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Base saturation studies of some Vancouver Island soils, and a method for estimating lime requirement Webster, Gordon Ritchie 1951

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BASE SATURATION STUDIES OF SOME VANCOUVER ISLAND'SOILS AND A METHOD FOR ESTIMATING LIME REQUIREMENT by GORDON RITCHIE WEBSTER A Thesis Submitted i n P a r t i a l Fulfilment of the Requirements f o r the Degree of Master of Science i n Agriculture i n The Department of Agronomy (Soils) We Accept this thesis as conforming to the standard required f o r candidates f o r the degree of MA3TJ3R.OF SCIENCE IN AGRICULTURE Members of the Department of Agronomy. THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1951. ABSTRACT. Brown* s Method was fount to "be a very satisfactory technique for determining the exchange capacity of s o i l s , T t was simple, rapid and gave comparable results with Shollenberger 1s technique for t h i r t y s o i l s from Vancouver Island. The Purl Method gave comparable results to B r o x i m r e but was too lengthy. Considerable v a r i a t i o n occurred at high percent base saturation levels when determined by Schollenberger, Brown and Purl Methods f o r these s o i l s . I t was concluded, however, that Brown1s Method ae well as being rapid and simple gave sati s f a c t o r y r e s u l t s . As much as twenty percent v a r i a t i o n In percent base saturation was noted f o r s o i l s having the same pH value. The percent base saturation of a s o i l cannot be estimated from i t s pH with a high degree of accuracy. The t o t a l t i t r a t i o n curves produced by adding i n -crements of calcium to hydrogen saturated s o i l s showed that the exchange capacity and base saturation could be determined by t h i s method. I t was also concluded the position and shape of the curves, indicated the buffer capacity of the s o i l . In a greenhouse experiment where' Vir g i n i a n Stocfc was grown as the indicator crop on f i v e l e v e l s of percent base and calcium saturation, the following conclusions were made: (1) That a relationship exists between calcium and base saturation of the s o i l and plant growth. (2) That the f l e x point for the growth saturation curves occurred at 30$ calcium saturation and 60% "base saturation f o r both s o i l types. (3) That response to lime i n the greenhouse coincided., with known response i n the f i e l d . (4) That a relationship exists between base saturation i n the s o i l and calcium content of the plant. (5) That 1200 gm. samples of s o i l were better suited for saturation studies than 300 gm. samples. (6) That below a certain percent base saturation calcium i s not avai l a b l e to plants. (7) That base saturation studies should form a sound basis fo r estimating the lime requirement o f s o i l s . The lime requirement of s i x s o i l types was estimated by three methods: (1) Percent Base Saturation expressed on a Volume Weight Basis. (2) Percent Base Saturation expressed on a weight basis. (3) T i t r a t i o n Curves on a weight basis. I t was concluded that the Percent Base Saturation Method expressed on a volume weight basis gave a g o o d i n -di c a t i o n of the lime requirement f o r the s i x s o i l types studied. The l a t t e r two methods indicated that very large quantities of lime were required for s o i l s with low apparent s p e c i f i c g r a v i t i e s . This may result i n overliming of the surface horizons. Page 1. ACKNOWLEDGMENTS. Grateful acknowledgment i s made to Dr. C.A. Rowles for his in t e r e s t and guidance and to Dr. D.G. L a i r i . f or his kindly advice and suggestions. The author would also l i k e to thank Mr. L.F Farstad f o r the great deal of assistance given during the c o l l e c t i o n and c l a s s i f i c a t i o n of sampl TABLE OF CONTENTS ACKNOWLEDGMENTS 1 INTRODUCTION 2 REVIEW OF LITERATURE Cation Exchange i n So i l s 3 Determination of Exchange Capacity 4 Determination of Exchangeable Hydrogen 9 Determination of Exchangeable Bases 11 The Effect of pH,Calcium Saturation, Base Saturation on Plant Growth 12 Lime Requirement of Soils. 17 EXPERIMENTAL So i l s Studied 22 Methods 24 Comparison of Methods 31 Exchange Capacity 31 Base Saturation 35 Exchangeable Calcium and Calcium Saturation 36 Base Saturation and pH 40 Uptake of Calcium by the S o i l 43 Relationship Between Base and Calcium Saturation and Plant Growth 45 Response of S o i l Types to Lime Application 45 Design of Greenhouse Experiment 47 Effect of Calcium Saturation on Plant Growth 51 Effect of Base Saturation on Plant Growth 54 Relationship Between Base Saturation and Percent Calcium i n the plant 62 Size of pot and Plant Growth 63 Quantity of s o i l on V a r i a b i l i t y Within the Experiment 63 Quantity of S o i l and Y i e l d 67 Lime Requirements 71 Porosity Studies 72 Lime Requirement by Base Saturation 73 Lime Requirement by T i t r a t i o n Curves 76 Summary and Conclusions 79 BIBLIOGRAPHY 83 TABLES. Table 1 Comparison of Exchange Capacity. 32 Table 2 Comparison of PereBBt Base Saturation. 35 Table 3 Comparison of Exchangeable Calcium and Calcium Saturation Methods 37 Table 4 Relationship Between pH and Percent Base Saturation 41 Table 5 Relation Between Percent Calcium Saturation by Shollenberger*s Method and Plant Growth 51 Table 5 Relation Between Percent Calcium Satura-t i o n by Shollenberger 1s Method and Plant Growth f o r Merville Loam 53 Table 7 Correlation Between Percent Base Satura-t i o n by Brown's Method ant Plant Growth 58 Table 8 Relation Between Percent Base Saturation by Brown's Method and Plant Growth 59 Table 9 . Relation of Percent Calcium i n the Plant with Percent Base Saturation of the S o i l 62 Table 10 Yields Expressed on Oven Dry Weight Basle f o r Cadboro Sandy Loam - Large Pots 64 Table 11 Yields Expressed on Oven Dry Weight Basis f o r Cadboro Sandy Loam - Small Pots 64 Table 12 Yields Expressed on Oven Dry Weight Basis for Merville Loam - Large Pots 65 Table 13 Yields Expressed on Oven Dry Weight Basis f o r M e r v i l l e Loam - Small Pots 65 Table 14 Comparison of Y i e l d Means of Large and Small Pots for Cadboro Sandy Loam 68 Table 15 Comparison of Y i e l d Means of Large ant Small Pots f o r Merville Loam 68 Table 16 Porosity and Apparent S p e c i f i c Gravity Determinations 72 Table 17 Dry Weight i n l b s . Expressed on a Volume Weight Basis 73 Table 18 The Lime Requirement by Percent Base Saturation Expressed on a Volume Basis 73 Table 19 Lime Requirement by Percent Base Satura-t i o n Method on a Weight Basis 75 Table 20 Lime Requirement as Determined by T i t r a t i o n Curves Expressed on a Weight Basis 76 FIGURES. Fi g . 1 Comparison of Calcium Saturation Methods 38 F i g . 2 Relationship Between pH and Base Satura-tion 42 F i g . 3 Total T i t r a t i o n Curves 44 F i g . 4 Relationship Between Plant Growth and Calcium Saturation 55 F i g . 5 Plant Growth on Four Levels of Calcium and Base Saturation for Cadboro Sandy Loam 56 Fig . 6 Plant Growth on Four Levels of Calcium and Base Saturation for Merville Loam 57 F i g . 7 Relationship Between Plant Growth and Base Saturation 61 F i g . 8 Core Samples of S o i l Indicating Size of Cores, Structure of S o i l and Shrinkage from Oven Drying 74 F i g . 9 T i t r a t i o n Curves 77 Page 2. INTRODUCTION. Base saturation l a a measure of the extent to which the exchange capacity of a s o i l i s occuppied "by basic cations. It has proved to be a very useful measure. In p a r t i c u l a r , It has been found to be rel a t e d to such things as, the a v a i l a b i l i t y of chemical elements, plant growth, physical properties of s o i l s , s o i l development, s o i l re-action and lime requirement. Information respecting the degree of base saturation of Vancouver Island s o i l s i s very l i m i t e d . I t would be ex-pected, however, that since these s o i l s have developed under a wide range of climatic conditions and from many types of parent material that t h e i r base saturation would vary con-siderably. The fact that the liming practices on the Island vary and are rather confused would indicate that t h i s i s true. These considerations prompted the studies reported here. Most methods currently i n use for estimating the base saturation of s o i l have the disadvantage that they are very time consuming. For t h i s reason s o i l reaction i s frequently used aa a basis for lime recommendations. I t was thought that from a study of the methods of estimating base status that a shorter method might be found that would be suitable f o r use on Vancouver Island s o i l s . I t was also thought that such a method would be desirable for estimating lime requirement. Page 3 REVIEW OF LITERATURE. Cation Exchange In S o i l s . The f i r s t laboratory experiment demonstrating the a b i l i t y ©f one ion i n solut i o n to replace another ion from the s o i l was conducted by Thompson (54) i n 1850. In 1855 L i e b i g (29) argued that this property, which he c a l l e d base exchange, could be a t t r i b u t e d to a physical function of the many d i f f e r e n t constituents of the s o i l . Gedroiz (17) did a great deal of work pertaining to the exchange properties on various s o i l s . He concluded that base exchange was a function of certa i n c o l l o i d a l aluminum and Iron s i l i c a t e s i n the s o i l . K e l l y , Hendricks, and Fry (30) concluded the clay p a r t i c l e carries a negative charge and i s therefore capable of a t t r a c t i n g and holding p o s i t i v e l y charged cations. In 1914 Gedroiz (17) demonstrated that the exchange reaction was instantaneous. Kelly (27) indicates that the exchange of cations on the exchange complex by other replacing cations should take place stochiometrically. However, Rost (43) found i n liming a s o i l that usually the increase i n calcium and magnesium coincided with a decrease i n exchangeable hydrogen but rarely was the exchange equivalent. In the majority of cases the calcium absorbed was greater than the hydrogen replaced. This discrepancy i n the exchange Page 4 would substantiate the fact that basic substances increase the absorptive capaeity of a s o i l . Ge&roiz (17), Kelly (27) and others have shown that the base absorption capacity of a s o i l i s not constant, but increases with increase i n the pH of the s a l t solution i n contact with the s o i l . The r e l a t i o n between pH and base absorption capacity was further exphasized by Matson ant Hester (32) who stressed the necessity of s t a t i n g the pH at which the absorption capacity was determined. Purl and Dppal (45) have suggested, that absorption capaeity be expressed i n the form of t i t r a t i o n curves from which the base absorbtion capacity can be determined at any pH value. From these ant other experiments i t i s evident that the cation exchange capacity i s dependent upon the organic ani. clay f r a c t i o n of the s o i l and the nature and reaction of the extracting solutions used. Determination of Exchange Capacity. Many methods have been developed for estimating the exchange capacity of s o i l s . Some ©f the e a r l i e r methods afe those described by Golden (18), who determined the base exchange capaeity of a number ©f s o i l s by several d i f f e r e n t methods; these included ammonium acetate, ammonium formate, sodium chloride, barium acetate, barium formate, barium chloridg, manganous acetate, manganous Page 5. chloride, potassium acetate, potassium chloride, b o i l i n g ammonium chloride, H acetic acid, N hydrochloric a c i d 2 "5 and N cuprlc acetate. The amounts of K, Mg, Ca and H 5 were determined quantitatively i n the leachate. Barium was absorbed i n the largest quantities but did not replace equivalent amounts of other cations. The K ion was found to be strongly absorbed on the exchange complex. Manganous and cupric acetate gave good and consistent t o t a l exchange values. The acetate ion gave the highest and most consistent results f o r the displacement of bases and f o r t o t a l exchange capacity. Ammonium acetate gave the best displacement of any of the solutions used. Pierre and Scarseth (41) found that barium acetate -ammonium chloride method was the best for t o t a l base ex-change and that barium acetate was the best method for determining exchangeable hydrogen. Schollenberger and Simon (50) determined the ex-change capacity and exchangeable bases i n several d i f f e r e n t s o i l s using ammonium acetate. This method has been used extensively by d i f f e r e n t investigators to determine the base exchange of s o i l s . I t offers many advantages, some of the more important ones being summarized by Gardner (14) as follows: (1) Ammonium acetate, being the s a l t of a weak acid and a weak base, tends to r e s i s t hydrolysis and thus i s a very stable solution. Page 6. Ammonia, the replacing cation, i s v o l a t i l e and there-fore the amount on the exchange i s easily determined by d i s t i l l a t i o n . The leaching solution i s easily prepared and i s not cost l y . Ammonia i s usually present i n very small amounts ©h the exchange complex and thus using I t as the replacing cation introduces a very s l i g h t error. The excess ammonia i n the leaehate i s easily removed during evaporation of the f i l t r a t e . Using a leaching s o l u t i o n of pH7 i s considered an advantage as i t Is near the pH of the "bicarbonate -carbonic a c i d buffer system at the p a r t i a l pressure ®f carbon dioxide l i k e l y to p r e v a i l i n the atmos-phere of a f e r t i l e s o i l during the season of active growth. Ammonium acetate i s Strongly buffered at i t s adjusted pH and i s therefore very r e s i s t a n t to a l t e r a t i o n during the leaching process. Golden (18) compared d i f f e r e n t leaching solutions and found that ammonium acetate gave the best d i s -placement and that the acetate ion gave the most consistent results i n the determination of base exchange. Ammonium acetate, because of i t s effect on the sur-face tension of water, has good penetrating and Page 7. wetting powers which a i d i n the removal ©f ex-changeable cations. (1G) The ammonium acetate does not disperse the clay p a r t i c l e s and therefore allows leaching to proceed at a good rate. The following disadvantages of the ammonium acetate method are l i s t e d by various investigators; (1) Schollenberger and Simon (50) report i t i s d i f -f i c u l t to t i t r a t e to a d e f i n i t e end point. This disadvantage i s easily overcome by using methyl red as reported by Peech (39) rather than phenol-phthaleln. (2) Schollenberger and Simon (50) also state that ammonium acetate has a solvent action on calcareous material. Hanna and Reed (19) observed that i n limed s o i l s appreciable amounts of calcium carbonate were d i s -solved when the s o i l was leached with ammonium acetate. This d i f f i c u l t y i s largely overcome by leaching the s o i l with water to remove the water soluble s a l t s before leaching with ammonium acetate. (3) Mehlich (33) observed that ammonium acetate gave a lower exchange capacity when used to leach s o i l s high i n organic matter than did buffered barium chloride. Golden, Gammon, and Thomas (18) state that potassium or barium acetate Is superior to ammonium acetate Page 8. i n estimating the t o t a l exchange capacity of a s o i l . P ari and Uppal (45) report that ammonium acetate leaches out a f r a c t i o n of the humus and thus lowers the exchange capacity. (4) Mehlich (33), Hanna and Reid (19) state that ammonium acetate i s not as ef f e c t i v e i n the replacement of exchangeable hydrogen as buffered barium chloride. (5) Mehlich (33) states that the exchange properties of a s o i l can be best established at a pH over 8.0. Purl and Uppal (45) claim that the base exchange capacity of a s o i l i s f a i r l y constant above pH 8.0. Peech (37) describes a method f o r determining the exchange capacity and cations present by u t i l i z i n g the centrifuge and spectrophotometer. The s o i l i s leached with ammonium acetate and the ammonia then leached out using sodium chloride. The ammonia i s determined c o l o r l m e t r l c a l l y by nes s l e r l z a t i o n . The cations are pe r c i p i t a t e d by a centrifuge and the supernatant i s de-canted o f f . Toth and Prince (55) analyzed leachates from s o i l s by means of a Flame Photometer and reported very s a t i s -factory results compared with other methods of analysis. Brown (10) found the exchange capacity by deter-mining the exchangeable hydrogen and exchangeable bases then by addition of these two quantities got the exchange capacity. The values obtained compared very favorably Page 9. with Schollenberger*s method. I t appears therefore that Schollenberger 1s ammonium acetate method i s one of the best methods f o r determining the exchange capacities of s o i l s . However, since the method i s time consuming other techniques such as those developed by Brown (10) and Peech (39) are rapidly gaining popularity. Determination of Exchangeable Hydrogen. Many d i f f e r e n t methods have been suggested f o r determining the amount of exchangeable hydrogen i n s o i l s . J o f f e and McLean (23) leached s o i l s with neutral s a l t solutions u n t i l free of calcium and then t i t r a t e d the leachate with a base. Parker (36) determined the exchangeable hydrogen by leaching the s o i l with barium chloride and then t i t r a t -ing the leachate with barium hydroxide using phenolphthalein as the i n d i c a t o r . I t was found, however, that the ex-changeable hydrogen shown by t h i s method was only a f r a c t i o n of the t o t a l exchangeable hydrogen present. Pierre (40) suspended collodion bags containing s o i l i n .1 N sulphuric a c i d and i n .1 N Ba(0H)g u n t i l equilibrium was obtained. The number of m i l l i equivalents required to bring the solution to a pH of 9.5 was obtained as well as the number of m i l l i equivalents of, sulphuric a c i d to bring the solution to a pH of 4.5. Stephenson (53) t i t r a t e d .01 N NaOH d i r e c t l y into an electrode vessel u n t i l the s o i l reached the desired Page 10. pH. This method was not e f f e c t i v e "because s u f f i c i e n t time was not allowed for equilibrium to take place. Parker (36) leached s o i l with N barium acetate adjusted to pH7. The leachate was t i t r a t e d with N barium 10 hydroxide to a pH of 7 and the number of m i l l l equivalents of exchangeable hydrogen calculated. He found that con-ductometric methods for estimating the exchangeable hydrogen content are not satisfactory because two or three breaks occur i n the t i t r a t i o n curve. He also found that the difference method gave reasonably accurate results f o r most s o i l s but that this method i s very slow and tedious. B r a d f i e l d (9) leached s o i l with a solution of .01 N NH.OH—N. NH.G1 solution. The leachate was 4 4 t i t r a t e d with HC1 to react with the excess base. One of the newer methods for determining the ex-changeable hydrogen content was introduced by Brown (10). He determined the exchangeable hydrogen of many s o i l s by t i t r a t i n g .2 N acetic acid into neutral normal ammonium aeetate and constructing a pH curve. S o i l samples were shaken with N ammonium acetate and the pH determined, then by r e f e r r i n g to the pH curve, the m i l l l equivalents of exchangeable hydrogen were obtained. I t i s assumed that the hydrogen i n the s o i l behaves i n the same manner as the hydrogen of acetic acid. Prom the l i t e r a t u r e reviewed, Brown's technique Page 11 appears to be one of the best methods f o r determining the exchangeable hydrogen. The results are usually ex-pressed i n m i l l i equivalents per 100 grams of s o i l . Determination of Exchangeable Bases. The exchangeable bases held by the exchange complex represent the base saturated portion of the exchange capaeity. Nearly every method used to determine the exchange capacity of the s o i l i s also used to determine a portion of or the t o t a l exchangeable bases. In Schollenberger 1e ammonium acetate method each cation i s determined separately and the sum of these cations gives the t o t a l bases held on the complex. This procedure i s very laborious but gives accurate and reproducible r e s u l t s . Brown (10) outlines a method f o r determining the exchangeable bases by r e f e r r i n g to an ammonium hydroxide-acetic a c i d t i t r a t i o n curve. The s o i l i s shaken with N ac e t i c acid, the pH determined and m i l l i equivalents of bases present read from the t i t r a t i o n curve. Brown re-ports close agreement with Schollenberger 1s ammonium acetate procedure. Jones - Merkle (24) compared Brown's method with many others and found them i n good agreement. They found however that s l i g h t l y higher exchangeable bases are ob-tained by Brown's method. This was to be expected since i n Brown*s method the extracting solution has a much lower Page 12. pH than those of the other extracting solutions used. The Effect of pH. Calcium Saturation and Base Saturation  on Plant Growth. It has been shown that there is a relationship between the base saturation of s o i l Golleids and the a b i l i t y of plants to obtain calcium and other bases from the s o i l . Rost (48) found that 85$ of soils below 60% base saturation responded to the application of lime and that complete saturation was obtained only when the pH of the s o i l was above pH 8.3. Hydrogen decrease was proportional to the lime applied with l i t t l e change taking place in the pH of the s o i l until 3 ©r 4 tons of limestone were applied. Allaway (6) reported, after working on suspensions of Peat, Kaolinite, Wyoming Bentonite, E l l i t e and Mississippi Bentonlte, that as the percentage of Ca - saturation i n -creased the amount of calcium released also increased. He also noted that the amount available to plants seemed about the same as that replaced by HC1. He states that a close relationship between amounts of calcium taken up by plants and amounts replaced by H ions offers additional support to the theory that plant feeding i s essentially a replacement of exchangeable eationsof the s o i l by hydrogen ions from the plant. Kelby (27) reports that in general a high percent-age of the Ga content of the clay minerals.is exchangeable « Page 13 and t h e r e f o r e a v a i l a b l e to p l a n t s . P u r l found no s i g n i f i c a n t c o r r e l a t i o n between pH values and the need f o r l i m e a p p l i c a t i o n . He p o i n t e d out t h a t t h i s i s not s u r p r i s i n g s i n c e p l a n t s are t o l e r a n t to a wide v a r i a t i o n i n pH. From t h i s b.e concludes that the determination of s o i l base s a t u r a t i o n w i l l g ive a more s a t i s f a c t o r y and v a l u a b l e estimation of lime r e -quirement and an approximate i n d i c a t i o n of i t s r e a c t i o n . Rost (48) noted t h a t the a v a i l a b i l i t y of calcium i n the r e placeable form was a f f e c t e d to the degree of un-s a t u r a t i o n . He found i n general that the Increase of calcium and magnesium c o r r e l a t e d w i t h the amount of lime a p p l i e d , eight tons r e s u l t e d i n twice the i n c r e a s e over a f o u r tono a p p l i c a t i o n . The increase seemed to be governed by the exchange capacity of the s o i l . The s o i l s w i t h the lower exchange c a p a c i t i e s becoming more nearly s a t u r a t e d w i t h calcium and magnesium upon l i m i n g than the f i n e r t e x t u r e d ones. Hydrated lime (48) proved about twice as e f f e c t i v e as ground limestone i n i n c r e a s i n g the exchangeable calcium ©n the complex. The a d d i t i o n of lime seemed to . Increase the exchange c a p a c i t y of the s o i l . Powers (42) found, i n conducting experiments on g l f a l f a , Hungarian vetch, mint and rhododendron that they gave t h e i r beet growth i n a s l i g h t l y a c i d medium. The maximum development was secured w i t h a l f a l f a at a pH 5.6 t o 6.0. Page 14 Vlamis (56) reports that lettuce rosette was pro-duced ©n a highly productive s o i l by addition of Mg and K amberlites. Ca and Sr amberlitesadded to t h i s s o i l produced healthy plants. Where rosetteappeared the amount of Ca i n the s o i l had not been changed, but the degree of Ca - saturation was lower. Where Mg was the complementary ion, and the (calcium saturation f e l l below 20$ there was a sharp reduction i n l e t t u c e growth. Lettuce rosette did not appear when the Ca - saturation was above 25$. Where K was the predominant complementary ion, the reduction i n y i e l d and appearance of rosette i n l e t t u c e occurred at 30$ Ca - saturation. Plant - tissue analysis revealed the reduction i n y i e l d and the l e a f symptoms to be a r e f l e c t i o n of the low-Ca status of plants grown In s o i l s at the lower de-grees of Ca - saturation. The rosette symptoms on lettuce plante grown i n water culture solutions low i n Ca were more severe i n solutions high i n Mg and K. Plant - tissue analysis re-vealed this to be a function of the low-Ca status of the plants under the competitive influence of Mg or K. Karraker (26) noted a delaying effect of limestone i n bringing about increased growth of a l f a l f a on a c i d s o i l s i n pots. Knowledge of this delaying effect i s important i n i n d i c a t i n g the d e s i r a b i l i t y of liming some-time ahead of seeding f o r maximum response to plant growth. Page 15 Peech and B r a d f i e l d (38) s t a t e that during the l a s t two decades there has been a growing tendency on the part of the many s o i l and p l a n t s c i e n t i s t s to a t t r i b u t e poor growth of p l a n t s on a c i d s o i l s p r i m a r i l y to calcium de-f i c i e n c y , presumably brought about by low exchangeable calcium content and f o r a low degree of calcium s a t u r a t i o n . M a r s h a l l and Ayers (31) have shown that the a c t i v i t y of the calcium ions i n c e r t a i n c l a y suspensions, as measured by the clay membrane e l e c t r o d e , remain r e -markably constant w i t h i n c r e a s i n g degree of calcium s a t u r a t i o n . They proved w i t h . .1,. many crops, maximum y i e l d responses are obtained by l i m i n g s o i l s t o giv e about 60$ calcium s a t u r a t i o n . Further, when studying the de-gree of calcium s a t u r a t i o n of the s o i l on plant growth, such a s s o c i a t e d v a r i a b l e s as pH, amount of exchangeable calcium, and p o s s i b l e t o x i c i t y of manganese, aluminum and i r o n at low pH values should be taken i n t o account. From t h i s they concluded that the exchangeable calcium alone would appear to be of l i t t l e value i n p r e d i c t i n g calcium d e f i c i e n c y or need f o r l i m i n g s o i l s except when one i s d e a l i n g w i t h extremely l i g h t s o i l s having an exchange ca p a c i t y below 2 m.e. per 100 gms. of s o i l . They t h i n k that the simple t e s t f o r s o i l r e a c t i o n a f f o r d s the most u s e f u l s i n g l e value f o r esti m a t i n g lime needs of s o i l s . Bear and Toth (8) conclude from an eight year study on twenty Important a g r i c u l t u r a l s o i l s of New Jersey, Page 16. t h a t a l f a l f a gives optimum growth under the f o l l o w i n g c o n d i t i o n s . (1) When 65$ ©f the exchange complex of the s o i l i s occupied by Ca, 10$ by Mg, 5$ by K and 20$ by H. (2) When Ca-K rati© In a l f a l f a exceeds 4:1, marked r e -sponses of a p p l i c a t i o n s of s o l u b l e K w i l l normally be obtained. (3) When one n u t r i e n t c a t i o n i s low i n the s o i l , more of the others move i n t o the a l f a l f a , the sum of c a t i o n equivalents i n the p l a n t per u n i t weight of dry t i s s u e tends to be constant. Since K i s more expensive than Ga and not as important i n the n u t r i t i o n of animals, i t proves necessary to have the s o i l i n balance. M i l e s (35) s t a t e s that i n s o i l s where the c a t i o n exchange capacity averages l e s s than 4 m.e./lOO gm. r e -l a t i v e l y small amounts of lime are needed to e f f e c t the d e s i r e d degree of s a t u r a t i o n . Further, the calcium from the organic and the k a o l i n l t i c type of c o l l o i d i s r e a d i l y a v a i l a b l e f o r optimum growth of p l a n t s . P u r v i s and Davidson (46) report a f u n c t i o n a l r e -l a t i o n s h i p between boron and calcium w i t h i n the p l a n t , and a h i g h i n t a k e of one of these n u t r i e n t s w i l l Increase the requirement of the p l a n t f o r the other. Smith and Hester (51) s t a t e i f calcium i s not a l i m i t i n g f a c t o r f o r the p a r t i c u l a r crop grown, the amount Page 17. added i n lime or f e r t i l i z e r s maybe such a small p a r t of the t o t a l a v a i l a b l e as to have an i n s i g n i f i c a n t e f f e c t on the composition of the p l a n t . Where calcium i s the only l i m i t i n g element f o r p l a n t growth, a d d i t i o n s to the s o i l may f a i l to i n c r e a s e the percentage i n the p l a n t i f i n -creased growth i s c l o s e l y r e l a t e d to r a t e of absorption. Where growth i s l i m i t e d by a d e f i c i e n c y of some other element, a d d i t i o n s of lim e may inc r e a s e the calcium content. K e l l y (27) found t h a t the a v a i l a b i l i t y of calcium i n s o i l s diminishes r a p i d l y w i t h base s a t u r a t i o n . I n summary i t i s seen that the calcium base s a t u r -a t i o n of the s o i l has a marked e f f e c t on pla n t growth and th a t when the calcium s a t u r a t i o n f a l l s below a c e r t a i n s a t u r a t i o n response to added calcium i s obtained. I t a l s o appears that the determination ©f the base or calcium s a t u r a t i o n ©f a s o i l should form a sound b a s i s f o r e s t i m a t i n g the lime requirement ©f a s©il. Lime Requirement of S o i l s . Many methods have been devised f o r estimating lime requirements of s o i l s . A great percentage of these are qu i c k t e s t e and merely estimate the amount of exchangeable calcium or some percentage of t h i s v alue. Some estimate the exchangeable hydrogen and many others Just the pH. I t i s t r u e t h a t a l l these methods gi v e an i n d i c a t i o n of the calcium s t a t u s of the s o i l but no c o r r e l a t i o n has been found between these v a l u e s , the lime requirement Page 18. and p l a n t growth. One ©f the l a t e s t methods used f o r estimating the l i m e requirements of s o i l s was o u t l i n e d "by Dunn (11) f o r the s o i l s of Western Washington. He shook, ten gram samples of s o i l w ith increments of .05 N calcium hydroxide. By p l o t t i n g pH against m i l l l equivalents of base n e u t r a l i z e d he constructed the t i t r a t i o n curve f o r the unsaturated p o r t i o n of the exchange complex. He estimated the l i m e requirement by determining the number of m i l l l equiva-l e n t s of base r e q u i r e d to r a i s e the s o i l to a c e r t a i n pH value. He found that the amount of lime r e q u i r e d to b r i n g the s o i l to a c e r t a i n pH value i n the f i e l d averaged 1.5 times as much as determined In the l a b o r a t o r y . R u s s e l l (49) found approximately twice as much lime was r e q u i r e d In the f i e l d . Summary of Past Lime Experiments Conducted ©n Vancouver  I s l a n d S o i l s . Annual reports from the Dominion Experimental S t a t i o n , Saanichton, l i s t a number of l i m e experiments. To observe the e f f e c t of l.ime on f r u i t trees ( l ) 60 l b s . of calcium hydroxide was a p p l i e d to a 29 year o l d plum t r e e i n March 1943. In 1944 the pH of the unlimed s o i l was 6.2 and the limed 7.4. Results reported i n 1944 showed no b e n e f i t i n f r u i t B e t from l i m i n g . This e x p e r i -ment was conducted on a Cadboro Sandy Loam s o i l type l o c a t e d on the Experimental S t a t i o n . Page 19 An a n a l y s i s of y i e l d data (2) from 1943 - 47 shows negative r e s u l t s f o r the use of lime i n regard to t u l i p flower produetion. Bulb q u a l i t y i n storage was not n o t i c e a b l y a f f e c t e d by lime a p p l i e d i n the f i e l d before p l a n t i n g at the r a t e of two, four and s i x tons of hydrated l i m e per acre. S i m i l a r r e s u l t s were obtained w i t h d a f f o d i l s i n 1945. The f i e l d t e s t s were conducted on Saanichton Clay and Cadboro Sandy Loam s o i l types. Hydrated lime was a p p l i e d at zero, one, two, three and f o u r tons per acre on a s o i l weight b a s i s to oat pot t e s t s . S o i l used was Cadboro Sandy Loam. No app r e c i a b l e a f f e c t on the top growth of the p l a n t s was obtained. The growth of oat roots was depressed on a l l limed s o i l s . The . l i m e a p p l i c a t i o n s had ho e f f e c t on the uptake of phosphorus. Lime was a p p l i e d at rates of two, four, s i x tons per acre to Dutch Clover (3) and I t a l i a n Rye Grass grown i n k i l o g r a m pots of Cadboro s o i l . R e s u l t s from two and f o u r tons per acre gave s i g n i f i c a n t i n c r e a s e i n top growth f o r the Dutch Glover but no s i g n i f i c a n t r e s u l t s on the I t a l i a n Rye Grass. S i x tons per acre gave decreased y i e l d s f o r both grass and c l o v e r . Two and four tons per acre gave s i g n i f i c a n t i n c r e a s e i n y i e l d f o r tobacco tops but not f o r tomato. S i x tons per acre gave a decrease i n y i e l d f o r both these crops. Hydrated li m e was a p p l i e d at rates of two, four and s i x tons per acre to a f i e l d p l o t l o c a t e d on Cadboro Sandy Loam. This a p p l i c a t i o n d i d not a f f e c t the y i e l d s (4) Page 20. of hay, com or wheat grown In a f i v e year r o t a t i o n . The pH values f o r the p l o t s were, check 6.37; two tone per acre p l o t 6.74; fo u r tons per acre p l o t 6.94; and i n s i x tons per acre p l o t 7.06. Results ( 5 ) of lime a p p l i c a t i o n obtained from 83 pot t e s t s were e s p e c i a l l y v a r i a b l e f o r s o i l s from Saanich and Duncan areas. However, r e s u l t s i n d i c a t e t h a t on the whole lime was i n e f f e c t i v e f o r these areas. Large v a r i a t i o n s i n response were obtained from Courtenay -Comox s o i l s , but the tendency f o r lim e t o be b e n e f i c i a l i n t h i s area was apparent. Results from the l i m i t e d number of t e s t s f o r A l b e r n i s o i l s i n d i c a t e l i m e to be i n e f f e c t i v e . The r e s u l t s w i t h peat s o i l s were p r a c t i c a l l y n egative and the v a r i a t i o n s i n responses on the whole were not great. Anderson (7) conducted f e r t i l i t y s t u d i e s on two peat s o i l s from Vancouver I s l a n d . He found that when the y i e l d of barley was p l o t t e d against degree of base s a t u r a t i o n a smooth curve was obtained, which l e v e l e d o f f at approximately 50$ base s a t u r a t i o n . He s t a t e d t h a t when the degree of base s a t u r a t i o n was in c r e a s e d above 50$ no s u b s t a n t i a l Increase i n y i e l d was obtained. He concluded from h i s s t u d i e s that base s a t u r a t i o n should p r o v i d e an accurate measurement f o r the lime requirement of s o i l s . From these reports i t i s evident that the response Page 21. from l i m e on Vancouver I s l a n d s o i l s i s v a r i a b l e . A need f o r a sound organised approach to the l i m i n g problem i s very apparent. Page 22. EXPERIMENTAL. S o i l s Studied. S i x s o i l types were s e l e c t e d from v a r i o u s sur-veyed p a r t s of Vancouver I s l a n d , two from the Saanich P e n i n s u l a , one from the A l b e r n i area, two from the Quallcum area and one from near Courtenay. These s o i l types are l o c a t e d under a range of c l i m a t i c c o n d i t i o n s (52). A b r i e f d e s c r i p t i o n (12) of these s o i l types f o l l o w s : Cadbor© Sandy Loam. These s o i l s occur on upland p o s i t i o n s having r o l l -i n g moranic topography. The surf a c e drainage I s moderately complete w i t h i n t e r n a l drainage moderate to alow. The A h o r i z o n v a r i e s from 2 - 1 2 i n . i n depth, has a pH 6 -6.5. The a g r i c u l t u r e c o n s i s t s of small f r u i t s , bulbs and other s p e c i a l i z e d farming. The l o c a t i o n sampled f o r t h i s study was at B u t l e r Bros, sand p i t on Keating Cross Road. Saanichton Clay Loam. These s o i l s occupy the w e l l drained p o s i t i o n s on the l a k e p l a i n i n the Saanich p e n i n s u l a . They have de-veloped from a very compact weakly s t r a t i f i e d water deposited m a t e r i a l . Surface drainage i s adequate. The A h o r i z o n v a r i e s from 0 to 2 Inches i n depth, has a strong g r a n u l a r to medium granular s t r u c t u r e . These s o i l s are almost a l l c u l t i v a t e d . Small f r u i t s , b e r r i e d f r u i t s , v egetables, bulbs and a number of other s p e c i a l i z e d Crops Page 23. are grown. The area sampled was on the west road 1/2 m i l e south of the Mount Newton - West Road i n t e r s e c t i o n . A l b e r n i Clay Loam. These s o i l s have developed from marine c l a y s . The s u r f a c e has a r i c h r e d d i s h "brown c o l o r o v e r l y i n g a . uniform c o l o r e d y e l l o w i s h brown s u b s o i l . The surface drainage i s moderate w i t h i n t e r n a l drainage r e s t r i c t e d . The r e l i e f i s smooth, gently s l o p i n g to undulating top-ography. Scarcely any A 1 h o r i z o n e x i s t s , the h o r i z o n i s approximately 7 Inches i n depth and has a s t r o n g l y developed shotty s t r u c t u r e and a pH of 5.8. The s o i l s are c u l t i v a t e d to a , l i m i t e d extent at the present time a l -though they are being r a p i d l y s e t t l e d . Cowichan Clay Loam. These s o i l s have developed on f l a t g l a c i a l l a k e , e s t u a r l n e or marine sediments under c o n d i t i o n s of poor e s t a b l i s h e d drainage. They occur mainly on f l a t , de-p r e s s i o n a l or pond-like areas. The A^ h o r i z o n ranges up to 8 Inches i n depth and i s f r i a b l e i n consistence. Immediately below t h i s organic surface i s l o c a t e d a p a l e brown cl a y w i t h massive to blocky s t r u c t u r e , s l i g h t m o t t l i n g and g e n e r a l l y q u i t e p l a s t i c when wet. The pH i s 5.2. The area sampled, was one m i l e south of Coombs on the A l b e r n i highway. M e r v i l l e Loam. The M e r v i l l e s o i l s are c h a r a c t e r i z e d by very dark brown to black surface o v e r l y i n g dark brown s t r o n g l y Page 24. s t r u c t u r e d s u b s o i l s below which i s a dense poorly aerated c l a y . The topography i s l e v e l to undulating. The A^ ^ h o r i z o n v a r i e s up to 8 Inches i n depth, i s f r i a b l e and weakly developed. The B h o r i z o n (pH 5.7) i s f r i a b l e o v e r l y i n g a compact, dense, h i g h l y mottled g l e i h o r i z o n . Area sampled was 1/2 m i l e east of Mr. Cassanave I l l u s t r a t i o n S t a t i o n , Courtenay. Peat. The peats on Vancouver I s l a n d are v a r i a b l e w i t h respect to a c i d i t y , percent organic matter and stage of decomposition. The peat sampled f o r t h i s study was from a farm area 5 miles northwest of Dashwood. The pH was 4.3, t h i s peat bog i s being s u c c e s s f u l l y farmed. I t i s apparent that the s o i l s chosen f o r study i n c l u d e d a wide v a r i e t y of types and represent a con-s i d e r a b l e area of a g r i c u l t u r a l s o i l on Vancouver I s l a n d . Methods. 1. Exchange Capacity. The exchange ca p a c i t y of the s i x s o i l s s t u d i e d was determined by the Shollenberger, Brown and P u r i methods. Shollenberger's Method (50) The s o i l s were leached w i t h n e u t r a l normal ammonium acetate and then the excess ammonia removed w i t h n e u t r a l 80% e t h y l a l c o h o l . The ammonia was d i s t i l l e d and t i t r a t e d . Brown's Method (10) Page 25. Brown's Method. ( 1 0 ) The exchangeable hydrogen (under exchangeable hydrogen determination) and exchangeable bases (under exchangeable bases determination) were determined and the exchange capacity dstermined by adding these values. P u r i Method ( 4 4 ) Hydrogen sa t u r a t e d s o i l s were formed by l e a c h i n g samples of s o i l w i t h .05 N H C 1 as de s c r i b e d under T i t r a t i o n Curves. The exchange ca p a c i t y was then estimated by de-termining the number m i l l i equivalents of base r e q u i r e d to r a i s e the p i of the a e i d o i d by p r e s c r i b e d amounts. These were: (a) The number of m i l l i equivalents of base r e -q u i r e d to r a i s e the pH of the a c l d o i d to three pH u n i t s above the o r i g i n a l pH of the a c l d o i d . (b) The number of m i l l i equivalents of base r e -q u i r e d to r a i s e the pH of the a c l d o i d t o four pH u n i t s above the o r i g i n a l pH of the a e i d o i d . 2. Exchangeable Hydrogen. The exchangeable Hydrogen was determined by a s l i g h t m o d i f i c a t i o n of Brown's Method ( 1 0 ) . F i v e gram samples of s o i l were shaken w i t h 50 cc of 1 N NH4AC ph7 f o r 30 minutes and the r e s u l t a n t pH of the HAC s o i l mixture was determined w i t h a Bechman pH meter. By r e -f e r r i n g to a p r e v i o u s l y constructed NH^AC _ HAC pH graph the exchangeable hydrogen i n m.e./lOO gm. of s o i l was Page 26. obtained. 3. Exchangeable Bases. The exchangeable bases were determined by Brown's Method (10). F i v e gram samples of s o i l were shaken wi t h 50 cc of 1 N HAC f o r 30 minutes and the pH of the mixture determined with a pH meter. By reference to a p r e v i o u s l y c o n s t r u c t e d HAC - NH^GH pH curve, the exchangeable bases i n m.e./lOO gm of s o i l were obtained. 4. Exchangeable Calcium. The exchangeable calcium was determined by two methods: Shollenberger's Method and a m o d i f i c a t i o n of Peech 1s Method. Schollenberger's Method (50) The leachate from the ammonium acetate l e a c h i n g was analysed f o r calcium. The calcium was p r e c i p i t a t e d as the oxal a t e and t i t r a t e d w i t h potassium permanganate. Peech's Method (39) The s o i l was leached w i t h sodium acetate and the calcium p r e c i p i t a t e d as the c i t r a t e . The p r e c i p i t a t e was h e l d i n suspension by a soap s o l u t i o n and compared to a s e t of standards by means of an A.C. Model F i s h e r Electrophotometer equipped w i t h magnifying g l a s s , number 650 Red F i l t e r and t e s t tube adaptor to ho l d 10 mm I.D. t e s t tubes. The parts per m i l l i o n were converted to m i l l ! e q u ivalents per 100 gm. of s o i l . Page 27. 5. pH Determinations. The pH determinations were made wit h a Beckman g l a s s e l e c t r o d e pH meter on a 1:2 s o i l water r a t i o . I n c o n s t r u c t -i n g t h e t i t r a t i o n curves a 1:5 s o i l water rati© was used because the s o i l was shaken w i t h increments of .05 N c a l c i u m hydroxide. T h i s d i l u t i o n gave c o n s i s t e n t l y h i g h e r pH readings than the 1:2 d i l u t i o n which n e c e s s i t a t e d a c o r r e c t i o n f a c t o r when comparing the two v a l u e s . 6. T i t r a t i o n Curves. T i t r a t i o n curves were determined by two methods: (1) Dunn Method (11). T i t r a t i o n curves f o r the u n s a t u r a t e d p o r t i o n of the exchange c a p a c i t y were c o n s t r u c t e d by a m o d i f i c a t i o n of Dunn's Method. Ten gram samples of s o i l were shaken w i t h increments o f .05 N Ca(0H)g f o r two hours and then l e f t to stand f o r t y - e i g h t hours to reach e q u i l i b r i u m . The pH o f the mixture was determined by means of a pH meter. A pH - m i l l i e q u i v a l e n t s of Ca(0H)g curve was c o n s t r u c t e d . (2) P u r i Method (44). T o t a l t i t r a t i o n curves t o study the a b s o r p t i o n of c a l c i u m by the s o i l through the e n t i r e range from a hydrogen s a t u r a t e d s o i l to a c a l c i u m s a t u r a t e d s o i l were c o n s t r u c t e d by a m o d i f i c a t i o n of P u r i ' s Method. AcldJoldidor hydrogen s a t u r a t e d s o i l s were mafte*byc";ed Page 28. l e a c h i n g a p o r t i o n of the s o i l w i t h .05 N HC1 u n t i l f r e e of calcium and then w i t h water u n t i l f r e e of c h l o r i d e s . Ten gram samples of the a c i d o i d were shaken f o r two hours w i t h increments of .05 N Ca(OH) and allowed to stand f o r f o r t y - e i g h t hours "before the pH was determined w i t h a pH meter. By p l o t t i n g m i l l i equivalents of calcium against pH the t i t r a t i o n curves were constructed. 7. Percent Calcium S a t u r a t i o n . The percent calcium was determined by two methods: S h o l l e n b e r g e r 1 s Method (50) The m i l l i equivalents of calcium determined on the ammonium acetate leachate d i v i d e d by exchange capacity gave the percent calcium s a t u r a t i o n . Peech - Brown Method (39) (10) The m.e. of calcium determined by Peech's Method were d i v i d e d by the exchange capacity as determined by Brown's Method. 8. Percent Base S a t u r a t i o n . The percent base s a t u r a t i o n was determined by three methods: Brown's Method (10) The percent base s a t u r a t i o n as determined by Brown*s Method i s the number of m i l l i equivalents of b&ees per hundred grams of s o i l d i v i d e d by the exchange c a p a c i t y . Page 29. Sho l l e n b e r g e r 1 s Method (50) Is the t o t a l number of m i l l ! equivalents of base determined on the leaehate d i v i d e d by the exchange c a p a c i t y . P u r l Method (44) This method i s the r a t i o of the number of m i l l ! e q u ivalents of base r e q u i r e d to r a i s e the pH of the a c i d o i d to the o r i g i n a l pH of the s o i l over the number of m i l l i equivalents of base r e q u i r e d to r a i s e the pH of the s o i l a c i d o i d , t o four pH u n i t s above the pH of the a c i d o i d before any base was added. See Base Exchange determination, P u r i Method B. 9. Plant A n a l y s i s . The oven d r i e d p l a n t m a t e r i a l was crushed, p l a c e d i n platinum c r u c i b l e s , moistened w i t h concentrated s u l p h u r i c a c i d and heated i n a muffle furnace at 550°C u n t i l i t be-came a white ash. The re s i d u e was d i s s o l v e d i n 8 N HCl and f i l t e r e d . The f i l t r a t e was analysed f o r calcium by p r e c i p i t a t i n g the calcium as the oxalate and then t i t r a t i n g w i t h .04 K potassium permanganate (50). Page 30. 10. P o r o s i t y S t u d i e s . Undisturbed core samples were obtained and used f o r the determination of n o n - c a p i l l a r y p o r o s i t y and apparent s p e c i f i c g r a v i t i e s . The amount of water w i t h -drawn from s o i l core under a tension of 40 cm. was con-s i d e r e d to represent the n o n - c a p i l l a r y pore space. The r e s u l t s are expressed as percentage of s o i l volume and can be determined by: a - b X 100 when a a s a t u r a t e d weight v b s weight a f t e r e x e r t i n g 40 cm of t e n s i o n . v a volume of c y l i n d e r (320ec). 11. Apparent S p e c i f i c G r a v i t y . Apparent s p e c i f i c g r a v i t y i s equal t o : weight of the oven dry s o i l i n core volume of core 12. Lime Requirement. (1) Percent Base S a t u r a t i o n . The lime requirement k)t Percent Base S a t u r a t i o n i s determined by the f o l l o w i n g formula: x - y X Exchange Capacity B m i l l i equivalents of calcium 100 per 100 gm. of s o i l . where x • d e s i r e d l e v e l of Percent Base S a t u r a t i o n . y a i n i t i a l l e v e l of Percent Base S a t u r a t i o n . Page 31 The m i l l l equivalents of calcium per 100 grams of s o i l i s converted t o l b s . of calcium carbonate per acre on a volume b a s i s or on a weight b a s i s . (a) Volume Weight B a s i s . The a c t u a l weight of s o i l to a depth of 6 2/3" as determined by the apparent s p e c i f i c g r a v i t y i s used i n the c a l c u l a t i o n s . (b) Weight B a s i s . The c a l c u l a t i o n s are made by assuming an acre of s o i l t o a depth of 6 2/3" weighs 2,000,000 l b s . (2) T i t r a t i o n Curves. The number of m i l l i equivalents of base per 100 gms. of s o i l r e q u i r e d to r a i s e the s o i l to a pH of 6.5 i s obtained from the t i t r a t i o n curves. This value i s con-v e r t e d to l b s . of calcium carbonate per acre on a weight b a s i s . Comparison of Methods. Exchange Capacity. The exchange c a p a c i t y of the s i x f i e l d and eight greenhouse s o i l s were determined by the Shollenberger, Brown and P u r l Methods. Results are given i n Table 1. Page 32 TABLE 1. Comparison b.f Exchange Capacity. S h o l l e n - B r o w n 1 s P u r l P u r l S o i l berger's m.e./lOO m.e./lOOgms m.e./lOOgms m.e./lOO gms gms. (A 4 3) (M4)  Cadboro 11.57 m. e. 12.14 m.e. 14.8G 14.80 16.10 23. Saanichton 24.22 23.44 23.70 24.70 26.00 34. A l b e r n i 24.42 25.06 25.60 25.60 23.00 30. C.C.P.D. 46.38 44.41 35.. 80 36.00 33.00 38. M e r v i l l e 37.00 38.50 34.10 34.20 3b. OG 43.50 Peat 92.25 90.25 74.60 74.60 36.00 48.00 Greenhouse 1 11.97 12.00 20.00 19.70 2 12.14 12.18 17.80 17.60 3 13.03 13.50 17.70 17.50 4 14.04 14.56 17.70 17.50 5 33.88 32.75 34.50 34.30 6 37.70 37.62 35.80 35.75 7 36.88 36.80 35.00 34.80 8 37.90 37.80 33.80 33.50 Page 33. Brown's method gave c o n s i s t e n t l y higher r e s u l t s than Shollenberger's f o r the s o i l s w i t h a low exchange capacity such as Cadboro and the four l e v e l s of percent base s a t u r a t i o n produced i n the greenhouse on t h i s s o i l type. This i s i n l i n e w i t h what Jones-Merkle (24) found when comparing these two methods. They e x p l a i n t h i s d i s -crepancy by s t a t i n g that the exchangeable bases are d i s p l a c e d by hydrogen ions at a pH of 2.3 i n Brown's Method, whereas i n the ammonium acetate method they are exchanged at n e u t r a l i t y . For s o i l s having an exchange c a p a c i t y of around 25 m.e. per 100 gm. such as Saanichton and A l b e r n i s o i l s , the two methods compared very f a v o r a b l y . Brown's Method gave lower r e s u l t s than shollenbergers f o r the h i g h base exchange s o i l s such as M e r v i l l e , Cowlchan Clay and Peat. These s o i l s are q u i t e high i n organic matter, which might c o n t r i b u t e to the discrepancy. Few, i f any, methods have been devised which w i l l g i v e an accurate determination of exchange capacity on peat and s o i l s high i n organic matter. Brown's Method i s a very r a p i d way of determining exchange capacity f o r i t requires only a f r a c t i o n of the time needed f o r Shollenberger's and many other methods. The v a r i a t i o n between d u p l i c a t e samples i s small and r e s u l t s are r e p r o d u c i b l e . Although i t was found to be accurate over a narrower range than Sfhollenberger' s Method, Brown's Method appeared to be very s a t i s f a c t o r y f o r determining the exchange c a p a c i t i e s of s o i l s . Great care must be e x e r c i s e d when using Brown's Method to see Page 3 4 . t h a t the pH meter Is f u n c t i o n i n g p r o p e r l y f o r readings are made over a very narrow range. The ammonium acetate -a c e t i c a c i d pH curve and a c e t i c a c i d - ammonium hydroxide pH curve should beochecked r e g u l a r l y . I f these r u l e s are observed comparable readings can be obtained by d i f f e r e n t operators. The exchange c a p a c i t i e s as determined by P u r l ' s Method (Table 1 ) using the number of m i l l i e quivalents of bases r e q u i r e d to r a i s e the pH of the a c i d o i d to three pH u n i t s above the o r i g i n a l pH of the a c i d o i d ( F i g . 3 ) g i v e comparable r e s u l t s w i t h Brown's Method and reasonably comparable r e s u l t s w i t h Shollenberger's Method. The value obtained f o r the peat was a much lower value than obtained by both Shollenberger's and Brown's Methods. Determining the exchange ca p a c i t y i n t h i s way by t i t r a t -ion' curves i s very l a b o r i o u s and time consuming but has a value f o r s p e c i a l problems. P u r l ' s exchange c a p a c i t i e s as determined by the, number of m i l l i equivalents of base r e q u i r e d to r a i s e the pH of the a c i d o i d t o four p H u n i t s above the pH of the a c i d o i d ( F i g . 3 ) before any a l k a l i was added i s a l s o l i s t e d i n Table 1 . These values are hig h e r i n general than by Shollenberger's and Brown's Methods. However, P u r i ( 4 4 ) s t a t e s that i f two or more methods f o r measur-ing a c e r t a i n constant g i v e c o n s i s t e n t l y d i f f e r e n t r e s u l t s the e r r o r i s not i n the methods but i n the conception of the constant being measured. Page 35 From the comparison mate between these four methods, i t was concluded t h a t Brown's Method i s r a p i d , r eproducible and compares favorably w i t h the l e n g t h i e r techniques. Base S a t u r a t i o n . The percent base s a t u r a t i o n was determined on s i x s o i l s by the Sfhollenberger, Brown and P u r i Methods. The Shollenberger Method waB used as the standard technique, the other two methods were compared to i t f o r accuracy. The percent base s a t u r a t i o n f o r the s i x s o i l types are l i s t e d i n Table 2. TABLE 2. Comparison of Percent Base S a t u r a t i o n S o i l Brown's Method Shollenberger'e P u r l ' s Method Method (A 4- 4) Cadboro 67.00 60.05 52. Saanichton 71.00 83.10 64.6 Cowlchan 64.50 73.00 65.7 A l b e r n i 60.00 26.00 40.0 M e r v i l l e 47.70 32.80 35.6 Peat 24.50 19.90 23.00 The r e s u l t s of the three methods compare reasonably w e l l although a v a r i a t i o n occurs between methods at the high percent base s a t u r a t i o n l e v e l s . P u r i 1 6 Method gave lower values than the other two methods f o r Cadboro and Saanichton s o i l types. The percent base s a t u r a t i o n v a r i e s from 60$ i n Brown's Method to 26$ i n Shollenberger's f o r the A l b e r n i type. This i s a shotty s o i l and leaching with Page 36. ammonium acetate d i d not di s p e r s e the shot so i n a l l p r o b a b i l i t y complete displacement of the bases d i d not r e s u l t . I n Brown's Method the s o i l was shaken with N a c e t i c a c i d to determine the exchangeable bases, the a c i d d i s p e r s e d the shot to a considerable extent. I t i s f e l t t h a t many o f the bases were l i b e r a t e d r e s u l t i n g i n a much higher percent base s a t u r a t i o n than by the other two methods. When the r e s u l t s are considered i n the l i g h t of f i e l d observations, the r e s u l t found by the Brown Method seems more l i k e l y the c o r r e c t one. This i s thought to be the case because i t i s d o u b t f u l whether the s o i l r e q u i r e s l i m e and i f I t were only 2 6 $ base saturated, as reported by Shollenberger's Method, a high response to lime would be expected. The exchange c a p a c i t i e s f o r peat b y the three d i f f e r e n t methods v a r i e d g r e a t l y ; however the percent base s a t u r a t i o n values are very s i m i l a r . Both M e r v i l l e and Feat gave low percent base s a t u r a t i o n values f o r a l l three methods. Exchangeable Calcium and Calcium S a t u r a t i o n . The exchangeable calcium and percent calcium s a t -u r a t i o n was determined by Shollenberger's Method. S e v e r a l s h o r t e r or s o c a l l e d quick methods were also used to determine the exchangeable calcium but when compared to Shollenberger's f a i l e d t o gi v e any c o r r e l a t i o n * A m o d i f i c a t i o n of Peech 1 s Method using the e l e c t r o photo-meter appeared to give reasonably accurate r e s u l t s . This Page 37. method was r a p i d and r e p r o d u c i b l e . The m i l l l equivalents of calcium per 1G0 gm. of s o i l determined by t h i s method d i v i d e d by Brown's exchange c a p a c i t i e s gave the percent calcium s a t u r a t i o n . The exchangeable calcium and per-cent calcium s a t u r a t i o n determined by t h i s method were compared f o r accuracy to the values obtained by S h o l l e n b e r g e r 1 s technique. These values are l i s t e d i n Table 3 and compared i n F i g . 1. TABLE 3. Comparison of Exchangeable Calcium and  Calcium S a t u r a t i o n Methods. Shollenberger's ; S o i l Exchangeable Calcium Calcium S a t u r a t i o n 1 Peech Exchangeable Calcium Peech/Brown Calcium S a t u r a t i o n Cadboro 3.80 32.5 3.16 21.30 Saanichton 14.70 65.00 10.00 41.30 A l b e r n i 2.19 8.74 1.00 3.90 Cowlchan 13.62 44.40 10.50 29.20 M e r v i l l e 5.41 14.50 3.0 8.80 Peat 13.94 13.50 6. 8.10 Greenhouse 1 1.591 13.30 .50 2.8 2 3.92 30.20 2.0 11.3 3 6.37 48.90 3.00 17.80 4 8.70 62.00 4.20 23.80 5 3.33 9.84 1.50 4.35 6 5.79 15.35 3.00 8.50 7 11.61 31.50 6.20 17.80 8 28.90 76.00 14.10 41.80 page co. PERCENT CALCIUM SATURATION (PEECH BROWN) FIG. I CALCIUM SATURATION Page 39. From the exchangeable calcium contents l i s t e d i n Table 3, i t i s evident that the ammonium acetate i n every ease replaced more calcium than the sodium acetate used i n Peech 1s Method. This observation i s i n agreement w i t h Golden's (18) work f o r he found the ammonium i o n was very e f f e c t i v e i n r e p l a c i n g exchangeable bases from the s o i l complex. The exchangeable calcium ranges from 1.59 m.e. to 28.90 m.e. per 100 gm. of s o i l or a range of 27.31 nue. f o r S h o l l e n b e r g e r 1 a Method. I t ranged from 0.5 m i l l l e q u ivalents to 14.10 m i l l i equivalents or a range of 13.60 m.e. per 100 gm. of s o i l f o r the Peech Method. I t appears t h a t Shollenberger's ammonium acetate removes approximately twice as much calcium as Peech 1 s sodium ac e t a t e method. In order to determine whether there v/as any c o r r e l a t i o n between the percent calcium s a t u r a t i o n by STiollenberger's Method and percent calcium s a t u r a t i o n by the Peech - Brown Method, the two values were p l o t t e d as shown i n F i g . 1. There appears to be a good c o r r e l a t i o n between the two methods. From these values, i t was concluded that the Peech -Brown Method i s a moderately accurate determination f o r the percent calcium s a t u r a t i o n of the s o i l . The method i s simple and r e s u l t s are r e p r o d u c i b l e . Page 40. Relationship Between Base Saturation of the S o l i and pH. Generally, the pH of a s o i l varies inversely with the base saturation. I f i t varied as some d e f i n i t e function, one could lime a s o i l to a given correct base saturation by u t i l i z i n g the pH-base saturation curve. To study the rela t i o n s h i p between pH and percent base saturation as determined by BrG\-/nrs Method, t h i r t y s o i l s were analysed to find the v a r i a t i o n between these two values. The s o i l s tested were as follows: 16 s o i l s from Vancouver Island - analysed by E. Rldeout (47). 5 s o i l s from Vancouver Island - analysed In this thesis. 9 s o i l s from Fraser Valley - analysed by H.F. Fletcher.(13) The values obtained are l i s t e d i n Table 4 and p l o t t e d i n Fi g . 2. Page 41. TABLE 4. R e l a t i o n s h i p Between pH and Percent Base S a t u r a t i o n . Percent Base No. pH S a t u r a t i o n . E 1 4.92 46.70 Eo 5.68 74.10 E * 4.98 51.60 E 4 5.47 65.30 E 5 4.72 45.20 E f i 5.26 55.30 •K- 5.13 41.20 EQ 5.56 56.90 E q 5.59 55.60 Ejo 5.94 67.60 Et-T 5.58 51.90 E T o 5.79 54.00 E T ? 5.29 46.40 E7]« 5.64 60.70 ET= 5.31 47.10 E T g 5.45 60.40 Cadboro 5.95 68.00 Saanichton 6.10 71.00 A l b e r n i 5.65 60.00 Cowichan 5.55 54.00 Bp, 5.30 49.00 B»i 4.20 23.00 B% 5.20 57.10 B 1 4 5.30 46.62 B , A 5.60 65.80 B T Q 5.72 63.20 B ™ 5.90 68.01 B f V 5 - 6 5 70.04 B r t 5.90 60.05 B g J 5.82 56.00 page in 7.0i 6 5 i 6.0-5.0-4-5-4.0-1 30 ~Zo 50 W P E R C E N T BASE S A T U R A T I O N "80" FIG. 2 R E L A T I O N S H I P B E T W E E N p H AND B A S E S A T U R A T I O N Page 43. The co r r e l a t i o n c o e f f i c i e n t f o r pH and percent base saturation values was .80. This represents a rather strong c o r r e l a t i o n between these two sets of readings. However, from F i g . 2 i t i s easily seen that quite a var-i a t i o n occurs within the o v e r a l l c o r r e l a t i o n . That i s , at any one pH value a v a r i a t i o n up to approximately 20$ base saturation could occur. One can conclude from these values that i t i s not possible to predict accurately the percent base saturation of a s o i l from i t s pH value. These results are i n agreement with other workers (41, 23) who found that s o i l s having the same reaction'could vary considerably i n t h e i r percent base saturation. A Study of the Uptake of Calcium by the S o i l . The amount of exchangeable calcium capable of being held on the exchange complex varies with the ex-change capacity of the s o i l . The uptake of calcium over the entire range from an H-saturated s o i l to a calcium saturated s o i l was ca r r i e d out using the six s o i l types studied. The m i l l i equivalents of calcium hydroxide neutralized w i l l give a measure of the buffer capacity. of the s o i l and the pH range over which this buffer capacity i s greatest. The exchange capacity and base saturation may be calculated from these t o t a l t i t r a t i o n c u r v e s ^ These values were determined and compared to the values obtained by Shollenberger and Brown Methods fable /) page 44. Page 45. Prom the t o t a l t i t r a t i o n curves i t was concluded that: (1) Different s o i l s have d i f f e r e n t t i t r a t i o n curves andfAe buffering properties me. shown by the shape and p o s i t i o n of the curve. (2) That there i s a break i n the curve at four pH units above the o r i g i n a l pH of the aeidoid. This i s i n agreement with what Purl found, who states that this represents the n e u t r a l i z a t i o n of the f i r s t hydrogen. He also states that the number of m i l l i equivalents of base required to r a i s e the pH to this point re-presents the exchange capacity. The exchange capacity determined by t h i s method was compared to Shollenberger and Brown Methods Table 1. (3) The number of m i l l i equivalents of base required to r a i s e the aeidoid to three pH units above the o r i g i n a l pH of aeidoid were also compared to Shollenberger and Brown exchange capacities Table 1. The Relationship Between Base and Calcium Saturation of the  S o i l and Plant Growth. The l i t e r a t u r e review revealed that a d e f i n i t e r e l a t i o n s h i p exists between calcium and base saturation of the s o i l and plant growth. In order to study t h i s re-l a t i o n s h i p on Vancouver Island s o i l s a greenhouse experiment was designed involving f i v e l e v e l s of percent base and calcium saturation on two s o i l types. The two s o i l types chosen were the Cadboro s o i l type from theSaanich Peninsula Page 46. and M e r v i l l e s o i l type from the Courtenay D i s t r i c t . Response of S o i l Types to Lime A p p l i c a t i o n . These two s o i l s were chosen because they represented a good range In exchange c a p a c i t y , base s a t u r a t i o n , ex-changeable calcium and b u f f e r capaeity. Cadboro Sandy Loam i s a s o i l type l o c a t e d on the Saanich Peninsula and rec e i v e s approximately 30 inches of annual r a i n f a l l . A g r i c u l t u r e on t h i s s o i l type c o n s i s t s c h i e f l y of growing small f r u i t s , potatoes, bulbs, seed production and l i m i t e d d a i r y i n g . Experiments have been conducted a t Saanichton Experimental S t a t i o n to determine the response from lime under greenhouse and f i e l d c o n d i t i o n s . No i n c r e a s e i n y i e l d was obtained from lime a p p l i c a t i o n s on the various crops t e s t e d . I t was s e l e c t e d as a s o i l which would notArespond to lime under f i e l d and green-house c o n d i t i o n s . M e r v i l l e Loam i s found i n the Courtenay D i s t r i c t and i s an important a g r i c u l t u r a l s o i l f o r t h i s area. I t re c e i v e s approximately 60 inches of annual r a i n f a l l . The a g r i c u l t u r e c o n s i s t s mostly of d a i r y i n g , growing potatoes and pasture crops. Information about the response to li m e under f i e l d c o n ditions f o r t h i s s o i l type i s q u i t e l i m i t e d . However, from f i e l d observations and farmers' r e p o r t s , i t appears the response to lime i 3 general. Prom pot t e s t s conducted at Saanichton Experimental S t a t i o n , the tendency f o r lime to be b e n e f i c i a l i s q u i t e apparent Page 47. and i t was chosen as a s o i l which w i l l l i k e l y respond to lime under "both greenhouse and f i e l d c o n d i t i o n s . Design of Greenhouse Experiment. Approximately 80 l b s . of s o i l from each of these two s o i l types were passed through a coarse screen to r e -move the stones, twigs and other d e b r i s . F i f t e e n l b s . of Cadboro was leached w i t h 3 l i t r e s of .05 N HC1 and f i f t e e n l b s . with 5 l i t r e s of .05 N HC1. F i f t e e n l b s . of the M e r v i l l e s o i l was leached w i t h 5 1/2 l i t r e s of 0.05 N HC1. During the l e a c h i n g process the leachate was analysed f o r calcium content using ammonium oxalate and the Spurway Quick Test Chart. When the d e s i r e d l e v e l s of calcium were reached the s o i l s were leached w i t h d i s t i l l e d water to r e -move the c h l o r i d e s . This l e a c h i n g w i t h 0.05 N HC1 produced two l e v e l s of calcium and base s a t u r a t i o n . Two l e v e l s of base s a t u r a t i o n above the o r i g i n a l s o i l were obtained by adding calcium hydroxide at two rate s of a p p l i c a t i o n . For the Cadboro Sandy Loam 1.2 m.e. of calcium per 100 gm. of s o i l was added to g i v e a t o t a l of 5 m.e. per 100 gm. I n c l u d i n g the o r i g i n a l ealcium already i n the s o i l . The other l e v e l was obtained by adding 3.20 m.e. of calcium per 100 gm. of s o i l to gi v e a t o t a l calcium content of 7 m.e. per 100 gm. of s o i l . For the M e r v i l l e Loam 6 m.e. of calcium per 100 gm. was added to giv e a l e v e l of 11.4 m.e. of calcium per 100 gm. of s o i l . The h i g h l e v e l was obtained by adding 25 m.e. Page 48. of calcium per 100 gm. of s o i l . F ive l e v e l s of calcium ant base s a t u r a t i o n l e v e l s were obtained then f o r the two s o i l types, each treatment was r e p l i c a t e d three times. The treatments f o r convenience are numbered as f o l l o w s : Cadboro 1 «. Leached w i t h f i v e l i t r e s of 0.05 N HCL Cadboro 2 - Leached w i t h three l i t r e s of 0.05 N HC1 contained 1.59 m.e. calcium a f t e r l e a c h -i n g . Cadboro 3 - O r i g i n a l f i e l d s o i l c o n t a i n i n g 3.80 m.e. of calcium per 100 gm. of s o i l . Cadboro 4 - O r i g i n a l s o i l plus 1.2 m.e. of calcium per 100 gm. of s o i l equivalent to 940 l b s . of Ca(0H)g per acre. T o t a l of 5 m.e. of calcium per 100 gms. of s o i l . Cadboro 5 » O r i g i n a l s o i l plus 3.20 m.e. of calcium per 100 gms. of s o i l equivalent to 2,430 l b s . / a c r e of Ca(0H)g t o g i v e a t o t a l of 7 m.e. of calcium per 100 gms. of s o i l . M e r v i l l e 6 - Leached w i t h 13 l i t r e s of 0.05 N HG1 M e r v i l l e 7 - Leached w i t h 5 1/2 l i t r e s of 0.05 N HCl contained 3.3 m.e. of calcium per 100 gms. of s o i l a f t e r l e a c h i n g . M e r v i l l e 8 - O r i g i n a l s o i l c o n t a i n i n g 5.4 m.e. of calcium per 100 gms. of s o i l . M e r v i l l e 9 - O r i g i n a l s o i l plus 6 m.e. of calcium per 100 gmB. of s o i l equivalent to 4,520 l b s . Ca(0H)g per acre g i v i n g a t o t a l of 11.4 Page 49. m.e. of calcium per 100 gm. of s o i l . M e r v i l l e 10- O r i g i n a l s o i l plus 25 m.e. of calcium per 100 gms. of s o i l equivalent to 19,000 l b s . of Ca(0H)g per acre g i v i n g a t o t a l of 30.4 m.e. of calcium per 100 gms. of s o i l . The f e r t i l i t y l e v e l of the two s o i l types was r a i s e d to a t h e o r e t i c a l optimum l e v e l l e a v i n g the calcium content as the only v a r i a b l e f a c t o r . A m o d i f i c a t i o n of Jenny's Method was used f o r supplying the added n u t i e n t s . The phosphate and nit r o g e n was a p p l i e d as ammonium d l -hydrogen phosphate i n the s o l i d form and mixed w i t h the s o i l . This was to reduce f i x a t i o n of the phosphorous on the s u r f a c e a6 i s often reported when phosphate i s added i n s o l u t i o n . Potassium was added as potassium c h l o r i d e and magnesium as magnesium sulphate. The l e v e l s f o r calcium, magnesium, potassium, n i t r o g e n and phosphorous were checked w i t h Morgan's Quick Test procedure. Minor elements boron, manganese, z i n c , coppesc and i r o n were added i n s o l u t i o n at the commencement of the experiment. S i z e of Pots. Tvro q u a n t i t i e s of s o i l were used i n the experiment, 300 gm and 1200 gm. based on an oven dry weight. The 300 gm. samples were placed In cardboard waxed containers 4" i n diameter by 3" i n height and the l a r g e samples i n containers measuring 5" i n diameter by 6" i n he i g h t . The cardboard Page 5 0 was trimmed.so t h a t only 1ft of the container protruded above the s o l i surface i n order to prevent any shading e f f e c t . Holes were punched i n bottoms and sides of the containers $o a l l o w good drainage and a i d I n a e r a t i o n of the s o i l . I n d i c a t o r Crop. V i r g i n i a n Stock ( C r u f i c e r a e Malcolmia Marltlma R.B.R.) seeds were sown i n f l a t s on January 8 and allowed to grow f o r three weeks. F i v e uniform p l a n t s , averaging from 1 t o 1 1/2 i n . i n hei g h t , were t r a n s p l a n t e d to the. l a r g e pots and four uniform p l a n t s to the small pots on February 1 s t . The pots were randomized every two weeks to overcome the e f f e c t s of any v a r i a b l e f a c t o r s In the greenhouse. The moisture content was maintained at an optimum l e v e l by surface I r r i g a t i o n . The pots were elevated on a p l a t f o r m t o w i t h i n three feet of the glass to prevent s p i n d l y growth. The temperature was maintained between 20°C and 30°C to allo w normal growth of the p l a n t s and the r e l a t i v e humidity was &ept h i g h on warm days to prevent w i l t i n g of the f o l i a g e . V i r g i n i a n Stock i s f r e -quently used i n New Zealand f o r base s a t u r a t i o n s t u d i e s . I t was found to respond to d i f f e r e n t degrees of percent base s a t u r a t i o n and f o r t h i s reason was used as the I n -di c a t o r * p l a n t In t h i s experiment. The p l a n t s were harvested on March 7th and the green weights recorded. The p l a n t s were d r i e d f o r 48 hours at 70°C and the .oven dry weights were recorded. Page 51. E f f e c t of Calcium S a t u r a t i o n on P l a n t Growth. Cadboro Sandy Loam. The oven dry weights of pl a n t m a t e r i a l harvested from f o u r l e v e l s of calcium s a t u r a t i o n are l i s t e d i n Table 5. The weight of each treatment i s the average of three r e p l i c a t e s . These weights are compared to the r e s p e c t i v e calcium s a t u r a t i o n values of the s o i l as de-termined by S h o l l e n b e r g e r 1 s Method (see Methods) and the c o r r e l a t i o n f a c t o r was determined. The r e s u l t s are shown i n F i g . 4. TABLE 5. R e l a t i o n Betvreen Percent Calcium Saturatlonm by Sholl e n b e r g e r 1 e Method and fflaht Growth. S o i l Percent Calcium S a t u r a t i o n Y i e l d Oven Dry Wt. (Grams) Cadboro 2 Cadboro 3 Cadboro 4 Cadboro 5 13.30 30.23 48.90 62.00 .0545 .6856 .8393 .4698 r = .57 S i g n i f i c a n t at b% l e v e l . A c o r r e l a t i o n c o e f f i c i e n t of 0.57 was obtained which i s s i g n i f i c a n t at the 5% l e v e l . This means that a moderately strong c o r r e l a t i o n was obtained between percent calcium s a t u r a t i o n of the s o i l and plant growth. Two of the treatments, numbers f o u r and f i v e , are above t h i r t y percent s a t u r a t i o n . Page 52. Treatment f i v e has a lower y i e l d than treatments three and f o u r . A d e f i c i e n c y symptom was apparent which resembled a phosphate d e f i c i e n c y . A d d i t i o n a l phosphates were added but the d e f i c i e n c y could not be remedied. From F i g . 5 i t can be seen that the p l a n t s were very s p i n d l y from t h i s treatment In comparison to treatments three and four. L i t t l e d i f f e r e n c e i n the morphology between treatments three and four was observed, the p l a n t s were very healthy and vigorous. Treatment four r e s u l t e d i n a l i m i t e d i n c r e a s e i n y i e l d over treatment three. Number one treatment i s not l i s t e d because the p l a n t s were i d e n t i c a l to number two treatment. The p l a n t s i n both these treatments were very s m a l l and unhealthy, the lower leaves turned y e l l o w and d i e d about three weeks a f t e r t r a n s p l a n t i n g . From t h i s data i t can be concluded that a c o r r e l a t i o n does e x i s t between calcium s a t u r a t i o n and p l a n t growth f o r t h i s s o i l type. From treatments one and two i t can be concluded that below a c e r t a i n calcium s a t u r a t i o n p l a n t growth cannot occur. The s o i l contained 1.59 m i l l ! e quivalents of calcium per 100 gms. of s o i l even at these low l e v e l s of calcium s a t u r a t i o n . This represents more calcium than was removed by the healthy p l a n t s on Gadboro 3 treatment and would be s u f f i c i e n t f o r growth had i t been a v a i l a b l e to1" plants. This i s i n agreement with K e l l y (27) who found that at low calcium s a t u r a t i o n values the p l a n t was unable to obtain calcium from the s o i l . Page 53. M e r v i l l e Loam. The r e s u l t s f o r M e r v i l l e Loam are shown In Table 6 and F i g . 4. TABLE 6. R e l a t i o n Between Percent Calcium S a t u r a t i o n  by Shollenberger's Method (see Methods) and Plant Growth f o r M e r v i l l e Loam. S o i l Percent Calcium Plant S a t u r a t i o n Growth M e r v i l l e 2 9.84 .1007 M e r v i l l e 3 15.35 .3742 . M e r v i l l e 4 31.50 1.0700 M e r v i l l e 5 76.00 1.4073 r s. 0.908 s i g n i f i c a n t at the 1% l e v e l . From the data above i t Is evident that a very strong c o r r e l a t i o n e x i s t s between p l a n t growth and calcium s a t u r a t i o n . A c o r r e l a t i o n f a c t o r of 0.908 i n d i c a t e s a l -most maximum c o r r e l a t i o n between these two values. I t i s noted that two treatments are below t h i r t y percent calcium s a t u r a t i o n , the p o i n t where the curve begins to f l a t t e n out. I t i s I n t e r e s t i n g that f o r both Cadboro and M e r v i l l e the f l e x p o i n t occurs at approximately the same calcium s a t u r a t i o n . This l e v e l i n g o f f of the graph i n d i c a t e s that the maximum response to calcium Is obtained below t h i r t y percent calcium s a t u r a t i o n . The h i g h e r cor-r e l a t i o n f a c t o r f o r M e r v i l l e ras compared to Cadboro i s explained by the f a c t that M e r v i l l e has more treatments below t h i r t y percent calcium s a t u r a t i o n . Page 54. I t i s important to note that Cadboro o r i g i n a l without added calcium represents the f l e x point and th a t response t o added lime i s not great. The M e r v i l l e o r i g i n a l without added l i m e , however, i s l o c a t e d on the "steep p o r t i o n of the graph ( F i g . 4) and response to added calcium i s very marked. I t was concluded that 30$ calcium s a t u r a t i o n by Schollenberger's Method ( F i g . 4) and 18$ by the Peech-Brown Method ( F i g . 1) represents the f l e x p o i n t f o r the calcium s a t u r a t i o n growth curves. A l l treatments below these two values gave s i g n i f i c a n t i n c r e a s e In y i e l d from the a p p l i -c a t i o n of lime ( F i g . 6). E f f e c t of Base S a t u r a t i o n on Pl a n t Growth. C The percent base s a t u r a t i o n of the f i v e treatments was determined by Brown's Method (see Methods) f o r both s o i l types Cadboro and M e r v i l l e . The values obtained were compared to the p l a n t over dry weights (Tables 7 and 8) harvested from the r e s p e c t i v e s o i l treatments. Page 56 F i g . 5 Pl a n t Growth on Four Levels of Calcium and Base S a t u r a t i o n f o r Cadboro Sandy Loam P i g . 6 P l a n t Growth on F o u r L e v e l s o f C a l c i u m and Base S a t u r a t i o n f o r M e r v i l l e Loam Page 58 Cadboro Sandy Loam. TABLE 7. C o r r e l a t i o n Between Percent Baae S a t u r a t i o n  by Brown's Method and P l a n t Growth. S o i l Percent Base Satur-a t i o n . (Average of Three Replicates.) Y i e l d i n Grams Oven Dry Weight (Average of three R e p l i c a t e s . ) Cadboro Cadboro Cadboro Cadboro Cadboro 1 2 3 4 5 46.60 51.00 59.50 62.00 71.00 .0441 .0545 .68 56 .8393 .4698 r s 0.69 s i g n i f i c a n t at the 1$ l e v e l . The c o r r e l a t i o n between percent base s a t u r a t i o n and p l a n t growth i s evident as shown by the 0.69 c o r r e l a t i o n f a c t o r . The base s a t u r a t i o n values ranged from 46.60$ to 71$ while the growth in c r e a s e d by twenty times. From F i g . 7 i t i s seen that the f l e x point occurs around 60$ base s a t u r a t i o n . I t v a r i e s s l i g h t l y f o r the two s o i l s but judging by the steepness of the graph up to t h i s value and the l e v e l i n g o f f that occurs, i t appears that l i m i n g to t h i s percent base s a t u r a t i o n i s optimum f o r t h i s crop under greenhouse c o n d i t i o n s . The Cadboro o r i g i n a l s o i l without lime added Is very nearly at the f l e x p o i n t and the response from lime i s s l i g h t . The decrease i n y i e l d f o r number f i v e treatment ( F i g . 5) may be explained on the same basis as i t was i n the previous s e c t i o n under calcium s a t u r a t i o n . Page 59. M e r v i l l e Loam. TABLE 6. R e l a t i o n Between Percent Base S a t u r a t i o n  by Brown's Method and Plant Growth. S o i l Percent Base S a t u r a t i o n Y i e l d i n Grams Gven Dry Weight M e r v i l l e M e r v i l l e M e r v i l l e M e r v i l l e M e r v i l l e 1 2 3 4 5 29.10 33.50 40.30 52.90 78.20 .0681 .1007 .3742 1.0700 1.4073 r s 0.96 s i g n i f i c a n t at 1$ l e v e l . The c o r r e l a t i o n "between percent base s a t u r a t i o n and p l a n t growth f o r t h i s s o i l i s very strong. From F i g . 7 i t i s evident that the f l e x p o i n t occurs around 53$ base s a t u r a t i o n . The spread i n percent base s a t u r -a t i o n between treatments f o u r and f i v e i s too great, another treatment around s i x t y percent s a t u r a t i o n would be h i g h l y d e s i r a b l e . Because treatment four i s s t i l l on the steep p o r t i o n of the curve, i t appears that the dotted l i n e v w o u l d represent approximately the curve had another l e v e l been i n s e r t e d . The f l e x point would then occur very c l o s e to s i x t y percent base s a t u r a t i o n . I f t h i s i s so, i t i s noted t h a t f o r the two s o i l s the f l e x p o i n t occurs at approximately the same value. The q u a n t i t y of p l a n t m a t e r i a l produced on the M e r v i l l e s o i l was much g r e a t e r than that produced en the Cadboro s o i l ( F i g . 5, 6). This i s c l e a r l y demonstrated by the v e r t i c a l distance between the twogrowth curves Page 60. produced ( F i g . 7 ) . The reason f o r t h i s i s d i f f i c u l t to answer and i s p o s s i b l y due to a number of f a c t o r s such as a e r a t i o n and other p r o p e r t i e s Inherent i n the nature of the s o i l . The small pots gave s i m i l a r l y shaped growth curves to the l a r g e pots, only on a d i f f e r e n t growth l e v e l . From data presented f o r the two s o i l s , i t i s apparent t h a t a c o r r e l a t i o n e x i s t s between growth and calcium s a t u r a t i o n and between growth and base s a t u r a t i o n . The occur f l e x p o i n t f o r the growth curves/at approximately t h i r t y percent calcium s a t u r a t i o n and s i x t y percent base s a t u r -a t i o n . This i s strong evidence that percent base s a t u r a t i o n or percent calcium s a t u r a t i o n may be used to p r e d i c t the need f o r calcium i n the s o i l . Page 61. PERCENT BASE SATURATION FIG- T RELATIONSHIP BETWEEN PLANT GROWTH ANO BASE SATURATION Page 62. R e l a t i o n s h i p Between Percent Base S a t u r a t i o n of the  S o i l and Percent Calcium .In the P l a n t . Of CM« Soil The percent base saturationAwas determined "by Brown's Method and the percent calcium (see Methods) i n the p l a n t was determined and expressed on a percent oven dry weight "basis. The values obtained f o r the two s o i l s are l i s t e d according to i n c r e a s i n g percent base s a t u r a t i o n . The two s o i l s were analysed together r a t h e r than s e p a r a t e l y . TABLE 9. R e l a t i o n of Percent Calcium.in the P l a n t w i t h  Percent Base S a t u r a t i o n of the S o i l . S o i l Percent Base Percent Calcium S a t u r a t i o n Oven Dry V/eight M e r v i l l e 7 33. 50 1.00 M e r v i l l e 8 40. 30 .70 Cadboro 2 51. 00 .88 M e r v i l l e 9 52. 00 1.63 Cadboro 3 59. 50 1.51 Cadboro 4 62. 00 2.15 Cadboro 5 71. 00 1.94 M e r v i l l e 10 78. 20 5.90 r = 0.80 s i g n i f i c a n t at b% l e v e l . From the above data a good general c o r r e l a t i o n e x i s t s between these two values. There i s , however, a f l u c t u a t i o n w i t h i n the c o r r e l a t i o n shown by treatments Cadboro 3 and M e r v i l l e 9. A f l u c t u a t i o n of t h i s nature might be expected, e s p e c i a l l y when comparing d i f f e r e n t s o i l s because one i o n may s u b s t i t u t e f o r another i o n i n the feeding of the p l a n t . The Ga/Mg r a t i o c ould i n f l u e n c e Page 63. the amount of calcium absorbed by a p l a n t as w e l l as many other f a c t o r s other than percent base s a t u r a t i o n of the s o i l . I t i s important to note, however, that the calcium content of the p l a n t can be r a i s e d by i n c r e a s i n g the base s a t u r a t i o n of the s o i l . The proper calcium content according to Hunter (22) must be maintained i n the p l a n t . The E f f e c t of the S i z e of Pot and Quantity of S o i l  on P l a n t Growth. In o u t l i n i n g the greenhouse experiment i t was f e l t t h at the amount of s o i l used i n the experiment might i n -f l u e n c e the y i e l d . That i s , f o r s o i l s having a low degree of base s a t u r a t i o n i t was thought that the p l a n t s might o b t a i n more calcium through contact with a l a r g e r number of s o i l c o l l o i d s . However, I f below a c e r t a i n de-gree of s a t u r a t i o n the cations became un a v a i l a b l e to the p l a n t , then i t would make l i t t l e d i f f e r e n c e how many c o l l o i d s the p l a n t contacted, and the elements would s t i l l be In short supply even though the amount of s o i l was i n -creased. The E f f e c t of the Quantity of S o i l on V a r i a b i l i t y  W i t h i n the Experiment. The y i e l d s are shown i n Tables 10, 11, 12 and 13. The oven dry weights were analysed s t a t i s t i c a l l y to de-termine whether s i g n i f i c a n t increase i n y i e l d s r e s u l t e d due to treatments. The standard e r r o r of mean was determined as a measure of v a r i a t i o n w i t h i n the experiment. Page 64. Cadboro Sandy Loam - Large Pots. TABLE 10. Y i e l d s Expressed on Oven Dry Weight B a s i s . Treatments R e p l i c a t e s M Cadboro 2 .0407 .0475 .0460 .0447 Cadboro 3 .6926 .6922 .6730 .6859 Cadboro 4 .8655 .8622 .7843 .8373 Cadboro 5 .4180 .6070 .3845 .4698 SE^ s 17.94$ S i g n i f i c a n t 5$ l e v e l M.S.D. = 0.189 Cadboro Sandy Loam - Small Pots. TABLE 11. Y i e l d s Expressed on Oven Dry Weight B a s i s . Treatments R e p l i c a t e s 15 Cadboro 1 .0407 .0475 .0410 .0431 Cadboro 2 .0563 .0528 .0500 .0530 Cadboro 3 .0178 .0963 .1148 .0763 Cadboro 4 .1168 .2214 .1531 .1638 Cadboro 5 .1864 .2394 .2722 .2327 SE^ c 58.48$ S i g n i f i c a n t 5$ l e v e l M.S.D. s 0.0751 Page 6 5 . M e r v i l l e Loam - Large Pots. TABLE 1 2 . Y i e l d s Expressed on Oven Dry Weight B a s i s . Treatments R e p l i c a t e s M M e r v i l l e 6 M e r v i l l e 7 M e r v i l l e 8 M e r v i l l e 9 M e r v i l l e 1 0 . 0 8 8 3 . 0 9 9 2 . 2 8 2 6 1 . 0 8 7 3 1 . 5 8 6 2 . 0 4 7 5 . 1 0 2 3 . 3 8 6 5 1 . 0 2 5 2 1 . 4 8 4 0 . 0 5 5 2 . 0 9 9 ? . 4 5 3 5 1 . 0 9 7 6 1 . 1 5 1 6 . 0 6 3 8 . 1 0 0 4 . 3 7 4 2 1 . 0 7 0 0 1 . 4 0 7 2 SEg m 2 4 . 2 3 $ S i g n i f i c a n t 1 $ l e v e l M.S.D. m 0 . 0 9 3 3 M e r v i l l e Loam - Small Pots. TABLE 1 3 . Y i e l d s Expressed on Oven Dry Weight B a s i s . Treatments R e p l i c a t e s M e r v i l l e 6 M e r v i l l e 7 M e r v i l l e 8 M e r v i l l e 9 M e r v i l l e 1 0 . 0 3 3 3 , 0 9 5 0 . 2 2 4 4 . 5 7 8 0 . 8 5 8 7 . 0 4 0 6 , 0 8 0 7 , 1 0 3 4 . 5 3 0 4 , 7 5 0 0 . 0 3 9 5 . 0 5 6 5 . 1 1 8 9 . 5 5 9 5 . 3 9 0 7 . 0 3 8 0 . 0 7 7 4 . 1 4 8 9 . 5 5 5 6 . 8 3 3 1 S E J J - 2 5 . 3 4 $ S i g n i f i c a n t 1 $ l e v e l M.S.D. a 0 . 0 6 7 1 Page 6 6 . The standard error of the mean for the large pots i s less than the standard error of the mean for the small pots. This i s true for both the Cadboro and Merville s o i l types. It would appear from this data that the large pots are better suited for a study of this nature. Significant increase in yields resulted for a l l treatments over Cadboro two in the large pot experiment. No sig-nificant increase in y ie ld resulted for treatment four over three, which Is the original s o i l without added lime. This further confirms the conclusion reached re-garding Fig . 4, that the flex point for the growth curve when plotted against percent calcium saturation, and Fig . 7 when plotted against percent base saturation, occurs at this treatment l eve l . From these three values one may conclude that calcium added to Cadboro Sandy Loam did not significantly increase plant growth over the original s o i l treatment. That i s , no response in y ie ld was obtained from the use of lime. Significant decrease In y ie ld re-sulted for treatment five over treatments three and four. The addition of lime to this level Induced deficiencies in the plant that could not be remedied. The y ie ld as a result i s lower than for the other two treatments. High significant differences between treatments resulted for the Merville Loam. In the large pot experi-ment, treatment seven gave a significant increase over six, treatment eight over seven, nine over eight and Page 67. treatment ten over nine. I f another treatment had been Inserted between treatments nine and ten representing a percent base saturation of sixty percent, a significant difference in y ie ld would not l ike ly have resulted for the last two treatments. The approximate y ie ld for this treatment, had i t been inserted, can be estimated from the graph in Fig . 7. This is further proof that the flex point for the growth percent base saturation occurs at sixty to sixty-two percent base saturation by Brown's Method and thirty to thirty-two percent calclumAby Shollenberger's Method. It was concluded then that for both Cadboro Sandy Loam and Merville Loam that the additions of lime to above approximately sixty percent base saturation and approximately thirty percent calcium saturation did not result in significant increase in yields,from the additions of lime for this particular crop under greenhouse conditions. This is also further evidence that the lime requirement of a s o i l may be estimated from i t s calcium and base saturation. The Effect of the Quantity of So i l on Plant Growth. The difference between the mean yields obtained in the small pots of so i l and the mean yields obtained in the large pots of s o i l xiras s t a t i s t i ca l ly analysed for both soi ls to see i f significant differences resulted. This should give an indication whether the amount of s o i l or the Page 68. feeding zone of the plant had any effect on the results obtained. Cadboro Sandy Loam. TABLE 14. Comparison of Yie ld Means of Large and Small Pots. Treatment Large A Small B A - B Cadboro 2 Cadboro 3 Cadboro 4 Cadboro 5 .0447 .6859 .8373 .4698 .0530 .0763 .1638 .2323 .0083 .6096 .6735 .2373 M.S.D. = .587 Merville Loam. TABLE 15. Comparison of Yie ld Means of Large and Small Pots. Treatment Large A Small B A _ B Mervil le 6 Mervil le 7 Merville 8 Merville 9 Mervil le 10 .6380 .1004 .3742 1.0700 1.4072 .6000 .0230 .2253 . 5144 .5741 .0258 .0230 .2253 .5144 .5741 M.S.D. e .387 Page 69. Significant differences between large and small pots resulted for treatments three and four on the Cadboro s o i l type, but not for treatments two and five. S ign i f i -cant differences between large and small pots resulted for treatments nine and ten, but not for treatments six, seven and eight for the Merville Loam. From the percent base saturation values for these treatments, i t appears that significant differences did not occur at the lower percent base saturation, but did occur for the higher percent base saturation values, especially between sixty and seventy percent saturation. It seems probable from the data obtained from these two soils that the quantity of s o i l or the total amount of calcium present in the feeding zone is not important at low percent base saturation levels . The calcium seems to f a l l off rather quickly in i t s avai labi l i ty for plant growth at these low levels . It is important to note that as much as 3.33 m.e. of calcium per 1G0 gm. of s o i l i s present in Merville 7 treatment and 5.79 m.e. of calcium per 100 gm. of s o i l for Merville 8 treatment and yet significant differences between means did not exist. On the other hand, Cadboro 3 treatment contains 3.92 m.e. of calcium per 100 gm. of s o i l but at a higher percent base and calcium saturation level than the two Merville treatments. The above comparison tends to prove that i t is not Page 70. the amount of calcium present i n m i l l i equivalents per 100 gm. of s o i l but i s rather a function of the calcium and base saturation. This i s also i n agreement with Kelly's (2?) remarks that the a v a i l a b i l i t y of calcium to plants f a l l s o f f very quickly below a certain calcium saturation. In summary, the calcium and base saturation of the s o i l had a pronounced effect on the y i e l d and composition of the plant. A good cor r e l a t i o n was obtained between both calcium and base saturation of the s o i l and yi e l d s obtained f o r both s o i l types. The f l e x point on the growth calcium saturation curve occurred at approximately 30$ calcium saturation and on the base saturation growth curve at approximately 60$ base saturation. The Increase i n y i e l d obtained above these saturation values was not s i g n i f i c a n t at the 5$ l e v e l . A c o r r e l a t i o n was obtained between percent base saturation i n the s o i l and percent calcium i n the plant. In order to determine the optimum calcium l e v e l i n the plant other cations should be determined. However, i t i s important to note that by increasing the percent base saturation of the s o i l the calcium content of the plant also increases. The s i z e of pot affected the v a r i a b i l i t y within the experiment, the 1200 gm. sample of s o i l giving a lower v a r i a b i l i t y than the 300 gm. sample. The quantity Page 71 of s o i l or s i z e of feeding zone d i d not s i g n i f i c a n t l y a f f e c t the y i e l d at the lower percent base saturation. For the treatments above 50$ base saturation, s i g n i f i c a n t differences In y i e l d f o r the 1200 gm. samples over the 300 gm. samples resulted. This indicates that below a c e r t a i n percent base saturation calcium i s not available for plant growth. Many quick methods fo r estimating the calcium l e v e l i n s o i l s may lead to erroneous conclusions for they estimate only the quantity of calcium present. Lime Requirement. I t was shown i n the previous sections that below a certain percent base saturation calcium Wesnot available for plant growth, between t h i s point and 60$ fease satur-ation good response was obtained, above which l i t t l e i n -creased growth from lime application resulted. Therefore, It i s evident that an estimate of lime requirement be founded on the base saturation of the s o i l . S o i l re-action i s most frequently used as basis f o r estimating lime requirement, but as was pointed out, i t i s not an exact measurement of base saturation. Other tests f r e -quently used include estimation of calcium content and exchangeable hydrogen. In t h i s study the lime requirement of the s i x f i e l d s o i l s was determined and compared by three methods I (1) Percent Base Saturation expressed on a volume weight basis. Page 72. (2) Pereent Base S a t u r a t i o n expressed on a weight b a s i s . (3) Dunn T i t r a t i o n Curves expressed on a weight b a s i s . Percent Base S a t u r a t i o n Method by Volume Weight. The conventional way of expressing the lime require* ment of a s o i l i s on a weight basis by assuming an acre of s o i l t o a depth of 6 2/3 inches weighs 2,000,000 l b s . Many s o i l s , however, weigh much l e s s than t h i s assumed f i g u r e . At the commencement of t h i s study cores of un-d i s t u r b e d s o i l were eramples and the n o n - c a p i l l a r y p o r o s i t y , c a p i l l a r y p o r o s i t y and apparent s p e c i f i c g r a v i t i e s were determined (Fig.. 8 ) . These values are l i s t e d i n Table 16. TABLE 16. P o r o s i t y and Apparent S p e c i f i c G r a v i t y , .Determinations. S o i l Non-Capillary T o t a l Apparent P o r o s i t y P o r o s i t y S p e c i f i c G ravity A l b e r n i 36.88 70.82 .753 Cowichan 17.90 53.35 .960 M e r v i l l e 14.98 65.25 .805 Peat 16.57 90.50 .166 The apparent s p e c i f i c g r a v i t i e s f o r the three m i n e r a l s o i l s v a r i e d from .605 to .960, the peat was low at .166. The weight of an acre of dry s o i l to a depth of 6 2/3 inches f o r the various s o i l types expressed on a volume weight b a s i s are l i s t e d In Table 17. For the method of c a l c u l a t i o n see Methods, Page 30. Page 73. TABLE 17. Dry Weight In l b s . Expressed on a Volume Weight B a s i s . S o i l l b s . per acre to a depth of 6 2/3 i n s . A l b e r n i 1,130,000 Cowlchan 1,440,000 M e r v i l l e 906,500 Peat 249,000 The lime requirement of four s o i l types was c a l -c u l a t e d on a volume weight ba3is using the values c a l c u l a t e d i n Table 17 as the weight of an acre of s o i l to a depth of 6 2/3 inches. The l b s . of calcium carbonate per acre r e -q u i r e d to r a i s e the s o i l to three l e v e l s of percent base s a t u r a t i o n are l i s t e d i n Table 18. TABLE 18. The Lime Requirement by Percent Base S a t u r a t i o n  Expressed on a Volume Weight B a s i s . S o i l Calcium Carbonate l b e ^ P e r Acre base satn. 65$ base satn. 70$ base satn A l b e r n i n i l f723 1,448 Cowichan n i l 129 1,381 M e r v i l l e 1,900 2,678 4,830 Peat 3,286 3,970 4,220 converted from calcium hydroxide. Page 7 4 No. S o i l Depth A± M e r v i l l e 0-3" B 1 M e r v i l l e 3-6" • Cn Peat D^^ Peat 0-3" 3-6" A o A l b e r n i 0-3" 3 2 A l b e r n i 3-6" C g Cowlchan 0-3" D 2 Cowichan 3-6" Core Samples of S o i l I n d i c a t i n g S i z e of Cores, S t r u c t u r e of S o i l and Shrinkage from Oven Drying Page 75 The amount of lim e r e q u i r e d to r a i s e the percent base s a t u r a t i o n of the s o i l to three l e v e l s was c a l c u l a t e d (see Methods). Some high lime requirement crops might g i v e optimum response from lime at the higher l e v e l s . At 60$ base s a t u r a t i o n the lime requirement i s q u i t e low f o r these f o u r s o i l types. These values would have to be i n c r e a s e d according to the l i m i n g f a c t o r . Percent Base S a t u r a t i o n Method by Weight. The lim e requirement f o r s i x s o i l types was deter-mined (see Methods) by the Percent Base S a t u r a t i o n Method expressed on a weight b a s i s . The l b s . of calcium carbonate per acre r e q u i r e d to r a i s e the s o i l s to three l e v e l s of percent base s a t u r a t i o n are l i s t e d i n Table 19. TABLE 19. Lime Requirement by Percent Base S a t u r a t i o n  Method on a Weight B a s i s . S o i l Calcium * Carbonate l b s . Per Acre 60$ base satn . 65$ base satn. 7C )$ base satn. Cadboro n i l n i l 442 Saanichton n i l n i l n i l A l b e r n i n i l 1,280 2,560 Cowlchan n i l 180 1,920 M e r v i l l e 4,200 5,900 10,660 Peat 26,400 31,900 33,900 converted from calcium hydroxide. Page 76. The values i n Table 19 represent the amount of calcium carbonate r e q u i r e d to r a i s e the various s o i l types to the three l e v e l s of percent base s a t u r a t i o n as c a l c u l a t e d i n the l a b o r a t o r y . Lime Requirement by Dunn T i t r a t i o n Curves. The lime requirement of the s i x s o i l types was determined from Dunn's T i t r a t i o n Curves ( F i g . 9) ex« pressed on a weight b a s i s . The l b s . of calcium, carbonate per acre r e q u i r e d to r a i s e the s o i l to a pH 6.5 are l i s t e d i n Table 20. TABLE 20. Lime Requirement as Determined by T i t r a t i o n  Curves Expressed on a Weight B a s i s . S o i l Calcium Carbonate l b s . / a c r e Calcium Carbonate l b s . / a c r e Liming Factor 1.5 Cadboro 1,053 1,582 Saanichton 540 810 A l b e r n i 1,880 2,820 Cowi chan 2,100 3,158 M e r v i l l e 5,000 7,500 Peat 15,800 23,700 The above c a l c u l a t i o n s represent the amount of calcium carbonate r e q u i r e d to r a i s e the various s o i l types to a pH 6.5. The amounts c a l c u l a t e d i n the r i g h t hand column represent the amounts of calcium carbonate needed assuming a l i m i n g f a c t o r of 1.5. P a g e 77. Page 78. It was concluded from a comparison of the three methods that: (1) Lime should be applied by the Percent Base Saturation Method expressed on a volume weight basis. This is especially important for peats and high organic soils with low apparent specific gravities. When lime requirement is calculated on a weight basis for these soils, sufficient lime is applied to raise an acre of s o i l to a depth of two to three feet to the required base saturation level. A l l this lime, however, is mixed with the surface 6 to 12 inches and overliming of these horizons may occur. (2) For a l l soils except the peat the lime requirement was higher by the Titration Curves than by the Per-cent Base Saturation Methods at the 60$ saturation level. (3) At 60$ base saturation a l l the mineral soils had pH values of less than 6.5. For different crops different base saturation levels would be desirable. The corresponding pH values could be predicted from the titr a t i o n curves. (4) Lime was required for the Cadboro and Saanichton soils when estimated by the Titration Curve Method but not when estimated by the Percent Base Saturation methods. Since these s o i l types do not respond to lime under f i e l d conditions, i t would appear then that the Percent Base Saturation methods give a better Page 79. approximation of the lime requirement than by Titrat ion Curves liming to a pH 6.5. (5) Lime requirement for the six soi ls determined by Percent Base Saturation method expressed on a volume weight basis gave lower values than the other two methods. (6) A liming factor may have to be determined from f i e ld experimentation. (7) That peats may not require liming to 60$ base satur-ation. This i s In agreement with Anderson (7) who found that Vancouver Island peats gave optimum yie ld at approximately 50$ base saturation. Summary and Conclusions. 1. The cation exchange capacities were determined on fourteen soils by the Shollenberger, Purl and Brown Methods. Shollenberger's Method is one of the most widely used procedures but is very time consuming. The other two methods were compared to this technique for rapidity, accuracy and precision. Brown's Method proved simple, rapid and gave reproducible results. It gave higher values for soils with low exchange capacities and lower values for soils with high exchange capacities than Shollenberger1 s Method. These differences, due to the different extracting solutions employed in the two methods, were consistent and Brown*s Method was con-sidered very satisfactory. The Puri Method gave comparable Page 80 r e s u l t s w i t h Brown's but was very lengthy. 2. Percent base s a t u r a t i o n values were determined by the Shollenberger, Brown and P u r i Methods. Considerable v a r i a t i o n occurred between methods, e s p e c i a l l y at the hi g h percent base s a t u r a t i o n l e v e l s . A l l three methods, however, d i s t i n g u i s h e d between hig h and low s a t u r a t i o n va l u e s . The Brown Method as w e l l as being r a p i d and simple gave s a t i s f a c t o r y r e s u l t s . 3. The r e l a t i o n s h i p between base s a t u r a t i o n and pH was determined f o r t h i r t y s o i l s . As much as twenty percent v a r i a t i o n i n base s a t u r a t i o n was noted between s o i l s having the same pH value. Therefore, percent base s a t u r a t i o n of a s o i l cannot be estimated w i t h a high degree of accuracy from i t s pH value. 4. Hydrogen sa t u r a t e d s o i l s were obtained by l e a c h i n g w i t h .05 N h y d r o c h l o r i c a c i d . The uptake of calcium by a s o i l was s t u d i e d over the e n t i r e range from a H-saturated s o i l to a Ca-saturated s o i l . Each s o i l had a d i f f e r e n t t i t r a t i o n curve. A break i n the curves occurred at approximately a pH of 8, i n d i c a t i n g the n e u t r a l i z a t i o n of the f i r s t hydrogen of a d i b a s i c a c i d . The p o s i t i o n and shape of the curves i n d i c a t e the b u f f e r capacity of the s o i l . 5. F i v e l e v e l s of percent base and calcium s a t u r a t i o n were produced on Cadboro and Saanichton s o i l types. V i r g i n i a n atook was grown as the i n d i c a t o r crop i n these s o i l s under Page 81. greenhouse conditions. Correlation coefficients for calcium saturation and plant growth were .57 and .91 for the Cadboro and Merville soi ls respectively. Base satur-ation and plant growth showed a correlation of .59 for the Mervil le and .90 for the Cadboro so i l s . The flex point for the growth-saturation curves on both s o i l types occurred at 30$ calcium saturation and 60$ base saturation. Significant increases in y ie ld were obtained up to these points. Response to the addition of lime In the greenhouse using the flex point as the optimum level of saturation coincided with known response in the f i e l d . This i s strong evidence that calcium or base saturation can be used to de-termine when a s o i l requires lime under f i e ld conditions. 6. A correlation coefficient of .80 was obtained for per-cent base saturation of the s o i l and percent calcium in the plant. The calcium content of the plants ranged from .7 to 5.90$. 7. Two quantities of s o i l , 300 and 1200 gm. samples, were used in the greenhouse study. Greater var iab i l i ty in growth occurred In the smaller pots indicating the larger pots were better suited for studies of this nature. Significant differences between the growth means for the small and large pots occurred for both soils at levels of base satur-ation above 50$. This indicates that calcium is not avai l-able to the plant at low base saturation levels . Further-more, an increase in the tota l calcium by using a larger Page 82. s o i l volume had l i t t l e effect. 8. The lime requirements for the six s o i l types were de-termined by three methods; (1) Percent Base Saturation expressed on a volume basis. (2) Percent Base Saturation expressed on a weight basis. (3) Titrat ion Curves expressed on a weight basis. The la t ter two methods indicated extremely large quantities of lime were needed for peat and soils high in organic matter. It was concluded such quantities were not economical and overllming of the surface horizons may result . 9. A method is suggested for testing a s o i l for lime re-quirement: (1) By indicating whether a s o i l requires lime. (2) By expressing i t s lime requirement on a Volume Weight basis. Page 83. BIBLIOGRAPHY. 1. Annual Report, "Tree F r u i t V a r i e t y Experiments" Dominion Experimental S t a t i o n , Saanichton, V o l . 1, p. 27, 1944. 2. Annual Report, " E f f e c t of Lime on the Increase of T u l i p Bulbs". Dominion Experimental S t a t i o n , Saanichton. V o l . 1, p. 84, 1947. 3. Annual Report, "The Value of Lime on Vancouver I s l a n d S o i l s " . Dominion Experimental S t a t i o n , Saanichton. V o l . 2, p. 263, 1945. 4. Annual Report, "The Value of Lime on R o t a t i o n of F i e l d Crops". Dominion Experimental S t a t i o n , Saanichton. V o l . 2, 1947. 5. Annual Report, "The F e r t i l i z e r Requirements and R e l a t i v e P r o d u c t i v i t y of Vancouver I s l a n d S o i l s as Determined "by Pot Tests". Dominion E x p e r i -mental S t a t i o n , Saanichtonj V o l . 2 , p. 280, 1946. 6. Allaway, W.H., " A v a i l a b i l i t y of Replaceable Calcium f o r D i f f e r e n t Types of C o l l o i d s as A f f e c t e d by -Degree of Calcium S a t u r a t i o n . " S o i l Science, V o l . 59, 1945. 7. Anderson, H.R., " F e r t i l i t y Studies on Some Vancouver I s l a n d Peat S o i l s " . Van. Dept. of Agron., Univ. of B r i t . C o l . (unpublished B a c h e r l c r s T h e s i s ) . 1949. 8. Bear, F.E. and Toth, S.J., " i n f l u e n c e of Calcium on A v a i l a b i l i t y of Other S o i l Cations". New Jersey A g r i c u l t u r a l Experiment S t a t i o n , S o i l Science, V o l . 65, 1948. 9. B r a d f i e l d , R., "The Use of E l e c t r o d i a l y s i s i n Physlo-Chemleal I n v e s t i g a t i o n s of S o i l s " . Proc. and Papers, F i r s t I n t e r n a t l . Cong., S o i l Science 2, p. 264, 1927. 10. Brown, I . C , "A Rapid Method f o r Determining Exchangeable Hydrogen and T o t a l Exchangeable Bases In S o i l s " , S o i l Science , V o l . 56, p. 353, 1943. 11. Dunn, L.E., "Lime Requirement Determination of S o i l s by Means of T i t r a t i o n Curves". S o i l Science, V o l . 56, p. 341, 1943. Page 34. 12. 15. 16. 17. 18. 19. 20. 21. 22. Farstad, L.F., " D e s c r i p t i v e Legend of Vancouver I s l a n d S o i l s " . Dom. Dept. of A g r l e . (unpublished). 1951. 13. F l e t c h e r , H.F., "Potassium E s t i m a t i o n , F i x a t i o n and Release i n Loxirer Fraser V a l l e y S o i l s " . Van, Dept. of Agron., Univ. of B r i t . C o l . (un-published Master's T h e s i s ) . 195<D. 14. Gardner, E.H., "Cation Exchange Studies on Cowlehan Clay and Keating Sandy Loam S o i l s of the Saanich Pe n i n s u l a " . Van. Dept. of Agron., Univ. of B r i t . C o l . (unpublished Bachelors T h e s i s ) . 1950. Gedroiz, K.K., " C o n t r i b u t i o n to Determining Z e o l l t i c Bases i n S o i l s " . Zhur., Opyln, Agron. (Russian) 19. Gedroiz, K.K., " M o b i l i t y of S o i l Compounds and the I n -fluen c e of Calcium Upon I t . " . Nossov. Agr. Exp. S t a t . , B u i . 43, 1926. Gedroiz, K.K., "Exchangeable Cations of S o i l and the P l a n t : I R e l a t i o n o f P l a n t to C e r t a i n Cations F u l l y S a t u r a t i n g the S o i l Exchange Capacity". S o i l Science, V o l . 32, p. 51, 1931. Golden, L.B., Gamon, N., and Thomas, R.P., "A Comparison of Methods o f Determining the Exchangeable Cations and the Exchange Capacity of Maryland S o i l s " . S o i l Science Society of America Proceedings., V o l . 7, 1942. Hanna, W.J. and Read, F.J., "A Comparison of Ammonium Acetate and Bu f f e r e d Barium C h l o r i d e Methods f o r Determining Cation Exchange P r o p e r t i e s of Limed S o i l s " . S o i l Science, V o l . 66, 1948. Harada, M., "Exchangeable Bases I n S o i l s " . B u i . , Agr., Chem., S o c , Japan 4} 41. H i s s i n k , D.J., "Base Exchange In S o i l s " . S o c i e t y , p. 551, 1920. Trans Faraday Hunter, A.S., " Y i e l d and Composition of A l f a l f a as A f f e c t e d by V a r i a t i o n s i n the Ca/Mg R a t i o i n the S o i l " . S o i l Science, V o l . 67, p. 53, 1941. 23. J o f f e , J.S. and McLean, H.C., " C o l l o i d a l Behavior of S o i l s and F e r t i l i t y I I The S o i l Complex Capable of Base Exchange and S o i l A c i d i t y " . S o i l Science 21, p. 181. 1927. Page 85. 24. Jonee, C.H., "The Determination of Lime Requirement by the Caleium Acetate Method". Amer. P e r t . 39, p. 27, 1913. 25. Happen, H., "Der Salegringszustand der Bodens und seine Bestimmung". F o r t s c h r . Landev 3, p. 1009, 1928. 26. Karraker, P.E., "The Delayed E f f e c t of Liming". S o i l Science 24, p. 147, 1926. 27. K e l l y , W.P., "Cation Exchange i n S o i l s " . Reinhold P u b l i s h i n g Corp., New York, U.S.A. 28. K e l l y , W.P. and Brown, S.M., "Replaceable Bases i n S o i l s " . C a l i f . Ag. Sta. Tech. Paper 14, 1924. 29. L l e b i g , J . Von, "Ueber Kieselsaurehydrat und K i e s e l s a u r e s Ammonlak". Ann. Chem. Pharm., 94, p. 373. 30. Lutz, H.J. and Chandler, R.F., "Forest S o i l s " . 31. M a r s h a l l , C.E. and Ayers, A.D., "Clay Membrane Electrodes f o r Determining Caleium A c t i v i t i e s " . S o i l Science Society of America Proceeding 11, p. 171. 1946. 32. Matson, S. and Hester, J.B., "The Laws of S o i l C o l l o i d a l Behavior: X Exchange N e u t r a l i t y and Combing Capacity". S o i l Science 34, p. 459, 1932. 33. Mehlieh, A., " E f f e c t of S o i l C o l l o i d on Cation Absorption Capacity and on Exchangeable Hydrogen and Calcium as Measured by D i f f e r e n t Methods". S o i l Science, V o l . 61, 1942. 34. Mehlieh, A., "Determination of Cation and Anion Ex-change P r o p e r t i e s of S o i l s . " S o i l Science, V o l . 66, 1948. 35. M i l e s , I . E . , " A v a i l a b l e Calcium Supply i n Poorly Buffered S o i l s " . S o i l Science, V o l . 65, 1948. 36. Parker, F.W., "The Determination of Exchangeable Hydrogen i n S o i l s " . J o u r n a l of American Soc i e t y of Agronomy, V o l . 21, p.. 1030. 1929. 37. Peech, M., "Determination of Exchangeable Cations and Exchange of S o i l s _ Rapid Micro - Methods U t i l i s i n g C entrifuge and Spectrophotometer'-!. S o i l Science, V o l . 59, 1945. Page 86. 38. Peech, M. and Bradfield, R., "Chemical Methods for Estimating Lime Needs of Soi l s " . So i l Science, Vol . 65, 1948. 39. Peech, M. and Leah, E . , "Rapid Microckemlcal So i l Tests". So i l Science, Vol . 57, p. 167. 1944. 40. Pierre, W.H., "Buffer Capacity of Soils and i ts Relation to the Development of Acidity from the use of Ammonium Sulphate". Journal of American Society of Agronomy, Vol . 19, p. 332, 1927. 41. Pierre, W.H. and Scarseth, G.D., "Determination of the Percentage Base Saturation of Soils and i t s Value in Different Soils at Definite pH Values". So i l Science, p. 99, 1931. 42. Powers, W.L. , "The Effect of Hydrogen-Ion Concentration on the Growth of Certain Plants". So i l Science 33, p. 290. 43. Puri , A . N . , "Interaction Between Ammonia and Soils as a Method of Determining the State of Saturation and the pH Values of So i l s " . So i l Science, Vol . 33, 1932. 44. Puri , A . N . , "Soils Their Physics and Chemistry". Reinhold Publishing Corp., 1949. 45. Puri , A.N. and Uppal, H . L . , "Base Exchange in So i l s : A C r i t i c a l Examination of the Methods of Finding Base Exchange Capaeity of Soi l s " . So i l Science, Vol . 47, 1939. 46. Purvis, E.R. and Davidson, O.W., "Review of the Relation of Calcium to the Avai labi l i ty and Absorption of Certain Trace Elements by Plants". New Jersey Agricultural Experiment Station. Soi l Science, Vol . 65, 1948. 47. Rideout, E . F . , "A Study of Slash Burning and i t s Effect on a Br i t i sh Columbia Forest S o i l " . Van. Dept. of Agron., Univ. of B r i t . Col. (un-published Master's Thesis). 1949. 48. Host, C O . and Zetterberg, J .M. , "Replaceable Bases in Soils of Southeastern Minnesota and the Effect of Lime Upon Them". Soi l Science, Vo l . 33, p. 249. 49. Russel, E.W., "Soi l Conditions and Plant Growth", Longmans, Green and Co., Toronto. Page 87. 50. Srhollenberger, C . J . , ani. Simon, R .H. , "Determination of Exchange Capacity and Exchangeable Bases i n S o i l " . So i l Science, Vol . 59, 1949. 51. Smith, G.E. and Heater, J .B . , "Calcium Content of Soils and Fert i l izers in Relation to Composition and Nutritive Value of Plants". Soi l Science, Vol . 65, 1948. 52. Spilsbury, R .H. , "So i l Survey Southeast Portion of Vancouver Island". B r i t . Col. Dept. of Lands and Forests, 1944. 53. Stepheneon, R . E . , "The Effect of Organic Matter on Soi l Reaction". So i l Science 12, p. 145, 1921. 54. Thompson, H.S. , "On the Absorbent Powers of So i l s " . Journal Royal Agricultural Society, 11, p. 68, 1927. 55. Toth, S.J.. and Prince, A . L . "Estimation of Cation Ex-change Capacity and Exchangeable Ca, X and Na Contents of Soils by Flame Photometer Techniques". So i l Science, Vol . 5 7 , 1949. 56. Vlamis, J . , "Plant Growth and Calcium Saturation of Soi l s " . So i l Science, Vo l . 67, 1949. 

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