were lower than those indicated by Baker. Total analysis fo r manganese and other elements are very tedious. Many factors control the results obtained and to ta l elemental analysis i s s t i l l in i t s i n -fancy with regards to manganese. The tota l manganese concentration in s o i l ^i-sf afvf^ctedamal p lyy bjththe 1 etMriia te serec!; f e f papaneriitaiiia te KI a J •* and time. The interact ion of these factors control the concentration of manganese deposited or leached away from a pa r t i cu l a r area. The tota l iron content of s o i l s expressed as Fe 2 0 3 ranges from 1 to 6 percent (Byers et a]_., 1935). There is negative enrichment 22 23 or iron as the s o i l weathers. The iron content of some Latosols and Later i tes may go as high as 20 to 80 percent (Alexander et a l_ . , 1962). The s i l i c o n content of many s o i l s , expressed in S i 0 2 ranges from 50 to 70 percent (Clarke et a l_ . , 1924). The concentration r ises in sandy s o i l and decreases with the r e l a t i v e increase in organic matter content (Feustal et a l_ . , 1930). Aluminum content of s o i l ranges from 2 to 12 percent expressed on the basis of A 1 2 0 3 , and may go as high as 60 per-cent in highly weathered s o i l s (Alexander et aj_., 1962). Leeper (1947) postulated that eight factors influence the d i s -t r i b u t i o n of manganese, i r o n , aluminum, s i l i c o n and other elements i n the s o i l p r o f i l e . They are: 1. the l i b e r a t i o n of metal ions from the weathering of minerals , rocks and l i v i n g organisms;: 2. t ranslocat ion of these ions down the s o i l p r o f i l e byppercolating water; 3. the dynamic equi l ibr ium between these ions in so lut ion and on the cation exchange s i t e s ; 4. uptake of these elements by plant roots , and i t s return to the s o i l surface from f a l l i n g leaves; 5. the oxidation of certain elements by oxygen or by e lec tron-accepting bacter ia ; 6. aging of the oxides from the highly reactive to the i n e r t forms; 7. reduction of the higher oxides by organic matter and bacter ia ; 8. u t i l i z a t i o n of the higher oxides d i r e c t l y , by plants and micro-organisms. 24 Leeper then predicted the d i s t r i b u t i o n of these elements i n the p r o f i l e of d i f f e r e n t types of s o i l . Leeper's statements are as fo l lows : i ) Leached s o i l . The surface horizon has a high concentration of these elements, o r i g i n a t i n g from decomposed plant mater ia l . The concentration in the immediate subsurface horizon i s at a minimum, and then a gradual increase with depth. This kind of s o i l i s found in a temperatera- c l imat i c zone, which has high p r e c i p i t a t i o n . In some leached s o i l s i l l u v i a t i o n does not take place , instead there i s a gradual decrease withr.depth. The s o i l i s highly leached and the parent material i s often poor i n the element concerned. i i ) Pedocals and unleached s o i l s . There i s a steady d i s t r i b u t i o n of the element throughout the p r o f i l e . In some pedocals, there i s an accumulation of the element jus t above the calcareous layer . Browman et al_. (1969), evaluating eight s o i l manganese tests found that the s o i l var iab les , pH, and tota l manganese often correlated s i g n i f i c a n t l y with the tes ts . The object ive of th is study was to determine the to ta l concen-t ra t ion of manganese together with aluminum and iron in some of the Lower Fraser Valley s o i l s . The re la t ionship between the tota l concen-t r a t i o n of these elements and other inherent chemical properties of the s o i l s was observed. The resul ts obtained w i l l be helpful for charac-t e r i z i n g the s o i l s in subsequent inves t igat ions . A comparison i s also made between the resul ts obtained with those of Safo for s o i l s derived from the same area. 1. 25 MATERIAL AND METHODS So i l s used in these studies were sampled from the Lower Fraser Valley of B r i t i s h Columbia. The B l u n d e l l , Grevell and Monroe series are derived from a l l u v i a l parent m a t e r i a l , and Tsawwassen, Cloverdale and Sunshine from marine parent mater ia l . A more comprehensive de-s c r i p t i o n of these s o i l s i s given by Luttmerding and Sprout (1967). Most of these s o i l s are subjected to a high water table throughout the year and the Blundell and Tsawwassen series are affected by the t i d e . Texture of the so i l svvary from loamy sand to s i l t y clay (Table 1.1). Sampling was done in late June. Samples from the f i e l d were a i r d r i e d , and large aggregates were crushed with a wooden r o l l e r , and passed through a 2.0 mm s ieve . The less than 2.0 mm samples were stored i n paper containers. Subsamp!es were taken and ground in an agate mortar to pass through a 100 mesh s ieve. So i l pH So i l pH was determined in both f i e l d conditions and fol lowing drying in the laboratory. The procedures using the r a t i o of 1:1 d i s -t i l l e d water and 1:2 0.01 M CaCl 2 (Jackson, 1958) were fol lowed. Corning Model 12 pH meter was used to make the pH measurement. Cation exchange capacity (CEC) The CEC of the s o i l s were determined using the < 2.0 mm samples by saturation of the s o i l with neutral normal ammonium acetate followed by displacement of the N H 4 + ions on the exchange s i tes with normal 26 potassium c h l o r i d e s o l u t i o n . The NH 4 + ions were analysed f o l l o w i n g the semi-micro k j e l d a h l procedure. This procedure was a c t u a l l y an adap-t a t i o n o f Chapman's ammonium s a t u r a t i o n procedure^™ C. A. Black's Methods of S o i l A n a l y s i s . Instead of using ammonium c h l o r i d e , potassium c h l o r i d e was used. The exchangeable forms of manganese, i r o n and aluminum were determined simultaneously from the e x t r a c t s , f o l l o w i n g s a t u r a t i o n of the s o i l with ammonium ions. S o i l organic matter The Walkley-Black procedure was followed using l e s s than 40 mesh samples. Potassium dichromate was used to o x i d i z e the organic matter i n concentrated s u l p h u r i c a c i d . Excess potassium dichromate was t i t r a t e d with ferrous sulphate s o l u t i o n and f e r r o i n i n d i c a t o r . Total manganese, i r o n and aluminum The mixed p e r c h l o r i c , h y d r o f l u o r i c a c i d procedure adapted from P r a t t ' s (1965) procedure f o r t o t a l potassium and sodium was used. About 1.00 gm of a i r - d r i e d 100 mesh s o i l i n a p o r c e l a i n c r u c i b l e was d r i e d a t 105°C f o r 16 hours, followed by ashing at 900°C. 5 N hydro-c h l o r i c a c i d was added to the ash and c e n t r i f u g e d . The supernatant s o l u t i o n was decanted and t h i s contained the major p o r t i o n of the a l k a -l i n e earth metals. The residue was then d i s s o l v e d with concentrated h y d r o f l u o r i c - h y d r o c h l o r i c a c i d mixture iinidaeT/ef/ton -beakerdan'd'evaporated to'cdnyness VvasThtsiepfoe'ediuriecwas hre'peaHe:d'i"us'.i-rhig -a hydrofTuori c^hydrochlori c 27 perchlor ic acid mixture. The residue which remained was again dissolved in 1.0 N hydrochloric a c i d , and d i l u t e d for atomic absorption ana lys i s . The procedure i s out l ined in greater de ta i l in Methods of S o i l Analysis by Prof . L. M. Lavkul ich , Department of S o i l Science, Univers i ty of B r i t i s h Columbia. This digestion procedure is r e l a t i v e l y accurate for the three elements—manganese, i r o n , and aluminum. S i l i c o n can also be determined by di f ference ; however, considering the large error involved, the total amount of s i l i c o n was not recorded. A l l the determinations for manganese, i r o n , aluminum and s i l i -con were carr ied out using a Perkin Elmer 306 atomic absorption spectro-photometer. An air-acetylene flame was used for manganese and i r o n , and nitrous oxide flame, for aluminum and s i l i c o n . 28 RESULTS AND DISCUSSIONS The pH of the samples varied from 4.0 to 8.0 (Table 1.2). No s i g n i f i c a n t difference was observed when the pH was determined in the f i e l d moisture condition or fo l lowing drying of the samples, for the surface horizon. A difference of around one pH unit was observed for the lower horizons. S imi lar trends were shown by the procedure using 0.01 M calcium c h l o r i d e . The pH determined by the l a t t e r procedure was lower than by using d i s t i l l e d water. Cation exchange capacity of the samples varied from 3.4 m.e./ 100 gm for the Grevell C and IIC horizons to 62.2 m.e./lOO gm for the Cloverdale Ahl horizon (Table 1.1). Results of the l a t t e r concurred with the high organic matter present (Table 1.1). The Blundell samples showed the lowest concentration of to ta l manganese (Table 1.2). The concentration of manganese remained steady in both Ap and Bg horizons, and increased s l i g h t l y in the'iCg horizon. The Ap and Bg horizons have acid pH while the Cg horizon had an a lka -l i n e pH. Manganese appears therefore to be mobilized from the upper horizons of the Cg horizon. The high organic matter present accounts for the retention of a r e l a t i v e l y high quantity of manganese in the surface horizon. The low concentration of manganese r e l a t i v e to the other s o i l s i s more of a genetic factor rather than due to leaching. The manganese concentration in the Tsawwassen samples also remained constant for the Ah and C horizon (Table 1.2). There was a s l i g h t decrease i n IIC horizon. The trend i s again related to the pH of the horizons. The surface horizon has an acid pH and therefore Table 1.1 Selected Physical and Chemical Properties of the Soi l s Order Sub-Group Series Texture Parent Material Hori zons Depth (inches) C E C me/100 g % Organic Matter Gleysols Saline-Rego Regosol Orthic Regosol Orthic Gleysol Humic Eluviated Brum'sol Podzol Degraded Eutr ic Mini-Humo Ferri c Blundell ( S i l t y Clay) Tsawwassen (Loamy Sand) Grevell (Loamy Sand) Cloverdale ( S i l t y Clay Loam) Monroe (Sandy Loam) Sunshine (Sandy Loam) A l l u v i a l Ap 0-7 55.5 17.7 Bg 7-20 23.8 4.3 eg 20+ 17.6 4.4 Mari ne Ah 0-12 8.1 3.0 C 12-30 1.1.8 0.2 IIC 30+ 22.2 0.1 A l l u v i a l Ah 0-2 22.4 8.6 C 2-12 3.4 0.1 IIC 12+ 3.4 0.1 Marine Ahl 0-14 62.2 19.0 Ah2 14-22 50.5 7.9 Bg 22-33 33.9 0.9 eg 33+ 31.7 0.4 A l l u v i a l Ap 0-7 24.2 4.0 Btj 7-14 18.9 1.7 HCg 21 + 10.3 0.4 Marine Ah 0-5 51.9 17.8 Bfl 8-15 32.7 4.5 Bf2 15-29 22.8 2.7 BC 29-35 16.3 1.3 C 36+ 15.1 0.9 ro Table 1.2 Total Manganese, Iron and Aluminum in Relation to pH of the Soi l pH - Wet pH - Dry Total Concentration H 20 0.01 M CaCl 2 H20 0.01 M CaCl 2 Mn Fe Al S o i l s Ratio 1:1 Rat ionl :2 Ratio 1:1 Ratio 1:2 (ppm) (PPm) (PPm) Blundell AP 4.90 4.4 5.0 4.6 297.0 28,410 55,540 Bg 4.1 3.9 4.1 3.8 302.1 44,430 62,210 eg 7.4 6.8 4.9 4.8 411.9 45,490 75,810 Tsawwassen Ah 5.9 4.9 5.9 5.0 663.6 30,050 62,600 C 7.4 6.6 7.3 5.8 665.8 31,290 66,330 IIC 8.6 7.5 8.0 7.4 593.2 28,790 63,830 Grevel1 Ah 6.0 5.4 5.9 5.3 633.5 26,610 34,210 C 6.9 5.6 6.0 5.0 575.0 26,370 48,970 IIC 7.1 5.9 6.3 5.2 706.0 33,820 57,620 Cloverdale A h l 5.2 4.4 5.1 4.5 1 ,366.0 44,910 56,800 mz 5.9 4.9 5.9 5.1 566.6 49,610 37,860 Bg 6.2 5.5 5.8 5.5 517.8 62,140 64,290 eg 6.5 5.8 6.0 5.7 994.2 60,840 81,550 Monroe AP 5.9 5.2 5.7 5.2 895.7 43,010 58,190 Btj 6.0 5.4 5.9 5.3 1,230.0 47,470 44,910 HCg 6.2 5.2 5.8 5.2 750.2 40,140 55,200 Sunshine Ah 4.3 3.9 5.3 3.9 573.6 28,810 43,210 Bf-1 5.5 4.9 5.2 4.6 756.9 38,880 68,690 Bf2 6.1 4.9 5.1 4.5 634.9 34,840 46,460 BC 6.1 4.8 5.1 4.7 642.1 34,400 77,710 C 6.3 4.8 5.3 4.7 626.3 33,100 61,100 31 Table 1.3 Exchangeable Manganese, Aluminum, and Iron and Organic Matter Content of the So i l So i l Horizons Exchangeable Forms Percent Mn Fe Al Organic (ppm) (ppm) (ppm) Matter Blundell Ap 3.8 10.0 35.0 17.7 Bg 1.5 6.3 17.5 4.3 eg 7.5 2.5 5.0 4.4 Tsawwassen Ah 12.3 3.8 2.5 3.0 C 3.5 2.5 - 0.2 IIC 2.0 2.5 - 0.1 Grevel1 Ah 59.0 5.0 2.5 8.6 C 9.5 7.5 5.0 0.1 IIC 7.0 2.5 2.5 0.1 Cloverdale Ahl 22.8 5.0 25.0 19.0 Ah 2 0.8 2.5 30.0 7.9 Bg" 5.3 2.5 - 0.9 eg 19.8 2.5 - 0.4 Monroe Ap 24.8 3.8 _ 4.0 Bt j 4.3 2.5 - 1.7 IIC 5.0 2.5 - 0.4 Sunshine Ah 8.8 32.5 82.5 17.8 B f l 7.3 5.0 40.0 4.5 Bf2 0.8 5.0 17.5 2.7 BC 0.5 5.0 15.0 1.3 C 0.5 5.0 - 0.9 32 probably the manganese has been mobilized to the C and IIC horizons which have a l k a l i n e pH. This observation also indicates that most of the manganese in the Tsawwassen s o i l s are from surface accumulation rather than from the parent mater ia l . The trend exhibited by Grevell and Cloverdale series were the same (Table 1.2). There was an i n i t i a l decrease in the subsurface horizon followed by an increase in the lower horizons. Leeper (1947) c i t e d this observation as the c h a r a c t e r i s t i c of leached s o i l s . (The Lower Fraser Valley area has a high annual p r e c i p i t a t i o n . ) Monroe and Sunshine ser ies showed an increase in the subsurface horizon followed by a decrease of manganese in the lower horizon. The middle horizons are zones of i l l u v i a t i o n . The Monroe s o i l has some clay in the B horizon and this would help to f i x manganese. The acid pH of the Sunshine Ah horizon probably mobilized the manganese al lowing i t s movement to the Bf horizon, where there is an abrupt increase in pH. Iron results showed a s i m i l a r trend as manganese, except for Cloverdale samples. In this case, there was a s i g n i f i c a n t increase from the Ah to Bg horizon followed by a decrease i n the Cg horizon (Table 1.2). Aluminum showed the same trend as manganese for Blundell and Tsawwassen horizons (Table 1.2). There was a gradual increase in a l u -minum with depth for G r e v e l l . Cloverdale samples indicated a decrease in aluminum from the surface Ahl to Ah2 horizon. This was followed by a s i g n i f i c a n t increase in Bg and Cg horizons which are the zones of i l l u v i a t i o n for the sesquioxides. This may also indicate the 33 contr ibution of both parent material and organic matter to the tota l content of elements in the s o i l . Safo (1970) reported the to ta l concentration of manganese of the Sunshine s o i l to be i n the range of 80 to 300 ppm; Grevell in the range of 250 to 550 ppm; and Monroe ranging from 350 to 700 ppm. Table 1.2 shows that the tota l manganese extracted in th is study was s i g n i -f i c a n t l y higher. Further modif icat ion of tota l elemental analysis i s necessary for precise comparison. Exchangeable manganese decreased with depth for the Tsawwassen, Grevell and Sunshine ser ies . For B l u n d e l l , Cloverdale and Monroe series there seemed to be a decrease in the subsurface horizons, followed by an increase again in the parent mater ia l . This observation correlated well with s o i l texture. Exchangeable iron decreased with depth in a l l cases. The highest amount was related to the highest organic matter content which corres-ponds with the surface horizons of Sunshine, G r e v e l l , and Blundell series (Table 1.3). Exchangeable aluminum was highest in the Sunshine Ah horizon. The concentration decreased with depth. The associat ion with other oxides might account for t h i s . Some of the horizons showed undetectable amounts of exchangeable aluminum. 34 CONCLUSION No d e f i n i t e trend was observed between the concentration of manganese, i ron and aluminum and the type of parent mater ia l . Iron resul ts were c lose ly re lated v.toh manganese but not for aluminum. This further stressed the s i m i l a r i t y in chemical properties of i ron and manganese in the s o i l . The to ta l concentration of manganese re-ported in this study was s i g n i f i c a n t l y higher than that reported by Safo (1970), even though the s o i l s were from the same area. Further studies are necessary for to ta l element ana lys i s . The resul ts for exchangeable manganese were also higher than Safo's resul ts for certa in horizons. The exchangeable manganese con-centration has been known to vary with the treatment of samples p r i o r to ex t rac t ion . Generally, the exchangeable concentration of manganese, iron and aluminum correlate well with the organic matter content of the s o i l . LITERATURE CITED Alexander, L. T . , and Cady, J . G. 1962. U.S.D.A. Tech. B u l l . 1282. Bear, F. E. 1946. S o i l s and F e r t i l i z e r s . New York, John Wiley and Sons, I n c . , p. 51. . 1964. Chemistry of the S o i l . 2nd E d i t i o n . ACS Monograph No. 160, Reinhold Publishing Corp. Black, C. A. 1965. Methods of S o i l Analys i s . Part 2. Agron. No. 9, American Society of Agronomy I n c . , Publ isher . Browman, M. G . , Chesters, G . , and Pionke, H. B. 1969. Evaluation of tests for predic t ing the a v a i l a b i l i t y of s o i l manganese to p lants . A g r i c . S c i . Camb. 72: 335-340. Byers, H. G . , Alexander, L. T . , and Holmes, R. S. 1935. U.S.D.A. Tech. B u l l . 484. Clarke, F. W., and Washington, H. S. 1924. "U.S . Geol. Survey Prof , paper 127." Feusta l , I . C . , and Byers, H. G. 1930. U.S .D.A. Techn. B u l l . 214. Lavkul i ch , L. M. 1974. Methods of S o i l Analys i s . Pedology Laboratory, Dept. of S o i l Science, Universi ty of B r i t i s h Columbia. Leeper, G. W. 1947. The forms and reactions of manganese in the s o i l . S o i l S c i . 63: 79-94. Luttmerding, H. A. and Sprout, P. N. 1967. Preliminary report of the Lower Fraser Valley S o i l Survey. B r i t i s h Columbia Dept. of A g r i c . , Kelowna, B.C. Robinson, W. 0. 1929. Detection and s igni f i cance of permanganate (MnOj in s o i l . So i l S c i . 27: 335-350. Safo, E. Y. 1970. Manganese status of some Lower Fraser Valley s o i l s developed from a l l u v i a l and marine deposits . M.Sc. thes is , iDept.: of sS'oiiKS'ete'nce^f Uniivefeiitycof B r i t i s h "Col unibtaJ ' ^ h C j"! urrrbi => 35 CHAPTER 2 EVALUATION OF FIVE EXTRACTANTS FOR THE EXTRACTION OF MANGANESE, IRON, ALUMINUM AND SILICON INTRODUCTION The conventional procedure for extract ing manganese from the s o i l i s biased towards i t s a v a i l a b i l i t y to plants . Not many l i t e r a t u r e described the extract ion of manganese in re la t ion to the other oxides, even though manganese i s commonly associated with these oxides in the s o i l . This study w i l l evaluate some of the common extractants for organical ly and inorganica l ly complexed oxides i n the s o i l . Acid ammonium oxalate presumably extracts the amorphous organic and inorganic forms, and very l i t t l e of the c r y s t a l l i n e forms of iron and aluminum in s o i l s (McKeague, 1967). Acid ammonium oxalate has been found to be useful in character iz ing the accumulation products of podzols and other s o i l s . Oxalate-extractable aluminum and iron also gives useful ind ica t ion of the development of Bf horizons, even though the parent material i s r i c h in iron oxides (McKeague and Day, 1966). The a c i d i t y of the extractant renders the sesquioxides soluble . The N H ^ ions displace the i ron and aluminum adsorbed or attached to the s o i l . Tlieioxalates'on (C2OO i s both*a;.strong chelating-agent as "wel l 1 as a0reducin"g- ;agentP^3A1-1 .thesecpfcoperties^account for its- usefulness. 37 Sodium pyrophosphate extracts the amorphous organic forms of iron and aluminum at pH 10.0 (McKeague et a l_ . , 1971). Results obtained allow d i s t i n c t i o n between amorphous organic and amorphous inorganic forms of iron and aluminum in the s o i l . At pH 7.0, sodium pyrophos-phate dissolved the ferrous s i l i c a t e minerals (Ti tova, 1962; Kononova et aj_., 1964). Bascomb (1968) t r i e d to d i f f e r e n t i a t e the d i f f e r e n t forms of i ron and aluminum oxides in s o i l and showed which extractant was useful for which forms as indicated in Figure 2 .1 . Bascomb con-cluded that 0.1 M sodium pyrophosphate at pH 10.0 ext rac ts : 1. c o l l o i d a l organic matter, 2. organic complexes of i ron and aluminum, 3. act ive amorphous inorganic forms of iron oxides , and poorly extracts aged " i n a c t i v e " inorganic oxides andviwell cry-s t a l l i z e d oxides. Bascomb's c l a s s i f i c a t i o n thus includes part of the inorganic amorphous oxides contradictory to McKeague's breakdown. Schnitzer (1962) showed'that the organic material involved i n the complexes with i ron and aluminum was f u l v i c a c i d , therefore any differences in r e s u l t between sodium pyrophosphate and acid ammonium oxalate extract ion would be due to the amorphous "aged" hydrous oxides portion (Refer to Figure 2 .1) . Dion et a]_. (1946) indicated that sodium pyrophosphate was useful i n extract ing the t r i v a l e n t form of manganese. They did not give the concentration and pH of the extractant . They postulated that a stable complex Na3(Mn H 2 P 2 0 7 ) was formed between the t r i v a l e n t manganese and sodium pyrophosphate. CO Inorganic Iron Compounds '•+ Organic Compounds W e l l - Amorphous Amorphous Acid Acid S i l i c a t e s C r y s t a l l i z e d "Aged" '.'Gel" Soluble Insoluble Oxides Hydrous Oxides Hydrous Oxides "Fulvate' "Humate" (pH 3.8) Di th ioni te (pH 3.0) Acid Oxalate (pH 7.0) Pyrophosphate (pH 10.0) Pyrophosphate Modified from Bascomb, 1968. Figure 2 .1 . E x t r a c t a b i l i t y of d i f ferent compounds of iron by d i f fe rent extractants. 39 DisodiumEDTA has been used as a chelating agent in s o i l studies by many workers. The s t a b i l i t y of a metal ion with a chelat ing agent i s dependent on the i o n i c radius , charge, and the presence of electrons on the d - o r b i t a l s . The s t a b i l i t y constant is d i r e c t l y proportional to the charge and inversely proportional to the radius . For the t r a n s i -t ion elements the s t a b i l i t y constant increases with increasing atomic number. Thus iron has a higher s t a b i l i t y constant with chelat ing agents than manganese. I r r e g u l a r i t i e s in the trend are due to the l igand f i e l d s t a b i l i z a t i o n energy (Murmann, 1964). Mortvedt et al_. (1970) t r i e d to calculate s t a b i l i t y constant diagrams for i ron and aluminum with EDTA at d i f f e r e n t pH values. I t was found that EDTA complexes with F e 3 + almost exc lus ive ly below pH 6.3. Complexation of A l 3 + by EDTA was only minor, between pH 4.0 to 9.0. The above observations were obtained from studies in aqueous so lu t ions . The heterogeneity of the s o i l has to be rea l ized when dealing with the chemical ef fects of the d i f f e r e n t extractants . The interact ions between cations as well as with the organic chelat ing agents present i n the s o i l would contribute large i r r e g u l a r i t i e s in the trend (Schnitzer and Skinner, 1966, 1967). Beckwith (1955) and Heintze (1957) indicated that disodiumEDTA i s s p e c i f i c for extract ing organica l ly bonded manganese. This i s not exactly true. A chelat ing agent w i l l extract any form of the element. Browman ejt a K (1969) evaluated the a v a i l a b i l i t y of manganese to plants using eight extractants , namely ammonium acetate, magnesium n i t r a t e , H 3 P O 4 , hydroquinone, 3.0 M N M 2 P O 4 , 1.5 M N H ^ P O ^ and EDTA. They 40 found that EDTA and r^ PO^  extractable manganese were more superior i n predic t ing manganese uptake. Safo (1970) t r i e d to show that "act ive manganese" (the forms of manganese that are avai lable to plants and extracted by d i s t i l l e d water, ammonium acetate, and hydroquinone) i s analogous to EDTA man-ganese. However, he found that EDTA extracted more manganese a f ter the extract ion of "act ive manganese." Dispersion of the s o i l aggregates by EDTA might account for the extra manganese released. Hydroquinone i s a good reducing agent. I t has been used in both s o i l and plant ana lys i s . I t prevents unwanted autooxidation and polymerization of organic compounds ( N o l l e r , 1968). The potential involves in o x i d i z i n g hydroquinone to quinone i s approximately 0.6994 V. 0 + 2H + + 2e" E° = 0.6994 V OH 0 [Hydroquinone] [Quinone] In s o i l science hydroquinone in neutral ammonium acetate has been used to extract the eas i ly reducible form of manganese. The pH of the extractant i s important in determining i t s ef fect iveness . Hydro-quinone i s also sens i t ive to exposure to l i g h t . Therefore, the time in terva l between preparing the extractant and extract ing the s o i l i s c r i t i c a l . Chao (1972) found that hydroquinone not only reduced man-ganese but also i r o n , and the l a t t e r always inter fered with manganese ana lys i s . M n 3 + and M n 4 + have oxidation potent ia ls of 1.51 V and 0.77 V, respect ive ly . Theoret ica l ly hydroquinone would bring i ron into so lut ion more e a s i l y than manganese. The forms of iron present in the s o i l are important i n studying the magnitude of the e x t r a c t i o n . Hydroxylamine hydrochloride has been used in s o i l and plant ana lys i s . 0.1 M hydroxylamine hydrochloride in 0.01 M n i t r i c acid was used by Chao (1970) to extract manganese from son'ils. He found that there was se lec t ive d i sso lut ion of manganese by hydroxylamine hydrochloride. This was found to be untrue for the Lower Fraser Valley s o i l s ( Z u l k i f l i , 1973). Hydroxylamine hydrochloride d id s o l u b i l i z e a large portion of i r o n , in fact comparatively higher than that of hydroquinone. Hydroxylamine hydrochloride i s a stronger reducing agent than hydroquinone. They have oxidation potentials of 0.496 V and 0.699 V, respect ively (Latimer, 1938). I t was th i s factor and the acid pH that lead to hydroxylamine hydrochloride being used i n this study as i t was f e l t i t would bring into so lut ion greater amounts of manganese, i r o n , aluminum and s i l i c o n than hydroquinone. Some biases can be seen in se lect ing the extractants to be used in th i s study. The extractants are those that extract the amor-phous oxides and the organically-complexed forms. Extractants that dissolve the c r y s t a l l i n e forms such as sodium bicarbonate-c i trate d i t h i o n i t e were not included because r e l a t i v e l y speaking these forms are not as act ive in a f fec t ing immediate properties of the s o i l . 42 MacKenzie and Meldau (1959) stressed that the amorphous oxides have a r e l a t i v e l y large surface area and consequently af fec t the properties of the s o i l s i g n i f i c a n t l y . Oades (1965) c i ted that amorphous forms of oxides were the active forms of oxide in the s o i l . Mi tche l l (1964) d i f f e r e n t i a t e d the "act ive" and " i n a c t i v e " oxides i n s o i l . "Act ive" oxides are those readi ly extractable by common extract ing agent and " i n a c t i v e " oxides"being those not readi ly extractable . Dixon (1958) stated that changing from amorphous to c r y s t a l l i n e forms involved reduction in surface area. Amorphous i ron and aluminum oxides were found to adsorp 109 to 137 times as much POi/ than the c r y s t a l l i n e forms (Gorbunov, et aj_., 1961). As indicated in the per iodic table iron and manganese are adja-cent to each other. The d i f f e r e n t oxidation states of iron and man-ganese have the fol lowing i o n i c r a d i i : M n 2 + = 0.80 A° Mn^ + = 0.66 A° F e 2 + = 0.74 A° F e 3 + = 0.64 A° Resemblances in the i o n i c r a d i i account for the occurrence of iron as well as manganese in the same complex. They can coordinate the same way, even though t h e i r s t a b i l i t y may vary. Aluminum and s i l i c o n are the 13th and M t h elements respect ively in the per iodic table . A l 3 + has an ionic radius of 0.50 A° and Si 4 " 1 " , 0.43 A°. This closeness of i o n i c r a d i i accounts for the p o s s i b i l i t y of aluminum displac ing s i l i c o n in the s i l i c a tetrahedra (Heslop and Robinson, I960). 43 Aluminum also forms many compounds with s i l i c a . Loughnan (1960) c i ted that alumina i n the amorphous form has great a f f i n i t y for s i l i c a to form a luminos i l i ca te compounds. The associat ion of i ron and manganese with a luminosi l i ca te compounds has been mentioned repeatedly in the l i t e r a t u r e . F r i p i at and Gastuche (1952) accounted* for the accumulation of i ron down the p r o f i l e as being the resul t of f i x a t i o n on the a luminos i l i ca te com-pounds. Hemstock and Low (1953) showed the p o s s i b i l i t y of manganese in associat ing i t s e l f with a luminosi l i ca te compounds. Taylor et a l . (1964) studying concretions and black coatings on s o i l crumbs, con-cluded that they were "micro c r y s t a l l i n e " aggregates of manganese, i r o n , aluminum and s i l i c o n with minute admixture of l i t h i u m , barium and other a l k a l i n e earth metals. A l l these f indings indicate that d i sso lut ion of a component of a s o i l would bring into so lut ion the other components associated with i t . In f a c t , th is procedure i s more n a t u r a l , since the elements i n the s o i l are not present as separate e n t i t i e s but (interact with one another. The purpose of this study was to evaluate the e x t r a c t a b i l i t y of manganese, i r o n , aluminum and s i l i c o n by f i v e extractants . They were: 1. 0.2 M ac id ammonium oxalate - pH 3.0 2. 0.1 M sodium pyrophosphate pH 10.0 3. 0.02 M disodiumEDTA pH 4.5 4. 0.1 M hydroxylamine hydro-chloride in 0.01 n i t r i c acid pH 2.0 44 5. 0.2 percent hydroquinone i n neutral normal ammonium acetate - pH 7.0 Emphasis w i l l be given to the d i s t r i b u t i o n of manganese in the d i f -ferent s o i l p r o f i l e s . C h a r a c t e r i z a t i o n of the d i f f e r e n t forms of these elements i s c a r r i e d out to d i f f e r e n t i a t e the d i f f e r e n t forms of man-ganese, i r o n , aluminum and s i l i c o n extracted by these extractants i n reference to hydroxylamine h y d r o c h l o r i d e . 45 MATERIAL AND METHODS S ix s o i l s of varying texture and parent material were used in th is study. A more deta i led descr ipt ion of the s o i l s was outl ined <i>n Chapter 1. One hundred mesh s o i l samples were used i n each case. The general procedure included shaking, centr i fuging and f i l t e r i n g the supernatant l i q u i d . Al iquots of the supernatant so lut ion were analyzed for manganese, i r o n , aluminum and s i l i c o n using the atomic absorption spectrophotometer. D i l u t i o n was done where necessary. A s o i l extractant,ratdio" o.fFJrSQswasimaintained <in.al-l-Gases^tD,ifferent shaking methods and..speeds of centr i fugat ion were used for the d i f -ferent extractants to coincide with conventional procedure. These were: i ) 0.2 M acid ammonium oxalate - pH 3.0 These samples were shaken in 100 ml centrifuge tubes i n the dark for 4 hours. The mixture was then centrifuged at 2,500 rpm for 10 minutes. i i ) 0.1 M sodium pyrophosphate - pH 10.0 The shaking was done overnight in a temperature regulated box. The samples were then centrifuged at 8,200 rpm for 10 minutes. i i i ) 0.1 M hydroxylamine hydrochloride in 0.01 M n i t r i c ac id - pH 2.0 0.2 percent hydroquinone in neutral normal ammonium acetate, and 0.02 M disodiumEDTA - pH 4.5 For these extractants the samples were shaken for 1 hour f o l -lowed by centr i fugat ion at 2,500 rpm. 46 In a l l these procedures only a c lear supernatant so lut ion was analyzed with the atomic absorption spectrophotometer. Centri fugation was repeated i f th is was not achieved. The time in terva l between the sample extract ion and processing through the atomic absorption spectro-photometer was also c r i t i c a l . Prolonged storage did lower the r e s u l t s . Samples were stored in the r e f r i g e r a t o r , since this should reduce th i s e f f e c t . S t a t i s t i c a l analysis Correlat ion studies between extractants and between s o i l pro-perties and extractants were done using the IBM 360/7 computer. The INMSDC of the Triangular Regression Package (TRIP) program was used. This prggram can be obtained from the Universi ty of B r i t i s h Columbia Computing Centre's l i b r a r y . 47 RESULTS AND DISCUSSIONS The to ta l manganese present i n the Tsawwassen horizons were uniform for the Ah and C horozons, and decreased s l i g h t l y in the IIC horizon (Table 1.2). The portion of the to ta l manganese extracted by acid ammonium oxalate decreased almost l i n e a r l y with depth (Figure 2 .2) . Greater amounts of the to ta l manganese is in the c r y s t a l l i n e form with depth. The trend showed by the other extractants , excepting sodium pyrophosphate, was almost the same. Hydroquinone extracted 3.8 percent of the to ta l manganese in the Ah horizon but decreased to 0.9 percent in the C horizon. I t remained at 0.9 percent for the IIC horizon. There was a wide difference between the amount of manganese in Ah and C horizons extracted by hydroxylamine hydrochloride and hydro-quinone. The results became c loser together in the IIC horizon. There must be some differences in the forms of manganese extracted by these two extractants , in the Ah and C horizons. The amounts extracted by disodiumEDTA, sodium pyrophosphate and hydroxylamine hydrochloride in the Ah horizon were very close together, however. Dispari ty in resul ts increased with depth. DisodiumEDTA and hydroxylamine hydrochloride showed a decrease with depth, but sodium pyrophosphate showed an i n -crease from the C to IIC horizon (Figure 2 .2) . A few things can be derived from these observations. The form of manganese extracted by sodium pyrophosphate, disodiumEDTA, and hydroxylamine hydrochloride appeared to be the same in the Ah horizon. This form decreased s i g n i -f i c a n t l y i n the C horizon. The r e l a t i v e l y higher resu l t shown by MANGANESE 48 •OF CONC. % O F TOTAL Ah C I C TSAWASSEN (LOAMY-SAND) ACID AMMONIUM OXALATE HYDROXYLAMINE HYDROCHLORIDE No 2 EDTA — O — O — SO?IUM PYROPHOSPHATE O HYDROQUINONE IN AMMONIUM ACETATE 10 CONC. % OF TOTAL Ap Bg Cg BLUNDELL (SILTY-CLAY) Ah| A h 2 Bg Cg CLOVERDALE (SILTY-CLAY LOAM) F i g u r e 2 . 2 : R e l a t i v e c o n c e n t r a t i o n o f m a n g a n e s e e x t r a c t e d by t h e e x t r a c t a n t s i n T s a w w a s s e n , B l u n d e l l and C l o v e r a l e s e r i e s . 49 disodiumEDTA and hydroxy1 amine hydrochloride in the C horizon could be due to t h e i r s p e c i f i c extract ing a b i l i t y . The high amount of sodium pyrophosphate manganese in the IIC horizon i s perhaps from the t r i -valent form. Manganese extracted from the Blundell by disodiumEDTA, hydroxyl-amine hydrochloride, hydroquinone, and acid ammonium oxalate showed the same trends in a l l horizons. Sodium pyrophosphate manganese i n -creased s i g n i f i c a n t l y from an undetectable amount i n the Ap horizon to the r e l a t i v e l y high amount in the Bg and Cg horizons (Figure 2 .2) . The high concentration could be derived from the ac id- inso luble humate portion (Figure 2 .1) . The pH of sodium pyrophosphate was more a l k a l i n e than any of the other extractants . The extra manganese could also be from the t r i v a l e n t form (Dion et a l_ . , 1946). There were great differences i n resul ts for the f i v e extractants with the Cloverdale 's Ah] horizon (Figure 2 .2) . Hydroquinone extracted higher amounts of manganese than disodiumEDTA. No s i g n i f i c a n t d i f -ference was observed between disodiumEDTA and sodium pyrophosphate extractions in Ah? and Bg horizons. The manganese extracted by sodium pyrophosphate, disodiumEDTA, hydroxy1 amine hydrochloride was again c lose ly related in G r e v e l l ' s Ah horizon and d i f fered s i g n i f i c a n t l y in the C horizon (Figure 2 .3) . DisodiumEDTA showed almost the same r e s u l t as hydroxylamine hydrochloride in the 11C horizon. Surpr i s ing ly sodium pyrophosphate manganese was lowest among the f i v e extractants in C and 11C horizons (Figure 2 .3) . The manganese extracted by hydroquinone, disodiumEDTA, hydroxylamine 50 M A N G A N E S E ACID AMMONIUM OXALATE HYDROXYLAMINE HYDROCHLORIDE Na 2EDTA o—o— SODIUM PYROPHOSPHATE - O HYDROQUINONE IN AMMONIUM ACETATE MONROE (SANDY-LOAM) SUNSHINE (SANDY-LOAM) 4 0 h A h C I C GREVELL (LOAMY-SAND) F i gure 2 . 3 : R e l a t i v e c o n c e n t r a t i o n o f manganese , e x t r a c t e d by the e x t r a c t a n t s i n G r e v e l l , Monroe and S u n s h i n e s e r i e s . 51 hydrochloride and acid ammonium oxalate i s perhaps from the well-aged amorphous oxides. Sunshine's acid ammonium oxalate , hydroxylamine hydrochloride, hydroquinone resul ts showed s i m i l a r trends for a l l horizons (Figure 2 .3) . Acid ammonium oxalate extracted the highest concentration of manganese followed by hydroxylamine hydrochloride and hydroquinone, respect ive ly . Sodium pyrophosphate extracted r e l a t i v e l y high amounts of manganese i n the Ah horizon, but decreased s i g n i f i c a n t l y in the B f l J h o r i z o n . Conversely the other three extractants showed an increase from the Ah to Bfl- horizon. DisodiumEDTA resul ts were again lower than hydroquinone results i n the Ah and BfT horizon. This observation further s i g n i f i e s that manganese i s extracted i n greater amounts by a reducing agent than jus t a chelat ing agent, espec ia l ly i n the lower horizons. The same d i s t r i b u t i o n of manganese was shown by acid ammo-nium oxalate , hydroxylamine hydrochloride, disodiumEDTA and hydroqui-none in the Monroe s o i l (Figure 2 .3) . Sodium pyrophosphate resul ts indicate a d i s t i n c t form of manganese i s present. Undetectable amounts of i ron were extracted by hydroquinone for a l l samples. Acid ammonium oxalate extracted the greatest port ion of i ron i n a l l Tsawwassen horizons (Figure 2 .4) . There was an increase in i ron content from the Ah to the C horizon. The trend was the same for the other three extractants . Sodium pyrophosphate extracted higher amounts of i ron than disodiumEDTA and hydroxylamine hydrochloride in the upper horizons but lower amounts i n the IIC horizon. The organic matter content of the IIC horizon was very low. To assume that 52 20 IRON ACID AMMONIUM OXALATE 15 CONC. % OF TOTAL 10 HYDROXYLAMINE HYDROCHLORIDE No 2 EDTA 5H —O—o— SOLIUM PYROPHOSPHATE A h C HC TSAWASSEN (LOAMY-SAND) 40f CONC. % OF TOTAL. 30 "20 10 h A / \ / ' \ A p Bg Cg BLUNDELL (SILTY-CLAY) 40 CONC. % 0 F TOTAL 30 20 10 k ^ \ ° \ \ o \ o Ahj A h 2 Bg Cg CLOVERDALE (SILTY-CLAY LOAM) F i g u r e 2 . 4 : R e l a t i v e c o n c e n t r a t i o n o f i r o n e x t r a c t e d by the e x t r a c t a n t s i n Tsawwassen , B l u n d e l l and C l o v e r d a l e s e r i e s . 53 disodiumEDTA only extracts organically-bonded iron is not exactly v a l i d . Sodium pyrophosphate presumably extracts the organically-complexed and the recent amorphous inorganic forms of i r o n . The observations there-fore indicate that disodiumEDTA and hydroxylamine hydrochloride also extract i ron from the aged amorphous inorganic p o r t i o n , as well as from the organica l ly complexed form. There was a decrease in percentage of sodium pyrophosphate and acid ammonium oxalate iron with depth for Cloverdale samples (Figure 2 .4) . This resu l t could be the r e s u l t of the re la t ive ; ; - increase in tota l concentration of i ron from Ah2 to Cg horizon. DisodiumEDTA' and• ^ngxyij-amine i hydnqch Tori de res u 1 ts .;w§re 0<§iQS e together,oan d na 1 most un i form with depth. One s i g n i f i c a n t difference between the Cloverdale and the coarse-textured samples (Tsawwassen and Grevell ) was the r e l a t i v e l y greater amount of i ron extracted by sodium pyrophosphate in comparison to disodiumEDTA and hydroxylamine hydrochloride. One possible reason for th i s i s the presence of greater concentration of organic and recent amorphous inorganic oxides in the Cloverdale s o i l . The f ine texture of the Cloverdale samples reduced the rate of decomposition of the organic complex, and aging of the amorphous oxides. Sodium pyrophosphate extracted higher amounts of i ron in the Blundell Ap horizon than did acid ammonium oxalate (Figure 2 .4) . The ac id-soluble humate port-iion may account for the extra i ron extracted. Percentage of ac id ammonium oxalate i ron increased s i g n i f i c a n t l y from Ap to Bg horizons. The other extractants showed a decrease with depth. DisodiumEDTA, hydroxylamine hydrochloride and sodium pyrophosphate gave the same trend as i n the Cloverdale samples. 54 The d i s t r i b u t i o n of i ron in the Grevell s o i l was the same for a l l extractants except sodium pyrophosphate (Figure 2 .5) . Sodium pyro-phosphate extracted lower concentrations of i ron in C and IIC horizons, i n comparison with disodiumEDTA and hydroxylamine hydrochloride. Hydroxylamine hydrochloride extracted higher amounts of iron than sodium pyrophosphate i n the Monroe Ap horizon (Figure 2 .5) . The hydroxylamine hydrochloride resul t was s i g n i f i c a n t l y d i f f e r e n t from disodiumEDTA. This was contradictory to the other two f ine- textured samples (Figure 2 .4) . In the l a t t e r , resul ts for both extractants were very c lose . The concentration of the e a s i l y - r e d u c i b l e form of iron must be high i n the Ap horizon. This coupled with hydroxylamine hydro-chloride ac id pH, brought intoo so lut ion more iron than the other two mild extractants . Figure 2.5 acid ammonium oxalate resul ts for i ron further showed that i t i s superior to any other extractant in detecting zones of i ron accumulation i n a Podzol. Hydroquinone did not extract a detectable concentration of aluminum i n the samples s tudied. The percentage of tota l aluminum extracted by sodium pyrophosphate decreased with depth in the Tsawwassen s o i l (Figure 2 .6) . The other extractants showed an i n i t i a l increase from Ah to C horizons and then decreased in the IIC horizon. This ob-servation corresponded to that of iron (Figure 2 .4 ) , another indica t ion of the close associat ion between the sesquioxides. The percentage of aluminum extracted by both sodium pyrophosphate and acid ammonium oxalate were very s i m i l a r in the Cloverdale Ahl and Ah2 horizons 55 25r 20 L C0NC. % 0 F TOTAL 15 10 h 5h Ah C E C GREVELL (LOAMY-SAND) I R O N ACID AMMONIUM OXALATE HYDROXYLAMINE HYDROCHLORIDE No 2 EDTA SODIUM PYROPHOSPHATE 20H CONC. % OF TOTAL I5h 10 Ap Btj E C g MONROE (SANDY- LOAM) 40 h CONC. % 0 F TOTAL 30 20\-10 / A \ V ' 0 » „ O -Ah Bfj Bf 2 BC C SUNSHINE (SANDY- LOAM) F i g u r e 2 . 5 : R e l a t i v e c o n c e n t r a t i o n o f i r o n e x t r a c t e d by t h e e x t r a c t a n t s i n G r e v e l l , Monroe and S u n s h i n e s e r i e s . 56 A L U M I N U M 4.01 ACID AMMONIUM OXALATE 3.0 CONC. % 0 F TOTAL 2.0 / X . HYDROXYLAMINE HYDROCHLORIDE Na 2 EDTA 1.0 Ah C I C TSAWASSEN (LOAMY-SAND) — O — SODIUM PYROPHOSPHATE 12 CONC. % OF TOTAL 40h Ol Ap Bg Cg BLUNDELL (SILTY-CLAY) CONC. % OF TOTAL 30 20 10 A ' w a' // / \ o\ w \ Ah| A h 2 Bg Cg CLOVERDALE (SILTY-CLAY LOAM) F i g u r e 2 . 6 : R e l a t i v e c o n c e n t r a t i o n o f a luminum e x t r a c t e d by the e x t r a c t a n t s i n Tsawwassen , B l u n d e l l and C l o v e r d a l e s e r i e s . 57 (Figure 2 .6 ) . Dispari ty increased in the Bg and Cg horizons. This may be due to the v a r i a b i l i t y in the aging process for the amorphous oxides. The trend exhibi ted by the other two extractants was the same except that the amount extracted was lower. A higher percentage of aluminum was extracted by sodium pyro-phosphate than acid ammonium oxalate in the Blundell Ap horizon (Figure 2 .6 ) , but the resul ts remained close together i n Bg and Cg horizons. The Blundell s o i l has a high organic matter content. Most of the a l u -minum was organica l ly complexed, as indicated by the higher amount of aluminum extracted by disodiumEDTA, compared to hydroxylamine hydro-ch lor ide . The i ron and aluminum resul ts did not show s i m i l a r trends in the f ine- textured s o i l s as i t did in the coarse-textured s o i l s . Iron assumes a more complex chemistry with the organic matter and c o l -l o i d a l material in the f ine- textured s o i l s . Aluminum and iron results from the Grevell s o i l are shown in Figures 2.7 and 2 .5 , and sodium pyrophosphate was again inconsistent with the other extractants . The d i s t r i b u t i o n of aluminum and iron in the Sunshine series was consistent (Figure 2 .7) . Acid ammonium oxalate extracted the highest percentage of aluminum for a l l Monroe's horizons (Figure 2 .7) . This was followed by sodium pyrophosphate, disodiumEDTA and hydroxylamine hydrochloride, consecutively. Results reported for s i l i c o n are i n concentration ppm rather than percent of the to ta l concentration. Only acid ammonium oxalate and hydroxylamine hydrochloride were e f f e c t i v e in extract ing s i l i c o n . Hydroxylamine hydrochloride extracted the lower amount of s i l i c o n . 58 ALUMINUM 4.0 3.0 CONC. % 0 F TOTAL 2.0 1.0 Ah C I C GREVELL (LOAMY-SAND) ACID AMMONIUM OXALATE HYDROXYLAMINE HYDROCHLORIDE NagEDTA SODIUM PYROPHOSPHATE CONC. % OF TOTAL A / \ \ \ 2 h _ o - ° ^ ° " 0 - x > . Ap Btj HTCg MONROE (SANDY- LOAM) 40 CONC % 0 F TOTAL 30 20 10 / \ / \ \ v \ Ah Bf, Bf 2 BC C SUNSHINE (SANDY- LOAM) F i gure 2.7: R e l a t i v e c o n c e n t r a t i o n of a luminum e x t r a c t e d by the e x t r a c t a n t s i n G r e v e l l , Monroe and S u n s h i n e s e r i e s . 59 The concentration of s i l i c o n extracted by acid ammonium oxalate in Tsawwassen samples increased s i g n i f i c a n t l y from Ah to C hor izon, and decreased again i n IIC horizon. S imi lar trends were observed for hydroxylamine hydrochloride (Figure 2 .8) . No d e f i n i t e trends were observed in the other samples (Figure 2.8 and 2.9) . Correlat ion studies Correlat ion among extractants and some of the properties of the s o i l are tabulated i n Table 2 .1 . Manganese extracted by hydroxyl-amine hydrochloride showed very high corre la t ion with acid ammonium oxalate and hydroquinone, being 0.9243 and 0.9250, respect ive ly . This indicates that the manganese extracted by hydroxylamine hydrochloride and ac id ammonium oxalate included the major port ion extractable by hydroquinone. Of a l l the elements, i ron and s i l i c o n showed the lowest corre la t ion for a l l extractants . This i s rather s u r p r i s i n g since man-ganese should be the lowest, considering i t s greater v a r i a b i l i t y in oxidation s tates . Aluminum results for a l l extractants , except sodium pyrophosphate, correlate very w e l l . This might indicate a more homo-geneous form of aluminum in the s o i l compared to the other elements. The aluminum and iron extracted by sodium pyrophosphate were s i g n i f i c a n t l y related to the percent organic matter i n the s o i l . This shows that only a minor portion of the sodium pyrophosphate, i ron and aluminum are derived from the amorphous inorganic hydrous oxide g e l . Aluminum extracted by hydroxylamine hydrochloride, disodiumEDTA and sodium pyrophosphate correlated well with the exchangeable aluminum 60 SILICON 200Cr I500h TOTAL CONC. / V \ PPM^ IOOOF ACID AMMONIUM OXALATE HYDROXYLAMINE HYDROCHLORIDE 500 Ah C E C TSAWASSEN (LOAMY - SAND) 2000h 15001 TOTAL CONC. PPM \000\ 500 Ap Bg Cg BLUNDELL (SILTY-CLAY) 2000 1500 TOTAL CONC. PPM 1000 500 A /\ / \ / \ / / / / Ahj Ahg Bg Cg CLOVERDALE (SILTY- CLAY LOAM) F i g u r e 2 . 8 : R e l a t i v e c o n c e n t r a t i o n o f s i l i c o n e x t r a c t e d by the e x t r a c t a n t s i n Tsawwassen, B l u n d e l l and C l o v e r d a l e s e r i e s . 61 SILICON 3000 ACID AMMONIUM OXALATE 2000} TOTAL CONC. PPM 10001 HYDROXYLAMINE HYDROCHLORIDE Ah C E C 6REVELL (LOAMY-SAND) 22001 16501 TOTAL CONC. PPM IIOOl 550 / / / 8000 6000 TOTAL CONC. PPM 4000 2000 / \ / \ / / / \ Ap MONROE Btj 31 Cg (SANDY- LOAM) Ah Bf, Bf 2 BC C SUNSHINE (SANDY- LOAM) F i g u r e 2 , 9 ; R e l a t i v e c o n c e n t r a t i o n o f s i l e x t r a c t e d by the e x t r a c t a n t s G r e v e l l , Monroe and S u n s h i n e i con i n s e r i e s . A c i d A n m o n l u a O x l a t e H i l e A l S I H y d r o j y l d i n l n a H y d r o c h l o r i d e H n l o A l S I M n f t A l S I S o d I u r n P y r o i i l i o i p h a t a H i I O A l S I H y d r o q u i n o n e f t ! F a A l O O O O O O O O —• O w O O O O O O o £ § M 5 1 § a g r e s u l t s . Acid ammonium oxalate , however, showed a lower value. The importance of exchangeable aluminum has been stressed; indeed this was one of the bas.es for choosing hydroxylamine hydroxhloride as the extractant for the s o i l treatment s tudies . 64 CONCLUSION Generally the trend exhibited by hydroxylamine hydrochloride, ac id ammonium oxalate , disodiumEDTA and hydroquinone, for the d i s t r i -bution of each element through each s o i l was the same. Hydroquinone was only e f f e c t i v e in extract ing manganese as only trace amounts of the other elements were detected by atomic absorption analys i s . This ob-servation i s contradictory to Chao's f indings (1972). Hydroquinone does not have a strong complexing a b i l i t y in addit ion to i t s reducing a b i l i t y , whereas the other extractants a l l have strong complexing a b i l i t i e s . Hydroxylamine hydrochloride, ac id ammonium oxalate , disodiumEDTA and sodium pryophosphate were e f f e c t i v e i n extract ing manganese, iron and aluminum. Only ac id ammonium oxalate and hydroxylamine hydrochloride extracted s i l i c a in detectable amounts. These two extractants have a r e l a t i v e l y low pH. Sodium pyrophosphate manganese results were not consistent with the other extractants . For example, in the Blundell s e r i e s , in contrast with the other extractants , sodium pyrophosphate manganese increased s i g n i f i c a n t l y from trace amounts in the Ap hor izon, to larger amounts in the Bg horizon, and decreased again to a r e l a t i v e l y low value in the Cg horizon (Figure 2 .2) . The other extractants showed a decrease i n the Bg horizon followed by an increase in the Cg horizon. This inconsistency was also shown in the Cloverdale, G r e v e l l , Monroe and Sunshine s o i l s . The observation did not coincide with McKeague's con-clusions (1967) that acid ammonium oxalate extracted both organic and 65 inorganic amorphous oxides while sodium pyrophosphate merely extracted the organic amorphous oxides. I f one agrees with Bascomb's d i f f e r e n -t ia t ions (Figure 2 . 1 ) , then the extra manganese must be associated with the ac id insoluble humate por t ion . Further invest igat ions are necessary to explain th is phenomenon. The graphs also indicate the wide differences in disodiumEDTA and sodium pyrophosphate results for manganese, iron and aluminum. Both extractants are known for t h e i r chelat ing a b i l i t i e s . In a l l cases, except extractable manganese from the Blundell s o i l , sodium pyrophos-phate extracted higher amounts than disodiumEDTA, for the surface h o r i -zons. The d i s p a r i t y in resul ts in the lower horizons depended on the type and texture of the s o i l . These two factors control led the types of oxides present in the s o i l . The higher resul ts shown by sodium pyrophosphate could be due to inorganic amorphous hydrous oxide ge l s , and the acid insoluble humate por t ion . Sodium pyrophosphate i s s i g n i -f i c a n t l y more a l k a l i n e than disodiumEDTA. The super ior i ty of disodiumEDTA as a chelat ing agent was shown in the lower horizons. Hydroxylamine hydrochloride and disodiumEDTA resul ts were in close agreement except for i ron in the Monroe Ap horizon. This raised the question whether the form of manganese, i ron and aluminum extracted by both extractants was the same. Hydroxylamine hydrochloride being a stronger reducing agent than hydroquinone imparted this proper.ty to a l l manganese r e s u l t s , except for the Blundell Bg and Cg, and Cloverdale Cg horizons. The l a t t e r observation may be experimental e r r o r . Hydroxylamine hydro-chlor ide i s also known for i t s strong complexing a b i l i t y . Therefore 66 to conclude that a l l the manganese extracted was that reduced from the higher oxides, i s not j u s t i f i e d . Re la t ive ly hydroxylamine hydrochloride extracted a l l four elements with a f a i r degree of consistency. Hydroxylamine hydro-chlor ide resul ts also correlated well with the other extractants as well as with the exchangeable forms of manganese, i ron and aluminum. LITERATURE CITED Bascomb, C. L. 1968. D i s t r i b u t i o n of pyrophosphate extractable i ron and organic carbon in s o i l s . o f various groups. J . S o i l S c i . 19: 251-268. Beckwith, R. S. 1955. The use of CaNa2EDTA for the extract ion of divalent manganese from s o i l s . Aust. J . Agr. Res. 6: 685-691. Chao, T. T. 1972. Se lect ive d i sso lut ion of manganese oxides from s o i l s and sediments with a c i d i f i e d NH20H.HC1. So i l S c i . Soc. Amer. Proc. 36: 764-8. Dion, H. G . , and Mann, P . J . G . 1946. Occurrences of t r i v a l e n t manganese, q J . Agr. S c i . 36: 239-245. F r i p i a t , J . J . and Gastuche, M. C. 1952. Physico-chemical studies of clay surfaces. Combination of k a o l i n i t e with t r i v a l e n t i ron oxides. Inst . Nat. et Agron. Congo beige Pub. Ser. S c i . No. 54, 59. Gorbunov, N. I . , Dzyaevich, G. S . , and Tunik, B. M. 1961. Methods of determining non-si ; l icate amorphous and c r y s t a l l i n e sesqui-oxides i n s o i l s and c l a y s . Soviet S o i l S c i . 11: 1252-59. Heintze, S. G. 1957. Studies on s o i l manganese cyc le . S o i l S c i . 8: 287-300. Hemstock, G. G. and Low, P. F. 1953. Mechanism responsible for the retention of manganese in the c o l l o i d a l f rac t ion of s o i l . S o i l S c i . 96: 331-343. fleslop, R. B. and Robinson, P. L. 1960. Inorganic chemistry. A guide to advanced study. E lsevier Publishing Co. Inc. Kononova, M. M . , Alexandrova, I . V . , and T i tova , N. A. 1964. Decom-posi t ion of s i l i c a t e s by organic substances in the s o i l . Soviet S o i l S c i . 1005-14. Latimer, W. M. 1938. The oxidation states of the elements and t h e i r potential in aqueous so lut ions . Prentice Hall I n c . , New York, pp. 104 and 138. Loughnan, F. C. 1969. Chemical weathering of the s i l i c a t e minerals. E lsevier Publishing Co. Inc. Mackenzie, R. C. and Meldau, R. 1959. The aging of sesquioxide gels . I . Iron oxide gels . Miner. Mag. 32: 153-165. 67 68 McKeague, J . A. and Day, J . H. 1966. Di th ioni te and oxalate extrac-table iron and aluminum as aids in d i f f e r e n t i a t i n g various classes of s o i l s . Can. J . S o i l S c i . 46: 13-22. . 1967. An evaluation of 0.1 M sodium pyrophosphate and pyro-phosphate d i t h i o n i t e in comparison with oxalate as extractants of the accumulation products in podzols and some other s o i l s . Can. J . So i l S c i . 47:95-99. , Brydon, J . E . , and M i l e s , N. M. 1971. D i f f e r e n t i a t i o n of forms of extractable iron and aluminum in s o i l s . S o i l S c i . Soc. Amer. Proc. 35:33-37. M i t c h e l l , B. D . , Farmer, V. C. and McHardy, W. J . 1964. Amorphous inorganic materials in s o i l s . Adv. Agron. 16: 327-383. Mortvedt, J . J . , Giordano, P. M . , and Lindsay, W. L. 1972. Micro-nutrients i n a g r i c u l t u r e . So i l S c i . Soc. Amer. Publ isher . Murmann, R. K. 1964. Inorganic complex compounds. Reinhold Pub-l i s h i n g Corp. , New York. N o l l e r , C. R. 1968. Textbook of Organic Chemistry. 3rd E d i t i o n . W. B. Saunders Co. Oades, J . M. 1963. The nature and d i s t r i b u t i o n of i ron compounds in s o i l s . S o i l s and F e r t i l i z e r s , XXVI: 69-80. Safoij, E. Y. 1970. Manganese states ofi-"some Lower Fraser Valley s o i l s developed from a l l u v i a l and marine deposits . M.Sc. (Agr ic . ) t h e s i s , Dept. of So i l Science, Universi ty of B r i t i s h Columbia. Schnitzer , M. and Desjardin, J . G. 1962. Molecular and equivalent weight of the organic matter of a podzol. So i l S c i . Soc. Amer. Proc. 26: 362-365. and Skinner, S . I . M . 1966. Organo-metallic interact ions in s o i l s : 5. S t a b i l i t y constants of C u 2 + - , F e 2 + - , and Z n 2 + - f u l v i c acid complexes. So i l S c i . 102: 361-5. and . 1967. Organo-metallic interact ions in s o i l s : 7. S t a b i l i t y constants of P b 2 + - , N i 2 + - , Mn2 - , Co 2 - , Ca 2 - , and M g 2 + - f u l v i c acid complexes. S o i l S c i . 103: 247-52. -Taylor, R. M . , McKenzie, R. M . , and N o r r i s h , K. 1964. The mineralogy and chemistry of manganese in some Austral ian s o i l s . Aust. J . S o i l Res. 2: 235-248. Z u l k i f l i , M. A. 1973. The extract ion of s o i l manganese using NH20H.HC1. B.Sc. (Agr ic . ) t h e s i s , Dept. of So i l Science, Universi ty of B r i t i s h Columbia. CHAPTER 3 SUCCESSIVE EXTRACTION OF MANGANESE, IRON, ALUMINUM AND SILICON INTRODUCTION The previous chapter has established the effectiveness of hydroxylamine hydrochloride in 0.01 M n i t r i c a c i d , as an extract ing agent for manganese, i r o n , aluminum.iiand s i l i c o n . Even though the mag-nitude of the concentration extracted was lower than that of acid ammo-nium oxalate , in terms of corre la t ion with other extractants and pro-perties of the s o i l , hydroxylamine hydrochloride was favoured. The forms of manganese, i r o n , aluminum and s i l i c o n extracted by sodium pyrophosphate and ac id ammonium oxalate has been established by Bascomb (1968). DisodiumEDTA as a strong chelat ing agent has been intens ive ly studied by Mortvedt et al_. (1972). Safo (1970) investigated whether "ac t ive" manganese ( i . e . the sum of water-soluble , exchangeable and eas i ly - reduc ib le manganese) was the same as EDTA extractable manganese. He found that EDTA extracted more manganese af ter extract ion of "ac t ive" manganese. The dispersive action of EDTA should be taken into consi -deration when analyzing these r e s u l t s . A reasonable assumption could be made that disodiumEDTA extracts both the organica l ly and inorganica l ly complexed elements, as well as those remaining free in so lut ion and 69 70 on exchange s i t e s . The magnitude of disodiumEDTA chelation varies according to the s t a b i l i t y constants of the d i f f e r e n t elements with EDTA and with other components of the s o i l . This part of the study investigated the re la t ionship of man-ganese, i r o n , aluminum, and s i l i c o n extracted by hydroxylamine hydro-chlor ide to the d i f f e r e n t categories of compounds (Figure 2 .1) . Results of th is study w i l l also give an idea of the r e d u c i b i l i t y of the d i f f e r e n t compounds in s o i l . Sequential analysis in which the s o i l was extracted with hydroxylamine hydrochloride followed by one of the other extractants , followed by hydroxylamine hydrochloride again were carr ied out. Comparison was made between the concentration ex-tracted by the extractants and the concentration when sequential analy-s i s was carr ied out. Comparisons were also made between manganese, i r o n , aluminum, and s i l i c o n extracted by hydroxylamine hydrochloride preceding the extractants and a f te r the extractants . The v a l i d i t y of the successive extract ion procedure was also investigated in this study. Successive e x t r a c t i o n ^ s o i l s had been used i n s o i l studies for a long time. The conventional exchangeable cations and cation exchange capacity determinations made use of suc-cessive extract ion procedure. Safo (1970) did successive extract ion for water s o l u b l e , exchangeable and eas i ly - reduc ib le manganese. In this case, d i s t i l l e d water, neutral ammonium acetate, and 0.2% hydro-quinone in neutral normal ammonium acetate were used successively. The e f fec t of the preceding extractant on the s o i l propert ies , cautioned against undertaking this procedure. D i s t i l l e d water s o l u b i l i z e s many 71 compounds, disperses the s o i l aggregates to a minor extent and also affects the i o n i c equi l ibr ium on the cation exchange s i t e s . Neutral ammonium acetate, a-3 so--has-.the. abodes me'n&i one.di:'ef.f e:etS£-.6n?-J;he, soji.l e tofoat?a^gjme'a&.e'r,-!magr* 1"tude.. Therefore, the extract ion of e a s i l y -reducible manganese fol lowing water soluble and exchangeable extrac-tions was on a modified s o i l system. Visentin (1973) introduced a new procedure for the successive extract ion of i r o n , aluminum and s i l i c o n from amorphous organic and inorganic oxides, and well c r y s t a l l i z e d oxides in s o i l s . Sodium car-bonate, sodium pyrophosphate, acid-ammonium oxalate and c i t r a t e d i -thionite-bicarbonate extractions were carr ied out on the samples suc-cess ive ly . A sodium acetate and sodium chlor ide mixture was used to bring the pH back to 5.0 between extract ions . Changes brought about by the preceding extractant on the s o i l system depended on the strength and other properties of the extractant. I t i s also hoped that these studies w i l l unravel some of the modifications brought about by the d i f f e r e n t extractants . The resul ts also give the chance for researchers to make a choice, whether to carry out successive extract ion analysis or fol low the arduous conventional procedures using fresh samples each time. 72 MATERIAL AND METHODS S o i l s used in the study were derived from the Lower Fraser Val ley . (Chapter 1 of this thesis gives further d e t a i l s on the pro-perties of the s o i l . ) One gram of a i r - d r i e d , 100 mesh samples were used. A s o i l : e x t r a c t a n t r a t i o of 1:50 was maintained at a l l times. The general procedures involved shaking and centr i fuging . Centrigu-gation was repeated u n t i l a c lear supernatant solut ion was obtained. Different shaking and centr i fuging procedures were carr ied out for d i f f e r e n t extractants . (Chapter 2, page 45 for a more complete d i s -cussion.) The supernatant solutions were analyzed for manganese, i r o n , aluminum and s i l i c o n using Atomic Absorption Spectrophotometry. The fol lowing extractants were used in this study: 1. 0.2 M acid ammonium oxalate pH 3.0 2. 0.1 M sodium pyrophosphate pH 10.0 3. 0.02 M disodiumEDTA pH 4.5 4. 0.1 M hydroxylamine hydrochloride in 0.01 M n i t r i c ac id pH 2.0 5. 0.2% hydroquinone in neutral normal ammonium acetate. -The fol lowing analysis was carr ied out: i ) Ex t rac t ion , using fresh samples each time for ac id ammonium oxalate , sodium pyrophosphate, disodiumEDTA, hydroxylamine hydrochloride and hydroquinone extractable manganese, i r o n , aluminum and s i l i c o n . i i ) Successive extract ion of s o i l using hydroxylamine hydrochloride then acid ammonium oxalate followed by hydroxylamine hydrochloride 73 again. The samples were washed three times with isopropanol between extract ions . i i i ) Procedure i i ) was repeated for sodium pyrophosphate, disodiumEDTA and hydroquinone. 74 RESULTS AND DISCUSSIONS Comparison between sodium pyrophosphate and hydroxylamine hydrochloride  followed by sodium pyrophosphate extractions Hydroxylamine hydrochloride followed by sodium pyrophosphate brought more manganese into so lut ion i n a l l samples except the Blundell Bg and Cg horizons (Table 3 .1) . The same results could be seen for aluminum i n a l l horizons. Sodium pyrophosphate by i t s e l f did not bring into so lut ion s i g n i f i c a n t amounts of s i l i c o n , but sodium pyrophosphate preceded by hydroxylamine hydrochloride extracted large amounts of s i l i -con. In some cases the resul ts were higher than shown by acid ammo-nium oxalate extract ion (Table 3.3) . Iron resul ts showed that hydroxyl-amine hydrochloride followed by sodium pyrophosphate d i d not bring more into in to so lut ion f o r some of the surface horizons, i . e . Blundell Ap and Bg, Tsawwassen Ah, and Cloverdale Ah and Bf. These observations indicate that the forms of manganese, i r o n , aluminum and s i l i c o n ex-tracted by hydroxylamine hydrochloride and sodium pyrophosphate were p a r t i a l l y the same. Table 3.2 shows that for most s o i l s the amount of sodium pyrophosphate manganese, extracted a f ter hydroxylamine hydro-chloride extracti ion, was lower except for the Blundell Ap; Cloverdale Bf, Cgl and Cg2; and Monroe Bt j and 11Cg horizons. The resul ts were again lower for i ron except for the Cloverdale Cgl and Cg2 horizons. Aluminum resul ts showed a subsequent increase for most of the f i n e -textured subsurface horizons. S i l i c o n results for sodium pyrophosphate a f ter hydroxylamine hydrochloride increased s i g n i f i c a n t l y from unde-tectable amounts. The increases might be due to the dispersion or Table 3.1 Comparison Between Sodium Pyrophosphate Extraction and a Combination of Hydroxylamine Hydrochloride and Sodium Pyrophosphate Extractions Hydroxy. Hydroch. and Sod. Pyro. Sod. Pyro. So i l s Mn (ppm) Fe (ppm) Al (ppm) Si (ppm) Mn (ppm) Fe (ppm) Al (ppm) Si (ppm) Blundell Ap Bg eg 30 38 4,500 4,500 3,000 6,500 2,000 1,500 -30 19 31 3,320 4,384 3,150 7,158 3,891 2,733 3,699 5,931 4,238 Tsawwassen Ah C IIC 38 13 25 1,000 1,000 430 750 630 380 - 64 46 35 979 1,252 791 1,151 1,298 913 1,083 1,987 1,117 Grevel1 Ah C IIC 150 38 63 1,000 300 1,000 1,000 130 630 - 193 144 194 1,170 893 1,945 1,113 898 1,787 1,385 1,602 3,041 Cloverdale Ah Bf Cgl . Cg2 450 13 8 23 9,500 8,000 1,500 330 10,000 13,000 1,500 500 -632 41 37 367 7,826 6,134 1,805 1,368 11,367 17,890 3,438 2,678 3,354 6,518 2,571 2,697 Monroe Ap Btj HCg 175 50 25 3,500 3,000 1,500 1,000 1,000 500 - 313 355 252 8,050 3,227 1,816 2,613 3,000 1,727 2,576 2,593 2,046 76 Table 3.2 Comparison Between Sodium Pyrophosphate Extract ion and Sodium Pyrophosphate a f ter Hydroxylamine Hydrochloride Extraction Sod. Pyro. a f t e r Sod. Pyro. Hydroxy. Hydroch. S o i l s Mn (ppm) Fe (ppm) Al (ppm) Si (ppm) Mn (ppm) Fe (ppm) Al (ppm) Si (ppm) Blundell Ap Bg eg 30 38 4,500 4,500 3,000 6,500 2,000 1,500 - 17 14 17 2,522 3,125 2,119 5,332 3,125 2,143 3,603 5,930 4,047 Tsawwassen Ah C IIC 38 13 25 1,000 1,000 430 750 630 380 -18 14 12 519 209 170 519 162 194 902 1,156 728 Grevel1 Ah C IIC 150 38 63 1,000 300 1,000 1,000 130 630 - 26 24 27 740 291 479 645 316 479 1,194 1,214 1,875 Cloverdale Ah Bf Cgl Cg2 450 13 2.8 23 9,500 8,000 1,500 330 10,000 13,000 1,500 500 - 212 32 14 48 7,155 . 5,764 1,595 1,011 9,123 15,130 2,762 2,071 2,314 6,323 2,381 2,408 Monroe Ap Bt j I lCg 175 50 25 3,500 3,000 1,500 1,000 1,000 500 - 90 102 72 2,806 2,755 1,397 1,886 2,130 1,148 2,300 2,315 1,746 77 Table 3.3 Comparison Between Acid Ammonium Oxalate Extraction and a Combination of Hydroxylamine Hydrochloride and Acid Ammonium Oxalate Extractions Hydroxy. Hydroch. and Acid Ammon. Ox. A c i d . Amm. Ox. Mn (ppm) Fe (ppm) Al (ppm) Si (ppm) Mn (ppm) Fe (ppm) Al (ppm) Si (ppm) Blundell Ap Bg eg 16 7 23 3,900 13,950 4,700 5,300 2,050 1,900 1,100 700 1,300 15 "2 14 3,450 12,213 3,963 4,800 1,863 1,375 875 375 875 Tsawwassen Ah C IIC 63 50 34 3,600 5,150 4,550 1,350 2,100 1,450 800 1,900 1,300 50 44 24 2,488 3,925 2,950 1,125 1,750 1,275 750 1,625 1,125 Grevel1 Ah C IIC 203 149 222 4,500 4,400 7,700 1,300 1,000 2,400 1,100 1,000 2,900 202 139 208 3,650 2,613 4,600 1,013 662 1,775 875 750 1,625 Cloverdale Ah Bf Cgl Cg2 846 69 45 355 13?750 9,250 4,800 6,100 8,750 13,750 4,000 3,300 800 2,100 900 1,400 732 40 34 249 11,075 6,288 2,463 762 8,025 10,763 2,638 575 625 1,625 750 725 Monroe Ap Btj I lCg 419 490 367 8,000 8,200 7,050 2,800 3,400 1,950 1,400 1,700 2,200 390 403 338 5,750 5,425 5,525 2,413 2,275 1,488 1,250 1,125 1,125 78 breakdown of complexes brought about by hydroxylamine hydrochloride. This extractant , having a pH of 2 .0 , might also have attacked some of the semi -c rys ta l l ine forms, exposing these forms to the subsequent treatment of sodium pyrophosphate. This greater exposure, as well as the a l k a l i n e pH of sodium pyrophosphate may account for the higher s o l u b i l i t y of s i l i c o n i n the samples. The low pH of hydroxylamine hydrochloride may also weaken the s o i l aggregates (prevalent mostly in the subsurface horizons of f i n e -textured s o i l s ) and make i t easy for the fol lowing sodium pyrophosphate dispers ive ac t ion . The pH of both extractants , being at two extremes may have brought into so lut ion both the acid soluble f u l v i c portion and the ac id insoluble humate por t ion . The reducing e f fec t of hydroxylamine hydrochloride also destabi-l i z e d some of the higher oxidation state complexes (generally the higher oxidation state has a higher s t a b i l i t y constant). Lower s t a b i l i t y constants of the complexes rendered them more susceptible to attack by sodium pyrophosphate. Comparison between acid ammonium oxalate and hydroxylamine hydrochloride  followed by acid ammonium oxalate The combined effects of hydroxylamine hydrochloride and ac id ammonium oxalate were expected to bring into so lut ion greater amounts of manganese, i r o n , aluminum and s i l i c o n . Instead lower concentrations of these elements were extracted i n comparison with extract ion by acid ammonium oxalate alone (Table 3 .3) . The forms of manganese, i r o n , a l u -minum and s i l i c o n extracted by hydroxylamine hydrochloride may be 79 included in the acid ammonium oxalate extract ion. This was further shown by the lower amounts of va i l the elements extracted by acid ammo-nium oxalate fol lowing hydroxylamine hydrochloride extract ion (Table 3.4). The preceding hydroxylamine hydrochloride treatment could have reduced the higher oxides, not eas i ly complexed by the oxalate ions. Theoret ica l ly , the f e r r i c and manganic forms have higher s t a b i l i t y constants with oxalate ions than the ferrous and manganous forms. The corresponding results fo r aluminum and s i l i c o n further s i gn i f y the close association of these four elements in the s o i l . Further studies have to be done on th i s aspect, to explain more f u l l y what was happening in the system. Comparison between disodiumEDTA and hydroxylamine hydrochloride followed  by disodiumEDTA DisodiumEDTA extracted detectable amounts of s i l i c o n from the parent material of the coarse-textured samples only (Table 3.5). But disodiumEDTA preceded by hydroxylamine hydrochloride extracted a s i g n i -f i cant amount of s i l i c o n in a l l horizons (Table 3.6), despite the fact that the pH of disodiumEDTA was s t i l l in the acid range. The e f fec t of pH of the extractant on the s o l u b i l i t y of s i l i c o n could be seen by comparing the hydroxylamine hydrochloride and sodium pyrophosphate results (Table 3.1) with hydroxylamine hydrochloride and disodiumEDTA results (Table 3.5). The former showed higher resu l t s . As mentioned e a r l i e r , hydroxylamine hydrochloride probably weakened the s o i l aggregates while at the same time reducing the higher oxides, which i nd i r e c t l y weakened the complexes in the s o i l . The 80 Table 3.4 Comparison Between Acid Ammonium Oxalate Extract ion and Acid Ammonium Oxalate a f ter Hydroxylamine Hydrochloride Extraction Acid Ammon. Ox. a f te r Acid Ammon. Ox. Hydroxy. Hydroch. Mn Fe Al Si Mn Fe Al Si S o i l s (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap 16 3,900 5,300 1,100 9 2,938 4,225 750 Bg 7 13,950 2,050 700 1 11,375 1,413 250 eg 23 4,700 1,900 1,300 6 3,288 1,125 625 Tsawwassen Ah 63 3,600 1,350 800 14 2,188 788 500 C 50 5,150 2,100 1,900 24 3,388 1,288 1,000 IIC 34 4,550 1,450 1,300 , 18 2,825 1,263 1,000 Grevell Ah 203 4,500 1,300 1,100 61 3,525 938 750 C 149 4,400 1,000 1,000 34 2,450 450 500 IIC 222 7,700 2,400 2,900 58 3,950 1,388 1,125 Cloverdale Ah 846 13,750 8,750 800 431 10,750 7,563 500 Bf 69 9,250 13,750 2,100 33 6,063 10,125 1,375 Cgl 45 4,800 4,000 900 20 2,350 2,538 500 Cg2 355 6,100 3,300 1,400 16 588 425 250 Monroe Ap 419 8,000 2,800 1,400 225 5,563 2,250 1,000 Bt j 490 8,200 3,400 1,700 224 5,275 2,088 875 IlCg 367 7,050 1,950 2,200 195 5,363 1,325 875 81 Table 3.5 Comparison Between DisodiumEDTA Extraction and a Combination of Hydroxylamine Hydrochloride and DisodiumEDTA Extractions Hydroxy. Hydroch. and Disod.EDTA Disod.EDTA Mn Fe Al Si Mn Fe Al Si So i l s (ppm) (ppm) (ppm) (ppm) (ppm) ;(ppm) (ppm) (ppm) Blundell Ap 8 1,300 1,500 - 12 2,000 2,188 224 Bg 2 1,500 750 - 3 2,783 1,487 804 eg 10 1,000 300 - 13 2,053 901 949 Tsawwassen Ah 23 450 350 - 46 766 633'. 421 C 26 1,050 1,050 1,200 30 1,097 1,035 1,377 IIC 13 600 400 500 19 736 712 853 Grevel1 Ah 148 600 200 - 209 1,426 486 459 C 80 500 300 200 127 1,004 572 795 IIC 156 1,450 1,400 1,500 179 1,734 1,222 1,464 Cloverdale Ah 101 750 1,850 - 281 2,224 2,402 124 Bf 1 350 1,900 - 14 661 591 309 Cgl 14 200 550 - 28 451 1,143 358 Cg2 232 250 450 - 95 457 527 482 Monroe AP 114 500 350 - 194 780 783 336 Bt j 27 200 400 - 322 739 1,010 447 IlCg 34 200 200 - 233 808 684 504 82 dispersive action of disodiumEDTA further exposed a greater surface area of s o i l for che la t ion . This was shown by the iron and aluminum results (Table 3 .6 ) , when the extract ion was preceded by hydroxylamine hydrochloride. The results for manganese further showed that the act ive manganese and disodiumEDTA extractable manganese were not from the same forms i n the s o i l . Comparison between hydroquinone and hydroxylamine hydrochloride followed  by hydroquinone by hydroquinone Hydroquinone merely extracted manganese and minute amounts of aluminum (Table 3.7) i n the Blundell Ap horizon and a l l the Cloverdale horizons. Hydroquinone preceded by hydroxylamine hydrochloride removed more manganese (Table 3 .8) . This further indicates that hydroxylamine hydrochloride breaks down the s o i l aggregates and exposes the inner surfaces to reduction by hydroquinone. Hydroquinone was not expected to reduce more manganese since hydroxylamine hydrochloride is a stronger reducing agent. Iron and aluminum resul ts (Table 3.8) further stress that hydroquinone is not a good extractant for iron and aluminum. Astonishingly , hydroquinone preceded by hydroxylamine hydrochloride brought considerable amounts of s i l i c o n into s o l u t i o n . The neutral pH of hydroquinone could account for this observation. S o l u b i l i t y of s i l i c a does increase above pH 7.0. Hydroxylamine hydrochloride extract ion af ter hydroxylamine hydro- chlor ide and sodium pyrophosphate extractions Hydroxylamine hydrochloride did not extract any further man-ganese in the Blundell s o i l and the Cloverdale Bf and Cgl horizons 83 Table 3.6 Comparison Between DisodiumEDTA Extraction and DisodiumEDTA af ter Hydroxylamine Hydrochil dri>de~ Extract i on Di sod.EDTA Disod.EDTA af ter Hydroxy. Hydroch. Mn Fe Al Si Mn Fe Al Si So i l s (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap 8 1,300 1,500 - 2 1,473 1,709 174 Bg 2 1,500 750 - 1 1,981 1,083 705 eg 10 1,000 300 - 3 1,371 703 740 Tsawwassen Ah 33 450 350 - 6 409 277 173 C 26 1,050 1,050 1,200 7 496 643 918 IIC 13 600 400 500 9 594 707 742 Grevel1 Ah 148 600 200 - 55 1,214 395 273 C 80 500 300 200 20 597 315 484 IIC 156 1,450 1,400 1,500 27 1,009 983 1,058 Cloverdale Ah 101 750 1,850 - 14 1,697 1,946 74 Bf 1 350 1,900 - 6 419 165 161 Cgl 14 200 550 - 12 330 1,034 135 Cg2 232 250 450 - 72 235 449 148 Monroe Ap 114 500 350 - 100 621 779 224 Btj 27 200 400 - 137 522 838 248 IlCg 34 200 200 - 86 578 515 258 84 Table 3.7 Comparison Between Hydroquinone Extraction and a Combination of Hydroxylamine Hydrochloride and Hydroquinone Extractions Hydroxy. Hydroch. Hydroq. and Hydroq. Mn Fe Al Si Mn Fe Al Si So i l s (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap 5 - 1 3 Bg 2 - -Cg 8 - -Tsawwassen Ah 25 - r C 6 - -IIC 5 - -Grevel1 Ah 100 - 9 C 75 -IIC 103 Cloverdale Ah 156 - 4 Bf 3 - 9 Cgl 12 - 4 Cg2 261 - 5 Monroe Ap 152 -Bt j 159 - -I lCg 127 - 10 659 988 42 - 1 1,096 600 87 - 10 821 433 319 44 386 512 294 - 27 853 956 933 - 12 179 35 134 r.- 159 271 225 250 - 119 528 437 476 - 172 1,026 842 983 429 595 1 ,117 _ - 8 278 1,256 130 - 23 147 358 230 - 348 281 267 415 233 360 286 339 - 276 347 569 386 - 197 231 275 280 85 Table 3.8 Comparison Between Hydroquinone Extraction and Hydroquinone a f ter Hydroxylamine Hydrochloride Extraction Hydroq. a f ter Hydroq. Hydroxy. Hydroch. Mn Fe Al Si Mn Fe Al Si Soi Is (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap Bg eg 5 2 - -8 13 1 25 13 5 13 44 91 Tsawwassen Ah C IIC 25 6 5 -1 9 - 84 89 Grevell Ah C IIC 100 75 103 -20 4 - -83 87 86 Cloverdale Ah Bf Cgl Cg2 156 3 12 261 4 9 4 5 9 37 4 21 9 21 17 5 46 46 Monroe Ap Bt j I lCg 152 1T50 127 - 49 24 42 -4 5 85 48 40 86 (Table 3.9) . Very small amounts of manganese were extracted in the other samples. These resul ts were s u r p r i s i n g , considering the pept iz ing e f fec t of sodium pyrophosphate which might have exposed greater surfaces of s o i l to attack by hydroxylamine hydrochloride. These low resul ts might d'.ust be c h a r a c t e r i s t i c of manganese. Sodium pyrophosphate had been used to extract the t r i v a l e n t form of manganese. Probably the major form of manganese extracted by hydroxylamine hydrochloride i s the t r i v a l e n t form. Hydroxylamine hydrochloride extracted more i r o n , aluminum and s i l i c o n a f ter sodium pyrophosphate extract ion (Tables 3.10, 3.11, and 3.12). In the case of aluminum and s i l i c o n , hydroxylamine hydrochloride extracted a greater amount than hydroxylamine hydrochloride p r i o r to sodium pyrophosphate e x t r a c t i o n . These resul ts showed the r e l a t i v e involvement of the d i f f e r e n t elements i n s o i l aggregation - Aluminum and s i l i c o n > i ron > manganese. Sodium pyrophosphate dispers ive action was probably responsible for breaking the s o i l aggregates. Hydroxylamine hydrochloride extract ion a f ter hydroxylamine hydrochloride  and acid ammonium oxalate extractions Greater amounts of aluminum and s i l i c o n were again extracted by hydroxylamine hydrochloride a f ter hydroxylamine hydrochloride and acid ammonium oxalate extract ions . These observations indicate that modifications were brought about by the acid ammonium oxalate treatment. The high amount of i ron and manganese recorded were probably the residual of oxalate complexing. As mentioned e a r l i e r , oxalate does not complex with manganous and ferrous as strongly as i t does with f e r r i c and man-ganic ions . 87 Table 3.9 Comparison Between Hydroxylamine Hydrochloride Extraction and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Different Extractants Element: Manganese Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. a f te r a f ter a f te r a f ter Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. Hydroxy. and Sod. and Acid and Disod. and So i l s Hydroch.. Pyro. Amm. Ox. EDTA Hydroq. Mn Mn Mn Mn Mn (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap 14 - 2 1 -Bg 6 - 4 - -eg 14 - 4 2 -Tsawwassen Ah 46 3 6 6 -C 32 8 9 7 1 IIC 23 4 9 5 1 Grevell Ah 166 7 18 14 8 C 120 8 14 10 4 IIC 167 17 19 14 6 Cloverdale Ah 419 13 105 51 30 Bf 10 - 9 2 2 Cgl 23 - 11 2 1 Cg2 319 9 93 10 18 Monroe Ap 224 27 24 42 15 Bt j 253 32 38 43 28 IlCg 179 38 21 34 20 88 Table 3.10 Comparison Between Hydroxylamine Hydrochloride Extract ion and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Dif ferent Extractants Element: Iron Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. a f ter a f ter a f ter a f ter Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. Hydroxy. and Sod. and Acid and Disod. and Soi Is Hydroch. Pyro. Amm. Ox. EDTA Hydroq. Fe Fe Fe Fe Fe (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap 798 144 500 631 106 Bg 1,259 137 1,588 956 283 eg 1,028 552 625 843 151 Tsawwassen 45'; - . - , Ah 461 190 875 501 59 C 1,044 638 K088 538 102 IIC 621 456 1,138 461 102 Grevel1 Ah 430 430 1,063 794 46 C 602 515 1,113 595 78 IIC 1,466 1,108 1,088 637 180 Cloverdale Ah 671 215 1,338 1,034 73 Bf 370 107 675 500 61 Cgl 209 114 1,300 312 41 Cg2 356 260 1,450 306 46 Monroe Ap 524 414 1,050 881 76 Btj 472 435 113 813 92 IlCg 419 588 1,050 709 84 89 Table 3.11 Comparison Between Hydroxylamine Hydrochloride Extraction and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Dif ferent Extractants Element: Aluminum Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. a f ter a f ter a f ter a f ter Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. Hydroxy. and Sod. and Acid and Disod. and Soi l s Hydroch. Pyro. Amm. Ox. EDTA Hydroq. Al Al Al Al Al (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap 479 509 825 338 55 Bg 404 483 350 69 48 eg 199 771 463 117 105 Tsawwassen Ah 356 208 350 187 17 C 392 822 425 384 13 IIC 66 621 350 307 45 Grevel1 Ah 91 210 375 121 46 C 257 476 275 155 9 IIC 239 1,233 413 323 26 Cloverdale Ah 456 429 975 337 21 Bf 426 1,226 1,088 615 9 Cgl 109 1,190 913 324 9 Cg2 78 895 1,100 116 9 Monroe Ap 4 934 588 142 13 Bt j 172 497 500 182 5 IlCg 169 648 388 129 4 90 Table 3.12 Comparison Between Hydroxylamine Hydrochloride Extraction and Hydroxylamine Hydrochloride Preceded by Hydroxylamine Hydrochloride and the Dif ferent Extractants Element: S i l i c o n Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. a f ter a f ter a f ter a f ter Hydroxy. Hydroxy. Hydroxy. Hydroxy. Hydroch. Hydroch. Hydroch. Hydroch. Hydroxy. and Sod. and Acid and Disod. and Soi Is Hydroch. Pyro. Amm. Ox. EDTA Hydroq. Si Si Si Si Si (ppm) (ppm) (ppm) (ppm) (ppm) Blundell Ap 50 192 500 225 127 Bg 100 182 375 111 174 eg 210 1,142 500 259 365 Tsawwassen Ah 248 181 375 124 84 C 459 924 375 285 89 IIC 111 874 375 236 90 Grevel1 Ah 186 191 375 260 125 C 311 680 375 235 43 IIC 406 1 ,749 500 394 128 Cloverdale Ah 50 179 375 75 86 Bf 148 487 375 161 44 Cgl 223 381 500 149 92 Cg2 334 482 750 124 92 Monroe Ap 112 276 625 224 85 Bt j 199 370 500 274 48 IlCg 246 399 500 246 80 91 Hydroxylamine hydrochloride extract ion a f te r hydroxylamine hydro- chloride and disodiumEDTA extractions More manganese, i r o n , aluminum and s i l i c o n were extracted by hydroxylamine hydrochloride fol lowing hydroxylamine hydrochloride and disodiumEDTA extractions (Tables 3 .9 , 3.10, 3.11, and 3.12). For some of the samples, greater amounts of i r o n , aluminum and s i l i c o n were extracted. DisodiumEDTA dispersed the s o i l aggregates. Its chelat ing a b i l i t y released some of the elements from the organic and inorganic complexes. The elements were thus more prone to attack by the sub-sequent reducing agent. Hydroxylamine hydrochloride extract ion a f ter hydroxylamine hydro- chloride and hydroquinone extractions Very l i t t l e manganese was extracted by hydroxylamine hydro-chloride (Table 3.11). In samples already low in eas i ly - reduc ib le manganese, non-detectable amounts were extracted by hydroxylamine hydro-c h l o r i d e . More aluminum, iron and s i l i c o n were extracted by hydroxyl-amine hydrochloride fo l lowing the two extract ions . The milder e f fec t of hydroquinone on the s o i l properties was shown by the concentration of manganese, i r o n , aluminum and s i l i c o n extracted by hydroxylamine hydrochloride (Tables 3 .9 , 3.10, 3.11, and 3.12). The reducing a b i l i t y of hydroquinone i s i n f e r i o r to that of hydroxylamine hydrochloride, but the hydroquinone extractant was made in ammonium acetate so lut ion and the ammonium ions have a strong d isp lac ing a b i l i t y . This d isplac ing a b i l i t y may account for the extra i r o n , s i l i c o n and aluminum extracted by hydroxylamine hydrochloride. 92 CONCLUSION Looking back at Bascomb's category of compounds: Inorganic Organic Wen-cry s t a l l i zed Amorphous oxides "aged" Amorphous oxi des " g e l " A c i d -soluble "Fulvate it A c i d -insoluble "Humate" Both the lower and higher.oxides of i ron and manganese are present i n these categories. The proportion of each oxidation state i n each cate-gory i s dependent on the redox potent ial of the system, r e l a t i v e aging and the s t a b i l i t y constant of the oxides. The redox potential of a metal ion is modified once i t i s complexed. General ly, the higher oxides as well as the higher valenced elements have a higher s t a b i l i t y constant than the lower valence form. The extractant used i n th is study did not a f fec t the w e l l - c r y -s t a l l i z e d forms of the oxides. Hydroxylamine hydrochloride extracted manganese and iron from the various portions by reducing and complexing. Since aluminummand s i l i c o n are not reducible i t i s safe to assume that they are complexed by hydroxylamine hydrochloride. Aluminum and s i l i c o n could have also been released as a consequence of manganese and iron reduction. The extent of reduction of these complexed elements by hydroxylaminehhydrochloride depends on the redox potential and the s t a b i l i t y constant. The s trength, pH and other chemical properties of these reagents are important for t h e i r effects on the s o i l . Acid ammonium oxalate , the 93 hydroxylamine hydrochloride, and sodium pyrophosphate have r e l a t i v e l y more d r a s t i c ef fects than disodiumEDTA and hydroquinone. The concen-t ra t ion of elements extracted by hydroxylamine hydrochloride fol lowing the other extractants i s dependent on the forms extracted. Complexing and chelat ing reagents often reduce the s t a b i l i t y constant of o r g a n i c a l l y -complexed elements and the higher oxides making them more susceptible to the fol lowing hydroxylamine hydrochloride reduction. Reducing agents are also known to reduce the s t a b i l i t y constant of complexes. Even though 100 mesh samples were used in th is study, the ex-tent of s o i l aggregation was s t i l l prominent enough to a f fec t the r e s u l t s . Dispersion of these aggregates by the extractants often showed a s i g n i -f i cant increase i n values. Therefore the concentration ofcelements extracted are dependent among other things on the extent of aggregation in the sample. This factor i s p a r t i c u l a r l y important in manganese, i r o n , aluminum and s i l i c o n a n a l y s i s , since they are cementing agents in s o i l s e i ther in the form of sesquioxides or organic complexes. I t i s a question of objectives that determine whether a re-searcher should carry out successive extract ion a n a l y s i s , or the arduous conventional procedure of using fresh samples for the d i f f e r e n t extrac-tants . I f the object ive i s to determine . quant i ta t ive ly the plant a v a i l a b i l i t y index, then successive extract ion procedure i s not recom-mended. Successive extract ion procedures are warranted, however, for q u a l i t a t i v e observations. This study indicated that the changes in the s o i l system affected by the preceding extractant d i d af fec t the r e s u l t s . LITERATURE CITED Bascomb, C. L. 1968. Dis t r ibut ion of pyrophosphate-extractable iron and organic carbon in s o i l s of various groups. J . S o i l S c i . 19: 251-268. Mortvedt, J . J . , Giordano, P. M . , and Lindsay, W. L. 1972. Micronut-r ients in a g r i c u l t u r e . S o i l S c i . Soc. Amer. Proc. Publ ishers . Safo, E. Y. 1970. Manganese status of some Lower Fraser Valley s o i l s developed from a l l u v i a l and marine deposits . M.Sc. (Agr ic . ) thes Dept. of S o i l Science, Universi ty of B r i t i s h Columbia. V i s e n t i n , G. R. 1973. Aspects of inorganic amorphous system of humo-f e r r i c podzols of the Lower Mainland of B.C. M.Sc. (Agr ic . ) thes Dept. of S o i l Science, Univers i ty of B r i t i s h Columbia. 94 CHAPTER 4 THE EFFECT OF SOIL PRETREATMENTS ON THE EXTRACTION OF MANGANESE, IRON, ALUMINUM, AND SILICON USING HYDROXYLAMINE HYDROCHLORIDE AS THE EXTRACTANT INTRODUCTION S o i l samples from the f i e l d are often treated and stored p r i o r to ex t rac t ion . The treatment and storage duration and condit ion af fec t e x t r a c t a b i l i t y of the elements. Fujimoto and Sherman (1945) working with Hawaiian s o i l s , found that exchangeable manganese increased upon a i r - d r y i n g . Oven-drying and s t e a m - s t e r i l i z a t i o n lead to an increase from a few parts per m i l l i o n to approximately three thousand parts per m i l l i o n . The release was found to be proportional to the duration and temperature of incubation. Subsequent moistening of the s o i l to the f i e l d capacity decreased the exchangeable manganese. They postulated that dehydration of the hydrated manganese complex [(MnO) (Mn0.2.)w(H20)7] x <~ y L causes the i n s t a b i l i t y of the structure leading to the release of the manganese oxide for the exchange s i t e s . Later (1948) they also found that steam s t e r i l i z a t i o n increased the exchangeable and water-soluble manganese but decreases the eas i ly - reduc ib le form. Christenson and Toth (1950) suggested that products of organic matter decomposition which increase with moisture content, form a strong complex with manganese. 95 96 Heintze and Mann (1947)showed that polycarboxylic and hydroxycarboxylic acids rare responsible for complexing manganous- and manganic-"tons. An increase of up to s i x hundred percent was observed when a i r -dried samples were analyzed a f ter being stored for one year (Boken, 1958). The increase was inversely proportional to the organic matter content. Hammes and Berger (1960) contradicted previous f indings by showing that oxidation of organic matter upon a i r - d r y i n g released the organically-complexed manganese. I t seems that there are two stages involved i n the e f fec t of organic matter on the e x t r a c t a b i l i t y of man-ganese. At the early stage, products of decomposition of organic matter complexed with manganese. Further exposure w i l l destroy these organic acids releasing the complexed manganese. Nish i ta and Haug (1971) examined the changes in physical and chemical properties of the s o i l as a r e s u l t of heating at d i f f e r e n t temperatures. They found that increased aggregation, due to ca lc ina t ion by iron oxides and a luminos i l i ca tes , takes place above 300°C. No changes were observed below this temperature. The cation exchange capacity was found to decrease af ter heating above 100°C. This reduction coincides with increased aggregation, dehydration and breakdown of the mineral crysta l l a t t i c e . The pH of the s o i l decreased to a minimum as the tem-perature i s increased to 200°C, and increased again with a further r i s e i n temperature. The i n i t i a l reduction in pH was due to oxidation of cer ta in elements, dehydration of c o l l o i d s and a r e l a t i v e increase of organic compounds. The ensuing increase in pH was due to the formation of oxides of many compounds. N i s h i t a and Haug also investigated the 97 water and ammonium acetate extractable forms of manganese, i r o n , cobal t , chromium and copper as a r e s u l t of incubation at temperatures of 100°C, 200°C, 300°C, 400°C, 500°C, 800°C, and 1,000°C. Incubating at 200°C lead to an increase in both extractable forms of most elements. At th is temperature ashing of the s o i l samples and dehydration of the hy-drated complexes may have taken place. Release from these complexes could therefore account for the marked increase at t h i s temperature. The authors also rea l ized the heterogeneity off the s o i l , because no d e f i n i t e conclusion could be derived from the study. Manganese and iron are highly affected by the redox potential of the s o i l . Microbial a c t i v i t y , organic matter and moisture content are some of the factors that a f fec t the redox p o t e n t i a l . Meek et a l . (1968) indicated that the combination of f l o o d i n g , organic matter and high temperature increased the level of s o l u b i l i z e d i ron and manganese. Patr ick and Turner (1968) found that conversion of eas i ly - reduc ib le manganese into exchangeable and water soluble forms i s intense below 400 mV/. Residual manganese ( h i g h l y - c r y s t a l l i z e d ) i s not affected by redox p o t e n t i a l . These f indings stressed further the importance of e a s i l y - r e d u c i b l e forms, also known as the amorphous oxides. The e f fec t of s o i l treatments on aluminum and s i l i c o n was not mentioned in these s tudies , despite the occurrence of a l l four elements simultaneously. L i t t l e work has been done on the eas i ly - reduc ib le forms of manganese with d i f f e r e n t treatments. These forms are more react ive and should be more sens i t ive to changes. The object ive of th is study was to investigate the e x t r a c t a b i l i t y of manganese, i r o n , aluminum and s i l i c o n by hydroxylamine hydrochloride 98 with special emphasis on manganese. The d i f f e r e n t treatments were designed to evaluate the differences between i n - s i t u extract ion and the conventional a i r - d r y i n g procedures. An attempt was also made to see the e f fec t of a i r - d r y i n g at two durat ions, one week and four months. Oven-drying at 50°C and 100°C were carr ied out to see the e f fec t of enhanced drying of moist samples. The freezing treatment was carr ied out to show the e f fec t of getting samples from the f i e l d i n the winter and cold seasons. I t i s also hoped that freezing treatments together with the a i r - d r y i n g treatments w i l l give some indica t ion of the seasonal f luctuat ions on the e x t r a c t a b i l i t y of manganese, i r o n , aluminum and s i l i c o n . The experiments were designed to observe quant i ta t ive ly the e f fect of d i f f e r e n t treatments on samples p r i o r to ex t rac t ion . The changes iim physical and chemical properties of the s o i l brought about by the d i f f e r e n t treatments are r e a l i z e d . No attempt was made to deter-mine what s p e c i f i c changes in physical and chemical properties lead to the quant i ta t ive observations. Hopefully this study w i l l lay the basic ground work for future s tudies , and w i l l also caution s o i l re-searchers about the var ia t ion in resul ts obtained when no uniform sampling proceduresis carr ied out. 99 MATERIALS AND METHODS Five s o i l series from the Lower Fraser Val ley were used in th is study. They were Tsawwassen, G r e v e l l , B l u n d e l l , Cloverdale and Sunshine. The general properties of these s o i l s are given in Chapter 1. For a more detai led descr ipt ion of these s o i l s re fer to Luttmerding and Sprout (1967). The general procedure involved shaking the s o i l for one hour in 0.1 M hydroxylamine hydrochloride in 0.01 M n i t r i c a c i d , centr i fuging at 2,500 rpm and f i l t e r i n g the supernatant s o l u t i o n . Centrifugation was repeated u n t i l the supernatant so lut ion remained c lear . The extract was made up to a volume of 250 ml and an a l iquot was analyzed by the Perkin Elmer 306 atomic absorption spectrophotometer for manganese, i r o n , aluminum and s i l i c o n . A s o i l :extractantt .ratio of2IC-:2'0swas"'maintaitied for each ex t rac t ion . Results were recorded, based on oven-dried s o i l weights. Treatment of the s o i l p r i o r to the general procedure involved: A. I n - s i t u extract ion Tared 100 ml of 0.1 M hydroxylamine hydrochloride solut ion in 250 ml centrifuge bott les were taken to the f i e l d . Approximately 10 gm of s o i l was sampled from the s i t e , with minimum exposure to the atmosphere. This was done using a s o i l corer. Five sets of sample were taken from each horizon. A duration of f i v e hours was allowed before carrying out the general procedure, so that the i n - s i t u extract ion was uniform for a l l the s i t e s . The exact weight of the s o i l s used was calculated by di f ference . 100 B. Oven-drying at 50°C for one week This treatment was carr ied out on glass plates . Samples taken for the general procedure were not i n contact with the glass plate to avoid s i l i c o n contamination. To ensure uniform heating of the samples, a th in layer of s o i l was used. Large aggregates of s o i l were broken up with a wooden r o l l e r . C. Oven-drying at 100°C for one week Procedure B was used but at the higher temperature. D. A i r - d r y i n g for one week A i r - d r y i n g was done on brown paper. Large aggregates of s o i l were crushed with a wooden r o l l e r . E. Storing moist in p l a s t i c containers for three months S o i l s in the f i e l d moist condition were used for th is purpose. The p l a s t i c bags were sealed to reduce aerat ion , and loss of moisture from the s o i l . F. A i r - d r y i n g for four months Pretreatment D was carr ied out except for a longer durat ion. G. Frozen for one month F i e l d moist samples were frozen i n the freezer . The samples were thawed af ter one month and analyzed. S t a t i s t i c a l analysis S i g n i f i c a n t test for the interact ion between treatments and horct-zons were carr ied out using computer. The program used was BMDI0V-General Linear hypothesis (No. 2) developed at the Health Sciences 101 Computing F a c i l i t y , Universi ty of C a l i f o r n i a , Los Angeles (1973). This program can be obtained from the Universi ty of B r i t i s h Columbia Computing Centre's L ibrary . FLSD values were then calculated for the d i f f e r e n t elements. The FLSD procedure for detecting the s i g n i f i c a n t differences between means was recommended by Carmer, S. G. et al_. (1971) The means and FLSD value for each element were tabulated in the Appendix. 102 RESULTS AND DISCUSSION Tsawwassen series The manganese resul ts for the d i f f e r e n t pretreatments varied much more i n the Ah horizon than in the C horizon (Figure 4 .1 ) . For the Ah horizon samples^, a i r - d r i e d for one week showed the lowest value and those stored moist in p l a s t i c containers gave the highest extract -able manganese. Storing in p l a s t i c containers may have reduced the higher oxides of manganese and made them more eas i ly - reduc ib le by hydroxyl-amine hydrochloride. Samples frozen for one month and the i n - s i t u ex-tract ions also gave r e l a t i v e l y high values. This observation was con-s i s ten t with the C horizon. The higher resul ts for the i n - s i t u extrac-t ion was due to a reduced p o s s i b i l i t y for the manganese compounds to undergo further oxidation upon a i r - d r y i n g . Freezing the s o i l may have helped to break the s o i l aggregates, causing greater exposure of the s o i l p a r t i c l e s to reduction. The other treatments did not d i f f e r s i g n i -f i c a n t l y in the i r r e s u l t s . Higher resul ts for i n - s i t u extractions than the a i r - d r y i n g sampling preparation should caution workers on the use of conventional sampling procedures for measuring the plant a v a i l a b i l i t y indices . The trend showed by Tsawwassen Ah and C horizons for i ron was the same as manganese (Figure 4 .2) . Samples stored moist in p l a s t i c containers showed the highest r e s u l t s , followed by i n - s i t u extract ion and those frozen for one month. A i r - d r y i n g for one week gave higher resul ts than a i r - d r y i n g for four months, and oven-drying at 50°C. A i r -drying for four months may have oxidized more iron into the "aged" 6 0 45^ 3 0 CONC. PPM B Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. 00venddrii:e'dr-l(l!00oC for 1 week D. Ai r -dr ied - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen for 1 month Ah Figure 4 . 1 . Tsawwassen - Concentration of hydroxylamine hydrochloride manganese extracted in re la t ion to the d i f ferent pretreatments. o co Sample Treatment 400n 300-A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen for 1 month ZOOA CONC] PPM 100-j B D Ah " • A B C D .*:.• UJ .. Figure 4 .2 . Tsawwassen - Concentration of hydroxylamine hydrochloride iron extracted i n re la t ion to the d i f fe rent pretreatments. 105 oxides. Oven-drying at 50°C may have dehydrated the s o i l aggregates, making i t more d i f f i c u l t for the dispersion by hydroxylamine hydro-ch lor ide . Oven-drying at 100°C may have decomposed some of the organic portions and released more i r o n . Storing samples moist in p l a s t i c containers did not give the highest r e s u l t for Tsawwassen aluminum values (Figure 4 .3) . Instead, the highest values were given by oven-drying at 100°C for the Ah horizon and frozen for one months for the C horizon. Oven-drying at 100°C may have released more aluminum from the organic matter of the Ah horizon. In the case oftithe C horizon, dispersion of the s o i l by freezing had a greater impact on the aluminum complexed by hydroxylamine hydrochloride. Both the Ah and C horizons showed the highest resul ts for s i l i c o n in samples stored moist in p l a s t i c containers (Figure 4 .4 ) . A i r - d r y i n g for one week was the next highest value for the Ah horizon. There was no s i g n i f i c a n t difference between the resul ts of a i r - d r y i n g for four months and i n - s i t u ex t rac t ion . Frozen samples showed non-detectable amounts of s i l i c o n in the Ah horizon, but a r e l a t i v e l y high concen-t ra t ion i n the C horizon. The i n - s i t u extract ion procedure gave higher resul ts than any of the a i r - d r y i n g procedures for Tsawwassen iron and manganese (Figures 4.1 and 4 .2 ) . A i r - d r y i n g values were close to that of i n - s i t u extrac-t ion for a l l s i l i c o n resul ts and Ah horizon aluminum. There was a . v tn),wii"demt dif ference between a i r - d r y i n g treatments and i n - s i t u extrac-t ion for C horizon aluminum (Figure 4 .3) . Oven-drying at 100°C released more manganese, i r o n , aluminum and s i l i c o n than oven-drying at 50°C 8 0 -Sample Treatment 6 0 -,A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r -d r ied - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r -d r ied - 4 months G. Frozen for 1 month 40-CONC. PPM 2 0 4 Ah o CT> Figure 4.3. Tsawwassen - Concentration of hydroxylamine hydrochloride aluminum extracted in re lat ion to the d i f ferent pretreatments. 65 45 CONC. PPM 25-1 D B 0 Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen for 1 month Ah Figure 4 .4 . Tsawwassen - Concentration of hydroxylamine hydrochloride s i l i c o n extracted i n re la t ion to the d i f ferent pretreatments. o 108 (Figures 4 . 1 , 4 .2 , 4 . 3 , and 4 .4 ) . Freezing the sample gave higher resul ts than any of the a i r - d r y i n g procedures for manganese, aluminum and iron (Figures 4 . 1 , 4 .2 , and 4 .3) . Grevell series Oven-drying at higher temperatures did not lead to the extrac-t ion of a higher concentration of manganese (Figure 4 .5 ) . These resul ts contradict the observations for Tsawwassen and Sunshine samples (Figures 4.1 and 4.17). The texture of the s o i l could not be the reason for these observations, since Tsawwassen has a s i m i l a r texture as G r e v e l l . Probably the form of manganese present i s d i f f e r e n t as Grevell i s a much more recent s o i l than Tsawwassen or Sunshine. I n - s i t u extract ion results were lowest for the C horizon but highest in IIC horizon (Figure 4 .5 ) . Samples stored moist in p l a s t i c containers showed r e l a t i v e l y high values for both C and IIC horizons, but gave the lowest value for the Ah horizon. The moist steady con-d i t i o n in the p l a s t i c containers was expected to create a reducing condition and therefore the release of greater amounts of manganese, but th is was not found to be the case for the Ah horizon. The manganese present in the Ah horizon may have been t i e d up with organic complexes, while the manganese in the C and IIC horizons was in the form of higher oxides. A i r - d r y i n g for four months gave lower resul ts than a i r - d r y i n g for one week for the C and IIC horizons (Figure 4 .5 ) . The reverse was true for Ah horizon. Decomposition of organic matter with time leads 260 -1 195-Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C f o r 1 week C. Oven-dried - 100°C f o r 1 week D. A i r - d r i e d - 1 week E. Stored: in p l a s t i c containers f o r 3 months F. A i r - d r i e d - 4 months' G. Frozen f o r 1-month 130-CONC. PPM 65-Ah H C Figure 4.5. G r e v e l l concentration of hydroxylamine hydrochloride manganese ex t r a c t e d i n r e l a t i o n to the d i f f e r e n t pretreatments. o no to a greater release of manganese in the Ah horizon. In the lower horizons most of the manganese was in the form of oxides. A longer duration of a i r - d r y i n g would only lead to oxidation into the higher oxidation s tate . The e f fec t of freezing was not s i g n i f i c a n t in the C and IIC horizons, but was so in the Ah horizon. This may have been due to the differences in texture. The Ah horizon was f ine- textured and had micro-aggregates. Freezing may have broken these micro-aggregates. The C and IIC horizons were mainly sand-size p a r t i c l e s . Oven-drying at 50°C gave higher resul ts than oven=drying at 100°C for iron in the Ah and C horizons (Figure 4 .6) . This trend was s i m i l a r to manganese r e s u l t s . The IIC horizon showed otherwise. The longer the a i r - d r y i n g process, the lower the amount of iron extracted from a l l horizons. Freezing the s o i l d i d not a f fec t the resul ts s i g n i -f i c a n t l y for Ah and C horizons but i t did for the IIC horizon. However, the manganese resu l t for the freezing treatment was among the highest in the Ah horizon. I n - s i t u extract ion gave the highest concentration for C horizon and r e l a t i v e l y high values for Ah horizon, but was the lowest for IIC horizon. There did not seem to be any trend between treatments for the d i f f e r e n t horizons. The heterogeneity of the s o i l and the various forms of iron complexes responded d i f f e r e n t l y to the d i f f e r e n t treatments. The resul ts obtained are related to the concen-t r a t i o n of the various forms in the s o i l . Ah horizon had a very low amount of aluminum (Figure 4 .7 ) . No s i g n i f i c a n t difference in resul ts was observed for the d i f f e r e n t t reat -ments. As in i r o n , i n - s i t u extract ion gave the highest value for the C 2 3 0 Sample Treatment A 0 ' I M - - K I . - I M . . - K Ah A. B. C. D. Extracted i n - s i t u Oven-dried - 50°C for 1 week Oven-dried - 100°C for 1 week A i r - d r i e d E. F. G. E C - 1 week Stored in p l a s t i c containers for 3 months A i r - d r i e d - 4 months Frozen for' 1 month Figure 4 .6 . Grevell - Concentration of hydroxylamine hydrochloride iron extracted in re la t ion to the d i f fe rent pretreatments. 112 horizon. I n - s i t u extract ion resul ts for IIC horizon were comparatively very low. Oven-drying at 100°C leads to a decrease in the amount of aluminum extracted compared to oven-drying at 50°C. The resul ts ob-tained for manganese, iron and aluminum with regard to oven-drying at high temperatures were completely reversed from that shown by Tsawwassen samples. Greater length of a i r - d r y i n g also lead to the lower recovery of aluminum. The same trend was observed for i r o n . The aluminum may have combined with the higher oxides of i r o n , thus reducing i t s extract -a b i l i t y . Storing samples moist i n p l a s t i c containers gave r e l a t i v e l y high extractable amounts of aluminum in the C and IIC horizons. This observation was the same as i r o n . Freezing the s o i l a f fec ts the IIC horizon p o s i t i v e l y in comparison with the i n - s i t u ex t rac t ion . However, i n - s i t u extract ion resul ts were higher than the freezing treatment in the C horizon (Figure 4 .7 ) . The i n - s i tu extract ion r e s u l t for s i l i c o n was the lowest for Ah and IIC horizons but highest for the C horizon (Figure 4 .8) . Oven-drying at 100°C released greater amounts of s i l i c o n than oven-drying at 50°C. This resu l t was contradictory to that observed for manganese and aluminum. One of the factors that could contribute to th is i s pH. S i l i c o n i s more soluble at a lka l ine pH. Aluminum and manganese are more eas i ly extracted at low pH. The s o l u b i l i t y of s i l i c a increases s ign i f i cant ly .above pH 7.0. A i r - d r y i n g for a longer period again de-creased the extractable amount of s i l i c o n . Freezing the s o i l increased the resul ts s i g n i f i c a n t l y for the M>G hbriizonzbut not the Ah>-and:-.C'-horizons. Storing in p l a s t i c containers did not give a high value for the Ah Sample Treatment no-80-50-CONCl PPM 20-fATBr-r-WFl A BUD E t b . A. E x t r a c t e d i n - s i t u B. O v e n - d r i e d - 50°C f o r 1 week C. O v e n - d r i e d - 100°C f o r 1 week D. A i r - d r i e d - 1 week E. S t o r e d i n p l a s t i c c o n t a i n e r s f o r 3 months F. A i r - d r i e d - 4 months G. Frozen f o r 1 month Ah I C F i g u r e 4.7. Grevel'l - C o n c e n t r a t i o n o f h y d r o x y l a m i n e h y d r o c h l o r i d e aluminum e x t r a c t e d i n r e l a t i o n t o the d i f f e r e n t p r e t r e a t m e n t s . JSOT 120-Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for *1 week D. A i r -dr ied - T week E. Stored in ; p l a s t i c containers for 3 months F. A i r -d r ied - 4 months G. Frozen for 1 month 8 0 -CONC. PPM 40-0 £ Ah 2EC Figure 4.8. Grevell T Concentration of hydroxylamine hydrochloride s i l i c on in re la t ion to the d i f ferent pretreatments. 115 horizon but the resul t was close to that of a i r - d r y i n g for four months in the C and IIC horizons (Figure 4 .8 ) . Blundell series A greater amount of manganese was extracted when the samples were oven-dried at 100°C compared to at 50°C (Figure 4 .9) . The Blundell s o i l i s f ine - tex tured , having a r e l a t i v e l y high organic matter content. Heating at high temperature may have released more manganese from the organic matter. Dehydration of the samples would also have des tab i l ized the hydrated manganese [(MnO)Y(Mn02) (H 20) ] releasing Mn02 and MnO. x y z Freezing the sample gave the highest resul ts for the Ap and Cg horizons (Figure 4 .9) . There was no s i g n i f i c a n t difference between treatments for the Bg horizon. I n - s i t u extract ion results were higher than the a i r - d r y i n g procedure. When the samples were extracted i n - s i t u , i t was s t i l l moist and e a s i l y dispersed by the extractant . Drying the s o i l increased the cohesion between s o i l p a r t i c l e s . Storing the samples moist i n p l a s t i c containers released greater amounts of man-ganese. The reducing environment may have released more e a s i l y -reducible manganese from the nodules which are prominent in these samples. Freezing and s tor ing moist i n p l a s t i c containers lead to greater release of iron i n a l l horizons (Figure 4.10) . This trend was s i m i l a r to that shown by manganese and iron in Tsawwassen samples. Drying the s o i l at two d i f fe rent temperatures did not show s i g n i f i c a n t changes. Manganese, on the other hand, showed an increase when heated to 100°C. Sample Treatment 111 A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. Ai r -dr ied - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r - d r t e d - 4 months 6. Frozen for 1 month CONC. PPM 3 4 Ap B Bg B eg Figure 4 .9 . Blunde.ll - Concentration of hydroxylamine hydrochloride manganese extracted in re la t ion to the d i f ferent pretreatments. Sample Treatment 1200, 90CW 600-C O N C . PPM 300-A p Bg A. B. C. D. E. F. G. Cg Extracted i n - s i tu Oven-dried - 50°C for 1 week Oven-dried - 100°C for 1 week A i r -d r ied - 1 week Stored in p l a s t i c containers for 3 months A i r -d r ied - 4 months Frozen for 1 month • Figure 4.TO. Blundell - Concentration of hydroxylamine hydrochloride iron extracted in re lat ion to the d i f ferent pretreatments. 118 Prolonged a i r - d r y i n g again decreased the i ron extracted (Figure 4.10) and this i s indicated by the low resul ts in re la t ion to i n - s i t u extrac-t ion r e s u l t s . Increase in pH and oxidation to higher oxides may account for th i s observation. Storing moist in p l a s t i c containers again gave s i g n i f i c a n t l y higher resul t s than mo.stco'f the other treatments for aluminum (Figure 4.11). Reduction of manganese and iron may also lead to release of aluminum from the complex. Increased duration of a i r - d r y i n g showed a greater release of aluminum. This r e s u l t was s i m i l a r to manganese (Figure 4.9) but opposite to that of i ron (Figure 4.10). One possible e f fec t of a i r - d r y i n g may have been the decomposition of organic matter and the subsequent release of aluminum and manganese. Iron i s much more strongly coordinated with organic compounds than e i ther manganese or aluminum. Drying at a higher temperature also released greater amounts of aluminum. I n - s i t u extractions gave higher results than any of the a i r - d r y i n g procedures for the Ap horizon and also higher resul ts than a i r - d r y i n g for one week, for Bg and Cg horizons. The highest amount of s i l i c o n was extracted when the samples were stored moist in p l a s t i c containers (Figure 4.12). This was followed by the freezing treatment. There was no s i g n i f i c a n t difference between the a i r - d r y i n g treatments for Ap and Bg horizons, however, longer duration of a i r - d r y i n g reduced the amount extracted for Cg horizon. This obser-vation coincided with that of i r o n . The formation of f e r r o - s i l i c a t e compounds upon prolonged a i r - d r y i n g could be a p o s s i b i l i t y . No changes Sample Treatment 6OO1 A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week; E. Stored in p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen'for 1 month 400-! CONC.j PPM ;.200« Ap Bfl Cg Figure 4.11. B lunde l l ' - Concentration of hydroxylamine hydrochloride aluminum extracted in re la t ion to the different"pretreatments. Sample Treatment 2 0 0 -150-4 A. B. D. E. F. G. Extracted i n - s i t u Oven-dried - 50°C for 1 . week Oven-dried - 100°C for 1 week A i r - d r i e d - 1 week Stored in p l a s t i c con-tainers for 3 months A i r - d r i e d - 4 months Frozen for 1 month ; loo-i C O N C . PPM 50 - j B Ap B :|p Bg B eg Figure 4.12. Blundel l - Concentration of hydroxylamine hydrochloride s i l i c o n extracted in re la t ion to the d i f fe rent pretreatments. 121 were observed between the two oven-drying treatments for Ap and Cg horizons (Figure 4.12). Heating at higher temperature released greater amounts of s i l i c o n i n the Bg horizon only. I n - s i t u extract ion gave higher resul ts than any of the a i r drying treatments. Cloverdale series Oven-drying at 100°C compared to oven-drying at 50°C released greater amounts of manganese in the Ahl and Ah2 horizons and lower amounts of manganese in the mineral horizons (Figure 4.13). The high temperature may have decomposed the organic matter, resu l t ing in greater extractable manganese in the Ah horizon. A longer duration of a i r -drying released greater amounts of manganese in the Ahl and Ah2 horizons. The reverse was true for Bf , C g l , and Cg2 horizons. The e f fec t of freezing the s o i l on extractable manganese values decreased with depth. Storing moist i n p l a s t i c containers gave r e l a t i v e l y high resul ts for the subsurface horizons. No d e f i n i t e trend was observed between i n - s i t u extract ion and any of the a i r - d r y i n g treatments. In some cases i n - s i t u extract ion results were lower than a i r - d r y i n g r e s u l t s , in others i t was higher. The results obtained for the various treatments showed a dif ference in effects on the d i f f e r e n t forms of manganese present in the s o i l . Two d i s t i n c t forms of manganese can be seen from th is obser-vat ion , the organically-complexed form and the oxides form. The e f fec t of oven-drying at 100°C for i ron was more prominent than any of the other treatments in A h l , Ah2, Cgl and Cg2 horizons. (Figure 4.14). No s i g n i f i c a n t difference was observed between these 480-3 6 0 Sample Treatment A. Extracted i n - s i tu B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen for 1 month 240-C O N C . PPM I 2 04 B 8 D B B Ah | A h 2 Bf Cg2 Figure 4.13. Cloverdale - Concentration of hydroxylamine hydrochloride manganese extracted, i n re la t ion to the d i f fe rent pretreatments. ro ro 5 2 0 T 39CH Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen for 1 month 2 6 0 CONC. PPM 130 B D B S 0 Ci 0 Ah| Ah. Bf Cg, C g 2 Figure 4.14. Cloverdale - 'Concentration of hydroxylamine hydrochloride iron extracted in re la t ion to the di f ferent pretreatments. ro CO 124 treatments for B l u n d e l l ' s i r o n . The Cloverdale samples had many root remnants and tubular nodules. The extra manganese released upon heating at higher temperature may have been derived from th is form. Again longer duration of a i r - d r y i n g released greater concentrations or i ron in A h l , Ah2, C g l , and Cg2 horizons but not in the Bf horizon. The e f fec t of freezing the s o i l was more s i g n i f i c a n t in the upper horizons. I n - s i t u extract ion resul ts were r e l a t i v e l y higher than a i r - d r i e d for one week treatment for A h l , Ah2 and Cg2 horizons, but not sor in Bf and Cgl horizons. This observation indicates some common properties of i ron in the surface horizons and the parent mater ia l . Iron in the middle of the s o i l p r o f i l e reacts d i f f e r e n t l y to the d i f f e r e n t treatments. I t i s in more of a t r a n s i t i o n state in th is horizon. Oven-drying at 100°C released lower amounts of aluminum than oven-drying at 50°C for most horizons (Figure 4 .15) , however, the e f fec t was i n s i g n i f i c a n t for Cgl and Cg2 horizons. The same trend was observed for Grevell samples. Freezing gave a more favorable e f fec t for aluminum in the surface horizon. Prolonged a i r - d r y i n g released lower amounts of aluminum. Storing in p l a s t i c containers did give high values for the subsurface horizons, but hot foraAn'Tehorizgn. ~? lTiT . s i i tutextrac t ion was lowest for Bf and Cgl horizon but was r e l a t i v e l y high for the other horizons. Greater amounts of s i l i c o n were extracted when the samples were oven-dried at 100°C compared to 50°C for a l l C16ver,dal,eahoriizons. horizons (Figure 4.16). This gesuHfiiistcontradiietory.ntohthat-.observed (for^al.uminumb'ias; shown inFig.jii3es4i 15(Figi. ,• lyHSi tu extgactioRL. -520-390-260-CONC. PPM 120-Ah, |H| 1AjB C[DjE|F|G A h 2 B C|D; Bf FigureSampfte Treatment A. B. C. D. E. F. G. J3 B Extracted i n - s i t u Oven-dried - 50°C for 1 week Oven-dried - 100°C for 1 week A i r - d r i e d - 1 week Stored in p l a s t i c containers for 3 months A i r - d r i e d - 4 months Frozen for 1 month D Cgi BfC F G Cg2 Figure 4.15. Cloverdale - Concentration of hydroxylami ne hydrochloride alumi num extracted i n . re la t ion to the d i f ferent pretreatments. Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week • C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week E. Stored i n p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen for 1 month 3004 2004 CONC. PPM 100-D B D E .A B 6 B « B * • • E F G D E F G A h j Figure 4.16. A h . Bf Cg, Cg 2 Cloverdale - Concentration of hydroxylamine hydrochloride s i l i c o n extracted in re la t ion to the d i f ferent pretreatments. 127 results were r e l a t i v e l y low • for Ahl and Ah2 horizons (Figure 4.16). The e f f e c t of s tor ing i n p l a s t i c containers was more s i g n i f i c a n t i n the upper horizons. Longer a i r - d r y i n g released a lower concentration of s i l i c o n in B.ifi],Cgili;'j,anddCg22horizons, but higher amounts i n Ahl and A'h2 horizons. The e f fec t of freezing the s o i l was even greater in the lower horizons, however, th i s does not coincide with the results of aluminum (Figure 4.15). Sunshine series The differences in results due to the d i f f e r e n t treatments were more s i g n i f i c a n t for the surface horizons (Figure 4.17). This co in-cided with the higher organic matter content, and the r e l a t i v e l y recent and unstable nature of the various compounds in the upper horizon. Freezing samples for one month gave the highest manganese resul ts for the Ah and Bf horizons. A i r - d r y i n g for four months showed the lowest resul ts for these horizons. In-s i tu extract ion was r e l a t i v e l y high for the Ah horizon, but was close to the resul ts of the other treatments for B f l , Bf2 and BC horizons. Oven-drying at 100°C released greater concentration of manganese than oven-drying at 50°C. S imi lar obser-vations were obtained in the Tsawwassen ser ies . The higher temperature not only released nutrients t i ed up in the organic matter, but also weakened the s o i l aggregates. The difference in resul ts for the two treatments was often greater for the Ah horizon. This i n d i r e c t l y re-f l e c t s the greater e f fec t of temperature on the e x t r a c t a b i l i t y of nut-r ients for s o i l s high in organic matter content. A. B. C. D. E. Sample Treatment Extracted i n - s i t u Oven-dried - 50°C for 1 week Oven-dried - 100°C for 1 week A i r - d r i e d - 1 week Stored in p l a s t i c containers for 3 months A i r - d r i e d - 4 months Frozen for 1 month Figure 4.17. Sunshine - Concentration of hydroxylamine hydrochloride manganese extracted in re la t ion to the d i f ferent pretreatments. 129 A i r - d r y i n g for one week was among the lowest results for a l l horizons. I t was quite close to the resul ts for oven-drying at 50°C in Ah and Bf horizons. The e f fec t of both treatments might be the same for both horizons. There was no s i g n i f i c a n t difference in resul ts for the d i f f e r e n t treatments in the BC horizon. Oven-drying at 100°C gave the highest resul t for i ron i n the Ah horizon (Figure 4.18). This was followed by a i r - d r y i n g for one week and oven-drying at 50°C. There was no s i g n i f i c a n t difference i n resul ts between the i n - s i t u extract ion and the other treatments. Oven-drying at 100°C again gave the highest resul ts for the B f l , Bf2 and C horizon. Considering the lower amount of organic matter i n these h o r i -zons, the higher value could be due to increased dispersion of the s o i l aggregates or increased rate of weathering of the s o i l at high tem-peratures. In-s i tu extract ion resul ts were quite s i m i l a r to the resul ts of a i r - d r y i n g for four months, but lower than a i r - d r y i n g for one week. The aluminum resul ts for d i f f e r e n t treatments varied throughout the horizons (Figure 4.19) . Again, drying at 100°C gave higher values than oven-drying at 50°C for a l l horizons. I n - s i t u extract ion resul ts were lower than any of the a i r - d r y i n g resul ts for Ah horizon. This trend was the same as for iron (Figure 4.18). A i r - d r y i n g for four months released greater amounts of aluminum than a i r - d r y i n g for one week in the B f l , Bf2 and BC horizons. Conversely, the e f fec t was the opposite in the Ah horizon. Storing moist in p l a s t i c containers and freezing the s o i l gave the highest values for the B f l , Bf2 and BC horizons. This observation 6 0 0 -4 0 C H CONC. PPM 2 0 0 -AlBlCjpjElFlG A h A|B|C|DlE|F|G Bf, Sample treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r - d r i e d - 4 months G. Frozen for 1 month * # •. t— • • 1 * rr. •V A B C 0 E F G B f 2 A|B[CJD|E|F|G BC Figure 4.18. Sunshine - Concentration of hydroxylamine hydrochloride ir.on extracted in r e l a t i o n to the d i f fe rent pretreatments. 1300-9 7 5 -Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r -dr ied - 1 week E. Stored in p l a s t i c containers for 3 months F. A i r -dr ied - 4 months G. Frozen for 1 month 6 5 0 -CONC.J PPM 3 2 5 H Ah Bf. BC Figure 4.19. Sunshine - Concentration of hydroxylamine hydrochloride aluminum extracted in re lat ion to "the d i f fe rent pretreatments. 132 was s i m i l a r to that of Tsawwassen aluminum. There was no s i g n i f i c a n t difference between the other treatments for the BC horizon. Oven-drying at 100°C contributed the highest resul t for s i l i c o n in the Ah horizon (Figure 4.20). This was followed by s tor ing moist in p l a s t i c containers. I n - s i t u and a i r - d r y i n g for four months showed the lowest values. There was no s i g n i f i c a n t difference between the other three treatments. I n - s i t u extractionsvadues were: -s ignif icant ly il',pwe[rfthandthe Qtheropretreatment values i n B f l and BC horizons. On the other hand, a i r - d r i e d for one week results were s i g n i f i c a n t l y d i f -ferent from the other pretreatments in Bf2 horizon. Further study i s necessary before a more d e f i n i t e conclusion can be attached to these observations 9 0 l ^ 60-C0NC-PPM 3 0-1 F. G. Stored in p l a s t i c containers f o r 3 months A i r - d r i e d - 4 months Frozen for 1 month Sample Treatment A. Extracted i n - s i t u B. Oven-dried - 50°C for 1 week C. Oven-dried - 100°C for 1 week D. A i r - d r i e d - 1 week B B B D B Ah Bf, ec Figure 4.20. Sunshine - Concentration of hydroxylamine hydrochloride s i l i c o n extracted i n re la t ion to the di f ferent pretreatments. to CO 134 CONCLUSION No d e f i n i t e trend could be observed with the e f fec t of the various treatments on the e x t r a c t a b i l i t y of manganese from the s o i l s . In general , increasing the oven temperature from 50°C to 100°C often lead to greater release of manganese. This e f fec t was shown more s i g -n i f i c a n t l y in the surface horizons, where the organic matter content was high. However, in Grevell series and certain subsurface horizons, the reverse trend was observed. Further studies are necessary to explain these observations. Freezing the samples produced higher re-sul ts than any of the a i r - d r y i n g procedures in most surface horizons. The concentration extracted from samples which were frozen was also higher than oven-drying treatments except for Grevell-Ah horizon. The trend showed by i n - s i t u extract ion resul ts vary in d i f f e r e n t s o i l series and d i f f e r e n t horizons. I t t d i d not coincide with any of the a i r drying procedures. Storing the samples moist in p l a s t i c containers generally brought out r e l a t i v e l y high concentrations of manganese. Iron resul ts indicated that i n - s i t u extractions showed higher values than a i r - d r y i n g - 4 month values for B l u n d e l l , Tsawwassen and Grevell samples and no observable difference in Sunshine and Clover-dale samples. Longer a i r - d r y i n g duration decreased the amount of iron extracted in B l u n d e l l , G r e v e l l , Sunshine and Tsawwassen s e r i e s ; however, there was an increase in concentration with time for Cloverdale samples except for the Bf hor izon. These resul ts are contrary to that observed for aluminum and s i l i c o n . Oven-drying at 100°C released more iron 135 than oven-drying at 50°C for Sunshine, Cloverdale, Tsawwassen samples and for Grevell IIC horizon. However, Grevell Ah and C horizons showed a decrease i n extractable iron with higher temperature dry ing . Blun-d e l l samples did not show any d i s t i n c t differences for the two oven-drying treatments. Storing moist in p l a s t i c containers lead to release of greater amounts of iron in Blundell Bg and Cg, and Tsawwasseri-Ah*w<«/asse" -. horizons. Only s l i g h t differences were observed between s tor ing moist in p l a s t i c container resul ts and a i r - d r y i n g results for Sunshine and Cloverdale samples. Freezing was found to a f fec t the s o i l samples s i g n i f i c a n t l y except for Sunshine ser ies . The response of aluminum and s i l i c o n to the d i f f e r e n t pretreat-ments was very s i m i l a r . Generally freezing and stor ing moist in p l a s t i c containers contributed very high r e s u l t s . Oven-drying at 100°C re-leased more aluminum and s i l i c o n than oven-drying at 50°C. This was more prominently observed in certain horizons. Again, i n - s i t u extrac-t ion resul ts did not coincide with any of the a i r - d r y i n g values. 11 EoEvSMshiiirieTsewifes'", ^signifieantgdiffeKeriicesfbetweenstheseeer, Lhc:-.-:• treatments were observed in the Ah horizon. The portion of these elements extracted by hydroxylamine hydro-chloride ats derived from both the amorphous organic and inorganic complexes. These forms are very sens i t ive to temperature, ox idat ion-reduction p o t e n t i a l s , moisture regime, and length of time exposed to the treatment. Temperature would af fec t the microbiological a c t i v i t y . Microorganisms are responsible for decomposing organic matter, o x i d i z i n g 136 and reducing of oxides and the weathering of minerals and rocks in the s o i l . Temperature also affects the rate of reactions in the s o i l . Extremely high temperatures decompose the organic matter releasing nutr ient elements. Oxidation-reduction potentials are affected by the moisture regime of the s o i l , aerat ion , length of time exposed to the d i f f e r e n t treatments and the microbiological a c t i v i t y . I t can be seen that these factors are in terac t ing with each other dynamically. The quant i tat ive results that we observed are the penultimate resul ts of these in terac t ions . The interact ions vary with d i f f e r e n t types of s o i l and for d i f f e r e n t horizons since proportions of the substances making up a s o i l vary. Results obtained from this study s i g n i f y the importance of uniform sample treatments p r i o r to s o i l ana lys i s . The extractable con-centration of the d i f f e r e n t elements also varies with seasons. This i s shown by differences between the freezing results and the a i r - d r y i n g and i n - s i t u r e s u l t s . The most appropriate procedure for extract ing s o i l should be the i n - s i t u ex t rac t ion . This procedure reduces the a l tera t ions that could take place with the samples. However, i n - s i t u extract ion has several l i m i t a t i o n s too. I t i s time consuming, and many sets of samples are required to ensure correct sampling. P a r t i c l e -s ize d i s t r i b u t i o n i s also important in determining the r e l i a b i l i t y of i n - s i t u ex t rac t ion . Fine-textured s o i l s containing an uneven d i s t r i -bution of coarse par t i c l es would lower the precis ion of the ana lys i s . LITERATURE CITED Baker, J . 1950. Dis t r ibut ion of manganese i n B r i t i s h Columbia s o i l s . M.Sc. (Agr ic . ) t h e s i s , Dept. of Agronomy ( S o i l s ) , Univers i ty of B r i t i s h Columbia. Boken, E. 1958. Investigations on the determination of the avai lab le manganese content of s o i l s . Plant and S o i l 9: 269-283. Carmer, S. G. and Swanson, M. R. 1971. Detection of differences be-tween means: A Monte Carlo study of f i v e pairwise mult iple com-parison procedures. Agron. J . 63: 940-945. Chi 1ds, F. D. 3and Jencks, E. M. 1967. Ef fect of time and depth of sampling upon s o i l test r e s u l t s . Agr. Journal 59: 537-540. Christensen, P. D . , Toth, S. J . and Bear, F. E. :1<950. The status of s o i l manganese as influenced by moisture, organic matter and pH. S o i l S c i . Amer. Proc. 15: 279-282. C l i n e , M. G. 1944. Pr inc ip les of s o i l sampling. So i l S c i . 58: 275-288. Fujimoto, C. K. and Sherman, G. D. 1945. The e f fec t of dry ing , heating and wetting on the level of exchangeable.manganese in Hawaiian s o i l s . So i l S c i . Soc. Amer. Proc. 10: 107-112. Hammes, J . K. and Berger, K. C. il'960. Chemical extract ion and crop removal of manganese from a i r - d r i e d and moist s o i l s . S o i l S c i . Soc. Amer. Proc. 25: 361-364. Heintze, S. G. and Mann, P . J . G . 1947. Soluble complexes of manganic manganese. J . Agr. S c i . 37: 23-26. Luttmerding, H. R. and Sprout, P. N. 1967. Preliminary report of the Lower Fraser Valley S o i l Survey. B r i t i s h Columbia Dept. of A g r i c . , Kelowna, B.C. Meek, B. D . , Mackenzie, A. J . and Grass, L. B. 1968. Effect of organic matter, f looding time, and temperature on d i sso lut ion of i ron and manganese from s o i l i n s i t u . S o i l S c i . Soc. Amer. Proc. 32: 634-638. N i s h i t a , H. and Haug, R. M. 1971. Some physical and chemical charac-t e r i s t i c s of heated s o i l s . S o i l S c i . 113: 422-430. 137 138 N i s h i t a , H. and Haug, R. M. 1973. Water and ammonium acetate-extractable z i n c , manganese, copper, chromium, cobalt and i ron in heated s o i l s . S o i l S c i . 118: 421-424. P a t r i c k , W. H. and Turner, F. T. 1968. Ef fect of redox potential on manganese transformation in waterlogged s o i l . Nature 220: 476-478. Safo, E. Y. 1970. Manganese status of some Lower Fraser Valley s o i l s developed from a l l u v i a l and marine deposits . M.Sc. (Agr ic . ) t h e s i s , Dept. of S o i l Science, Univers i ty of B r i t i s h Columbia. SUMMARY The to ta l manganese content of the Lower Fraser Valley s o i l s has previously been invest igated. The results obtained d i f f e r e d s i g n i -f i c a n t l y . In this study, the perch lor i c -hydrof luor i c ac id mixture digestion procedure was carr ied out to measure the to ta l manganese, aluminum and iron in the s o i l s s tudied. Total manganese concentration was found to be higher than those reported by Safo (1970), even though the s o i l samples were derived from the same area. Total manganese ranged from 1,365 ppm in the Cloverdale-Ah horizon to 297 ppm in the Blundell -Ap horizon, and the t o t a l i ron content was found to range from 2.6 percent i n the Grevel l -C horizon to 6.2 percent in the Clover-dale-Bg horizon. The tota l aluminum concentration was highest at 8.2 percent in the Cloverdale-Cg horizon and lowest at 4.5 percent in the Monroe-Btj horizon. No d e f i n i t e trend was observed between the resul ts obtained and the parent material of the s o i l . The d i s t r i b u t i o n of iron and manganese in the s o i l pedon was, however, c lose ly re la ted . Other selected chemical properties of the s o i l were also determined to characterize the s o i l s for the subsequent studies . S o i l manganese was extracted according to i t s oxidation states and i t s r e d u c i b i l i t y from the higher oxidation s tate . This was f e l t rather unnatural since manganese in the s o i l i s mostly present as mineral c rys ta ls or as amorphous organic and inorganic complexes, 139 140 frequently i n combination with i r o n , aluminum and s i l i c o n . An evalu-ation was therefore f e l t to be necessary for the extract ion of man-ganese w i t h : 1. Acid ammonium oxalate , 2. Sodium pyrophosphate, 3. DisodiumEDTA, 4. Hydroxylamine hydrochloride, and 5. Hydroquinone. The trends showed by hydroxylamine hydrochloride, ac id ammo-nium oxalate , disodiumEDTA and hydroquinone were generally the same in the s o i l pedons s tudied. Only the r e l a t i v e concentrations were d i f f e r e n t . Hydroquinone was only e f fec t ive for extract ing manganese, while disodiumEDTA, acid ammonium oxalate , sodium pyrophosphate and hydroxylamine hydrochloride extracted detectable amounts of i ron and aluminum a lso . Only ac id ammonium oxalate and hydroxylamine hydro-chlor ide were found to extract s i l i c o n . The former extract ing a higher concentration than the l a t t e r . Sodium pyrophosphate resul ts were not consistent with the other extractants . Further studies are necessary to explain this phenomena. No re la t ionship was observed between sodium pyrophosphate and disodiumEDTA extrac t ions , even though both have chelat ing propert ies . The difference i n pH, i . e . disodiumEDTA being 4.5 and sodium pyrophosphate 10.0, may account for th is observation. DisodiumEDTA and hydroxylamine hydrochloride results were very s i m i l a r in most cases. There i s a p o s s i b i l i t y that the form of man-ganese, iron and aluminum extracted by both reagents i s the same. 141 Hydroxylamine hydrochloride extracted higher amounts of manganese than hydroquinone. This i s the resu l t of the fact that the former has stronger reducing c a p a b i l i t y . Successive extract ion analysis using hydroxylamine hydrochloride followed by one of the other extractants , then hydroxylamine hydro-chloride again, was undertaken to invest igate the o r i g i n of reducible forms of manganese and the other elements extracted by hydroxylamine hydrochloride. This study also investigated the r e l i a b i l i t y of suc-cessive extract ion procedures. Results indicated that the e a s i l y -reducible portion of manganese and iron are derived from the organi-c a l l y and inorganica l ly complexed forms. Since the oxidation reduction potentials of these complexed metal ions are a l tered as a resul t of the complexation, the extent of reduction by hydroxylamine hydrochloride varies with the type of compounds in ifche s o i l . The properties of the preceding extractants are important i n a f fec t ing the concentration of manganese, i r o n , aluminum and s i l i c o n extracted by hydroxylamine hydrochloride in the successive extract ion studies . Only very small amounts of manganese were extracted by hydroxyl-amine hydrochloride a f ter the samples had been extracted by hydroxyl-amine hydrochloride and any of the other extractants successively. Generally, more i r o n , aluminum and s i l i c o n were extracted by hydroxyl-amine hydrochloride a f ter e i ther acid ammonium oxalate or disodiumEDTA extractions than hydroxylamine hydrochloride p r i o r to these extractants . The differences were more s i g n i f i c a n t in f ine- textured s o i l s . More aluminum and s i l i c o n were also extracted by hydroxylamine hydrochloride 142 af ter sodium pyrophosphate and hydroxylamine hydrochloride extrac t ions . These resul ts indicate the changes in the s o i l system i n i t i a t e d by the preceding extractant . The r e l i a b i l i t y of successive extract ion pro-cedures f o r quant i ta t ive analysis i s therefore questioned. The effects of sample pretreatments on the e x t r a c t a b i l i t y of manganese, i r o n , aluminum and s i l i c o n by hydroxylamine hydrochloride were also s tudied. The pretreatments were: A. I n - s i t u ex t rac t ion , B. Oven-drying at 50°C for one week, C. Oven-drying at 100°C for one week, D. A i r - d r y i n g for one week, E. Storing moist in p l a s t i c containers for three months, F. A i r - d r y i n g for four months, and G. Freezing the s o i l for one month. S i g n i f i c a n t differences in results were observed between i n -s i t u extractions and the a i r - d r y i n g procedures for some horizons. Oven-drying at 100°C compared to oven-drying at 50°C often lead to greater e x t r a c t a b i l i t y of these elements in most horizons. Generally a longer duration of a i r - d r y i n g resulted i n a smaller concentration of extractable elements. Freezing and s tor ing moist in p l a s t i c containers gave d i s -t i n c t l y higher values for most samples. Hydroxylamine hydrochloride extracts the eas i ly - reduc ib le portion of manganese, i ron and the asso-ciated aluminum and s i l i c o n . The complex chemistry of these elements, and the greater r e a c t i v i t y of th is portion of manganese, i r o n , aluminum and s i l i c o n , made i t impossible to show a d e f i n i t e trend on the ef fects of the d i f f e r e n t pretreatments on the s o i l s s tudied. The resul ts d i d , however, lay the .basic ground work for further s tudies . APPENDIX 1 Concentration of Manganese by Pretreatments for S i g n i f i c a n t Test Using FLSD FLSD = 20.7 (0.05) S o i l A* B* C* D* E* F* G* Blundell Ap 9.5 7.9 8.8 6.7 8.8 8.0 10.8 Bg 2.5 1.7 2.3 1.9 2.7 2.2 2.6 Cg 3.1 2.2 2.5 2.3 4.3 2.5 5.1 Tsawwassen Ah 42.7 37.1 41.2 34.5 51.2 40.7 44.9 C 19.9 14.2 14.5 15.4 17.3 14.4 20.9 Grevel1 Ah 157.0 224.3 182.5 162.7 143.0 191.5 206.0 C 121.1 220.7 160.0 241.9 202.4 162.6 137.9 IIC 153.8 116.6 92.6 137.4 129.9 100.0 108.9 Cloverdale Ahl 291.9 235.7 245.1 195.8 242.4 408.8 349.7 Ah2 249.5 179.2 412.3 250.0 403.3 276.2 471.1 Bf 174.9 366.7 196.7 372.3 220.9 212.2 248.5 Cgl 138.1 129.2 108.6 137.5 168.0 88.5 108.9 Cg2 122.4 204.2 168.4 225.3 182.7 168.2 121.3 Sunshine Ah 69.8 33.9 48.1 34.8 59.2 28.0 71.9 Bf l 53.5 56.6 64.3 54.5 56.2 42.3 66.9 Bf2 20.9 23.8 25.9 17.1 19.4 22.3 20.8 BC 4.0 4.5 5.8 5.4 6.8 4.7 4.8 A - I n - s i t u extract ion B - Oven-dried at 50?C for one week C - Oven-dried at 100°C for one week. D - A i r - d r i e d for one week.. E - Stored moist in p l a s t i c containers for three months F - A i r - d r i e d for four months G - Frozen for one month 143 APPENDIX 2 Concentration of Iron by Pretreatments for S i g n i f i c a n t Test Using FLSD FLSD = 51.0 (0.05) Soiiil A* B* C* D* E* F* G* Blundell Ap 340.1 446.0 454.2 343.7 309.1 231.7 406.5 Bg 547.9 718.0 630.7 675.9 884.8 561.5 903.3 Cg 738.1 1,088.4 1,028.2 752.5 1,480.1 503.0 1,257.4 Tsawwassen Ah 234.5 69.4 98.3 113.6 369.5 62.3 219.1 C 114.9 73.3 94.5 103.0 105.4 61.3 136.4 GrSvell Ah 86.0 101.6 55.2 100.5 80.4 54.4 52.3 C 272.6 130.8 105.2 157.9 129.6 98.1 79.0 IIC 125.2 142.8 199.4 105.7 151.6 131.7 221.5 Cloverdale Ahl 180.6 129.9 254.0 96.7 88.1 244.0 274.4 Ah2 170.5 100.9 428.1 109.2 148.5 171.1 270.8 Bf 132.7 192.9 279.1 186.1 97.6 146.5 192.6 Cgl 125.1 148.3 265.4 120.8 102.9 154.3 117.2 Cg2 110.3 72.5 145.3 79.7 77.5 96.3 103.6 Sunshine Ah 115.2 311.1 574.0 288.8 88.1 93.4 70.1 Bf l 70.8 72.0 113.3 108.7 50.3 57.1 80.9 Bf2 54.4 62.1 102.2 47.5 35.9 63.5 59.4 BC 31.9 59.1 80.5 58.5 26.9 39.6 35.9 A - I n - s i t u extract ion B - Oven-dried at 50°C for one week C - Oven-dried at 100°C for one week D - A i r - d r i e d for one week E - Stored moist in p l a s t i c containers for three months F - A i r - d r i e d for four months G - Frozen for one month 144 Appendix 3 Concentration of Aluminum by Pretreatments for S i g n i f i c a n t Test Using FLSD FLSD = 68.0 (0.05) S o i l A* B* c* D* E* F* G* Blundell Ap 185.3 170. 0 237.3 145. 0 299. 7 161.4 260. 7 Bg 309.6 223. 5 344.4 245. 4 551. 5 370.4 532. 3 eg 132.9 143. 3 157.8 139. 1 528. 8 245.8 324. 9 Tsawwassen Ah 12.3 7. 5 29.6 7. 9 25. 0 7.5 20. 0 C 227.4 24. 4 59.0 39. 2 71. 0 58.2 80. 1 Grevell Ah 3.7 3. 7 3.7 4. ,2 2. 4 3.7 -C 66.2 14. 2 3.0 16. ,7 24. 0 3.5 2. 0 IIC 7.2 102. 9 68.0 95. ,3 76. 6 50.1 56. 5 Cloverdale Ahl 264.0 500. 7 316.4 347. ,5 188. 7 239.8 357. 7 Ah2 319.7 412. 8 396.8 241. ,3 373. 1 218.4 265. 0 B f l 119.8 528. 8 406.9 442. ,6 304. 3 218.9 233. 2 Cgl 24.0 64. 0 65.8 73. .3 61. 2 45.0 48. 0 Cg2 42.6 37. 1 22.9 39. .2 40. 9 18.3 20. 7 Sunshine Ah 245.8 864. 3 1,260.1 430, .3 300. 1 328.1 219. 9 Bf l 427.5 336. 1 446.5 302. .1 559. 6 374.5 638. 9 Bf2 595.7 303. 7 422.8 236. .2 617. 1 407.2 648. 7 BC 354.0 338. 2 367.3 304, .3 590. 1 404.7 546. 1 A - I n - s i t u extract ion B - Oven-dried at 50°C for one week C - Oven-dried at 100°C for one week D - A i r - d r i e d for one week E = Stored moist in p l a s t i c containers for three months F - A i r - d r i e d for four months G - Frozen for one month 145 Appendix 4 Concentration of S i l i c o n by Pretreatments fofoSigmjifican.tnTest Using FLSD FLSD = 17.0 (0.05) Soiiil A* B* c* D* E* F* G* Blundell AP 22 .2 25. 0 25. 7 15 .0 56.5 19. 0 27. ,2 Bg 70 .6 42. 8 86. 7 28 .6 194.4 30. 4 64. ,1 eg 67 .5 79. 1 75. 0 41 .8 139.5 22. 8 104. ,8 Tsawwassen Ah 11 .1 7. 5 8. 3 15 .0 37.0 12. 5 -C 30 .8 24. 9 35. 0 29 .1 61.0 37. 5 34. ,8 Grevell Ah 45 .3 62. 3 77. 2 66 .7 47.6 60. 8 69. ,8 C 156 .6 81. 3 89. 6 112 .4 72.0 70. 1 62. ,3 IIC 54 .8 116. 6 128. 5 137 .4 108.1 104. 5 142. ,6 Cloverdale Ahl .229 .4 162. 3 84. 3 :37 .6 203.2 48. 1 64. .4 Ah2 33<fc .7 :54. il: 100. 1 29 .2 373.1 32. 9 64. .5 Bf - 1 3!l> .5 181. 2 86. 6 62 .7 304.3 37. 8 56. .3 Cgl 68 .% 129. a 141. 4 104 .2 61.1 101. 7 108. .9 Cg2 23;l: .3 156. 5 203. 4 162 .7. 40.9 142. 9 220. .1 Sunshine Ah 17 .0 36. 8 88. 3 44 .1 65.2 18. 7 33. .2 Bf l 29 .4 79. 1 77. 7 58 .3 76.0 55. 8 76. .1 Bf2 L84 .2 83. 3 86. 0 54 .1 92.3 74. 7 84, .6 BC 43 .6 83. 3 75. 0 63 .9 96.1 74. 3 87, .9 A - I n - s i t u extract ion B - Oven-dried at 50°C for one week C - Oven-dried at 100°C for one week D - A i r - d r i e d for one week E - Stored moist in p l a s t i c containers for three months F - A i r - d r i e d for four months G - Frozen for one month 146 

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