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Soil testing for phosphorus availability to some conifers in British Columbia Curran, Michael Patrick 1984

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SOIL TESTING FOR PHOSPHORUS AVAILABILITY TO SOME CONIFERS IN BRITISH COLOMBIA by MICHAEL PATRICK CURRAN B.Sc. Biology and Geography, The University of V i c t o r i a , 1981 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of S o i l Science) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA October 1984 ® Michael P a t r i c k Curran, 1984 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of S O I L S C I E N C E The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date OCTOBER 1 2 , 1 9 8 4 . DE-6 (3/81) ABSTRACT Two complementary investigations were conducted as a preliminary study to f i n d an adequate method for estimating " a v a i l a b l e " phosphorus (P) i n B r i t i s h Columbia forest s o i l s . Eight s o i l materials provided a range of B r i t i s h Columbia f o r e s t s o i l properties, P forms and P l e v e l s . The 12 methods evaluated were H 20-soluble P, Truog, modified Olsen (using polyacrylamide to remove coloured organic c o n s t i t u e n t s ) , Bray Pj and P2, modified Bray P^ and P 2 (longer extraction time), modified double-acid (0.05 N HC1 + 0.025 N H 2S0 4, using polyacrylamide), NR\0Ac (ammonium acetate) at pH 4.8, modified (using polyacrylamide) NH4HCO3-DTPA (diethylene triamine pentaacetic a c i d ) , 0.01 _N HC1, and new-Mehlich. The f i r s t study investigated r e l a t i o n s h i p s among 12 s o i l test methods for estimating s o i l a v a ilable P and 4 chemical P f r a c t i o n s . The 4 chemical P fr a c t i o n s were obtained by a modified Chang and Jackson procedure. The second study evaluated the test methods as indices of "t r e e - a v a i l a b l e P" through a greenhouse pot t r i a l with the 8 s o i l materials x 2 P treatment l e v e l s (P added and control) x 3 tree species (Douglas-fir, western hemlock, and lodgepole pine). The f i r s t study revealed that most methods extract the greatest amount of P from f o r e s t f l o o r samples (apart from a P f e r t i l i z e d s o i l ) and the l e a s t from Podzolic B horizon samples. Similar to the l i t e r a t u r e , P l e v e l s obtained by a number of the methods are s i g n i f i c a n t l y correlated with each other. Modified Olsen values are s i g n i f i c a n t l y correlated with values from the greatest number of other - I i i -methods. The 4 Bray methods, modified double-acid and new-Mehlich methods yielded the next l a r g e s t group of s i g n i f i c a n t c o r r e l a t i o n s . Water-soluble P and 0.01 HC1 values were seldom s i g n i f i c a n t l y c o rrelated, and NHitOAc(pH 4.8) values were not correlated, with other method test values. Contrary to a g r i c u l t u r a l s o i l s l i t e r a t u r e , only one s i g n i f i c a n t c o r r e l a t i o n existed between the s o i l test values and P forms: NH^OAc (pH 4.8) extraction with the Ca-P f r a c t i o n . Correlations between P f r a c t i o n s were also not as extensive, with only reductant-soluble P and Fe-P being s i g n i f i c a n t l y related for a l l 8 s o i l s . Across the 5 "Podzolic" s o i l s , Ca-P and Al-P were also s i g n i f i c a n t l y related ( n e g a t i v e l y ) . In the greenhouse study, seedling growth was best on the fo r e s t f l o o r m aterial, and worst on the calcareous s o i l material for lodgepole pine and Douglas-fir and on a Podzolic B horizon for western hemlock. A l l species displayed dramatic responses to P on some of the s o i l s . In a h i e r a r c h i c a l s o i l analysis screening (12 methods x 3 s o i l s ; then 3 candidate methods x 5 remaining s o i l s ) the new-Mehlich values were the most s i g n i f i c a n t l y correlated with f o l i a r P concentration for a l l three species in the f i r s t stage. Many of the methods were s i g n i f i c a n t for lodgepole pine. Modified Olsen and modified NHi+HCO3-DTPA also appeared good for Douglas-fir, but these a l k a l i n e extractants were considered too cumbersome for routine laboratory anaysis of the study s o i l s . The three chosen candidate methods were new-Mehlich; 0.01 IJ HC1, and Bray P]^. Evaluating these methods across various groups of the 8 s o i l s for each species ( i . e . without' the organic, calcareous, eluviated^ - iv -and P - f e r t i l i z e d s o i l materials i n turn and i n combinations) suggested that the new-Mehlich method may be best. Bray commonly did not corr e l a t e well with Douglas-fir f o l i a r P. The 0.01 _N HC1 did not appear as good as i t had in the preliminary screening, but did well across Podzolic horizons alone. A l l methods correlated poorly with western hemlock f o l i a r P under c e r t a i n conditions. The new-Mehlich method was evaluated for the i n d i v i d u a l treatment r e p l i c a t e s , y i e l d i n g c o r r e l a t i o n s with f o l i a r P which were consistent with p r i o r r e s u l t s . Correlations f o r the organic and eluviated s o i l s were highly s i g n i f i c a n t for a l l three species. For i n d i v i d u a l s o i l s , no s i g n i f i c a n t c o r r e l a t i o n s existed for a l l but two Podzolic s o i l m aterials. However, grouped Podzolic s o i l s yielded strong c o r r e l a t i o n s for the new-Mehlich method. The r e s u l t s reported here need f i e l d testing and i t i s recommended that the new-Mehlich and Bray P^ s o i l tests s t i l l be considered together u n t i l adequate f i e l d data provide further information. - v -TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS v LIST OF TABLES v i i ACKNOWLEDGEMENTS v i i i CHAPTER 1: INTRODUCTION 1 Terminology 4 Li t e r a t u r e Review 5 1. P r i n c i p l e s of S o i l Testing 6 2. S o i l Testing Objectives and C r i t e r i a For an Adequate S o i l Test 9 3. Growth and N u t r i t i o n Factors Beyond the Scope of a Chemical S o i l Test 10 4. Chemical C h a r a c t e r i s t i c s of Phosphorus i n S o i l s 11 5. Review of S o i l Test Methods and Procedural Considerations 20 > 6. Corr e l a t i n g and Interpreting the Results 33 7. Research Needs' 35 Thesis Objectives...................... 36 CHAPTER 2: CORRELATIONS AMONG TWELVE EXTRACTABLE PHOSPHORUS METHODS AND FOUR CHEMICAL PHOSPHORUS FRACTIONS 38 Introduction 38 Materials and Methods 40 Results and Discussions 44 - v i -Page CHAPTER 3: GREENHOUSE EVALUATION OF METHODS TO ESTIMATE PHOSPHORUS AVAILABILITY TO DOUGLAS-FIR, LODGEPOLE PINE, AND WESTERN HEMLOCK 56 Introduction 56 Experimental Design 58 Materials and Methods 61 Results and Discussions 64 Conclusions 78 CHAPTER 4: THESIS SUMMARY AND CONCLUSIONS 80 LITERATURE CITED 83 APPENDIX 1 - A n a l y t i c a l Method Documentation 97 2 - Phosphorus Test Value and Fraction Correlations f o r Podzolic S o i l s Alone 114 3 - Phosphorus Extraction Data for Greenhouse Study 115 4 - Additional S t a t i s t i c a l Tests for Experimental Data 118 5 - R e f l e c t i o n on the Experiment... 130 - v i i -LIST OF TABLES Page Table 1 - Summary of Study S o i l s . 42 Table 2 - Available Phosphorus Methods Tested 43 Table 3 - Summary of Phosphorus Extraction and Frac t i o n a t i o n Data for the Study S o i l s , 45 Table 4 - Co r r e l a t i o n C o e f f i c i e n t s for the Relationships Among S o i l Phosphorus Test Values Obtained from 12 Extraction Methods 49 Table 5 - Cor r e l a t i o n C o e f f i c i e n t s for the Relationsips Between Extractable Phosphorus and Phosphorus Fractions 51 Table 6 - Co r r e l a t i o n C o e f f i c i e n t s for the Relationships Among Phosphorus Fractions ' 53 Table 7 - Correlation C o e f f i c i e n t s for the Relationship Between Soil-Extractable Phosphorus and F o l i a r Phosphorus for 12 Methods and 3 S o i l s 66 Table 8 - Co r r e l a t i o n C o e f f i c i e n t s for the Relationship Between Soil-Extractable Phosphorus and F o l i a r Phosphorus for 3 Candidate Methods and a l l 8 S o i l s . . . . 71 Table 9 - Correlation C o e f f i c i e n t s for the Relationship Between S o i l Phosphorus Extracted by the new-Mehlich Method and F o l i a r Phosphorus for a l l Treatment Replicates. 75 - v i i i -ACKNOWLEDGEMENTS I am very g r a t e f u l to my thesis advisor, Dr. T.M. B a l l a r d , for this opportunity and his continued support and guidance. I would also l i k e to thank Dr. A.A. Bomke and the members of my thesis committee: Dr. L.E. Lowe, Dr. L.M. Lavkulich, and Dr. K. Klinka, for their advice and guidance. Numerous students i n S o i l Science and Forestry helped with the project at various stages. In this regard, I wish to thank Gerry Davis, Rick Kabzems, Mark Runge, Scott MacDougall, Nik Majid, and Reid Carter for their i n d i v i d u a l e f f o r t s . The assistance of J u l i e Lansiquot, Eveline Wolterson, and Rosemary Lowe in greenhouse watering and s o i l analyses i s g r a t e f u l l y acknowledged, as i s the frequent advice and assistance of Mr. Bernie von Spindler. The advice and recommendation of Dr. Hans Schrier, Dr. George Eaton, Dr. Malcolm Grieg, and Dr. Antal Kozak, concerning experimental design and s t a t i s t i c a l methods i s greatly appreciated, as i s the assistance of Mr. Barry Wong in helping with the data a n a l y s i s . I also acknowledge Dr. J. Otchere-Boateng for his design of this experiment and the B r i t i s h Columbia Min i s t r y of Forests for f i n a n c i a l support. Very s p e c i a l thanks are due to my wife Kathy and our sons Shawn and Brian for their continued love, support, and understanding during my studies. - 1 -CHAPTER 1 INTRODUCTION Phosphorus i s an e s s e n t i a l macronutrient, required by a l l higher plants for normal metabolism, growth, development, maturation, and reproduction. In most ecosystems, s o i l phosphate represents e s s e n t i a l l y the only source for plants, atmospheric inputs being very low (Emsley 1982). The a v a i l a b i l i t y of s o i l phosphorus to plants i s severely r e s t r i c t e d by low "mobility" which i s the product of many complex chemical, b i o l o g i c a l , and physical i n t e r a c t i o n s . Thus, inadequate phosphorus supply to crops i s a widespread a g r i c u l t u r a l problem in most parts of the world, and phosphorus f e r t i l i z e r use i s second only to nitrogen (Tisdale and Nelson 1975). Many s o i l tests have been developed to attempt to predict that amount of the s o i l phosphorus which i s a v a i l a b l e to a given crop. No one s o i l P test appears to be su i t a b l e for a l l s o i l s (Mattingly and Talibudeen 1967). Such s o i l tests must be c a l i b r a t e d for l o c a l s o i l conditions. In f o r e s t r y , a s i m i l a r trend i n the phosphorus problem has developed. Although P deficiences are not p a r t i c u l a r l y widespread, managed pine stands i n Europe, southeastern United States, and the Southern Hemisphere are often P - d e f i c i e n t (Baule 1973). In 1977, the to t a l f o r e s t area f e r t i l i z e d with P was approximately 500,000 ha (R. Balla r d 1980). The incidence of P d e f i c i e n c i e s i s expected to increase s t e a d i l y on a dramatic scale with increased intensive s i l v i c u l t u r e ( P r i t c h e t t 1976). Recent investigations i n the P a c i f i c Northwest (e.g., Heilraan and Ekuan 1980a) have revealed low f o l i a r P l e v e l s i n trees on some coastal f o r e s t s o i l s . In some areas i n the B r i t i s h Columbia i n t e r i o r , T. Bal l a r d (1981) reported s l i g h t to moderate P d e f i c i e n c i e s In some lodgepole pine (Pinus contorta Dougl.) stands (based on f o l i a r analysis) and noted that d e f i c i e n c i e s may be expected to increase i n severity and extent following N f e r t i l i z a t i o n . Similar cases may be c i t e d for the other major timber species. With Increasing intensive f o r e s t management i n B r i t i s h Columbia the problem of P d e f i c i e n c i e s i s l i k e l y to increase. Severe N def i c i e n c y i s common throughout B r i t i s h Columbia (T. Ballard 1983) and f o l i a r P concentrations are known to decrease following a p p l i c a t i o n of N f e r t i l i z e r s (e.g., 0tchere-Boateng 1981). I t i s thought that the f o r e s t f l o o r supplies s u b s t a n t i a l l y higher quantities of available P to the growing trees than the mineral s o i l horizons. Hence, planted tree seedlings would l i k e l y suffer from P d e f i c i e n c i e s i n some areas where logging a c t i v i t i e s or s i t e preparation lead to (1) the removal of a s i g n i f i c a n t portion of the forest f l o o r material, and/or (2) mixing of the fo r e s t f l o o r with mineral s o i l (because of increased P f i x a t i o n ) . E x o c e l l u l a r phosphatase enzymes are considered responsible for P mine r a l i z a t i o n from organic matter (Ho 1979). The a c t i v i t y of phosphatase enzymes may be dramatically reduced by even low l e v e l s of heavy metal (e.g., Cu and Mn) p o l l u t i o n (Tyler 1976); such atmospheric l e v e l s may be present i n B r i t i s h Columbia i n regions with mineral ore smelters and/or concentrators, or i n d u s t r i a l and urban centers. Concern about s o i l P a v a i l a b i l i t y therefore exists - 3 -for some species on some forest s o i l s i n B r i t i s h Columbia and may well be expected to s u b s t a n t i a l l y increase i n severity and s p a t i a l extent i n the near future. However, response to P f e r t i l i z a t i o n has so f a r not been reported i n f i e l d t r i a l s i n the P a c i f i c Northwest (Heilman 1981), although some greenhouse studies using Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings, and s o i l s from areas believed to be P - d e f i c i e n t , have given excellent tree response to P treatments (e.g., Strand and Austin 1966; Heilman and Ekuan 1980a, 1980b; Curran and T. B a l l a r d 1984). Responses to P are also noted i n newly established nurseries and P f e r t i l i z a t i o n i s an i n t e g r a l part of nursery management (van den Driessche 1969). I t i s possible that the lack of response to applied N or P i n some stands may be p a r t i a l l y due to some unfavourable P or N i n t e r a c t i o n s . (For example, a p p l i c a t i o n of N f e r t i l i z e r s (e.g., urea) to some western hemlock stands and Douglas-fir plantations i n the coastal area of the P a c i f i c Northwest (from B r i t i s h Columbia to Oregon) has also not increased tree growth (University of Washington, College of Forest Resources 1974; Heilman and Ekuan 1980a.) The above discussion indicates the increasing need for an "adequate" s o i l test for estimating "available P" status of fo r e s t s o i l s i n B r i t i s h Columbia. An "available P" extraction method which i s a good predictor of tree growth or tree P status i n one area, may be inadequate i n another l o c a l i t y . Thus, before a given method i s used o p e r a t i o n a l l y i n B r i t i s h Columbia, i t must be evaluated, or c a l i b r a t e d , against l o c a l tree growth and/or P status. - 4 -This thesis reports on a study designed to provide a preliminary evaluation of s o i l test methods for estimating "available phosphorus" to f o r e s t trees i n B r i t i s h Columbia. In the f i r s t study, methods are compared among themselves and with c e r t a i n chemical phosphorus f r a c t i o n s . Based on the analysis of a greenhouse experiment in the second study, two methods are selected which are considered the most adequate to provide the best index of "available phosphorus" for Douglas-fir, lodgepole pine, and western hemlock. Further evaluation of the recommendations presented here must be based on f i e l d t r i a l s , which w i l l ultimately help develop some guidelines for i n t e r p r e t i n g s o i l test r e s u l t s for operational P f e r t i l i z a t i o n i n B r i t i s h Columbia. TERMINOLOGY In the l i t e r a t u r e , a number of terms are used interchangeably, t h e i r use i s defined here for c l a r i t y (expanded from Curran and T. B a l l a r d 1984). The symbol "P" w i l l r e f e r to phosphorus. "Total P" represents the total of a l l s o i l P present. "Available P" i s that f r a c t i o n of the t o t a l P that i s available to growing plants (e.g., usually over one growing season for a g r i c u l t u r a l crops; as yet undefined time period for B r i t i s h Columbia c o n i f e r s ) . "P f r a c t i o n s " are quasi s p e c i f i c portions of the t o t a l P obtained by various e x t r a c t i o n procedures (e.g., inorganic or chemical P f r a c t i o n s , and organic P f r a c t i o n s ) . "Fixed P" i s a loose term r e f e r r i n g to P bound i n secondary ( s o i l ) minerals (and probably organic complexes), strongly enough that - 5 -i t i s not part of the ava i l a b l e P pool. For some time, i n the . l i t e r a t u r e , s o i l P was considered as " l a b i l e P" (often analagous to av a i l a b l e P) and "non-labile P" after Russell et a l . (1954); however, these terms are now usually avoided (e.g., Larsen 1967) because i t i s thought that this two-compartment picture oversimplifies the problem. LITERATURE REVIEW N u t r i t i o n a l evaluation for f o r e s t trees may be investigated through s o i l a n a l y s i s , f o l i a r analysis, v i s u a l symptoms, f e r t i l i z e r pot t r i a l s , f e r t i l i z e r f i e l d t r i a l s , bioassays, and/or indicat o r plants (Tamm 1964; Z o t t l 1973; R. Ballard 1977; P r i t c h e t t 1979). For most s o i l n u t rients, the use of s o i l analysis for the assessment of nutrient a v a i l a b i l i t y and p r e d i c t i o n of growth for forest trees has not been very successful (Armson 1973; van den Burg 1976; P r i t c h e t t 1979; Khanna 1981). This i s not unreasonable i f one considers the many other s i t e and plant factors involved i n regulating growth and n u t r i t i o n . However, P r i t c h e t t (1979) notes that some success with s o i l P test procedures has been reported i n New Zealand, A u s t r a l i a , southeastern United States, Netherlands, and Finland, with subsequent extensive use of s o i l P testing programmes i n some of these countries. This successful use of s o i l P testing may perhaps be explained by the overwhelming importance of s o i l chemical factors to P m o b i l i t y . i Ideas that a g r i c u l t u r a l s o i l tests were of l i t t l e use to f o r e s t r y probably stemmed from e a r l i e r work, such as that i n A u s t r a l i a by K e s s e l l - 6 -and Stoate (1938) and Young (1948), which found correlations with t o t a l P rather than extractable P (R. Ballard 1980). R. Ball a r d (1980), i n hi s review of phosphorus n u t r i t i o n and f e r t i l i z a t i o n of f o r e s t trees, notes that s o i l tests currently used for P i n fo r e s t r y are generally the successful a g r i c u l t u r a l s o i l tests ( such as the Olsen, Bray P^ or P£, Truog, Morgan (1941), and H20-soluble P). A g r i c u l t u r a l l y based s o i l P tests are also commonly used f or nursery management (e.g., Switzer and Nelson 1956; Stoeckeler and Jones 1957; Wilde 1958; Stoeckeler and Slabaugh 1965; van dan Driessche 1969; Aldhous 1972). Increased s o p h i s t i c a t i o n i n nursery management and continued N and P f e r t i l i z a t i o n t r i a l s i n d i c a t e that a c a l i b r a t e d f o r e s t s o i l P test (or tests) for modern fo r e s t management i n B r i t i s h Columbia i s i n need of development; subject areas of concern for further l i t e r a t u r e review include (1) p r i n c i p l e s of s o i l testing; (2) s o i l test objectives and c r i t e r i a ; (3) growth and n u t r i t i o n factors beyond the scope of a chemical s o i l test; (4) chemical c h a r a c t e r i s t i c s of P i n s o i l s ; (5) review of s o i l test methods and procedural considerations; (6) c o r r e l a t i o n and i n t e r p r e t a t i o n of r e s u l t s ; and (7) research needs. More s p e c i f i c discussions of l i t e r a t u r e relevant to experimental r e s u l t s w i l l occur i n the i n d i v i d u a l thesis chapters. 1. P r i n c i p l e s of S o i l T e s t i n g C l e a r l y , i t i s only the plant that can accurately determine the amount of a nutrient available from the s o i l (Fried and Dean 1952, V i e t s 1980). However, i n d i v i d u a l plants within a crop d i f f e r - 7 -p h y s i o l o g i c a l l y . Also, a nut r i e n t deficiency (and consequent l o s t productivity) has already occurred by the time plant analysis detects i t , and we often wish to assess a v a i l a b l e nutrients before planting. Thus, s o i l testing plays an important role i n providing an "index" of nutr i e n t a v a i l a b i l i t y to p a r t i c u l a r crops on given s o i l (Viets 1980). Such s o i l testing involves rapid chemical analysis that i s inexpensive and accurate, serving to transfer experience (gained i n f i e l d , greenhouse and laboratory research) into r e l i a b l e f e r t i l i t y predictions (Melsted and Peck 1973). S o i l testing, i n one form or another, has a long h i s t o r y . Melsted and Peck (1973), i n reviewing p r i n c i p l e s of s o i l testing, suggest that early search for the " p r i n c i p l e of vegetation" a c t u a l l y led to the development of the science of chemistry. Modern s o i l testing for. nutrient a v a i l a b i l i t y had i t s or i g i n s in the nineteenth century with the c l a s s i c a l research of L i e b i g (1840) (Melsted and Peck 1973). Study of plant n u t r i t i o n gained momentum with some major contributions from Daubeny (1845) through the concept of "active" nutrient forms and the CO2 s o i l test, and Dyer (1894) i n development of the c i t r i c acid s o i l test based on a c i d i t y studies of root sap (Kamprath andWatson 1980). Much of the s o i l test research early i n this century focused on or included P (e.g., Russell and Prescott 1916-1917; Bray.1929; Truog 1930; Spurway 1933). Since the 1940's, s o i l testing has been widely accepted i n a g r i c u l t u r e as an e s s e n t i a l tool for s o i l f e r t i l i t y management (Melsted and Peck 1973; Bertrand 1981). Modern s o i l testing no longer attempts to mimic the s o i l - p l a n t system but rather seeks a sound physical chemistry basis that may be - 8 -more universal (Viets 1980). Researchers working with s o i l tests now recognize the need to consider both " i n t e n s i t y " and "capacity" (Larsen 1967, V i e t s 1980). Intensity i s a measure of nutrient present i n s o i l s o l u t i o n , whereas capacity i s a measure of the s o i l ' s present buffering capacity or a b i l i t y to maintain the l e v e l of i n t e n s i t y throughout the growing season. These are important d e s c r i p t i v e classes of s o i l P because they are f u n c t i o n a l l y related by the s o l i d - s o l u t i o n e q u i l i b r i a discussed l a t e r . (Olsen and Khasawneh (1980) note that a new terra, quantity or quantity f a c t o r , i s more appropriate to define "quantity of s o l i d phase P that can act as a reserve" and current use of "capacity" generally describes the gradient c o n t r o l l i n g desorption, which r e l a t e s "quantity" to " i n t e n s i t y . " ) In s o i l testing for P, the above are important considerations because s o i l s o l u t i o n concentrations of P are usually very low and must be replenished on a continuous basis during each growing season day (Barber 1962). However, most s o i l tests s u i t a b l e for operational s o i l testing programs can neither quantify i n t e n s i t y and capacity (Viets 1980) nor f u l l y account for the process Involved i n renewal of the s o i l s o l u t i o n ( L e i t c h et a l . 1980), but provide some form of i n t e g r a t i o n between the two. This f a i l u r e of s o i l P tests to account for the rate ( k i n e t i c s ) of P migration from s o l i d - t o - s o l u t i o n - t o - p l a n t root i s their main l i m i t a t i o n ( L e i t c h e_t a l . 1980). However, Mengel (1982) doubts that an assessment of both i n t e n s i t y and P-buffering capacity would be a s u i t a b l e approach for routine estimation of available P. A number of reaction kinetics-based methods are discussed by Larsen (1967) and Venkat Reddy et a l . (1982) (e.g., surface P, L-value, - 9 -E t value and A-value). Detailed study of capacity i s generally r e s t r i c t e d to research involving i s o t o p i c d i l u t i o n analysis (e.g., P sorption isotherms) and radio-isotope exchange (Larsen 1967). Detailed studies can characterize the "P f i x i n g power" of a s o i l , which may be expected to range for very strongly acid s o i l s i n North America from about 20 to 125 tons of 20 percent superphosphate per acre-furrow s l i c e (Brady 1974). A sound s o i l testing programme consists of four phases: (1) sample c o l l e c t i o n ; (2) extraction and determination of " a v a i l a b l e " nutrients; (3) i n t e r p r e t a t i o n of a n a l y t i c a l resuts; and (4) making f e r t i l i t y recommendations (Melsted and Peck 1973). The actual s o i l test method employed represents only a small part of this process and i s only important to the extent that i t s a t i s f i e s the test programme's objectives and c r i t e r i a . Also, a successful programme depends at l e a s t as much on good judgements and technique throughout the process, although the actual chemical analysis employed i s the popular scapegoat i f things appear i n error (Melsted and Peck 1973). 2. S o i l T e s t i n g Objectives and C r i t e r i a f o r an Adequate S o i l T e st Objectives for s o i l testing for P generally f a l l into one or more of three testing programme objectives (Fassbender 1980; Kamprath and Watson 1980): (1) grouping of s o i l s into a v a i l a b i l i t y classes i n the making of f e r t i l i z e r recommendations; (2) p r e d i c t i o n of the p r o b a b i l i t y of g e t t i n g a p r o f i t a b l e response to a p p l i c a t i o n of P f e r t i l i z e r , and (3) providing an index of the amount of available P a s o i l can supply. - 10 -S o i l testing for operational forest f e r t i l i z a t i o n with P f a l l s into category (2) and nursery applications generally f a l l under (1*) above. C r i t e r i a that a good s o i l test for P should meet include (1) i t should extract a l l or a proportionate part of the "a v a i l a b l e " form of a nu t r i e n t from s o i l s with v a r i a b l e properties ( i . e . , provide an index of a v a i l a b i l i t y across a range of s o i l s ) ; (2) nu t r i e n t extraction and determination should be possible with reasonable accuracy, r e p r o d u c i b i l i t y , and speed; (3) the amount extracted should be correlated with growth and the response of each crop to that nutrient under various (environmental and s o i l ) conditions; and (4) i n t e r p r e t a t i o n of s o i l data should allow grouping of s o i l s (e.g., high, medium, low) based on f i e l d experience ( c a l i b r a t i o n ) with the method ( a f t e r Bray 1948; Fassbender 1980). 3 , Growth and Nutrition Factors Beyond the Scope of a Chemical Soil  Test Before discussing the chemical behavior of P i n B r i t i s h Columbia fo r e s t s o i l s , i t i s appropriate to bring into view the many other f a c t o r s i n f l u e n c i n g growth and n u t r i t i o n of forest trees. Factors of nutrient a v a i l a b i l i t y relevant to s o i l testing have been discussed by Mengel (1982). Important factors that are generally not determined i n routine s o i l t e sting, but that a f f e c t both growth and n u t r i t i o n of forest trees ( i . e . , s o i l test correlation) include (with some examples from the l i t e r a t u r e ) : water r e l a t i o n s (Webber 1974; Mahtab et a l . 1972; Brockley 1981); other c l i m a t i c f a c t o r s , including - 11 -those influenced by slope and aspect; nutrient i n t e r a c t i o n s (van Lear and Smith 1972); i n i t i a l P i n t e n s i t y and capacity (Barrow and Shaw 1976a, 1976b, 1976c; Mengel 1982); 1 s o i l structure, compaction, rooting depth, parent material and pedogenic age; b i o l o g i c a l competition at a l l trophic l e v e l s (immobilization r a t e ) , m ineralization rate, raycorrhizae (Thomas et a l . 1982), tree physiology, and genetics (e.g., provenance d i f f e r e n c e s ) . Growth and n u t r i t i o n observed for a given f o r e s t stand represent an in t e g r a t i o n of a l l these factors and others. Considering t h i s , and the tremendous v a r i a b i l i t y within and among many forest s i t e s , i t i s amazing that many good s o i l testing programmes have been developed for fo r e s t r y . In greenhouse studies, such as in the second part of th i s t h e s i s , many of these factors are held at low v a r i a b i l i t y to maximize comparison among treatments such as d i f f e r e n t s o i l s . 4 . Chemical C h a r a c t e r i s t i c s of Phosphorus i n S o i l s The chemical behavior of phosphorus i n s o i l s i s as yet not well characterized. Our current state of knowledge i s summed up by Bohn e_t a l . (1979) who note that (despite intensive study that i s second only to nitrogen) our ignorance of the state of s o i l P and our i n a b i l i t y to increase the a v a i l a b i l i t y of P ranks as one of the greatest f r u s t r a t i o n s and challenges of s o i l chemistry. Phosphate has a high a f f i n i t y for Mengel (1982) notes that of p a r t i c u l a r concern i s the dynamic changes i n s o i l properties (such as pH and actual P-buffering power) in the actual "root depletion zone," which can s i g n i f i c a n t l y d i f f e r from parameters i n the bulk s o i l . - 12 -cations (e.g., most often A l 3 + , F e 3 + , C a 2 + , Mg 2 +, and H +) (Bohn et a l . 1979) and takes part i n many reactions a f f e c t i n g i t s a v a i l a b i l i t y , with a these and other c a t i o n i c species, both within the l i q u i d phase and between the l i q u i d and s o l i d phase (sorption and desorption). The chemical behavior of P i n s o i l s i n general w i l l be discussed through the topics of (a) geochemistry; (b) s o i l solution; (c) sorption and desorption; (d) phosphate minerals; (e) and s o i l organic phosphorus. i a . Geochemistry of Phosphorus Phosphorus occurs n a t u r a l l y almost e x c l u s i v e l y as the highly charged cation (P 5*) i n the complex oxyanion orthophosphate (Lindsay and Vlek 1977; Bohn et _al. 1979). Phosphorus i s the tenth most abundant mineral In the Earth's crust; however, the geologic P cycle turns over very slowly and new inputs to s o i l systems are generally very low (although these may be enough to o f f s e t leaching losses, which are also very low (Emsley 1982). S o i l s contain 0.02 to 0.15% P (Mengel and Kirkby 1982) which, during pedogenesis, weathers from calcium phosphates (e.g., apatite) to forms more associated with Fe and Al compounds and organic matter (Walker and Syers 1976). Organic P can represent from 20 to 80% of the t o t a l s o i l P (Floate 1960; Larsen 1967; Dalai 1977; Mengel and Kirkby 1982). Phosphate i s biocycled by vegetation and accumulates near the surface i n most s o i l s (Floate 1960; Pierrou 1976), (where i t i s hence more susceptible to disturbance such as in s i t e preparation). - 13 -b. S o i l S o l u t i o n Phosphorus In the s o i l s o l u t i o n , P i s present as dissociated phases of the weak acid H3P0i| (e.g., H 2 P 0 t f ~ ) , as complexes and in ion pairs (Taylor and Gurney 1962; Larson 1965, 1966) , and coraplexed with organic matter (Weir and Soper 1963; Dalai 1 9 7 7 ) . Our current knowledge suggests that i t i s not safe to assume that even the bulk of s o i l s o l u t i o n P i s always present as l ^ P O i / " and HP01+ . S o i l s o l u t i o n P concentration (P in t e n s i t y ) i s usually very low (e.g., 0 .1 - 1.0 ppm reported by Larsen .(1967) and i s controlled by the heterogeneous e q u i l i b r i a between the l i q u i d and s o l i d phase. c. Phosphate Sorption and Desorption Since s o i l solution P occurs at very low concentrations, P sorption and desorption are the most important and most complex aspect of P a v a i l a b i l i t y (e.g., "the r a t e - l i m i t i n g step"). Phosphate sorption may occur as "true" adsorption to surfaces, as p r e c i p i t a t i o n i n the form of small and poorly c r y s t a l l i z e d s o l i d s (e.g., c o l l o i d s ) , and as some surface-associated P (Bonn et a l . 1979 ) . An important aspect of P desorption i s that i t i s incongruent (Larsen 1967 ) . Sorption The discussion of P sorption i n the l i t e r a t u r e may apply to incidents dominated by either or a l l scenarios presented above (which w i l l be discussed i n turn). The q u a n t i t y - i n t e n s i t y r e l a t i o n s h i p can often be described by a Langmuir isotherm, using a series of two to f i v e - 14 -Langmuir equations ( P a r f i t t 1978). Sorption of P i n so l u t i o n may occur onto A l , Fe (and Mn) oxides and hydrous oxides at low to neutral pH, clay minerals ( e s p e c i a l l y 1:1 l a t t i c e structures, which e x h i b i t greater surface area dominated by aluminum) over a more neutral pH range, and calcium minerals (also magnesium minerals) at higher pH ranges ( P a r f i t t 1978; Ryden and Pra t t 1980). Ryden and Pra t t (1980), i n reviewing P sorption surfaces for s o i l s , stress the importance of A l and Fe hydrous oxides. C r y s t a l l i n e hydrous oxides ( i . e . , hematite and gibbsite) sorb 5 to 10 times greater P than c r y s t a l l i n e aluminosilicates or calcium carbonate; i n addition, amorphous components (such as Fe oxide gels) sorb 10 to 100 times more P than their c r y s t a l l i n e counterparts (thus up to 1000 times more P than the c r y s t a l l i n e aluminosilicates and calcium carbonates (e.g., Syers and Williams 1977). In B r i t i s h Columbia f o r e s t s o i l s (generally weakly to moderately weathered), we may expect to find a considerable proportion of Fe and Al hydrous oxides to be amorphous, consistent with current concepts of podzolization (e.g., Farmer 1982). Even at higher pH, amorphous hydrous oxides may reduce to minor importance P sorption by calcium carbonate, as demonstrated for calcareous s o i l s by Holford and Mattingly (1975). The above helps to explain why many workers have found a c o r r e l a t i o n of s o i l P sorption capacity with extractable Al or Fe, or exchangeable A l (e.g., Sree Ramulu and P r a t t 1970; R. Ballard and F i s k e l l 1974; F l i n n et _al. 1982). This i s also true for s o i l test values for P (e.g., Grigg 1968; R. B a l l a r d and F i s k e l l 1974; R. Ballard 1978). Also, s i g n i f i c a n t - 15 -c o r r e l a t i o n s between organic matter content and P adsorption suggest existence of Fe or Al chelates of high molecular weight (e.g., Weir and Soper 1963). Organic matter can also form complexes with Fe and Al compounds, reducing P sorption (Brady 1974). P r e c i p i t a t i o n of P complexes from the s o i l s olution i s also important. Again, A l , Fe, (Mn), Ca, and (Mg) are the important constituents involved. Mengel and Kirkby (1982) note for reactions involving Ca2*- and Ca minerals, that (whereas desorption from Ca most l i k e l y dominates i n s o i l s r i c h i n A l , Fe and clay minerals) p r e c i p i t a t i o n apparently plays a major role i n calcareous s o i l s , poor sandy s o i l s , and organics. Their r a t i o n a l e for calcareous s o i l s i s that high Ca 2* concentration and pH promote desorption of P (e.g., the high a f f i n i t y of P for cations) and i t s p r e c i p i t a t i o n (as calcium phosphates of low s o l u b i l i t y ) ; which process dominates w i l l depend on i n d i v i d u a l s o i l conditions a f f e c t i n g s o i l s o l i d - s o l u t i o n e q u i l i b r i a (e.g., HC03~ concentration). Many factors a f f e c t P sorption and p r e c i p i t a t i o n ; these include nature of sorption s i t e s , s o r p t i o n / p r e c i p i t a t i o n mechanisms, quantity and i n t e n s i t y r e l a t i o n s h i p s ( i . e . , capacity), reaction k i n e t i c s , and external factors such as pH. Sorption s i t e s and mechanisms have been reviewed by P a r f i t t (1978). Again Fe and Al appear to be of major importance. Holford and Mattingly (1975), using n a t u r a l l y occurring calcium carbonate which contained 0.1 - 0.3% Fe, suggested that P sorption could be.predominantly l o c a l i z e d on the Fe s i t e s . However, the importance of C a 2 + in s o l u t i o n reactions with P (e.g., p r e c i p i t a t i o n ) should not be overlooked. - 16 -Of the external factors a f f e c t i n g P s o l i d - s o l u t i o n e q u l i b r i a , CO2 concentration, organic matter, and pH are probably of greatest importance (Larsen 1967). Desorption The concentration of P i n the s o i l s olution has often been conceived to be determined by sparingly soluble compounds. Larsen (1967) describes these s o l u b i l i t y e q u i l i b r i a as being complex. As sorbed P increases ( i . e . , further saturates the P adsorption capacity) the l e v e l of P i n s o l u t i o n ( i n t e n s i t y ) w i l l increase to a point controlled by the s o l u b i l i t y of some "soluble P compound." S i m i l a r l y , as s o i l s o l u t i o n P ( i n t e n s i t y ) decreases, sparingly "soluble P compounds" w i l l dissolve u n t i l the sorption complex (capacity) i s saturated to a degree corresponding to the s o l u b i l i t y of the l e a s t stable P "compounds" present. Phosphorus concentration i n acid s o i l s i s i n the range of the s o l u b i l i t i e s of the Fe and Al minerals strengite and v a r i s c i t e and the isomorphous s e r i e s between them (Larsen 1967). S i m i l a r l y , P concentrations i n a l k a l i n e s o i l s are i n the range of the s o l u b i l i t i e s of octacalcium phosphate and apatite. Larson (1967) notes that these r e l a t i o n s h i p s have led past researchers to the unfortunate conclusion that P a c t i v i t i e s could be calculated based on equilibrium with various P minerals. However, due to the complexity of factors determining s o i l s o l u t i o n P l e v e l s , the above c o r r e l a t i o n i s nevertheless too crude to predict plant available P. - 17 -I t i s also important to be aware that Ksp values are for pure minerals ( i . e . , synthesized or removed from the s o i l environment) under standard conditions. S o i l minerals are often complicated by impurities, which tend to raise the actual Ksp observed (Larsen 1967). Also, Ksp v a r i e s with pH and temperature. Therefore, some of the apparent complications i n comparing concentration of P in solution with determined s o l u b i l i t i e s of pure minerals must a r i s e out of the above s i m p l i f i c a t i o n of r e a l i t y . Also, l i t t l e i s known as to which P minerals are a c t u a l l y present and in contact with the s o i l s o l u t i o n i n s o i l s . Perhaps the most important aspect of P mineral d i s s o l u t i o n i s that i t i s incongruent (Larsen 1967). The important process that may be involved i s the "aging" of the P mineral formed by sorption ( i n c l u d i n g p r e c i p i t a t i o n ) . Gaitho (1978) reviewed this important character of P " f i x a t i o n " and noted how, over time, P compounds formed are transformed in t o more stable (and thus l e s s soluble) forms (consistent with basic thermodynamics). For example, Fe and Al phosphates may be "adsorbed" when newly formed; this represents a thermodynamically unstable form r e l a t i v e to amorphous forms which are i n turn le s s stable than c r y s t a l l i n e forms (Hsu 1982; Sims and E l l i s 1983). This progression (from amorphous to c r y s t a l l i n e structure) represents a decrease i n r e a c t i v i t y f o r P (capacity for P adsorption; Sims and E l l i s 1983) due to decreased surface area and probably P penetration into the i n t e r n a l structure. A common reference for early work on this phenomenon Is Fujiwara (1950). C l e a r l y , the incongruence of P sorption has fundamental importance i n understanding plant-available P and P minerals. P a r f i t t (1978) - 18 -r e f e r s to this process as involving slow reactions. Keerthisinghe and Mengel (1979) noted that "P aging" i s e s p e c i a l l y rapid i n calcareous s o i l s . For Fe and Al hydrous oxides, Ryden et a l . (1977) noted that most P sorption was completed i n a few hours. Thus, the process of "P aging" may be expected to occur f a i r l y soon af t e r sorption or p r e c i p i t a t i o n . C l e a r l y , the r e v e r s i b i l i t y of this process decreases with age (Tisdale and Nelson 1975). The process of "P aging" provides an exc e l l e n t basis for conceptualizing P mineral dynamics and the notion of " l a b i l e P." Many authors refer to d i f f e r e n t minerals on the surface of other more stable minerals (e.g., "mineral succession;" e.g., Larsen 1967; P a r f i t t 1978; Ryden and Pra t t 1980). In terms of P mineral dynamics, this process means that large quantities of P minerals can e x i s t i n the s o i l , but not be i n equilibrium with the s o i l s o l u t i o n . S o i l testing for tree-a v a i l a b l e P i s a very complicated undertaking because of this s o i l - s o l u t i o n interface from which " l a b i l e P" is ' r e l e a s e d (and that may be expected to undergo many changes even during a portion of'a single growing season). i d. Phosphate Minerals Phosphate forms a group of minerals on i t s own (Larsen 1967; Lindsay and Vlek 1977). Again the usual cations A l 3 + , F e ^ , Ca2*", and Mg2"1" are the most important. Actual composition depends on the r a t i o of such cations, H +, and P concentrations during p r e c i p i t a t i o n (Larsen 1967), and perhaps "aging" (e.g., the calcium phosphate s e r i e s ) . Due to - 19 -the tetrahedral nature of phosphate, i t tends to form quite regular c r y s t a l l i n e structures, some of which are s i m i l a r to the clay minerals (Lindsay and Vlek 1977) (perhaps again representing the tendency towards more stable forms during "aging"). I d e n t i f i c a t i o n of s o i l P minerals i s very d i f f i c u l t since they apparently occur primarily i n the clay-sized f r a c t i o n and as very small c r y s t a l s on other s o i l surfaces and any concentration procedures a l t e r their forms (Larsen 1967). Mengel and Kirkby (1982) note that, there have been many (unsuccessful) attempts to re l a t e "non-labile P" to s p e c i f i c P minerals; a very complicated venture, considering i m p u r i t i e s , the v a r i e t y of c a t i o n i c species a v a i l a b l e i n a given s o i l , "aging", and no " r e a l " Ksp data. A number of authors (e.g., Larsen 1967; Ryden et a l . 1973) consider the existence of strengite and v a r i s c i t e u n l i k e l y ; however, this should be q u a l i f i e d i n terms of " i n equilibrium with the s o i l s o l u t i o n " since these more stable minerals can e x i s t "behind" surfaces. Of the calcium phosphates, Larsen (1967) notes that there i s no reason to assume that any form other than hydroxyapatite i s permanently present i n s l i g h t l y acid s o i l s since other forms of apatite weather r e a d i l y i n a c i d i c s o i l s (apatites are the most s i g n i f i c a n t P minerals g l o b a l l y ) . e. S o i l Organic Phosphorus S o i l organic P usually represents 20 to 80% of t o t a l P (Larsen 1967; Dalai 1977). Dalai (1977) also notes that a very s i g n i f i c a n t amount of s o i l s o l u t i o n P i s i n organic forms that are considered only - 20 -poorly a v a i l a b l e to plants (and believed to be c o l l o i d a l ) . Only a few s o i l organic P forms are presently known; these are predominantly i n o s i t o l phosphates, phospholipids, and deoxyribonucleic acid (DNA) and r i b o n u c l e i c acid (RNA) (Dalai 1977). The dynamics of s o i l organic P may be considered most relevant to s o i l t e s ting. The s o i l organic system a f f e c t s s o i l chemistry relevant to plant a v a i l a b l e P through m i n e r a l i z a t i o n , c h e l a t i o n , surface coatings, acid production and buffering, and CO2 production. Organic matter mineralization may represent a major source of a v a i l a b l e P (e.g., Radwan and Shumway (1983) found the best extractable P c o r r e l a t i o n for hemlock growth using forest f l o o r samples). I t i s now accepted that the ex o c e l l u l a r s o i l phosphatase enzymes are l a r g e l y responsible for P m i n e r a l i z a t i o n (Ho 1979). Thus, s o i l organic P i n s o l u t i o n may be far more available to plants than suggested by D a l a i (1977). Chelated Al and Fe have been demonstrated as important s i t e s for P sorption (e.g., Weir and Soper 1963). S i m i l a r l y , organic matter may coat stationary A l and Fe surfaces, thereby reducing P sorption (Brady 1974). Organic acid production during decomposition i n B r i t i s h Columbia f o r e s t s o i l s maintains and buffers low pH conditions which are more conducive to P sorption by Al and Fe. Carbon dioxide produced during r e s p i r a t i o n can lead to increased P d i s s o l u t i o n . i 5. Review of S o i l Test Methods and Procedural Considerations The l a t t e r section, on the chemical c h a r a c t e r i s t i c s of P i n the s o i l , c l e a r l y indicates that there i s no one s i n g l e , e a s i l y extractable ) - 21 -form of plant-available P, such as Ca for Ca. Phosphate undergoes many reactions, such as sorption, p r e c i p i t a t i o n , and complexing with a number of s o i l constituents and i s hence subject to many complex e q u i l i b r i a . Thus, there are many d i f f e r e n t P forms that d i f f e r i n quantity and s o l u b i l i t y (and hence plant a v a i l a b i l i t y ) depending on s o i l and environmental conditions that may be periodic (e.g., s o i l s o l u t i o n ion a c t i v i t i e s , pH, water content) or somewhat s t a t i c (e.g., texture, mineralogy, pedogenic age) i n a given s o i l ( a f t e r L e i t c h et a l . 1980). This i s why developing a s o i l testing programme for P i s a large research undertaking. S o i l test extractants devised to index a v a i l a b l e P vary widely i n their chemical nature. Release of P i s mediated through the reactions of H + (acid s o l v a t i o n ) , OH- (hydrolysis of, cations binding P), F~ (complexing of cations binding P) and/or anions including HC0 3~, SOi* -and organic anions such as acetate ( a l l which contribute to anion replacement) (Thomas and Peaslee 1973; Kamprath and Watson 1980). Available P test extractants can be grouped into seven classes (expanded from Kamprath and Watson 1980) which w i l l now be discussed i n terms of physical chemistry under the larger groupings of a c i d i c , a l k a l i n e , and near-neutral extractants: A. Acidic Extractants Hydrogen ions greatly increase the s o l u b i l i t y of a l l Ca-P including primary Ca-P such as hydroxyapatite (Thomas and Peaslee 1973). The rate and extent of reaction depend on the hydrogen ion concentration. Al-P - 22 -and Fe-P can also be attacked, although rates become progressively slower, r e s p e c t i v e l y . Hence, the order of P removal by H* i s Ca-P > Al-P > Fe-P. Sulfate and organic anions i n a c i d i c solution prevent readsorption of phosphate displaced by other ions (Nelson et a l . 1953; Thomas and Peaslee 1973; Kamprath and Watson 1980). (Sulfate ions compete poorly with phosphates f o r Fe and Al (Kamprath j^t _al. 1956) and are thus noted by Thomas and Peaslee (1973) to be important i n preventing readsorption of P displaced by H4" (which attacks primarily Ca-P).) Organic anions can also form complexes with such polyvalent cations, releasing P (Kamprath and Watson 1980). Nelson _et al. (1953) note that other associated anions ( i . e . , N O 3 - , C l - ) have very l i t t l e e f f e c t on the extr a c t i o n . 1. D i l u t e strong acids j D i l u t e strong acid extractants are generally 0.002 _N to 0.5 _N H C 1 , HNO3 and/or H2S0i+ of pH 3 or l e s s . This class includes Truog (1930), double-acid ("North Carolina" or "old" Mehlich) (Nelson et a l . 1953), and 0.01 N_ HC1 i n this study. Reactions occur involving strong H + (and SOi, ~ i f included) . 2. D i l u t e weak acids D i l u t e weak acids include solutions of carbonic, c i t r i c , and l a c t i c acid and/or their s a l t s . D i lute weak acids include amonium acetate (NH^OAc) at pH 4.8 ("University of F l o r i d a " method) used here (Breland 1957; a modification of Morgan 1941). Reactions occur involving weak H + and organic anions or HC03~. - 23 -3. D i l u t e weak and strong acids Dilute weak and strong acids usually combine the anion e f f e c t s with a strong H + r e a c t i v i t y . The Egner method from Europe (Egner _et a l . 1960) (0.02 N Ca l a c t a t e + 0.02 N HC1) i s a mixture of weak and strong acids. This was not used in this study, although the new-Mehlich method mentioned below has both weak and strong acids plus a complexing ion. 4. D i l u t e acid(s) plus a s p e c i f i c complexing ion Addition of a complexing ion to d i l u t e acids creates a very powerful extractant. The most common complexing ion i s f l u o r i d e which forms very strong complexes with A l , thereby releasing P. Fluoride ions also s p e c i f i c a l l y p r e c i p i t a t e soluble Ca and thus extract P from more soluble Ca-P minerals such as CaHPO i+ ( Thomas and Peaslee 1973). With the a c i d i f i c a t i o n , more basic Ca-P and Fe-P are also affected by the extractant. The Bray (Bray and Kurtz 1945) and new-Mehlich (Mehlich 1978) extractants are d i l u t e acids with F~ as the complexing ion. B. Alkaline Extractants A l k a l i n e extractants i n v a r i a b l y use HCO3- ions which a c t u a l l y replace P adsorbed to surfaces of CaC03 and hydrated oxides of Al and Fe. HCT>3~ also p r e c i p i t a t e s C a 2 + as CaC03, further favoring P release. Thomas and Peaslee (1973) state that bicarbonate ions do not attack basic Ca-P, or Al-P and Fe-P covered with oxide coatings to any extent. (In this respect bicarbonate ions are s i m i l a r to f l u o r i d e ions, although F~ reacts more vigorously and removes P unavailable to HCO3-.) Hydroxyl ions extract P from Al-P and Fe-P (due to hydrolysis of A l and - 24 -Fe) but have l i t t l e effect on basic Ca-P (Dean 1938). Solutions of high pH can cause dispersion of organic matter. 5. Buffered alkaline solutions These alkaline extractants are generally 0.05 M to 1 M HCO3- at pH 7.6 to 8.5. This class includes modified Olsen eii _al. (1954) which uses NaHC03 (Banderis ejt a l . 1976) and modified ammonium bicarbonate-diethylene triamine pentaacetic acid (NHi+HCO 3-DTPA; Soltanpour and Workman 1979) methods. C. Near-Neutral Extractants Near-neutral extractants vary from water to dilute salts and also include the powerful isotopic exchange methods. Effects of experimental procedure, such as C0 2 build-up (and subsequent increased HC03~ activity) from unchecked microbial activity, may be profound due to the otherwise f a i r l y inert reagents. 6. Water or dilute salt solutions Water or dilute salt solutions are most commonly d i s t i l l e d water alone or 0.01 M CaCl 2. Some consider that these extractants yield an estimate of so i l solution P; soiltsolution ratios from saturation extract to 1:60 are in use. This class includes H20-soluble P used i n this study. The 0.01 M CaCl 2 reduces the "dilution effect" (Schofield and Taylor 1955), and concentration of P in CaCl 2 extracts i s generally one-third to one-half that of comparable water extracts (Olsen and Watanabe 1970; Soltanpour et a l . 1974). - 25 -7. Isotopic exchange media Ion exchange media generally work based on i s o t o p i c exchange and mass anion e f f e c t , without appreciably a l t e r i n g s o i l pH; include C l ~ saturated anion exchange resin(AER). Larsen (1967) notes that AER presents a p r a c t i c a l i n t e g r a t i o n of i n t e n s i t y and capacity, with minor s o i l chemical change, and i s well correlated with plant growth. Mattingly and Talibudeen (1967) suggest that this method of evaluating P i s more r e l i a b l e than extraction with d i l u t e acid or a l k a l i n e solutions (with some exceptions). Olsen and Sommers (1982) note that AER i s a useful method to approximate P uptake mechanisms by roots and to measure a v a i l a b i l i t y of residual phosphates from f e r t i l i z a t i o n . However, the AER methods were considered more time consuming than most other s o i l tests examined in this study. F r a c t i o n a t i o n of S o i l Phosphorus F r a c t i o n a t i o n of s o i l inorganic P was i n i t i a l l y attempted by Dean (1938). Chang and Jackson (1957) improved the i n i t i a l procedure and i t i s their successive ( i . e . , one-sample) f r a c t i o n a t i o n method that forms the basis of current f r a c t i o n a t i o n procedures (e.g., Olsen and Sommers 1982). Some modifications and revised nomenclature include Glenn et a l . (1959), Peterson and Corey (1966), Williams et a l . (1967, 1971a, 1971b) and Syers et a l . (1972). Up to six f r a c t i o n s may be analyzed i n the i n i t i a l Chang and Jackson (1957) procedure; these include soluble-P ( f i r s t wash), Al-P, Fe-P, Ca-P, reductant-soluble P, and occluded-P ( s o i l s high i n sesquioxides). In the modified procedure of Peterson and - 26 -Corey ( 1 9 6 6 ) , (which follows the re-ordering of Glenn et a l . (1959) e a s i l y - s o l u b l e and loosely-bound P may be determined i n the f i r s t wash ( i n NH^Cl); extraction with a l k a l i n e 0 .5 N NHi+F (pH 8 .2 ) attacks only the Al-P (Chang and Jackson ( 1 9 5 7 ) , thus permitting determination of Al-P; 0 .1 N NaOH extracts Fe-P by hydrolysis ( a l l Al-P having previously been removed); reductant-soluble-P i s extracted by d i t h i o n i t e and c i t r a t e which i s then oxidized by KMnO^ (rather than H2O2 c a l l e d for by Chang and Jackson (1957) i n this step which removes P insoluble i n NHi+F and NaOH; Ca-P i s then dissolved by strong acid ( 0 . 5 N H 2 S 0 i t ) . A thorough review of s o i l P f r a c t i o n a t i o n Is presented by Olsen and Khasawneh ( 1 9 8 0 ) . Determination of P i n Soi l Extracts T y p i c a l l y , any s o i l P test procedure involves two steps: (1) extraction of P and (2) determination of P concentration i n extract s o l u t i o n . A f a s t and accurate method of P determination i n s o i l extracts i s de s i r a b l e . In the 1950 's, four d i f f e r e n t P determination methods were i n use to s u i t the v a r i e t y of d i f f e r e n t P analyses (e.g., Jackson 1 9 5 8 ) . These methods were a l l based on the reduction of a molybdophosphate complex for the co l o r i m e t r i c determination of P i n solutions based on Denige*s ( 1 9 2 0 ) . This y i e l d s the "molybdenum blue" colour. A few methods use an unreduced vanadomolybdate phosphate complex that i s yellow i n colour. Stannous chloride was the i n i t i a l reducing agent i n the method of Denige"s and was r e a d i l y adopted i n s o i l testing and used for some time (Truog and Meyer 1929; Truog 1930; Bray and Kurtz 1945; Olsen et a l . 1 9 5 4 ) . - 27 -The major development to the method has been the replacement of the SnCl2 reductant with ascorbic acid to produce a more stable molybdophosphate reduction. Fogg and Wilkinson (1958), i n describing their experimental work on i n t e r f e r i n g ions i n the co l o r i m e t r i c determination of P, note that Amnion and Hinsberg (1936) were the f i r s t to use ascorbic acid and go on to describe a method requiring heating. Murphy and Riley (1962) described a single-reagent ascorbic acid method for the determination of P i n natural waters; their method incorporates antimony i n l i e u of heating and i t i s from their work that modern s o i l methods have stemmed. Watanabe and Olsen (1965) tested the Murphy and Ri l e y method and found i t to be accurate for determining s o i l P i n water and NaHC03 extracts. Since that time, the "ascorbic acid method" has '• .-.V gained favour and now enjoys nearly universal acceptance. (For example, this method was proven successful f o r t o t a l P and the Chang and Jackson procedure by Alexander and Robertson i n 1968 and 1970, and modified for use with water extractions by Omanwar and Robertson i n 1969). John (1970) modified the Murphy and Riley method and tested the new approach with regard to range i n P concentration, pH, time, temperature, reagent concentrations, and i n t e r f e r i n g ions; he proved i t acceptable for most commonly used P extractants. Hence (although Olsen and Sommers (1982) note that each P method has i t s own co l o r i m e t r i c method and caution the reader to follow recommended procedures) the above discussion indicates i t i s desirable i n developing s o i l tests f o r a new area or i n using proven s o i l tests to use the "ascorbic acid method". - 28 -Procedural Considerations Apart from the usual care i n sample c o l l e c t i o n , preparation, and laboratory p r e c i s i o n , a number of procedural considerations are important for P extraction methods; these include s o i l mineralogy (e.g., percent and type of c l a y ) , s o i l pH, extraction solution pH buffering, s o i l P buffering capacity, s o i l : e xtraction solution r a t i o , extraction time, shaking type, f i l t e r i n g lag time, glassware, temperature, charcoal, microbial a c t i v i t y , C0£ build-up, i n t e r f e r i n g ions, and hydrophobic samples. In addition to author comments in their i n d i v i d u a l method d e s c r i p t i o n s , the following may be noted from the l i t e r a t u r e : Kamprath and Watson (1980) noted i n their review that percent and type of clay are important for the double-acid and Bray methods, with double-acid better related to plants on s o i l s with k a o l i n i t e and Bray better below 20% clay (e.g., Blanchar and Caldwell 1964). S o i l pH and extracting solution pH buffering go hand i n hand, with most d i l u t e solutions of strong acids (e.g., double-acid) working best (although this depends on s o i l : solution r a t i o ) below pH 7.0 (Kamprath and Watson 1980). The Bray methods work best on non-calcareous s o i l s (Olsen and Sommers 1982) due to problems encountered on calcareous s o i l s from H + n e u t r a l i z a t i o n and CaF 2 formation ( S m i l l i e and Syers 1972; Syers et a l . 1972). S o i l P buffering capacity i s also important (Barrow and Shaw 1976a, 1976b, 1976c; Mengel 1982). Barrow and Shaw (1976b) note that as P capacity increases, the i n i t i a l P extracted decreases and secondary adsorption during extraction increases, y i e l d i n g a s i g n i f i c a n t drop i n - 29 -the P e x t r a c t i o n value (again s o i l : s o l u t i o n r a t i o i s also important). S o i l rextractant r a t i o can profoundly a f f e c t the P extraction value. D i l u t i o n i s most commonly manipulated in the Bray (P^ or P2)» often to reduce e f f e c t s of high clay content (Blanchar and Caldwell 1964) or high CaC0 3 l e v e l s (Randall and Grava 1971). Grigg (1965b), i n studying potato n u t r i t i o n i n New Zealand found that modifying the Bray P 2 t e s t , to 5 minutes shaking and 1:50 d i l u t i o n r a t i o , resulted i n an improved i n d i c a t i o n of the "capacity of the s o i l to supply P" through the e n t i r e growing season. Olsen and Sommers (1982) note that, f or H2O-soluble P, highest extract P concentrations occur with the lowest s o i l : s o l u t i o n r a t i o s . S o i l : s o l u t i o n r a t i o i s an important consideration for s o i l s that strongly resorb P during e x t r a c t i n g . (Data obtained by the method of Olsen £t a l . (1954) are probably among the l e a s t altered by d i l u t i o n r a t i o s , because secondary p r e c i p i t a t i o n reactions are reduced to a minimum due to the concentrations of A l , Fe, and Ca remaining at a low l e v e l i n the extract, according to Olsen and Sommers (1982).) Ratios may have to be altered for organic s o i l , such as f o r e s t f l o o r . ! E x t r a c t i o n time i s also an important consideration and has been discussed for the Bray Pj by Agboola and Omueti (1980), who note, as did Bray and Kurtz (1945), that extracted P drops o f f a f t e r 5 minutes, due to p r e c i p i t a t i o n with A l and Fe. Common observations with B r i t i s h Columbia s o i l s suggest that this drop may occur more often before the 5 minute mark (e.g., data reported i n Chapter 2, which in d i c a t e that, for Podzolic s o i l s , the 5-minute extraction yielded l e s s - 30 -than the 1-minute e x t r a c t i o n ) . Regardless of extraction method, time i s thus an important variable to keep consistently under control when analyzing for P. Shaking type i s yet another consideration and generally f a l l s into two categories: r o t a t i o n a l (e.g., "wrist-action") or r e c i p r o c a l (e.g., end-to-end). Agboola and Omueti (1980) found no s i g n i f i c a n t d i f f e r e n c e between s t i r r i n g (analogous to swirling) and shaking for the Bray P^ s o i l t est, although s w i r l i n g tended to extract s l i g h t l y more P and they considered i t to be more convenient for routine analysis. Shaking speed i s also important, and generally the faster the speed the greater the extracted P (Olsen et a l . 1954). F i l t e r i n g lag time i s a consideration that i s of more recent o r i g i n (many of the e a r l y methods used c e n t r i f u g a t i o n or overnight s e t t l i n g to obtain a clear e x t r a c t ) . Many methods recommend immediate f i l t e r i n g . Studying the Bray P^ test in N i g e r i a , Agboola and Omueti (1980) observed that the f i l t e r i n g lag time e f f e c t s depended on the type of extractant and the l e v e l of s o i l P ( i . e . , r e l a t e d to s o i l P buffering capacity as described by Barrow and Shaw (1976b) e a r l i e r ) . They concluded that, for the Bray P^ test, f i l t e r i n g should be done between 5 and 15 minutes a f t e r shaking. This allows for v a r i a t i o n between 6 and 20 minutes of actual extracting time before f i l t e r i n g , and the a c c e p t a b i l i t y of such practice depends on l o c a l s o i l conditions and extractant c h a r a c t e r i s t i c s . New laboratory glassware i s usually contaminated with arsenic (an i n t e r f e r i n g ion i n the P determination procedure). Washing i n s t r u c t i o n s - 31 -to overcome this problem are presented by Lavkulich (1981). Temperature can have a s i g n i f i c a n t e f f e c t , generally increasing amount of P extracted as the temperature r i s e s . Olsen et _al. (1954) noted that temperature i s another possible source of v a r i a t i o n for their method and calculated that, for s o i l s of 5 to 40 ppm P, extractable P rose 0.43 ppm for each °C from 20 to 30°C. Similar e f f e c t s occur with other methods. Charcoal should probably no longer be considered as an agent for decolouring s o i l extracts. Charcoal i s known to adsorb P (e.g., Beaton e_t ^ 1 . 1960), ei t h e r adding to or taking from extraction-values; i t i s also very messy to work with. Methods that formerly employed "Darco" carbon or i t s equivalent (e.g., Olsen j e t _ a l , 1954; Soltanpour and Schwab 1977) have now been modified to use polyacrylamide as an adsorbent for coloured organic constituents i n the extract s o l u t i o n (e.g., Banderis et a l . 1976; Soltanpour and Workman 1979). Mi c r o b i a l a c t i v i t y and CO2 build-up ( e i t h e r due to microbe r e s p i r a t i o n or s o i l reaction) are yet two more considerations. These can lead to increased P extraction due to m i n e r a l i z a t i o n and HC0 3 -a c t i v i t y , r e s p e c t i v e l y . Microbial a c t i v i t y may also be responsible for immobilization of P i n extractions. E x t r a c t i o n methods that use near neutral extraction solutions and long shaking times generally employ toluene or chloroform to retard any microbial a c t i v i t y (e.g., Humphreys and P r i t c h e t t 1972 for H20-soluble P). However, one may s t i l l wish to consider that any phosphatase enzymes i n the s o i l would most l i k e l y not be hydrolyzed i n near-neutral extracts and may contribute to extraction. E x t r a c t i o n methods that are known to generate C0 2(g) - 32 -often c a l l for shaking i n non-stoppered flasks (e.g., Soltanpour and Schwab 1977); this prevents CO2 build-up and consequent HC03~ formation which would then displace sorbed P and confound r e s u l t s . A number of ions i n t e r f e r e with P determination i n s o i l extracts by the ascorbic acid method. These have been studied i n d e t a i l by Fogg and Wilkinson (1958) and John (1970) and the reader i s directed there for d e t a i l e d discussion. The ascorbic acid method developed by John (1970) aft e r Murphy and R i l e y (1962) i s designed rigorously to maximize u t i l i t y , one aspect of which i s i n t e r f e r i n g ions. A l a s t consideration i s hydrophobic samples (e.g., a f t e r a i r - d r y i n g , f o r e s t f l o o r s often become hydrophobic). These may be a problem i n that they are very slowly wetted, a f f e c t i n g e s p e c i a l l y the r e s u l t s of methods employing s w i r l i n g for a short time period. Reciprocal shaking, longer time periods and/or greater d i l u t i o n are e f f e c t i v e means of reducing v a r i a b i l i t y caused by hydrophobic!ty. Gaitho (1978) allowed his hydrophobic samples to s i t to overnight with d i s t i l l e d water and then added the equivalent chemical solution to make up the reagent. However, as discussed above, a number of other sources of v a r i a b i l i t y may be introduced by this practice i f l e f t unchecked (e.g., microbial a c t i v i t y , phosphatase a c t i v i t y , slow equilibrium reactions, etc.) and the practice also may not be considered convenient for routine s o i l a n a l y s i s . In summary, a large number of procedural considerations are 1 important i n precise s o i l testing for P. Interpretive usefulness of data may be l i m i t e d i f these considerations are not appreciated by the analyst. - 33 -6 . Correlating and Interpreting the Results In their detailed review of s o i l and plant testing for P, Kamprath and Watson (1980) note that correlations with extractable P may use plant growth parameters such as y i e l d , percent y i e l d , P uptake, and P concentration in tissues (e.g., F i t t s and Nelson 1956), or estimates of l a b i l e P such as the "A" or "L" value (e.g., Larsen 1967). A basic p r i n c i p l e of s o i l testing i s that, under most conditions, the s o i l test value can be assumed to be (1) a v a r i a b l e independently related to crop growth and (2) a measured quantity of the nutrient l e v e l i n the s o i l that w i l l , or can be used to, define or express the "rate f a c t o r " (of a v a i l a b i l i t y ) of that p a r t i c u l a r nutrient (Melsted and Peck 1973, 1977). If the above assumptions cannot be met (at some acceptable l e v e l ) , every other y i e l d v a r i a b l e might have to be estimated before the s o i l test value w i l l be of i n t e r p r e t i v e value. (In the case of N H i | + and NO3- for N , the meaning of 2 above may be l e s s straightforward, but becomes clearer i f one considers that a measured N l e v e l i s i n f e r r e d to express the rate of N a v a i l a b i l i t y . ) Simple l i n e a r c o r r e l a t i o n s represent the most common s t a t i s t i c a l analyses in the l i t e r a t u r e reviewed for f o r e s t s o i l s (e.g., P r i t c h e t t and Llewelyn 1966; Alban 1972; Baker and Brendemuehl 1972; R. Ballard 1974, 1978; Webber 1974; Kadeba and Boyle 1978; Hopmans et a l . 1978a; Banerjee and Chand 1975; Lea et d . 1980; Tiarks 1982; and others). These studies have used y i e l d , P uptake and/or f o l i a r P concentration as the plant v a r i a b l e . - 34 -Kamprath and Watson (1980) reviewed numerous studies that demonstrate quantitative r e l a t i o n s h i p s between nutrient concentration i n plant tissue and plant growth, including f o l i a r P concentration i n pine species (e.g., Terman and Bengtson 1973; R. Balla r d and P r i c h e t t 1975a). In-depth reviews on p r i n c i p l e s and problems of f o l i a r analysis (Leaf 1968; Armson 1973; Z o t t l 1973; Everard 1974; Morrison 1974; van den Driessche, 1974) suggest good u t i l i t y f o r s o i l test c o r r e l a t i o n s . F o l i a r analysis i s now a common basis of nutrient status diagnosis for fo r e s t r y i n B r i t i s h Columbia (e.g., T. Ballard 1981; T. Ballard and Carter 1983). Some simple data manipulations may be used to improve s o i l test c o r r e l a t i o n s . Bremer (1984), evaluating the Olsen and Bray P i methods for a g r i c u l t u r e i n the B r i t i s h Columbia i n t e r i o r , found better i correlations when the log of the s o i l test value was used. This i s presumably due to the f a c t that growth response to a nutrie n t tends to the asymptotic. Percentage y i e l d and/or percentage of maximum "plant P" may also improve r e s u l t s , although not i n Bremer's (1984) case. A major consideration a f f e c t i n g s o i l test c o r r e l a t i o n s for for e s t r y i s the i n i t i a l s o i l sampling. Trees root across a v a r i e t y of genetic s o i l horizons, and v a r i a b i l i t y i n tree root d i s t r i b u t i o n and s o i l v a r i a b i l i t y complicate sampling. There are d i f f e r i n g reports i n the l i t e r a t u r e on successful sampling schemes. R. Balla r d (1980) noted that the surface layer of s o i l i s generally better correlated i n l i t e r a t u r e reports (e.g., Alban 1972; R. Ballard and P r i t c h e t t 1975b). However, other studies report improved success by considering the lower solum - 35 -(e.g., Kessel and Stoate 1938) and/or averaging P for the rooting zone (e.g., MacDougall 1984). Webber (1974), studying c o r r e l a t i o n with s o i l test P f o r Douglas-fir on Vancouver Island, found that consideration of e i t h e r the upper or entire solum did not e f f e c t the r e s u l t s appreciably. C l e a r l y the r e s u l t s vary with the s i t e and this demonstrates the importance of each of the four phases of s o i l testing discussed e a r l i e r . R. Ballard (1980) notes that the sampling problem may be expected to become more acute with stand age (e.g., f o r e s t f l o o r complications), suggesting a r e l a t i o n s h i p with the most successful studies reported in the l i t e r a t u r e having involved young stands. Interpretation of s o i l test data follows the same general practices as a g r i c u l t u r e except that R. B a l l a r d (1980) notes that the actual s o i l test values used as i n t e r p r e t a t i o n thresholds are usually lower for f o r e s t trees than for a g r i c u l t u r a l crops. 7. R e s e a r c h Needs Topics for i n v e s t i g a t i o n i n developing a c a l i b r a t e d s o i l test for a region include ( a f t e r Melsted and Peck 1973; FAO 1980) (1) the s i g n i f i c a n t chemical forms of the nutrient i n the s o i l s of the area; (2) s u i t a b i l i t y of extractants for accurately and r a p i d l y measuring (indexing) the a v a i l a b l e nutrient forms ( i n c l u d i n g an evaluation of " o p e r a b i l i t y " for routine laboratory use); (3) pot t r i a l s including the expected range of l o c a l s o i l conditions for i n i t i a l screening of P extractants based on the best and most consistent correlations with plant growth and/or nutrient status; (4) f e r t i l i z e r t r i a l s i n the f i e l d - 36 -( c r o p r e s p o n s e s m o n i t o r e d f o r v a r y i n g r a t e and method of f e r t i l i z e r a p p l i c a t i o n and f u r t h e r s o i l t e s t s c r e e n i n g and c a l i b r a t i o n f o r r e s p o n s e p r e d i c t i o n c a p a b i l i t y ) ; and (5) m e t h o d o l o g i c a l r e f i n e m e n t type r e s e a r c h ( e . g . , f i e l d s a m p l i n g t e c h n i q u e s , e t c . ) . G e n e r a l l y , the f i r s t th ree t o p i c s r e p r e s e n t the i n i t i a l background r e s e a r c h and the l a t t e r two r e p r e s e n t a t f i r s t background and then o n g o i n g r e s e a r c h . L e i t c h et al. (1980) note t h a t , when w o r k i n g up and t e s t i n g a c h e m i c a l s o i l t e s t , i t i s n e c e s s a r y to work w i t h s o i l samples of known c r o p r e s p o n s e and which g i v e a range i n c r o p r e s p o n s e s ( i . e . , the l o c a l range i n s o i l c o n d i t i o n s ) . T h e r e f o r e , i n d e v e l o p i n g a s o i l t e s t i n g programme f o r P f o r f o r e s t r y i n B r i t i s h Co lumbia we r e q u i r e i n i t i a l background r e s e a r c h on : (1) the s i g n i f i c a n t c h e m i c a l forms of P i n B r i t i s h C o l u m b i a f o r e s t s o i l s ; (2) the e x t r a c t a n t s most adequate to i n d e x a v a i l a b l e P i n B r i t i s h C o l u m b i a f o r e s t s o i l s ; and (3) p o t t r i a l s on a s u i t a b l e range of B r i t i s h C o l u m b i a f o r e s t s o i l s f o r i n i t i a l s c r e e n i n g of P e x t r a c t a n t s . THESIS OBJECTIVES The main o b j e c t i v e of t h i s t h e s i s i s to f i n d an adequate method ( o r methods) f o r e s t i m a t i n g the f o r e s t s o i l P w h i c h i s " a v a i l a b l e " to D o u g l a s - f i r , l o d g e p o l e p i n e , and w e s t e r n hemlock g rowing i n v a r i o u s k i n d s of B r i t i s h C o l u m b i a f o r e s t s o i l m a t e r i a l s , u s i n g g reenhouse pot c u l t u r e . The o b j e c t i v e w i l l be a c c o m p l i s h e d by a p r e l i m i n a r y s t u d y t h a t w i l l e v a l u a t e the f o l l o w i n g s p e c i f i c o b j e c t i v e s : „ - 37 -a. i d e n t i f y s i g n i f i c a n t inorganic P f r a c t i o n s i n a v a r i e t y of B r i t i s h Columbia forest s o i l materials, b. investigate correlations among res u l t s obtained by various s o i l test methods, c. evaluate relationships between the s o i l test r e s u l t s and the abundance of chemical P forms, d. determine which s o i l test method (or methods) gives the best r e l a t i o n s h i p with the P status of B r i t i s h Columbia c o n i f e r s , and e. evaluate test methods for routine laboratory a n a l y s i s . Objectives a, b, and c w i l l be addressed in Chapter 2. "Amounts and Correlations of Extractable Phosphorus Obtained by 12 Methods and Chemical Phosphorus Fractions from F r a c t i o n a t i o n . " Objective d i s the fundamental objective of Chapter 3. "Greenhouse Evaluation of Methods to Estimate Phosphorus A v a i l a b i l i t y to « Douglas-fir, Lodgepole Pine, and Western Hemlock." Objective e i s addressed through both Chapters 2 and 3, with f i n a l concluding remarks i n Chapter 3. - 38 -C H A P T E R 2 AMOUNTS AND CORRELATIONS OF EXTRACTABLE PHOSPHORUS OBTAINED BY 12 METHODS AND CHEMICAL PHOSPHORUS FORMS FROM FRACTIONATION INTRODUCTION In B r i t i s h Columbia, s o i l testing for phosphorus (P) in f o r e s t s o i l s i s i n the e a r l y stages of development. Many methods e x i s t in the l i t e r a t u r e for characterizing s o i l P a v a i l a b i l i t y to agronomic species (Olsen and Sommers 1982). However, no one P s o i l test may be considered universal; each new region or crop i n a region requires a s o i l test that i s "adequate" for the l o c a l s o i l - p l a n t conditions of i n t e r e s t . Forest s o i l s represent a generally wider range of chemical properties of importance to s o i l testing for P (such as pH, organic matter content, P forms and P l e v e l ) than most managed a g r i c u l t u r a l systems. In evaluating s o i l tests for adaptation to f o r e s t r y , the existence of various chemical P forms, and of r e l a t i o n s h i p s of these with s o i l a v a i l a b l e P test values, w i l l be of i n t e r e s t across the range of expected s o i l conditions. In developing a c a l i b r a t e d s o i l test for a region, two i n i t i a l topics for i n v e s t i g a t i o n I d e n t i f i e d by Melsted and Peck (1973) and the FAO (1980) are (1) the s i g n i f i c a n t chemical forms of the nutrient i n the regional s o i l s , and (2) the s u i t a b i l i t y of various extractants for measuring the a v a i l a b l e nutrient forms. I t i s of i n t e r e s t how well the - 39 -many various s o i l P test r e s u l t s are correlated with chemical P forms and with the r e s u l t s of other s o i l tests. Such information serves an important role in providing valuable i n s i g h t on s o i l P chemistry i n l o c a l s o i l s and i n enabling investigators to view the r e s u l t s in the perspective of a f a m i l i a r s o i l test method. Accordingly, the objectives of this Chapter are to (a) i d e n t i f y s i g n i f i c a n t inorganic P f r a c t i o n s i n a v a r i e t y of B r i t i s h Columbia forest s o i l materials, (b) investigate c o r r e l a t i o n s among r e s u l t s obtained by various s o i l test methods, and (c) evaluate relationships between the s o i l tests and the abundance of chemical P forms. The s i g n i f i c a n t chemical forms of P i n s o i l are usually evaluated through a f r a c t i o n a t i o n procedure. The s o i l inorganic P f r a c t i o n a t i o n procedure, i n i t i a l l y attempted by Dean (1938) and improved by Chang and Jackson (1957), forms the basis of some current methods (e.g., Olsen and Sommers 1982). Some modifications and revised nomenclature include Glenn ejt a l . (1959), Peterson and Corey (1966), Williams et a l . (1967 , 1971a, 1971b) and Syers et al.(1972). The Ca-P f r a c t i o n commonly dominates t o t a l inorganic P i n s o i l s that are r e l a t i v e l y young and the Al-P and Fe-P f r a c t i o n s are generally dominant in more weathered s o i l s (Williams et. a l . 1967; Walker and Syers 1976). Extractants of "available P" can be grouped into seven classes (1) Dilute strong acids; (2) Dilute-weak acids; (3) D i l u t e , mixed weak and strong acids; (4) D i l u t e acid(s) plus a complexing ion; (5) Buffered a l k a l i n e solutions; (6) Water or d i l u t e s a l t ; or (7) Isotopic exchange media (e.g., anion exchange r e s i n — n o t studied here). Numerous studies - 40 -have reported test values and correlations for various P e x t r a c t i o n methods; however, only a few of these report on regional f o r e s t s o i l s (e.g., Gaitho 1978; Radwan and Shumway 1983) or on B r i t i s h Columbia a g r i c u l t u r a l s o i l s (e.g., John 1971, 1972; Bremer 1984). Correlations between s o i l test values and P f r a c t i o n s are of i n t e r e s t , i n developing a s o i l testing programme, for r e l a t i n g the various extractants to nutrient forms and for comparison with r e s u l t s from other s o i l s . Many studies have correlated the amount of P extracted by s o i l tests with various chemical P forms from Chang and Jackson type"fractionations. Data reviewed by Kamprath and Watson (1980) indicate that, for a wide range of s o i l s ( i n c l u d i n g some B r i t i s h Columbia s o i l s studied by John 1972), r e s u l t s obtained by the Olsen i (buffered alkaline) and Bray P^ ( d i l u t e acid with complexing ion) methods were primarily correlated with the Al-P f r a c t i o n ; whereas P extracted by d i l u t e strong acids(Truog, double-acid) was correlated with the Ca-P f r a c t i o n in s o i l s high i n Ca-P and with Al-P i n s o i l s low i n Ca-P. A l l f r a c t i o n a t i o n studies noted have involved a g r i c u l t u r a l s o i l s -. and ( i n addition to meeting the s p e c i f i c objectives) i t i s of i n t e r e s t i f the above relationships extend to forest s o i l conditions. MATERIALS AND METHODS Eight f o r e s t s o i l materials were selected from coastal and i n t e r i o r B r i t i s h Columbia to represent a range of f o r e s t s o i l conditions such as pH (3.65 to 7.60 in H2O), texture (sand to s i l t loam), parent materials, - 41 -P forms and P l e v e l s (Table 1). The selected s o i l materials represented some Podzolic, B r u n i s o l i c , and Regosolic forest s o i l materials of southern and central B r i t i s h Columbia. The s o i l samples were a i r - d r i e d and sieved (< 2 mm). Available P was estimated by 12 P extraction methods (Table 2), and four chemical P f r a c t i o n s (Al-P, Fe-P, reductant-soluble P (Red-P), and Ca-P) were extracted by the Chang and Jackson (1957) procedure as modified by Peterson and Corey (1966). Measurement of P i n a l l s o i l extracts was by ascorbic acid reduction of a phospho-molybdate complex (Murphy and Riley 1962) as described for s o i l extracts by Watanabe and Olsen (1965). Color i n t e n s i t y was read on a G i l f o r d Stasar II at 700 nm. Modified Olsen and modified NH^HCO 3 -DTPA were also read at 880 nm with a red f i l t e r on a Bausch and Lomb Spectronic 20, to reduce error from effervescence, by increasing the l i g h t path length through the s o l u t i o n . Readings at 880 mm with a red f i l t e r are preferred; as the G i l f o r d lacks this c a p a b i l i t y , readings at 700 mm are used as an a l t e r n a t i v e (Murphy and R i l e y 1962). The G i l f o r d i s more e f f i c i e n t to use because of i t s flow-through c a p a b i l i t y and low sample volume requirement. Data analysis was performed on the University of B r i t i s h Columbia computing system. Simple l i n e a r c o r r e l a t i o n s formed the basis of the data a n a l y s i s , with Spearman rank c o r r e l a t i o n c o e f f i c i e n t s calculated as a check and recorded in Appendix 4. (With small sample size normality assumptions are considered to play a greater role for s i g n i f i c a n t 2 parameters (Dr. Malcolm Greig personal communication). 2Head Analyst, S t a t i s t i c a l Analysis, U n i v e r s i t y of B r i t i s h Columbia Computing Center. - 4 2 -Table 1. Summary of Study Soils Symbol Name ( T h i s Study) H o r i z o n pH Used H 20 C a C l 2 Texture Sampling L o c a t i o n Notes EL E l u v i a t e d Ae 3.65 3.15 LS UBC Research F o r e s t AP Ap h o r i z o n Ap 4.35 4.20 CM P - f e r t i l i z e d CU-FF MI CA Non P - f e r t i l i z e d F o r e s t f l o o r Memekay Ca l c a r e o u s Ap 4.65 4.40 Ap 5.00 4.60 (F) H 3.75 .3.30 Bf 4.90 4.60 Ck 7.60 7.20 TS Tsus Bf 5.15 4.80 MSL SL LS S i L S i L UBC Research F o r e s t Campbell R i v e r Nursery Campbell R i v e r Nursery U n i v e r s i ty Endowment Lands N o r t h of Campbell R i v e r N o r t h of L i l l o o e t ( P a v i l i o n Lake) E a s t of P r i n c e George (Tsus Creek) Ae h o r i z o n from O r t h i c Humo-Ferric P o d z o l developed i n g l a c i a l d r i f t domi-nated by a c i d - i g n e o u s m a t e r i a l s . S c a r i f i e d s u r f a c e h o r i z o n from O r t h i c Humo-Ferric P o d z o l developed i n g l a c i a l outwash dominated by g r a n i t i c c l a s t s . P - f e r t i l i z e d n u r s e r y s o i l on Vancouver I s l a n d , . made' by m i x i n g v a r i o u s s o i l ma t e r i a l s . U n f e r t i l i z e d , newly s c a r i f i e d n u r s e r y s o i l (Humo-Ferric P o d z o l developed i n g l a c i a l outwash). Western Hemlock f o r e s t f l o o r ( O r t h i c Humimor ) O r t h i c Humo-Ferric P o d z o l developed i n marine c l a y . C a l c a r e o u s O r t h i c Regosol developed i n l i m e s t o n e C o l i u v i m a , d i s p l a y s apparent Fe d e f i c i e n c i e s i n c o n i f e r s i n the f i e l d . O r t h i c Humo-Ferric P o d z o l developed i n g l a c i a l outwash, d i s p l a y s apparent Fe d e f i c i e n c i e s i n c o n i f e r s i n the f i e l d . Notes: Hand T e x t u r e (M » mucky). 2 K l i n k a et a l . 1981. 3 S o i l CA i s from S i t e 5 i n M a j i d (1984); TS from S i t e 1. Table 2. Available Phosphorus Methods Tested Method Extrac tion Solution Soil/Sol'n Shaking (g/inl) Time (min.) Type 1. H 2 0-soluble P (Humphreys and Pritchett, 1972) 2. Truog (1930) 3, 3A. Modified Olsen (Banderis j2_t a l . 1976) 4. Bray Pi H2O + CHCI3 1:10 0.002 N H 2 S O 4 1:200 buffered with (NHi»)2S04 - pH 3 . 0 0.05 M NaHC03 - pH 1:20 8 . 5 (Polyacrylamide instead of carbon black) 960 reciprocal 0.03 N. NH4F + 0.025 N HC1 - pH 2.7 1:10 30 30 reciprocal reciprocal ro ta tional 5. Modified Bray Pi 6. Bray P 2 7. Modified Bray P 2 8 . Double-acid (Nelson et al.) 9. NH40Ac at pH 4.8 (Breland 1957) 1 0 . 1 0 A . 3 Modified NHi^HCOa - DTPA Solantanpour and Workman (1979) 1 1 . 0 . 0 1 N_ HC1 1 2 . New-Mehlich (Mehlich 1978) 0.03 H NHi^F + 1:10 0.025 N_ HC1 - pH 2.7 0.03 N NH4F +. 1:10 0.1 _N HC1 - pH 1.5 0.03 JN NHijF + 1:10 0.1 N. HC1 - pH 1.5 0.05 N HC1 + 1:5 0.025 N_ R2SOlt 1 M NH40Ac adjusted 1:10 with acetic acid pH 4.8 1 M NH^HCOs-DTPA 1:2 pH 7.6 0.01 N, HCL 1:10 0.02 N NHi^d + 1:10 0.2 _N HOAc + 0.015 U NliijF + 0.012 N HC1 - pH 2.5 15 rotational rotational rota tional reciprocal reciprocal reciprocal 5 rotational 5 reciprocal 1 Detailed descriptions appear in Appendix 1. 2 A l l extractions were filtered immediately through Whatman No. 42 F i l t e r paper (No. 40 for modified Olsen). Phosphorus determined in a l l extracts by ascorbic acid reduction of phosphomolybdate complex and read at 700 nm (880 nm for 3 and 10, 700 nm for 3A and 10A). - 44 -RESULTS AND DISCUSSION Phosphorus Forms Phosphorus forms obtained through f r a c t i o n a t i o n varied considerably among the s o i l s (Table 3 ) . The Podzolic horizons (TS, MI, CIT and inc l u d i n g the s c a r i f i e d AP, and P - f e r t i l i z e d CM s o i l s ) were dominated by the Al-P and Fe-P fra c t i o n s and yielded high amounts of P ( i n the order of 300 to 800 ppm t o t a l for sum of a l l four f r a c t i o n s ) . The CA s o i l (although y i e l d i n g a to t a l sum of fractionated P of about 265 ppm), was dominated by the Ca-P f r a c t i o n . The FF and EL s o i l s yielded much less summed P from a l l f r a c t i o n s (under 100 ppm and under 10 ppm respectively) and both contained primarily Al-P. Observations for the Podzolic s o i l materials agree with r e s u l t s of previous studies on a g r i c u l t u r a l s o i l s i n western Canada (e.g., John 1971). I t appears reasonable that most of the P bound by organic matter would be detected i n the f i r s t step of f r a c t i o n a t i o n , which involves NaOH. The EL s o i l appears extremely low i n P, which i s not unreasonable, considering that a l l but a c i d - r e s i s t a n t primary minerals have been eluviated from this material i n the course of s o i l development. Extractable Phosphorus A l l a v a i lable P extractants (except the Troug, Bray P 2, double-acid and the NH^OAc at pH 4 . 8 ) yielded highest test values, among u n f e r t i l i z e d s o i l materials, with the FF. The double-acid and Bray P 2 - 45 -Table 3. Summary of Phosphorus Extraction and Fractionation Data for the Study Soils Soil Method FF EL TS CM AP ppm P MI CU CA 1. H20-soluble P 128.0 1.5 .6 .1 0.0 0.0 .2 .5 2. Truog 40.0 2.0 16.0 50.0 10.0 2.0 3.0 50.0 3. Mod. Olsen et a l . (880 run)3 22.5 2.3 14.5 38.0 11.5 .5 6.5 12.0 3A. Mod. Olsen et a l . (700 run) 56.8 8.1 17.5 54.8 20.8 3.54 4.8 31.1 4. Bray Pi - 1 min. 51.0 7.0 50.0 84.0 30.0 2.0 16.0 .5 5. Bray P i - 5 inin. 59.0 8.8 36.0 61.0 20.0 2.0 11.5 .5 6. Bray ?2 ~ 1 min. 53.0 7.8 71.0 127.0 49.0 3.3 ' 29.0 0.0 7. Bray P 2 - 5 min. 60.0 9.0 64.0 109.0 35.5 2.3 23.0 .5 8. Doable-acid 32.0 4.8 34.0 54.5 12.0 1.3 . 8.5 4.4 . 9. NU40Ac at pH 4.3 38.3 .6 2.8 7.1 2.9 1.1 2.3 95.0 10. Mod. NH4HC03-DTPA (880 run)3 18.4 .7 5.8 17.8 2.1 .7 .6 16.9 10A. Mod. NH4HCO3-DTPA (700 run) 33.2 N.V.2 5.9 13.5 3.7 1.8 N. . 12.0 11. 0.01 N HC1 32.0 1.3 2.2 1.3 .5 .2 .2 1.8 12. New-Mehlich (1978) 32.0 3.0 13.5 32.5 5.0 :2.1 5.0 26.0 FRACTIONATION A l - P 86.51* 3.6 208.0 409.0 477.3 267.5 114.0 26.0 F e - P 0.0 0.0 304.5 153.5 134.0 \ 164.8 54.3 0.0 Reductant-soluble P 1.8 2.3 176.8 71.0 46.5 110.5 60.8 7.8 C a - P 4.0 2.0 76.8 55.5 25.3 42.8 77.0 230.3 Data represents means of duplicate analyses. !N.V. - no value attained, due to operational d i f f i c u l t i e s , in two separate attempts. 'All other determinations made at 700 nm. Data represents one determination. ,/ - 46 -extractants yielded highest u n f e r t i l i z e d s o i l test values with the Podzolic TS s o i l . The Troug and NHi+OAc at pH 4.8 yielded highest P with the calcareous CA s o i l * The P - f e r t i l i z e d CM s o i l yielded higher s o i l test r e s u l t s than FF with the Truog, Olsen (880 nm), a l l Bray methods, modified double-acid and new-Mehlich methods. For the FF, H 20-soluble P was the highest and for the CA; NH4OAC at pH 4.8 was the highest. The NR\0Ac at pH 4.8 extracted very l i t t l e P from the eluviated EL s o i l and Podzolic MI and CU, as did modified NHi+HCO3-DTPA. The 0.01 N HC1 and H 20 extracted l i t t l e P from a l l s o i l s but FF. The Bray P 2 (1 minute shake) and Bray P i (1 minute) almost i n v a r i a b l y yielded the highest and second highest extractable P, re s p e c t i v e l y , for the Podzolic and eluviated s o i l materials (TS, CM, AP, CU and EL). For the Bray methods, the 1-minute was always higher than the 5-minute version except for the eluviated EL, organic FF, and often the calcareous CA, where the opposite was true. A l l Bray methods extracted very l i t t l e P from the CA (amounts s i m i l a r to H 20-soluble P). High P test r e s u l t s for the FF are consistent with other reports for B r i t i s h Columbia forest f l o o r s (Gaitho 1978; Carter 1983). (Along with the very high value for H 20-soluble P, this suggests the importance of the fo r e s t f l o o r as a major pool of available P i n f o r e s t ecosystems.) The strongly a c i d i c Bray P 2 extractant would be expected to p r e f e r e n t i a l l y dissolve Al-P and Fe-P, over o r g a n i c a l l y bound P, i n a Podzolic Bf horizon such as TS. Both the NHitOAc at pH 4.8 and new-Mehlich solutions effervesced the most with the calcareous CA s o i l , y i e l d i n g f a i r l y high P concentrations; - 47 -perhaps the reaction involved acetate, since acetic acid was present i n both. However, the strong a c i d i c extractants ( i . e . , Bray P2) did not extract much P from this s o i l . High Truog P for CA i s consistent with the presence of Ca-P in a slowly soluble form released i n longer shaking. Extracts f i l t e r e d very slowly for NH^OAc at pH 4.8 and Truog, prolonging e f f e c t i v e extraction time. In comparison, Bray methods yielded much lower P for CA, most l i k e l y due to H + n e u t r a l i z a t i o n and CaF 2 formation ( S m i l l i e and Syers 1972; Syers et a l . 1972; Olsen and Sommers 1982), and possibly also due to shorter extraction time. Those methods which yielded higher P for the P - f e r t i l i z e d CM over the organic FF p r e f e r e n t i a l l y release e a s i l y soluble P, and include strongly a l k a l i n e solutions with HC0 3~ (modified Olsen method), and strongly a c i d i c extractants with F~ (Bray and new-Mehlich methods) or 2— SO^ (Truog and double-acid methods). The Olsen method has been shown to act on Ca-P to a sim i l a r degree as Bray P^ (Kamprath and Watson 1980). Time of extraction has been proven very important i n Bray extractions (Bray and Kurtz 1945; Agboola and Omueti 1980). Extracted P generally declines after 1 or 5 minutes due to resorption. (The M i l l e r and Axley (1956) test uses H2S0i+ instead of HC1 i n the Bray P j reagent; 2— this most l i k e l y cuts down on P resorption through SO^ a c t i v i t y . ) The NHi,0Ac at pH 4.8 and modified NHi^HCO3-DTPA extracted l i t t l e from the eluviated EL, because of s o i l a c i d i t y and low P status. The Modified NHi»HCO3-DTPA employs a narrow s o i l : s o l u t i o n r a t i o which may also explain low extraction values with MI and CU due to very low s o i l pH (perhaps a wider r a t i o would have been b e t t e r ) . The 0.01 N HC1 has no active anion - 48 -to prevent resorption of P or to aid in P release to the extracting s o l u t i o n , explaining the commonly low test values. Co r r e l a t i o n s Among Extractable Phosphorus Obtained by Various Methods S o i l test values obtained by a number of the methods are s i g n i f i c a n t l y correlated (Table 4 ) . Modified Olsen (700 nm) values are s i g n i f i c a n t l y correlated with the greatest number of values from other methods: Truog, a l l Bray methods, double-acid, modified NHitHCO3-DTPA and new-Mehlich. A l l four Bray method modification r e s u l t s are s i g n i f i c a n t l y correlated with each other and those from the double-acid method. Bray Pi 5-minute data are s i g n i f i c a n t l y correlated with new-Mehlich data. Modified NHitHCO3-DTPA values are also s i g n i f i c a n t l y correlated with 0.01 JN HC1 extractable P. Values obtained from NHi+OAc at pH 4.8 were not correlated with any values obtained by other methods. Olsen extractable P i s commonly correlated with Bray extracted P and r e s u l t s from other a c i d i c P methods with SO^ or F~ since they a l l extract P forms s i m i l a r l y (Kamprath and Watson 1980). Similar c o r r e l a t i o n s among Bray P i , Olsen, Truog and new-Mehlich values have been observed for other B r i t i s h Columbia forest s o i l materials by Gaitho (1978). Olsen and Bray s o i l test values have also been demonstrated very s i g n i f i c a n t l y correlated with each other for B r i t i s h Columbia a g r i c u l t u r a l s o i l s by John (1972). Spearman rank c o r r e l a t i o n c o e f f i c i e n t s (Appendix 4-1) agree with r e s u l t s discussed. Table 4. Correlation Coefficients for the Relationships Among S o i l Phosphorus Test Values Obtained From 12 Extraction Methods 1 P Extraction Method 1. H 20-soluble P 2. Truog .3439 3. Mod. Olsen et a l . (880 nm)3 .2973 .7891* 3A. Mod. Olsen et a l . (700 nm) .6085 .8829** .8953** 4. Bray Pj - 1 min. .2829 .5008 .9123** .7308* . 5. Bray Pj. - 5 min. .5633 .5361 .8775** .8211* .9500*** -6. Bray P 2 - 1 min. .0957- .4428 .8895** .6361 .9795*** .8703** 7. Bray P 2 - 5 rain. .2339 .4914 .9107** .7060 .9979*** .9334*** .9871*** 8. Double-acid .2750 .5760 .9 2 64*** .7516* .9851*** .9388*** .9573*** .9867*** 9. NH40Ac at pH 4.8 .2373 .694 5 .1204 .3925 -.2387 -.1403 -.3041 -.2537 -.1483 10. Mod. NH4HC03-DTPA (880 nm)3 .5104 .9807*** .7901* .9274*** .5318 .6190 .4402. .5153 .6054 .6601 1 OA.1 Mod. NH4HCO3-DTPA (700 nm) .9169* .63 56 .5171 .8401* .3798 .644 6 .1992 .3421 .4083 .3812 .7890 11. 0.01 N. HC1 .9981*** .3790 .3240 .6326 .3061 .5831 .1169 .2573 .3049 .2623 .5432 .9289** 12. New-Mehlich .5191 .9666*** .8643** .9624*** .6444 .7161* .5591 .6277 .7008 .5653 .9877*** .7977 .5515 1. 2. 3. 3A. 4. 5. 6. 7. 8. 9. 10. 10A.1 11. *>** >***Signif leant at the 5, 1 and 0.1X levels, respectively - 8 except for 10A (mod. NH4HCO3-DTPA) where N = 6 - 50 -Co r r e l a t i o n s of Extractable Phosphorus with Phosphorus Fractions Only one s i g n i f i c a n t r value e x i s t s i n the c o r r e l a t i o n matrix (Table 5). This i s NH40Ac at pH 4.8 which correlates s i g n i f i c a n t l y at the a =• .05 l e v e l with the Ca-P f r a c t i o n obtained from the modified Chang and Jackson procedure. This may be explained by the apparent a f f i n i t y of this extractant for basic Ca-P as demonstrated by previous discussion of the CA data. These observed r e s u l t s for the 8 f o r e s t s o i l materials tested are contrary to numerous studies i n the l i t e r a t u r e (Chang and Juo 1963; Shelton and Coleman 1968; T r i p a t h i et a l . 1970; Zubriski 1971; John 1972; Susuki et a l . 1963; Ahmed and Islam 1975; Cajuste and Kussow 1974). Data from the l i t e r a t u r e indicate that, for a wide range of primarily a g r i c u l t u r a l s o i l s , Olsen and Bray P i extractable P values are primarily correlated with the Al-P f r a c t i o n , whereas d i l u t e acid extractants (Truog, double-acid) are related to the Ca-P f r a c t i o n i n s o i l s high i n calcium and to the Al-P f r a c t i o n i n other s o i l s . In studying B r i t i s h Columbia a g r i c u l t u r a l s o i l s , John (1972) found s o i l test values from the Olsen, Bray P± and double-acid methods to be correlated with P forms as above. Results here follow general trends as discussed above, but are not s i g n i f i c a n t , p a r t i a l l y due to the very wide range of s o i l s tested in this one study. The existence of r e l a t i o n s h i p s among extractable P and P forms i s primarily of i n t e r e s t i n a f o r e s t s o i l P testing programme i f i t occurs across this range of s o i l p r operties. However, examining the c o r r e l a t i o n s across Podzolic s o i l horizons only (without CA, E L , F F ; Appendix 2) does not s u b s t a n t i a l l y - 51 -Table 5. C o r r e l a t i o n C o e f f i c i e n t s for the Relationships Between Extractable Phosphorus and Phosphorus Fractions P Fracti o n A v a i l a b l e P Method Al-P Fe-P Red-P Ca-P 1. H 2 0-soluble P -.2672 -.3822 -.3878 -.3337 2. Truog -.0087 -.1939 -.2854 .4676 3. Mod. Olsen et a l . (880 nm) 3 .3863 .1413 -.0087 -.0040 3 A. Mod. Olsen et a l . (700 nm) .1511 -.1642 -.3076 .0149 4. Bray ?i - 1 min. .4971 . .3990 .2498 -.2988 5. Bray P^ - 5 min. .3153 .2059 .0783 -.3811 6. Bray P 2 - 1 min. .5953 .4718 .3174 -.2503 7. Bray P 2 - 5 min. .4969 .4145 .2729 -.2779 8. Mod. Double-acid .3926 .3907 .2660 -.1972 9. NH^OAc at pH 4.8 -.4577 -.4988 -.4767 .7809* 10. Mod. NH4HCO3-DTPA (880 nm) 3 -.0750 -.2337 -.3107 .3476 10A. Mod. NH 1 +HC03-DTPA (700 nm) -.4976 -.6326 N.S.2-.6050 -.1719 11. 0.01 N H C 1 -.2784 -.3642 -.3735 -.3061 . 12. New-Mehlich (1978) .0266 -.1597 -.2594 .2679 • S i g n i f i c a n t at 5% l e v e l % = 8 except 10A where N = 6 2N.S. = not s i g n i f i c a n t (N = 6) at a = .10 3A11 other P determinations made at 700 nm. improve r e s u l t s from those reported above, with respect to the l i t e r a t u r e observations. Spearman rank c o r r e l a t i o n c o e f f i c i e n t s (Appendix 4-2) disagree with the r e s u l t s discussed i n that no s i g n i f i c a n t c o r r e l a t i o n s (at a = .05) e x i s t . Therefore, although many more observations are required to test for normality, i t i s suggested from both c o r r e l a t i o n s that, for study s o i l s , test r e s u l t s are generally not correlated with P forms from a Chang and Jackson type f r a c t i o n a t i o n . Correlations Among Phosphorus Frac t i o n s Across a l l eight study s o i l s only the Fe-P and Red-P f r a c t i o n s are s i g n i f i c a n t l y correlated (Table 6a). For Podzolic s o i l horizons only ( i . e . , without CA, EL, FF) the above c o r r e l a t i o n holds true and also, Al-P i s s i g n i f i c a n t l y and negatively correlated with Ca-P (Table 6b). These r e s u l t s are consistent with, but less extensive than those of John (1972), Pra t t and Garber (1964), and Westin and Buntley (1966). Their studies also found s i g n i f i c a n t c o r r e l a t i o n s ( a = .01 level) between Red-P and Al-P and negative c o r r e l a t i o n between Ca-P and Fe-P. The negative c o r r e l a t i o n between Ca-P and Al-P i s due to the re l a t i o n s h i p between Ca-P and Al-P in the s o i l ( i . e . , r e l a t i v e to pH). Most previous studies used a narrower range of s o i l s ; the fact that more co r r e l a t i o n s e x i s t across a subset of study s o i l s (Table 6b) suggests that poor c o r r e l a t i o n s here are again partly due to the wide range of s o i l properties selected for i n v e s t i g a t i o n . - 53 -Table 6 - C o r r e l a t i o n C o e f f i c i e n t s for the Relationships Among Phosphorus Fractions. 6A. Correlations Across a l l 8 S o i l s (N=8) Fe-P Red-P Ca-P Al-P .5952 .4006 -.2781 Fe-P .0179 .9549*** -.1003 Red-P -.4166 .8922 + -.0245 Ca-P -.8269+ .1886 .4848 Al-P Fe-P Red-P 6B. Correlations Across Podzolic S o i l Horizons 1 (N=5) + ,*** s i g n i f i c a n t at 10, and 0.1% l e v e l s , r e s p e c t i v e l y . Without FF(organic), CA(calcareous), EL(eluviated). Spearman rank c o r r e l a t i o n c o e f f i c i e n t s (Appendix 4-3) agree with the r e s u l t s discussed. CONCLUSIONS i The B r i t i s h Columbia forest s o i l s tested present a v a r i e t y of amounts and d i s t r i b u t i o n s of P forms obtained from a Chang and Jackson type f r a c t i o n a t i o n . This suggests diverse s o i l chemistry r e l a t i v e to P a v a i l a b i l i t y to forest trees. This indicates that either a s o i l test method capable of extracting P from a l l important P forms, or more than one kind of s o i l test method, w i l l be required f o r s o i l testing for P a v a i l a b i l i t y to forest s o i l s i n B r i t i s h Columbia. The twelve s o i l P extraction methods tested vary greatly i n their a b i l i t y to extract P from the various study s o i l s . (However, the limited scope of this study does hot warrant discarding any methods prior to the greenhouse analysis involving f o r e s t trees.) Almost a l l methods extract more P from f o r e s t f l o o r than u n f e r t i l i z e d mineral s o i l s , suggesting the importance of the forest f l o o r as a reservoir of av a i l a b l e P i n forest s o i l s . On B r i t i s h Columbia forest s o i l s , test methods y i e l d correlated r e s u l t s s i m i l a r to reports i n the l i t e r a t u r e reviewed. However, on B r i t i s h Columbia s o i l s , P forms (fractionated by a modified Chang and Jackson procedure) do not appear as well correlated among themselves or with s o i l P test values as in the l i t e r a t u r e for a g r i c u l t u r a l s o i l s . This suggests somewhat d i f f e r e n t P chemistry i n B r i t i s h Columbia forest - 55 -s o i l s r e l a t i v e to a g r i c u l t u r a l s o i l s , which i s consistent with the f a c t that a wide range of s o i l conditions was tested. Spearman rank, c o r r e l a t i o n c o e f f i c i e n t s (Appendix 4) present no major discrepancies with the simple l i n e a r correlations presented i n the text, improving confidence i n the r e s u l t s . CHAPTER 3 GREENHOUSE EVALUATION OF METHODS TO ESTIMATE PHOSPHORUS AVAILABILITY TO DOUGLAS-FIR, LODGEPOLE PINE, AND WESTERN HEMLOCK INTRODUCTION Objectives for a forest s o i l testing programme for P f a l l into a l l three categories defined by Fassbender (1980) and Kamprath and Watson (1980): (1) Grouping s o i l s into a v a i l a b i l i t y classes for making f e r t i l i z e r recommendations (e.g., nursery s o i l s as discussed by van den Driessche 1969); (2) predicting p r o b a b i l i t y of a p r o f i t a b l e response to f e r t i l i z a t i o n ; and (3) providing an index of P supplying capacity of a s o i l . In B r i t i s h Columbia, s o i l testing for P i n forest s o i l s i s i n the early stages of development. Preliminary and on-going research are the fundamental basis to a r e l i a b l e s o i l testing programme (Melsted and Peck 1973; L e i t c h e£ _al. 1980). Topics for i n v e s t i g a t i o n include ( a f t e r Melsted and Peck 1973; FAO 1980): (1) s i g n i f i c a n t chemical forms of P across the range of s o i l s ; (2) s u i t a b i l i t y of P extractants for accurately and r a p i d l y indexing P across the range of s o i l s ; (3) pot t r i a l s , Including the expected range of s o i l conditions, for i n i t i a l screening of P extractants based on the best and most consistent co r r e l a t i o n s with seedling growth or P status; (4) f e r t i l i z e r t r i a l s i n the f i e l d (responses to varying rate and method of f e r t i l i z e r - 57 -a p p l i c a t i o n for each species and further s o i l test screening and c a l i b r a t i o n for response prediction c a p a b i l i t y ) ; and (5) methodological type research (e.g., f i e l d sampling techniques, e t c . ) . A l l f i v e topics above represent preliminary research whereas the l a s t two should also be of an on-going nature and are j u s t as important to a successful s o i l testing programme as choosing the proper method. The previous chapter reported on research i n v e s t i g a t i n g amounts and r e l a t i o n s h i p s among s o i l P forms and s o i l P extracted by various methods (1 and part of 2 above); this chapter reports on a greenhouse study designed to provide an i n i t i a l screening of s o i l test methods for P i n B r i t i s h Columbia forest s o i l s (3 and part of 2 above). The s p e c i f i c objective of this Chapter i s to i d e n t i f y the test method (or methods) giving the best r e l a t i o n s h i p with f o l i a r P concentration, through an i n i t i a l screening based on pot t r i a l s with Douglas-fir, lodgepole pine and western hemlock. Further evaluation of the s u i t a b i l i t y of the s o i l test methods for routine laboratory analysis of B r i t i s h Columbia forest s o i l s w i l l also be addressed. F i n a l s e l e c t i o n and c a l i b r a t i o n of a suitable s o i l test method for P w i l l depend upon f i e l d f e r t i l i z e r t r i a l s (4 above). C r i t e r i a that an "adequate" f o r e s t s o i l test for P should meet include ( a f t e r Bray 1948; Fassbender 1980): (1) i t should extract a l l or a proportionate part of the available form(s) of P from s o i l s with v a r i a b l e properties ( i . e . , provide an index of a v a i l a b i l i t y across the expected range of s o i l s ) ; (2) P extraction and determination should be possible with reasonable accuracy, r e p r o d u c i b i l i t y , and speed; (3) the - 58 -amount extracted should be correlated with the growth and response of each tree species to P under various (environmental and s o i l ) conditions; and (4) i n t e r p r e t a t i o n of s o i l data should allow grouping of s o i l s (e.g., high, medium, low) based on f i e l d experience with the method. In Western Canada, currently developed s o i l P testing programmes for a g r i c u l t u r a l crops employ the Olsen method (NaHC0 3 at pH 8.5, Olsen et a l . (1954)), the Bray P i method (0.025 N_ HC1 + 0.03 N NR\F, Bray and Kurtz 1945) and the M i l l e r and Axley extractant (0.03 N H 2S0 1 + + 0.03 N NH^F, M i l l e r and Axley 1956) ( L e i t c h et a l . 1980). In B r i t i s h Columbia, the Bray ?^ method i s dominantly used along with some recent use of the Olsen for c e r t a i n (e.g., calcareous) s o i l conditions (Bertrand 1981; Bremer 1984). The Bray P^ test has t r a d i t i o n a l l y been used i n B r i t i s h Columbia f o r e s t nursery management (van den Driessche 1969; 1981); however, nursery s o i l s do not present the complete range of B r i t i s h Columbia f o r e s t s o i l s for which evaluations may be desired. EXPERIMENTAL DESIGN This study involved a greenhouse pot t r i a l with 8 s o i l s x 2 P l e v e l s (P added vs. control) x 3 tree species (lodgepole pine, Douglas-fir, western hemlock.) x 4 r e p l i c a t i o n s arranged in a randomized block design according to s o i l s . The 8 s o i l s (Table 1) represented a range of B r i t i s h Columbia f o r e s t s o i l conditions of i n t e r e s t i n s o i l t e s t i n g for P (organic [FF], s c a r i f i e d [AP, CU], Podzolic B [MI, TS], - 59 -eluviated [EL], calcareous [CA], and P - f e r t i l i z e d [CM] s o i l m a t e r i a l s ) . The P treatments were designed to enhance interpretations of study r e s u l t s ; i n e f f e c t , they enabled comparisons for s o i l s which d i f f e r only in P l e v e l s , i n a sense doubling the scope of the experieraent without r e q u i r i n g the c o l l e c t i o n of double the number of s o i l s . To be meaningful for purposes of i n t e r p r e t i n g data from s o i l s which are not f e r t i l i z e d with P, the P added in this study was to resemble native s o i l P, rather, than conventional, soluble f e r t i l i z e r P. The mixture represented a range of P forms ( s t r e n g i t e , taranakites, c o l l o i d a l Al-P and t r i b a s i c Ca-P) which are thought to occur n a t u r a l l y i n s o i l s or c l o s e l y resemble n a t u r a l l y occurring s o i l phosphates. The amount applied was approximately equivalent to 100 kg /ha for both the organic and the mineral s o i l materials. In studying sources of P for slash pine, R. Ballard and P r i t c h e t t (1975b) found that strengite was not nearly as e f f e c t i v e , but that potassium taranakite was j u s t as e f f e c t i v e as normal f e r t i l i z e r sources. On a weight basis, because of bulk density d i f f e r e n c e s , the f e r t i l i z e r addition to the organic material was greater than to the mineral s o i l m a terial. This was considered appropriate because of the s u b s t a n t i a l l y higher extractable P l e v e l i n organic material (Table 3 ) . Good r e s o l u t i o n of the diffe r e n c e between treated and untreated s o i l would require a r e l a t i v e l y large addition. Gaitho (1978), studying s i m i l a r B r i t i s h Columbia f o r e s t s o i l s with two exotic conifer species, used f e r t i l i z e r P treatments of 20 and 200 ppm P ( i . e . , approximately 40 and 400 kg P/ha). He found that both treatments yielded r e s u l t s - 60 -d i f f e r i n g from the co n t r o l , so i n this study, 100 kg P/ha was expected to y i e l d useful r e s u l t s . Twelve a g r i c u l t u r a l s o i l test methods for "av a i l a b l e " P were selected based on previous l o c a l experience with a g r i c u l t u r e and f o r e s t r y (John et a l . 1967; van den Driessche 1969, 1981; John 1971, 1972; Gaitho 1978; Le i t c h et a l . 1980; Bertrand 1981) and forestry l i t e r a t u r e (Switzer and Nelson 1956; Stoeckler and Jones 1957; Wilde 1958; Stoeckler and Slabaugh 1965; P r i t c h e t t and Llewelyn 1966; Alban 1972; Baker and Brendmuehl 1972; Humphreys and P r i t c h e t t 1972; R. Balla r d 1974, 1978; Webber 1974; Kadeba and Boyle 1978; Hopmans et a l . 1978; Lea et j i l . 1980; Tiarks 1982). S o i l test methods chosen (Table 2) covered 5 of the 7 classes of s o i l P extractants defined i n the l i t e r a t u r e review and Chapter 2. Use of f o l i a r P concentrations (rather than P uptake or some measure of yield) was considered to be the most r e l i a b l e plant c r i t e r i o n for s o i l test c o r r e l a t i o n s because of sub s t a n t i a l v a r i a b i l i t y i n seedling development between and within s o i l s . F o l i a r P has commonly been used with good success i n the l i t e r a t u r e (e.g., Terman and Bengston 1973; R. Ba l l a r d and P r i t c h e t t 1975a, 1975b; MacCarthy and Davey 1976 and others). The s o i l test methods were screened on the basis of the c r i t e r i a presented i n the introduction. S o i l samples were i n i t i a l l y analyzed as composites of treatment r e p l i c a t e s , with f o l i a g e samples analyzed i n d i v i d u a l l y . Simple l i n e a r c o r r e l a t i o n s formed the basis of the data analysis to enable comparison with the l i t e r a t u r e . Spearman rank c o r r e l a t i o n c o e f f i c i e n t s were - 61 -calculated to improve confidence in the simple l i n e a r c o r r e l a t i o n s . Analysis of variance and covariance were performed to evaluate some fact o r e f f e c t s on the f i n a l s o i l analysis with r e p l i c a t i o n . Screening of test methods was by a h i e r a r c h i c a l approach involving f i r s t three, then f i v e s o i l s . Three s o i l s (FF, EL and TS), representing the extreme ranges of the study s o i l s with reasonable seedling growth (high organic matter, highly eluviated, and high sesquioxide content, respectively) were analyzed with a l l 12 methods. Based on these i n i t i a l r e s u l t s , the three most promising methods were selected and tested further on the remaining f i v e s o i l s (AP, MI, CM, CU and CA). The apparently most promising method was then analyzed for the i n d i v i d u a l treatment r e p l i c a t e s to provide an assessment for each i n d i v i d u a l s o i l type. The o v e r a l l r e s u l t s were considered i n the f i n a l recommendations. MATERIALS AND METHODS Large quantities of s o i l samples were obtained from selected locati o n s i n coastal and i n t e r i o r B r i t i s h Columbia (Table 1). These s o i l samples were a i r dri e d , screened to remove coarse fragments l a r g e r than about 5 mm and homogeneous subsamples placed i n p l a s t i c pots to a standard volume (with a l l r e p l i c a t e s of a single s o i l type kept at a constant weight). Potassium taranakite, ammonium taranakite, s t r e n g i t e , and c o l l o i d a l aluminum phosphate were prepared according to procedures described by Taylor et a l . (1960) and Taylor and Gurney (1961). T r i b a s i c calcium - 62 -phosphate was obtained as a commercially a v a i l a b l e reagent chemical. A phosphate mix was then formulated as follows: 8.00 g strengite (16.5% P) 14.27 g K-taranakite (18.5% P) 13.62 g N H u-taranakite (19.4% P) 26.76 g c o l l o i d a l Al-P (14.8% p) 21.41 g t r i b a s i c Ca-P (18.5% P) 84.06 g total = 1.32 g P = 2.64 g P = 2.64 g P = 3.96 g P • 3.96 g P - 14.52 g P In P-treatment pots, the phosphate mixture additions were 285 mg (about 50 mg P) per kg of mineral s o i l and 2300 mg (about 400 mg P) per kg of organic s o i l (roughly equivalent to P f e r t i l i z a t i o n at 100 kg/ha). The phosphate mixture was then mixed thoroughly into the s o i l materials which, along with the control pots, were then watered to a weight corresponding to " f i e l d capacity" (previously determined for each s o i l by means of a porous-plate tension-table device). Pots were then covered with p l a s t i c f i l m and re-watered d a i l y u n t i l s o i l water content had remained near " f i e l d capacity". (This procedure was necessary because some of the s o i l s , p a r t i c u l a r l y the forest f l o o r samples, had become hydrophobic on air-drying.) Several seeds were then sown i n each pot and the f i l m replaced u n t i l germination appeared complete. The pots were placed on the greenhouse benches at random, subject to natural plus 12 hours of fluorescent and incandescent l i g h t per day. Watering with tap water was done d a i l y during hot weather, les s frequently when cooler. To f a c i l i t a t e reasonable growth and P demand by the seedlings, a macro-nutrient (except P) f e r t i l i z e r solution was prepared based on Swan (1966) and added i n l i e u of watering on a few occasions. - 63 -Seedlings were harvested 13 months after germination and dried at 70°C u n t i l the foliage was dry (12 to 18 h r s ) . (Douglas-fir needles were stripped prior to drying, lodgepole pine and western hemlock afterwards.) Foliage samples were ground u n t i l uniformly fin e and digested by a modified Parkinson and A l l e n (1975) wet oxidation procedure (T. Balla r d 1981; T. Ballard unpublished d a t a ) 3 . Total P was determined on a Technicon Autoanalyzer I I . Following harvesting, the greenhouse s o i l s were a i r dried and sieved (< 2 mm). Forest f l o o r samples were ground i n a Waring blender. Extraction methods used to extract available P were detailed i n Chapterl (Table 2). Measurement of P i n a l l s o i l extracts was by ascorbic acid reduction of a phospho-molybdate complex (Murphy and Riley 1962) as described for s o i l extracts by Watanabe and Olsen (1965). Samples were read on a G i l f o r d Stasar II at 700 nm. Modified Olsen and modified Nh\HC03 - DTPA were also read at 880 nm with a red f i l t e r on a Bausch and Lomb Spectronic 20. Data analysis was performed on the Univ e r s i t y of B r i t i s h Columbia computing system. 3 Dr. T.M. Ba l l a r d , Professor, S o i l Science Department, U n i v e r s i t y of B r i t i s h Columbia. - 64 -RESULTS AND DISCUSSION Operational Evaluation of Tested P Extractants The two alkaline-based P extractants (Modified Olsen and modified NHi+HCO3-DTPA) were very cumbersome, and therefore undesirable for routine laboratory testing of the study s o i l s . The HCO3- and 0H~ ions i n these extractants react with organic matter, causing foaming and organic matter dispersion that often r e s u l t s i n dark s o i l extracts and p r e c i p i t a t i o n upon a c i d i f i c a t i o n for P determination. P e r s i s t e n t effervescence of some samples complicates spectrophotometer readings and often necessitates use of more time-consuming apparatus. Both these methods are recommended for a l k a l i n e s o i l s (Olsen j e t _ a l , 1954; Soltanpour and Schwab 197.7); however, their wide ranging success ( i n c l u d i n g the use of the Olsen test on B r i t i s h Columbiaagricultural s o i l s ) was reason for their i n c l u s i o n in this study. Seedling Growth Generally, the organic FF displayed the best seedling growth for a l l the species, the calcareous CA the worst for Douglas-fir and lodgepole pine and the Podzolic CU the worst for western hemlock. This demonstrates the importance of the f o r e s t f l o o r as a n u t r i e n t r e s e r v o i r i n B r i t i s h Columbia forest s o i l s . A l l species displayed a dramatic response to P treatment on at l e a s t some s o i l s which i s i n agreement with other greenhouse studies from the region (e.g., Heilman and Ekuan 1980a). Response to P was most dramatic for western hemlock and l e a s t - 65 -for lodgepole pine. Westen hemlock growth and sur v i v a l were poor on a number of the mineral s o i l s . Low biomass precluded obtaining western hemlock f o l i a r P data for a l l r e p l i c a t e s of CU with P added and three r e p l i c a t e s of CU without P. Necrosis of lodgepole pine f o l i a g e on the calcareous CA s o i l precluded meaningful f o l i a r a n a l y s i s . C l e a r l y , other n u t r i t i o n a l and environmental factors have affected growth. Correlations of Extractable P with F o l i a r P Concentration In the preliminary analysis of a l l 12 methods, the amount of P extracted by the various methods (Appendix 3) again followed the obser-vations of Chapter 2. Correlations of s o i l extractable P with f o l i a r P, by species, varied (Table 7); almost a l l methods were s i g n i f i c a n t at a = .05 for lodgepole pine, but new-Mehlich was the only one s i g n i f i c a n t at a = .01. The new-Mehlich was also the only one s i g n i f i c a n t for western hemlock (at a = .20) and was s i g n i f i c a n t f o r Douglas-fir at a = .05. The 0.01 jN HC1 and modified Olsen were s i g n i f i c a n t for Douglas-fir at a = .20 and for lodgepole pine at a » .05. Modified NHi+HCO3-DTPA also showed well, being s i g n i f i c a n t f o r lodgepole pine at a = .05 and for f i r (n = 5) at a = .05. In the o v e r a l l c o r r e l a t i o n (no s t r a t a , to test a method's adequacy across a l l three species, Table 7) almost a l l methods were s i g n i f i c a n t at a = .10, but new-Mehlich and modified Olsen were the only ones s i g n i f i c a n t at a = .05; modified NH^HCO3-DTPA and 0.01 N HC1 were s i g n i f i c a n t at a = .10. In the se l e c t i o n of three candidate methods for further a n a l y s i s , the operational l i m i t a t i o n s of modified NH^HCO3-DTPA and modified Olsen Table 7 - Correlation Coefficients for Che Relationship Between Soll-Extractable Phosphorus and Foliar Phosphorus for 12 Mecho-i's and 3 -Soils Species H20 sol. p 2 Truog Mod. Olsen (380 nm) 3 A Mod. Olsen (700 nm) 4 Bray Pj Mod. Bray Bray p2 7 8 9 10 11 12 Mod. 3ray Double NH^ OAc it Mod. NH^ HCOj 0.01 new-Mehllch P, Acid pH '..3 DTPA .HC1 Lodgepole Pine Western Hemlock Douglas-fir .7987" .3885 .2582 .3557" .8704* .4306 .5583 .4247+ .8901* .4382 .64 51" .4685* .8441* .4289 .5700 .4666*' .3248 .3316" .8665* .4348 .5229 .4091+ -.04 90 .0197 .8682* .1725 .4488 .3 64 8" .8669* .3250" .89 84 » .5508 .92681* .4 609+ .9313** .5342 .4388* *, ** Significance at 20, 10, 5 and IX levels, respectively. * S " 5 For modified NH^ OAc with Douglas-fir due to effervescence. Os Os - 67 -ruled out the i r further consideration. Thus, the methods chosen for further analysis were new-Mehlich, 0.01 N[ HC1 because of their apparent "good" cor r e l a t i o n s with f o l i a r P, and the "standard " Bray P^ (1 minute shake) because of i t s current widespread use. (Bray P], was s i g n i f i c a n t o v e r a l l at o = .20 and for lodgepole pine at a = .05). The Bray P2-I minute shake appeared considerably d i f f e r e n t from the other Bray methods. Re-extraction confirmed this r e l a t i o n s h i p (Appendix 4-5). The three chosen methods are quite s i m i l a r chemically (which helps to confirm the screening r e s u l t s ) , a l l being a c i d i c extractants, with Bray P i and new-Mehlich having a complexing ion ( F ~ ) , and 0.01 HC1 being of si m i l a r a c i d i c strength. The new-Mehlich also has the organic anion acetate which may be expected to aid i n improving the consistency of r e s u l t s through anion replacement, both preventing P readsorption during extraction (Nelson et a l . 1953; Thomas and Peaslee 1973), and relea s i n g P by forming complexes with polyvalent cations (Kamprath and Watson 1980). I t i s not su r p r i s i n g that many of the proposed methods were s i g n i f i c a n t l y correlated with lodgepole pine since many studies i n the l i t e r a t u r e report s i g n i f i c a n t c o r r e l a t i o n s for pine species with various methods (e.g., P r i t c h e t t and Llewelyn 1966; Alban 1972; Humphreys and P r i t c h e t t 1972; R. Ballard 1974, 1977; R. Balla r d and P r i t c h e t t 1975a, 1975b; Gaitho 1978; Kadeba and Boyle 1978; Tiarks 1982; MacDougall 1984; and others). Gaitho (1978) in a greenhouse study with Pinus patula on three B r i t i s h Columbia forest s o i l materials (Bf, Ah, LFH) found that a l l e x t r a c t i o n methods tested (Truog, Olsen, Bray P i , Modified Bray P i , ' 1 - 68 -new-Mehlich) yielded s i g n i f i c a n t c o r r e l a t i o n s with P uptake. Many of the methods which appear inadequate ( i n addition to the modified Olsen and modified NR\HC03-DTPA) have acted predictably. (Such methods were included i n the study based on experience i n the l i t e r a t u r e with other s o i l s . ) H 20-soluble P represents an estimate of s o i l s o l u t i o n P ( i n t e n s i t y ) (Humphreys and P r i t c h e t t 1972; Olsen and Sommers 1982) and might be expected to y i e l d very low l e v e l s on strongly P - f i x i n g s o i l s . (Low test l e v e l s may be considered unacceptable, regardless of c o r r e l a t i o n strength, due to Increased p o t e n t i a l error and, perhaps, l i m i t e d opportunity for mathematical manipulation such as logarithms.) The Truog (1930) extractant i s a non-buffered d i l u t e s o l u t i o n of strong acid which (although perhaps s i m i l a r to some root environments) might be expected to be slow at d i s s o l v i n g Al-P and even slower for Fe-P. Bray s o i l test methods have been noted to extract P forms that are unavailable to plants (Grigg 1965a); perhaps this explains poor c o r r e l a t i o n s with the stronger, Bray P 2 methods. Local s o i l s commonly y i e l d less Bray extractable P i n 5 minutes shaking (Chapter 2) than i n 1 minute. Therefore, since a l l s o i l s vary i n their P buffering capacity, one might expect to find the r e s u l t s of the best c o r r e l a t i o n with the le s s e r extraction time and the weaker Bray extractant. The double-acid method has been noted to be s a t i s f a c t o r y on s o i l s under pH 7.0 (Kamprath and Watson '1980). The NH^OAc at pH 4.8 method i s derived from the Morgan (1941) reagent which has been noted by Kamprath and Watson (1980) to be the l e a s t e f f e c t i v e (of the P s o i l tests they - 69 -discussed) for a wide range of s o i l s . However, this would have been an advantageous reagent because Klinka et a l . (1980) found the most successful method for extracting s o i l cations for forest p r o d u c t i v i t y studies in southwestern B r i t i s h Columbia was NaOAc at pH 4.8; perhaps NHtfOAc at pH 4.8 would serve both purposes. '•k I t i s important to note that, although a given P extraction method may not be s a t i s f a c t o r i l y correlated with f o l i a r P concentration in this study, i t may s t i l l be s i g n i f i c a n t l y correlated with other growth and n u t r i t i o n parameters. Examples of this from the l i t e r a t u r e on pine species include i d e n t i f i c a t i o n of s i t e s that w i l l respond to f e r t i l i z a t i o n (Hopmans et a l . 1978; Tiarks 1982) and prediction of growth on u n f e r t i l i z e d s i t e s (R. Bal l a r d 1974). However, the data i n this study provide no a l t e r n a t i v e to use of f o l i a r P for this purpose. Spearman rank c o r r e l a t i o n c o e f f i c i e n t s (Apendix 4-4) agree with r e s u l t s discussed above, with one major exception. The 0.01 _N HC1 i s the only method s i g n i f i c a n t l y correlated with western hemlock f o l i a r P concentration at a = .20, suggesting perhaps a strong c u r v i l i n e a r type of r e l a t i o n s h i p (Dr. George Eaton, personal communication) The presence of s i g n i f i c a n t c o r r e l a t i o n s with both s t a t i s t i c a l methods for the new-Mehlich and 0.01 N HC1 favoured their s e l e c t i o n . The Bray P i was chosen over two others because of current use i n f o r e s t r y (and Professor of H o r t i c u l t u r e , Department of Plant Science, U n i v e r s i t y of B r i t i s h Columbia. - 70 -despite differences i n rank c o r r e l a t i o n s , Truog, Bray P j , and NR\OAc at pH 4.8 were s i m i l a r l y correlated i n Table 7) suggesting the Bray P\ to be d e s i r a b l e . O v e r a l l Comparison of the Three Candidate Methods Correlations of s o i l extractable P with f o l i a r P, by species, were performed across a l l eight s o i l s and various subgroups of the eight s o i l s (Table 8). Across a l l eight s o i l s , new-Mehlich appeared best o v e r a l l , always s i g n i f i c a n t at o = .01 or l e s s ; Bray P i was next, being better than new-Mehlich for lodgepole pine, and s i m i l a r to new-Mehlich for western hemlock, but s i g n i f i c a n t only at a = .05 for Douglas-fir. The 0.01 HC1 did not appear as good as these other two methods i n any case ( a = .05 or more). In an o v e r a l l c o r r e l a t i o n , across a l l three species and eight s o i l s , both the new-Mehlich and Bray P i were s i g n i f i c a n t at a = .001 (with new-Mehlich somewhat higher). The 0.01 N HC1 was s i g n i f i c a n t at a = .05. A modification of the new-Mehlich ( r o t a t i o n a l shaking) was tested and compared favourably with the r e s u l t s reported for new-Mehlich, extracting s l i g h t l y more P (Appendix 4-7). The r e s u l t s of the' r e s t of the c o r r e l a t i o n s (Table 8) suggest that the new Mehlich method i s the most universal s o i l test for P, for the study s o i l s and species. This r e l a t i o n s h i p holds true without FF, AP, CU and CA ( i n turn and i n groups) and EL data alone. Bray P^ appears better where only the calcareous s o i l (CA) and the eluviated EL are removed for purposes of c o r r e l a t i o n . (However, Bray P^ did not generally correlate well with Douglas-fir.) Looking at only the Table 8 - Correlation Coefficients for the Relationships Between Soil-Extractable Phosphorus and Foliar Phosphorus for 3 Candidate Methods and 8 Soils Soils Species n Bray Pj 0.01 N HC1 New-Mehlich A l l A l l A5 .5242*** .3192* .5582*** A l l Lodgepole pine 14 .8418*** .5630* .7486** A l l Western hemlock 15 .6789** .5018* .6633** A l l Douglas-fir 16 .5398* .4110 .8221*** A l l but CA Lodgepole pine 14 .8418*** .5630* .74 86** •• Western hemlock 13 .6026* .5190+ .7291** Douglas-fir 14 .7583** .4474 .84 58*** A l l but CU, CA Lodgepole pine 12 .84 61*** .5550+ .7443** tl Western hemlock 12 .5986* .5125+ .7278** Douglas-fir 12 .7413** .4073 _ .8273*** A l l but FF Lodgepole pine 12 .7801** .4588 .8068** •t Western hemlock 13 .5606* .5514+ .6094* •• Douglas-fir 14 .5005+ .5598* .8725*** A l l but FF, CA Lodgepole pine 12 .7801** .4588 .8068** •• Western hemlock 11 .4440 .7832** .7996** - Douglas-fir 12 .7672** .5242+ .8830*** A l l but FF, AP Lodgepole pine 10 .7963** .5145 .8757*** Western hemlock 11 .5891+ .5324 + .5916+ •• Douglas-fir 12 .5117+ .5795* .8980*** A l l but FF, AP, CA Lodgepole pine 10 .7963** .5145 .8757*** Western hemlock 9 .4638 .7846* .8004** Douglas-fir 10 .7871** .5518+ .9194*** Table 8 c o n t i n u e d . . . Table 8 continued Soils Species n Bray P i 0.01 N HCl New-Mehlich A l l but EL Lodgepole pine 12 .8900*** .5709+ .7395** •• Western hemlock 13 .9208*** .5518+ .7519** Douglas-fir 14 .54 64* .3785 .8013*** A l l but EL, CA Lodgepole pine 12 .8900*** .5709+ .7393** Western hemlock 11 .8994*** .5780+ .8298** " Douglas-fir 12 .8360*** .4183 .8294*** A l l but FF, EL, AP Lodgepole pine 8 .9053** .9076** .8789** •• Western hemlock 9 .8980** -.3199 .5419 Douglas-fir 10 .5229 .7321* .8979*** Al l but FF, EL, AP, CA Lodgepole pine 8 .9053** .9076** .8789** Western hemlock 7 .8573* .9057** .8228* " Douglas-fir 8 .93 25*** .9597*** .9190** A l l but CM Lodgepole pine 12 .7982** .7242** .8028** Western hemlock 13 .5960* .63 53* .6690* Douglas-fir 14 .2768 .5755* .8055*** A l l but CM, CA Lodgepole pine 12 .7982** ' .7242** .8028** - Western hemlock 11 .5063 .6526* .7405** <Douglas-fir 12 .6029* .6736* .8475*** +» *> **» *** significance at 10, 5, 1 and 0.1% levels, respectively. - 73 -Podzolic s o i l horizons TS, MI, CM and CU ( i . e . , without FF, AP, EL, CA), 0.01 N_ HCl was the method y i e l d i n g most si g n i f i c a n c e for a l l three species (although Bray P^ and new-Mehlich were also s i g n i f i c a n t at a = .05 or l e s s ) . However, without the operationally P - f e r t i l i z e d CM, and without CA, new-Mehlich i s the most s i g n i f i c a n t for a l l three species (a = .01 or l e s s ) . The r e s u l t s with the modified new-Mehlich method are very s i m i l a r to the comparison between s t i r r i n g ( s i m i l a r to swirling) and r e c i p r o c a l shaking made by Agboola and Omueti (1980) for Bray P^ and another NHi+F extractant. The authors found that, although not s t a t i s t i c a l l y s i g n i f i c a n t , s t i r r i n g tended to extract s l i g h t l y more P and they considered s t i r r i n g more adaptable to rapid routine analysis. However, with hydrophobic samples there can be problems with getting consistent wetting from s w i r l i n g . Reciprocal shaking s t i l l appears better for this reason, along with increased risks of error associated with other a l t e r n a t i v e s for hydrophobic samples, as discussed i n the l i t e r a t u r e review. I t i s i n t e r e s t i n g that the Bray P j method appears to be not very well correlated with Douglas-fir f o l i a r P status i n a number of instances. Current s o i l testing programs for f o r e s t nursery management in B r i t i s h Columbia employ the Bray P^ method (van den Driessche 1980, 1981). A much narrower range of s o i l s i s involved in the nurseries and the Bray P^ test seems well correlated with Douglas-fir across the more sim i l a r Podzolic horizons. The 0.01 N_ HCl did not perform well and t h i s , along with the fa c t that i t extracts quite low amounts of P from a number of study s o i l s - 74 -(making the method more susceptible to e r r o r ) , suggests that the method should not be considered f u r t h e r . Spearman rank c o r r e l a t i o n c o e f f i c i e n t s (Appendix 4 - 6 ) agree with r e s u l t s discussed above, except that Bray P.i i s the method that i s commonly the l e a s t s i g n i f i c a n t l y correlated with f o l i a r P concentration and 0 . 0 1 _N H C 1 appears better than discussed. This evaluation supports the choice of the new-Mehlich method for further testing, because i t gives the best r e l a t i o n s h i p with plant P status for both c o r r e l a t i o n methods. Further Evaluation of New-Mehlich Correlations of s o i l extractable P with f o l i a r P, by species, across a l l eight s o i l s were consistent with prior r e s u l t s (Table 9 ) , with the new-Mehlich being s i g n i f i c a n t for a l l three species at a = . 0 0 1 . Overall c o r r e l a t i o n s , for a l l species and a l l s o i l s and groups thereof, were a l l s i g n i f i c a n t at a =» . 0 0 1 . Also of i n t e r e s t i n this section are c o r r e l a t i o n s by species for each of the i n d i v i d u a l s o i l s . Correlations with f o l i a r P on FF and EL were s i g n i f i c a n t at a = . 0 1 or l e s s , for a l l three species. Only two other s i g n i f i c a n t c o r r e l a t i o n s existed among the remaining six s o i l s : AP was s i g n i f i c a n t (at a = . 0 1 ) with Douglas-fir and MI with lodgepole pine. The remaining s o i l s without c o r r e l a t i o n s represent some calcareous and Podzolic horizons of B r i t i s h Columbia. Strong c o r r e l a t i o n s with plant P status indicate a useful a n a l y t i c a l method. However, a l i m i t e d range of s o i l P data may y i e l d a Table 9 - Correlation C o e f f i c i e n t s for the Relationships Between S o i l Phosphorus Extracted by the New-Mehlich Method and F o l i a r Phosphorus for a l l Treatment Replicates. S o i l Species n r A l l A l l 176 .5169*** A l l but CA A l l 162 .5679*** A l l but FF A l l 152 .6173*** A l l but EL, CA A l l 145 .5180*** A l l Lodgepole pine 56 .7485*** A l l Western hemlock 56 .4942***' A l l Douglas-fir 64 .7406*** FF Lodgepole pine 8 .9763*** FF Western hemlock 8 .9456*** FF Douglas-fir 8 .9183*** AP Lodgepole pine 8 .4555 AP Western hemlock 8 .3395 AP Douglas-fir 8 .9621** MI Lodgepole pine 8 .8862** MI Western hemlock 8 -.2155 MI Douglas-fir 8 .5831 CM Lodgepole pine 8 .3918 CM Western hemlock 6 .2928 CM Douglas-fir 8 .1767 EL Lodgepole pine 8 .8569** EL Western hemlock 15 .8035** EL Douglas-fir 8 .9885*** TS Lodgepole pine 8 .0590 TS Western hemlock 4 .4948 TS Douglas-fir 8 .4949 CU Pine 8 .5909 CU Western hemlock (too few cases for analysis) CU Douglas-fir 8 .2540 CA Lodgepole pine 0 N/A CA Western hemlock 6 .4110 CA Douglas-fir 8 .4491 +>*>**,***significant at the 10, 5, 1 and 0.1% l e v e l s r e s p e c t i v e l y . - 76 -weak c o r r e l a t i o n , obscuring a r e a l r e l a t i o n s h i p . Consequently, the absence of a strong c o r r e l a t i o n does not necessarily mean that a method i s not useful for evaluating available P. (For most of the Podzolic horizons, there was l i t t l e difference i n P test values between P-treated and control samples.) I t i s important to r e c a l l from Table 8 that the new-Mehlich method was very well correlated with plant P status across groups of Podzolic horizons that provided the necessary v a r i a t i o n to provide a c o r r e l a t i o n a n a l y s i s . I t i s not surp r i s i n g that the new-Mehlich method i s not well correlated with f o l i a r P concentrations on the calcareous CA s o i l . In s o i l testing for white clover i n New Zealand, Holford (1980) noted that the new-Mehlich method extracted excessive (non-labile) P at pH > 6.0. (The new-Mehlich method has been found s i g n i f i c a n t l y correlated with f o l i a r P for Pinus patula by Gaitho (1978) and Lea et a l . (1980).) Regarding the Podzolic horizons, the f a c t that the new-Mehlich method may not be s i g n i f i c a n t l y correlated with f o l i a r P both agrees and contrasts with other findings for B r i t i s h Columbia Podzolic horizons. John (1971) i n studying B r i t i s h Columbia a g r i c u l t u r a l s o i l s , was not able to get any s i g n i f i c a n t s o i l test c o r r e l a t i o n s with Olsen or Bray P i on Podzolic horizons. However, Gaitho (1978) found s i g n i f i c a n t c o r r e l a t i o n s , using three P l e v e l s , with Pinus patula on the Bf horizon he studied, with a l l 5 methods he tested and noted that new-Mehlich may be the best index of ava i l a b l e P i n Podzolic horizons (based also on the most s i g n i f i c a n t c o r r e l a t i o n with Cupressus l u s i t a n i c a seedling P uptake). However, Gaitho (1978) also noted that the new Mehlich was not - 77 -s i g n i f i c a n t for Pinus patula on an Ap horizon, consistent with this study.) In evaluating s o i l test methods on New Zealand s o i l s high i n sesquioxides, Grigg (1968) found that the degree of c o r r e l a t i o n with rye grass y i e l d was proportional to a s o i l test's a b i l i t y to extract Al and Fe phosphates from surfaces; he rated Olsen > Bray P i > Bray P 2 > Truog, i n this regard. However, John's (1971) study employed both Olsen and Bray P i to no a v a i l . The record of Bray P i i n B r i t i s h Columbia f o r e s t nurseries suggests that i t should be included in further analyses of this kind. Spearman rank c o r r e l a t i o n c o e f f i c i e n t s (Appendix 4-8) agree with the r e s u l t s discussed (although only western hemlock i s s i g n i f i c a n t on FF and EL). The analysis of variance (Appendix 4-9) revealed a s i g n i f i c a n t s o i l x tree species x P l e v e l i n t e r a c t i o n which complicates i n t e r p r e t a t i o n (Hicks 1973), and i n t e r p r e t a t i o n may be considered beyond the scope of current s o i l testing programme objectives. The analysis of covariance (Appendix 4-10) displays less s i g n i f i c a n t factor contributions as would be expected when a covariate accounts for v a r i a t i o n in the y i e l d v a r i a b l e , however this i s also complicated by the same i n t e r a c t i o n y i e l d i n g the same conclusion regarding i n t e r p r e t a t i o n . Similar variance analyses for the previous phases of this experiment, which have no r e p l i c a t i o n , would require use of the s o i l x tree species x P l e v e l i n t e r a c t i o n as the error term, y i e l d i n g a "conservative" analysis (Dr. George Eaton, personal communication) 5 Professor of H o r t i c u l t u r e , Department of Plant Science, U n i v e r s i t y of B r i t i s h Columbia. - 78 -that, due to the i n t e r a c t i o n noted above, may again be considered beyond the scope of the objectives. CONCLUSIONS In agreement with the second chapter i n this thesis, the twelve s o i l P e xtraction methods tested vary greatly In their a b i l i t y to extract P from the various study s o i l s but almost a l l extract the most from the forest f l o o r (apart from the P f e r t i l i z e d s o i l ) . Test methods with a l k a l i n e extraction solutions do not appear f e a s i b l e for routine laboratory analysis of B r i t i s h Columbia f o r e s t s o i l s . This preliminary study suggests that the new-Mehlich and Bray P^ test methods appear the most adequate ( i n that order) for s o i l testing for P in B r i t i s h Columbia f o r e s t s o i l s . Detailed analysis r e s u l t s for the new-Mehlich are inconclusive for some i n d i v i d u a l s o i l s and i t i s possible that the method may prove inadequate on some Podzolic and calcareous horizons. However, across groups of Podzolic horizons the new-Mehlich method was very well correlated with plant P status. C l e a r l y , there i s need for further background research involving f i e l d t r i a l s . I t i s recommended that the two candidate methods s t i l l be considered together in further research on developing a s o i l P test programme for f o r e s t r y i n B r i t i s h Columbia. (The new-Mehlich may a f f o r d greater u t i l i t y since i t was developed to extract various n u t r i e n t cations i n addition to P.) r - 79 -With some modification of the 0.01 N_ HC1 method (enabling extraction of more P to lessen the s i g n i f i c a n c e of laboratory e r r o r ) , i t may prove viable for use with Podzolic B horizons i f the two proposed methods (or modifications of them) are found to be unacceptable on these s o i l s . In f i e l d t r i a l s on calcareous s o i l s , reinstatement of one of the a l k a l i n e based extractants might be considered to provide an a l t e r n a t i v e i f the new-Mehlich and Bray P± again appear inadequate under these s o i l conditions. - 80 -CHAPTER 4 THESIS SUMMARY AND CONCLUSIONS Based on this study, Involving a range of B r i t i s h Columbia s o i l conditions for lodgepole pine, western hemlock and Douglas-fir, the following conclusions can be made regarding the status of P in B r i t i s h Columbia forest s o i l s , P f r a c t i o n s i n B r i t i s h Columbia forest s o i l s , s o i l test methods, and cor r e l a t i o n s of s o i l test values with tree P s ta tus. The forest f l o o r has the highest index of P a v a i l a b i l i t y among u n f e r t i l i z e d s o i l materials (Indicating i t s reported importance in P c y c l i n g ) . S o i l P test methods vary greatly i n their a b i l i t y to extract P from the range of B r i t i s h Columbia f o r e s t s o i l s studied. Although r e s u l t s i n Chapter 2 revealed that a number of s o i l test methods y i e l d r e s u l t s correlated with each other, only a few yielded r e s u l t s well correlated with f o l i a r P status of trees i n Chapter 3 . B r i t i s h Columbia forest s o i l s generally present a wider range of s o i l conditions than most a g r i c u l t u r a l comparisons. A more diverse cross-section of s o i l P chemistry i s suggested for the f o r e s t s o i l s by the r e s u l t s that P f r a c t i o n s are not as well correlated with each other or with s o i l P test values, as reported i n the l i t e r a t u r e for a g r i c u l t u r a l s o i l comparisons. S o i l test methods inv o l v i n g with a l k a l i n e extracting solutions are not f e a s i b l e for routine laboratory analysis of nutrient status i n the - 81 -range of B r i t i s h Columbia forest s o i l s studied. This i s due to operational d i f f i c u l t i e s r e s u l t i n g from organic matter dispersion, and effervescence of sample extracts. This study suggests that, of the methods tested, the new-Mehlich and Bray methods are the most promising ( i n that order) for s o i l testing for P in B r i t i s h Columbia f o r e s t s o i l s for the three tree species studied. Detailed analysis of the new-Mehlich i s inconclusive for i n d i v i d u a l s o i l s and i t i s possible that this method may prove inadequate on a r e s t r i c t e d range of Podzolic horizons. The new-Mehlich appears excellent for the organic and eluviated s o i l s and was very well correlated with f o l i a r P across groups of Podzolic s o i l s . The three species varied i n their depletion of extractable P from the s o i l (Appendix 3), with Douglas-fir appearing to y i e l d the lowest s o i l test values and lodgepole pine the highest, on most s o i l s tested. Despite t h i s , the new-Mehlich method appears capable of indexing P a v a i l a b i l i t y to each of these species. The Bray P i method does not appear as well correlated with Douglas-fir. Results for western hemlock (which may be considered l e s s conclusive due to poor growth on mineral s o i l s ) provide the same recommendation of methods for future research. There i s the need for further research, p a r t i c u l a r l y f i e l d t r i a l s , to c a l i b r a t e more promising methods. I t i s recommended that the new-Mehlich and Bray P i methods be considered ( i n that order) for further evaluation. If problems on Podzolic horizons a c t u a l l y become apparent, other methods (e.g., 0.01 IN HC1) are recommended. I t i s recommended that further s o i l test evaluation on calcareous s o i l s consider reinstatement of one of the alkaline-based s o i l P extractants. - 82 -A consideration for future soil testing on British Columbia forest soils is the possible lack of currently tested methods to correlate well with plant P status on a restricted range of Podzolic horizons. Correlation tests over a wider range of soil extractable P values is recommended. It i s recommended that future f e r t i l i z a t i o n trials with P use the new-Mehlich and Bray P^  methods for soil testing, unless special conditions (e.g., calcareous soils) suggest that alternatives are desirable. The poor growth of western hemlock on mineral s o i l , as demonstrated here and in the f i e l d , may be considered a topic of great interest and importance. - 83 -LITERATURE CITED Agboola, A,A. and J.A.I. Omueti. 1980. 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Comparison of two a v a i l a b i l i t y tests with inorganic phosphorus f r a c t i o n s among s o i l s e r i e s . S o i l S c i . Soc. Am. Proc. 30:248-253. Wilde, S.A. 1958. Forest s o i l s . The Ronald Press Co., New York. Williams, J.D.H., J.K. Syers, and T.W. Walker. 1967. Fractionation of s o i l inorganic phosphate by a modification of Chang and Jackson's procedure. S o i l S c i . Soc. Am. Proc. 31:736-739. Williams, J.D.H., J.K. Syers, R.F. Harris and D.E. Armstrong. 1971a. Fractionation of inorganic phosphates i n calcareous lake sediments. S o i l S c i . Soc. Am. Proc. 35:250-225. Williams, J.D.H., J.K. Syers, D.E. Armstrong, and R.F. H a r r i s . 1971b. Characterization of inorganic phosphate in noncalcareous lake sediments. S o i l S c i . Soc. Am. Proc. 35:556-561. Young, H.E. 1948. The response of l o b l o l l y and slash pine to phosphate manures. Queensl. J . Agric. S c i . 5:77-105. <Cited by R. B a l l a r d 1980>. Z o t t l , H.W. 1973. Diagnosis of n u t r i t i o n a l disturbances i n f o r e s t stands, p. 75-96 In Int. Symp. on forest F e r t i l i z a t i o n , P a r i s . 3-7 Dec. 1973. Publ. by FAO/IUFRO. Z u b r i s k i , J . C 1971. Relationships between forms of s o i l phosporus, some indexes of phosphorus a v a i l a b i l i t y and growth of sudan grass i n greenhouse t r i a l s . Agron. J . 63;421-425. - 97 -APPENDIX 1: ANALYTICAL METHODS INDEX Test Method Page Notes on P Standards, Duplication, F i l t e r i n g , Hydrophobic Samples 98 1 H 20 soluble P , . 100 2 Truog (1930) 101 3A Modified Olsen 102 3 Modified Olsen (880 nm) 103 4 Bray P i - 1 minute shake 104 5 Bray Pj - 5 minute shake 105 6 Bray P 2 - 1 minute shake.... 106 7 Bray P 2 - 5 minute shake 107 8 Double-acid 108 9 NH^OAc at pH 4.8 109 10A ; Modified NHi+HCOa -DTPA 110 10 Modified NH^HCX^ - DTPA (880 nm) I l l 11 0.01 N HC1 112 12(B) New-Mehlich 113 Note: References cited are l i s t e d in the L i t e r a t u r e Cited Section. Phosphorus determination reagents for the "ascorbic acid method" are not described i n this section (see John 1970). Watanabe and Olsen (1965) was followed i n the r e s u l t s reported i n this t h e s i s . - 98 -A. Notes on P Standards, D u p l i c a t i o n , F i l t e r i n g , Hydrophobic Samples P Standards: These were prepared for each extraction method as follows: Reagents: Stock 100 ppm P solution - dissolve 0.4393 g of oven dry mono-basic potassium phosphate (IQ^PO^) in d i s t i l l e d water, d i l u t e to 1 l i t r e (Olsen and Sommers, 1982). (Stored i n r e f r i g e r a -tor.) P Working Standards - pipette 0,1,2,3,4,5,7 and 10 ml stock 100 ppm P so l u t i o n i n 100 ml volumetric, make to volume with extracting s o l u t i o n . (These represent 0-10 ppm P.) Store i n r e f r i g e r a t o r (record P determination absorbance values to v e r i f y standard concentrations over time). Duplication: A l l blanks and one third of the samples analyzed on the greenhouse s o i l s were duplicated to v e r i f y p r e c i s i o n in the laboratory determinations. Pre-greenhouse s o i l samples representing the s o i l s being analyzed were also run in dupl i c a t e . Most duplications were very close to one another. This "double d u p l i c a t i o n " (samples and reference samples duplicated) provided i n s i g h t on v a r i a b i l i t y between and within analysis batches for a l l extraction techniques. A l l standards were duplicated in the P determination step to further v e r i f y laboratory p r e c i s i o n . F i l t e r i n g : This study incorporated 9 cm f i l t e r paper (Whatman #42.) for extractions of 20 to 25 mis, based on previous experience i n the laboratory. In many cases larger f i l t e r paper ( i . e . 11 cm) - 99 -would have been better. This i s noted in the following method descriptions along with further recommendations regarding fa s t e r f i l t e r paper in some instances. Hydrophobic Samples: A number of the dried s o i l samples, pa r t i c u l a r l y , the FF samples, displayed hydrophobic!ty and did not wet up well with the extracting solutions during the extracting times involving s w i r l i n g ( r o t a t i o n a l shaking). Some studies have allowed hydrophobic s o i l s to s i t overnight in d i s t i l l e d water i and then make them up to an equivalence of the normal extract-ing s olution strength (Gaitho 1978). However, perhaps stronger a g i t a t i o n ( r e c i p r o c a l shaking) may be more appropriate. - 100 -P EXTRACTION METHOD NO.1 - H20-soluble P ORIGINAL METHOD; Humphreys and P r i t c h e t t (1972) 1 Procedure Followed: 1. Weigh 5g s o i l into container 2. Add 50 ml d i s t i l l e d H 20 3. Add 5 drops chloroform (CHCI3 to check microbial a c t i v i t y 4. Shake for 16 hrs (960 min.) 5. F i l t e r 6. R e f i l t e r i f not clear 7. P determination volumes: Std - 2ml FF - 2ml AP,TS,CM,CU,EL,MI - 20 ml CA-8 ml Modifications from O r i g i n a l Method Extr a c t i n g Solution: D i s t i l l e d H 20 with 5 drops CHC13 per sample - pH: — not determined S o i l : S o l u t i o n Ratio: 5g:50ml Container: 125 ml p l a s t i c b o t t l e Shaking - type: r e c i p r o c a l - time: 16 hrs (960 min.) F i l t e r Paper: Whatman #42 Size: 15 cm P determined by: "Ascorbic Acid Me thod" - spectrophotometer: G i l f o r d - wavelength: 700 nm Commen ts/References 4. " e q u i l i b r a t i n g " for 16 hrs stated in o r i g i n a l method - we have inferred shaking 5. o r i g i n a l method does not mention f i l t e r i n g Inconveniences Noted: Minor-very slow f i l t e r i n g ; perhaps use Whatman #40 (may be worthwhile to consider centifuging or use of 0.05% polyacrylamide). C a l c u l a t i o n : ppm P s o i l = (ppm solu t i o n - ppm blank*) [50 ml ] \ 2 ml std 1 5g x ml aliquot *also subtracted ppm color blank for dark and/or large volumes (PA) Reagents: (P-determination: see page 1-14) Extra c t i n g Solution: D i s t i l l e d H 20 - 5 drops CHC13 added to each i n d i v i d u a l extraction prior to shaking. 1 O r i g i n a l method for the procedure followed; many researchers have studied H20-soluble P. - 101 -P EXTRACTION METHOD NO.2 - Truog (1930) ORIGINAL METHOD: Truog (1930) Procedure Followed: 1. Weigh 1 g s o i l into container 2. Add 200 ml ext. solution 3. Shake for 30 minutes 4. F i l t e r 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml AP,CU,EL,MI,TS - 20 ml CA,CM,FF - 8 ml Ext r a c t i n g Solution: 0 .002 _N H 2 S0it - pH: 3 . 0 S o i l : S o l u t i o n Ratio: 1 g:200 ml Container: 250 ml p l a s t i c bottle Shaking - type: r e c i p r o c a l - time: 30 minutes F i l t e r Paper: Whatman #42 Size: 15 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Modifications from O r i g i n a l Method 1. 1 g instead of "2 g" 2. 200 ml instead of "400 ml" 4. r e f i l t e r i f not clear instead of "discard f i l t r a t e u n t i l i t comes through p e r f e c t l y c l e a r " Comments/References 1 g:200 ml i s a common sub s t i t u t i o n for 2 g:400 ml Inconveniences Noted: Large extract volumes Ca l c u l a t i o n : ppm P s o i l = Reagents: Stock Solutions: (ppm solution - ppm blank) [200 ml] U m l _ s t d J r 1 g x ml sample 1.0 N H2S0,t - add 28.7 ml cone. H 2S0 l t to about 300 ml of d i s t i l l e d H 20; make up to 1 l i t r e . Check normality by t i t r a t i n g a portion against a standard a l k a l i . E x tracting Solution: Dilute 4 ml 1.0 H E2S0k t o 2 l i t r e s . Adjust pH of solution to pH 3.0 by adding 3 g of (NH^-SOir or K^SOtj per l i t r e of so l u t i o n . - 1 0 2 -P EXTRACTION METHOD N0.3A - Modified Olsen ORIGINAL METHOD: Olsen et a l . (1954), modified by Banderis et a l . (1976) Procedure Followed: 1. Weigh 2.5 g s o i l into container 2. Add 50 ml extracting solution 3. Shake for 30 minutes 4. F i l t e r 5. R e f l i t e r i f not clear 6. P determination volumes: Std - 10 ml CU,CM,FF,MI,TS - 5 ml AP,CA,EL - 10 ml Modifications from O r i g i n a l Method 1. 2.5 g instead of 5 g 2. polyacrylamide In extract solution rather than Darco carbon Extracting Solution: 0.5 M NaHC03 with polyacrylamide - pH: 8.5 So i l : S o l u t i o n Ratio: 2.5 g:50 ml Container: 125 ml polyethylene bottle Shaking - type: r e c i p r o c a l - time: 30 minutes F i l t e r Paper: Whatman #40 Size: 15 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Comments/References Banderis et a l . (1976) Inconveniences Noted: Major-procedure i s d i f f i c u l t because of the need for color blanks, because of efferverscence when acid added to reduce pH to 5.0 and p r e c i p i t a t i o n upon a c i d i f i c a t i o n . C a l c u l a t i o n : ppm P s o i l = / , J , ^ , % [50 ml If 10 ml std } (ppm so l u t i o n - blank - color blank) ^r—= J l : :: ; r r 2.5 g x ml sample a l i q u o t Reagents; Stock Solutions: 1. 0.5 M NaHC03 2. 0.05% aqueous polyacrylamide so l u t i o n (BDH chemicals -MW > 5 x 1 0 , No. 29788-3N). Ex t r a c t i n g Solution: 1. Add 5 ml 0.05% aqueous polyacrylamide per l i t r e of 0.5 M NaCH03. 2. Adjust pH to 8.5 with NaOH. 3. Add mineral o i l to avoid exposure of solution to a i r . 4. Store i n a polyethylene container (may be stored over one month, but pH must be checked before use). - 103 -P EXTRACTION METHOD NO.3 - Modified Olsen ORIGINAL METHOD: Olsen et a l . (1954) modified by Banderis et a l . (1976) Procedure Followed: E x t r a c t i n g Solution:0.5 M NaHC0 3 n 3. Shake for 30 minutes 4. F i l t e r 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 10 ml CU,CM,FF,MI,TS - 5 ml AP,CA,EL - 10 ml Container: 125 ml polyethylene b o t t l e Shaking - type: r e c i p r o c a l - time: 30 minutes F i l t e r Paper: Whatman #40 Size: 15 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: Bausch and Lomb - wavelength: 880 nm Modifications from O r i g i n a l Method 1. 2.5 g instead of 5 g 2. polyacrylamide i n extract so l u t i o n rather than Darco carbon Comments/References Banderis et a l . (1976) Inconveniences Noted: Major-procedure Is d i f f i c u l t because of the need f o r color blanks, because of f i z z i n g when acid added to reduce pH to 5.0 and p r e c i p i -tation upon a c i d i f i c a t i o n . Also, standards are not l i n e a r . C a l c u l a t i o n : ppm P s o i l = (ppm s o i l by using l i n e a r regression, assuming l i n e a r i t y to 3 ppm) Reagents: Stock Solutions: 1. 0.5 M NaHC03 2. 0.05% aqueous polyacrylamide solution (BDH chemicals -MW > 5 x 10 5, No. 29788-3N). Extr a c t i n g Solution: 1. Add 5 ml 0.05% aqueous polyacrylamide per l i t r e of 0.5 M NaCH0 3. 2. Adjust pH to 8.5 with NaOH. 3. Add mineral o i l to avoid exposure of solution to a i r . 4. Store i n a polyethylene container (may be stored over one month, but pH must be checked before use). - 104 -P EXTRACTION METHOD NO .4 - Bray P i : 1 min. shake ORIGINAL METHOD: Bray and Kurtz (1945) Procedure Followed: E x t r a c t i n g Solution: 0.03 JN NHi+F + 0.025 N HC1 1. Weigh 2 g s o i l into container - pH: 2.7 2. Add 20 ml extracting solution S o i l : S o l u t i o n Ratio: 2.00 g/20 ml 3. Shake for 1 minute exactly Container: 50 ml Erlenmeyer fla s k (pyrex) 4. F i l t e r immediately Shaking - type: hand s w i r l i n g - time: 1 min. exactly 5. R e f l i t e r i f not clear F i l t e r Paper: Whatman #42 Size: 9 cm 6. P determination volumes: P determined by: "Ascorbic Acid Std - 2 ml Method" CM,FF,TS - 1 ml - spectrophotometer: G i l f o r d AP,CA,CU,EL,MI - 2 & 4 ml - wavelength: 700 nm Modifications from O r i g i n a l Method Comments/References 1. 2 g instead of 1 g Not a l l laboratories use the same 2. 20 ml instead of 7 ml proportions or shaking time 3. handswirling instead of stoppered (Olsen and Sommers 1982) s w i r l i n g - common lab methodology S t i r r i n g (analogous to swirling) 4. f i l t e r e d instead of allowed to s e t t l e recommended for operational use i n N i g e r i a by Agboola and Omueti (1980) F i l t e r i n g mentioned by Bray and Kurtz (1945) Whatman #42 c a l l e d for In Olsen and Sommers (1982) Inconveniences Noted: None observed for study s o i l s . 11 cm f i l t e r paper would be better. C a l c u l a t i o n : , , „. , [20 ml If 2 ml std 1 ppm P s o i l = (ppm solution - ppm blank u-- J 1 - ; — - J v r 2 g x ml sample aliquot Reagents: (Color development: see page 1-14) Stock Solutions: 1.0 N NHi+F: Dissolve 37 g NHi+F i n d i s t i l l e d water, make to a volume of 1 l i t r e . Store in polyethylene b o t t l e . 0.5 JN HC1: Dilute 40.4 ml cone. HC1 to a volume of 1 l i t r e . E x t r a c t i n g Solution: Add 30 ml 1.0 JN NHi+F and 50 ml 0.5 JN HC1 to d i s t i l l e d water, make to a volume of 1 l i t r e . This w i l l keep in glass bottle for over 1 year. - 105 -P EXTRACTION METHOD NO.5 Bray P^: 5 min. shake ORIGINAL METHOD: Bray and Kurtz (1945) Procedure Followed: 1. Weigh 2 g s o i l into container 2. Add 20 ml extracting s o l u t i o n 3. Shake for 1 minute exactly 4. F i l t e r immediately 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml CM, FF, TS - .5 & 1 ml AP, CA, CU, EL, MI - 2 & 4 ml Modifications from O r i g i n a l Method 1. 2 g instead of 1 g 2. 20 ml instead of 7 ml 3. open s w i r l i n g instead of stoppered sw i r l i n g - common lab methodology. 4. f i l t e r e d Instead of allowed to s e t t l e recommended for operational use i n Nige r i a by Agboola and Omueti (1980) F i l t e r i n g mentioned by Bray and Kurtz (1945) Whatman #42 ca l l e d for in Olsen and Sommers (1982) Inconveniences Noted: None observed for study s o i l s . 11 cm f i l t e r paper would be better. C a l c u l a t i o n : , ^ u - . i f20 ml I f 2 ml std 1 ppm P s o i l - (ppm solution - ppm blank l _ _ m l s a m p l £ a l l q u Q t J E x t r a c t i n g Solution: 0.03 N_ NHi+F + 0.025 N HCl - pH: 2.7 S o i l : S o l u t i o n Ratio: 2.00 g/20 ml Container: 50 ml Erlenraeyer f l a s k (pyrex) Shaking - type: r o t a t i o n a l - time: 5 min. exactly F i l t e r Paper: Whatman #42 Size: 9 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Comments/References Not a l l laboratories use the same proportions or shaking time (Olsen and Sommers 1982) S t i r r i n g (analogous to swirling) Reagents: Stock Solutions: 1.0 N NH^F: Dissolve 37 g NH^F i n d i s t i l l e d water, make to a volume of 1 l i t r e . Store i n polyethylene b o t t l e . 0.5 HCl: Dilute 40.4 ml cone. HCl to a volume of 1 l i t r e . E x t r a c t i n g Solution: Add 30 ml 1.0 N NH 4F and 50 ml 0.5 N HCl to d i s t i l l e d water, make to a volume of I l i t r e . This w i l l keep i n glass b o t t l e for over 1 year. - 106 -P EXTRACTION METHOD NO.6 - Bray P 2: 1 min. shake ORIGINAL METHOD: Procedure Followed: Bray and Kurtz (1945) 1. Weigh 2 g s o i l into container 2. Add 20 ml extracting solution 3. Shake for 1 minute exactly 4. F i l t e r immediately 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml CM, FF, TS - .5 & 1 ml AP, CA, CU, EL, MI - 2 & 4 ml Modifications from O r i g i n a l Method 1. 2 g instead of 1 g 2. 20 ml instead of 7 ml 3. open s w i r l i n g instead of stoppered sw i r l i n g - common lab methodology Ex t r a c t i n g Solution: 0.03 N_ NHi+F + 0.10 N HC1 - pH: 1.5 S o i l : S o l u t i o n Ratio: 2.00 g/20 ml Container: 50 ml Erlenmeyer f l a s k (pyrex) Shaking - type: hand s w i r l i n g - time: 5 min. exactly F i l t e r Paper: Whatman #42 Size: 9 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Comments/References Not a l l laboratories use the same proportions or shaking time (Olsen and Sommers 1982) S t i r r i n g (analogous to swirling) 4. f i l t e r e d instead of allowed to s e t t l e recommended for operational use i n Nige r i a by Agboola and Omueti (1980) F i l t e r i n g mentioned by Bray and Kurtz (1945) Whatman #42 c a l l e d for In Olsen and Sommers (1982) Inconveniences Noted: None observed for study s o i l s . 11 cm f i l t e r paper would be better. C a l c u l a t i o n : 2 ml std ppm P s o i l = (ppm solution - ppm blank 1^ 0. m,l.] [ v v ft- 2 g x ml sample aliq u o t ] Reagents: Stock Solutions: 1.0 N NH^F: Dissolve 37 g NH\F i n d i s t i l l e d water, make to a volume of 1 l i t r e . Store i n polyethylene b o t t l e . 0.5 N_HC1: Di l u t e 40.4 ml cone. HCl to a volume of 1 l i t r e . E x t r a c t i n g Solution: Add 30 ml 1.0 Nf NH«tF and 50 ml 0.5 _N HCl to d i s t i l l e d water, make to a volume of 1 l i t r e . This w i l l keep i n glass b o t t l e for over 1 year. - 107 -P EXTRACTION METHOD NO.7 Bray P 2: 5 min. shake ORIGINAL METHOD: Bray and Kurtz (1945) Procedure Followed: 1. Weigh 2 g s o i l into container 2. Add 20 ml extracting solution 3. Shake for 1 minute exactly 4. F i l t e r immediately 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml CM, FF, TS - .5 & 1 ml AP, CA, CU, EL, MI - 2 & 4 ml Modifications from O r i g i n a l Method 1. 2 g instead of 1 g 2. 20 ml instead of 7 ml 3. handswirling instead of stoppered sw i r l i n g - common lab methodology 4. f i l t e r e d instead of allowed to s e t t l e recommended for operational use In Nige r i a by Agboola and Omueti (1980) F i l t e r i n g mentioned by Bray and Kurtz (1945) Whatman #42 ca l l e d for in Olsen and Sommers (1982). Ext r a c t i n g Solution: 0.03 N_ NHi+F + 0.10 N HCl - pH: 1.5 S o i l : S o l u t i o n Ratio: 2.00 g/20 ml Container: 50 ml Erlenmeyer f l a s k (pyrex) Shaking - type: r o t a t i o n a l - time: 5 min. exactly F i l t e r Paper: Whatman #42 Size: 9 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Comments/References Not a l l laboratories use the same proportions or shaking time (Olsen and Sommers 1982) S t i r r i n g (analogous to swirling) Inconveniences Noted: None observed f o r study s o i l s . C a l c u l a t i o n : 11 cm f i l t e r paper would be better. ,, , , „. KI i L?_0 ml ] [ 2 ml std 1 ppm P s o i l = (ppm solution - ppm blank 1—= J 1 = ; r~: -J v v v v r v 2 g x ml sample a l i q u o t Reagents: (Color development: see page 1-14) Stock Solutions: 1.0 _N NHi+F: Dissolve 37 g NHi^F i n d i s t i l l e d water, make to a volume of 1 l i t r e . Store i n polyethylene b o t t l e . 0.5 N HCl: Dilute 40.4 ml cone. HCl to a volume of 1 l i t r e . E x t racting Solution: Add 30 ml 1.0 N NH^F and 50 ml 0.5 N HCl to d i s t i l l e d water, make to a volume of 1 l i t r e . This w i l l keep i n glass b o t t l e for over 1 year. - 108 -P EXTRACTION METHOD NO.8 Double-Acid (Nelson et a l . 1953; North Carolina or "old" Mehlich Method) ORIGINAL METHOD: Procedure Followed: Barton (1948)t 1. Weigh 4 g* s o i l into container 2. Add 20 ml extracting solution 3. Shake for 5 minutes 4. F i l t e r 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml CM, FF, TS - 1 ml CA, EL, MI - 4 ml AP, CU - 2 ml (* used 2 g for FF) Modifications from O r i g i n a l Methodt 1. 4 g instead of 5 g 2. extracting solution contains 0,05% polycrylamide, Darco carbon not used. 6. P determination by Ascorbic Acid Method rather than ammonium vanadate reducing agent. Inconveniences Noted: None noted. 11 cm f i l t e r paper would be better. C a l c u l a t i o n : E x t r a c t i n g Solution: 0.05 N HCl and 0.025 N H 2S0 4 - pH: not determined S o i l : S o l u t i o n Ratio: 4 g*:20 ml Container: 60 ml p l a s t i c b o t t l e Shaking - type: r e c i p r o c a l - time: 5 minutes F i l t e r Paper: Whatman #42 Size: 9 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Comments/References tDifferences from Olsen and Sommers (1982) ppm P s o i l *2 g FF , . , [20 m l l f 2 ml s t d 1 (ppm s o l u t i o n - ppm b l a n k S — 3 — - 1 r 4 g* x ml sample a l i q u o t Reagents: Stock Solutions: 2.5 _N HCl - add 208 ml cone. HCl to about 600 ml d i s t i l l e d H 20; make to a volume of 1 l i t r e with d i s t i l l e d water. 1.0 _N E 2 s o k ~ add 28 ml cone. H 2S0^ to about 300 ml d i s t i l l -ed H2O; make to a volume of 1 l i t r e with d i s t i l l e d water. E x t r a c t i n g Solution: Add 20 ml 2.5 N HCl and 25 ml 1.0 N H^Oi* to about 300 ml d i s t i l l e d water. Add 5 ml 0.05% aqueous polyacrylamide and make up to a volume of 1 l i t r e . - 109 -t EXTRACTION METHOD SO.9 - NH^OAc at pH 4.8 ("University of Florida" Method) P r i t c h e t t and Llewellyn (1966) ORIGINAL METHOD: Procedure Followed: Breland (1957) 1. Weigh 2 g s o i l into container 2. Add 20 ml extracting solution 3. Shake for 5 minutes 4. F i l t e r 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml FF - 4 ml AP, CU, CM, EL, MI, CA - 1 ml Modifications from O r i g i n a l Method Ext r a c t i n g Solution: 1.0 N NH^OAc adjusted with a c e t i c acid to pH 4.8 - pH: 4.8 So i l : S o l u t i o n Ratio: 2 g:20 ml Container: 50 ml erlenmyer Shaking - type: r o t a t i o n a l - time: 5 minutes F i l t e r Paper: Whatman #42 Size: 9 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Comments/References 1. 2 g instead of 5 g sample 2. 20 ml instead of 25 ml extracting s o l u t i o n 3. O r i g i n a l method c a l l s for r e c i p r o c a l shaking for 30 min 4. Whatman #5 ca l l e d for i n o r i g i n a l method Inconveniences Noted: Ae horizon effervesced and was slow i n f i l t e r i n g , would be better. 11 cm f i l t e r paper C a l c u l a t i o n : ppm P s o i l = (ppm solu t i o n - ppm blank Reagents: Ex t r a c t i n g Solution: [20 ml If 2 ml std 1 2 g x ml sample aliqu o t 1.0 N NHifOAc adjusted with a c e t i c acid to pH 4.8 - 110 -P EXTRACTION METHOD NO. 10A - Modified NHi+HC0 3 - DTPA ORIGINAL METHOD; Soltanpour and Schwab (1977) Procedure Followed; 1. Weigh 10 g s o i l into container 2. Add 20 ml extracting s o l u t i o n 3. Shake for 15 minutes, flasks open 4. F i l t e r 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml FF - 1 ml AP, EL - 4 ml CA, CM, TS - 2 ml CU, MI - 8 ml Ext r a c t i n g Solution: 1.0 M NHI+HC0 3 and 0.005 M DTPA and polyacrylamide - pH: 7.6 S o i l : S o l u t i o n Ratio: 10g:20ml (FF:5g) Container; 125 ml erlenmyer (FF:250 ml) Shaking - type: r e c i p r o c a l - time: 15 minutes F i l t e r Paper: Whatman #42 Size: 9 aa P determined by; "Ascorbic Acid Method" - spectrophotometer: G i l f o r d - wavelength: 700 nm Modifications from O r i g i n a l Method Comments/References 2. polyacrylamide instead of carbon black Soltanpour and Workman (1979) Inconveniences Noted: Major - troublesome because of efferverscence problem, need f o r color blanks and p r e c i p i t a t e s . FF reacts quite v i o l e n t l y , had to use 250 ml erlenmeyer. FF slow f i l t e r i n g . Post-greenhouse s o i l s could not be read on G i l f o r d due to efferverscence problems. Ca l c u l a t i o n : ppm P s o i l = , , J , i v - i i \ r l p m l , r 2 ml std , (ppm s o l u t i o n - ppm blank - ppm color blank) l-ft-g-] [ x ^ g a m p l e a l i q u o t l Reagents: Ex t r a c t i n g Solution: Add 1.97 g DTPA to 800 ml d i s t i l l e d H 20, add 2 ml 1:1 NHi+OH s o l u t i o n (aids d i s s o l u t i o n and prevents effervescence i n next step), s t i r to di s s o l v e most of the DTPA. Add 79.06 g NH^HCOs and s t i r gently to di s s o l v e , add 5 ml 0.05% aqueous polyacrylamide. Adjust pH to 7.6 with NHi+OH and make to 1 l i t r e with d i s t i l l e d water. Use so l u t i o n Immediately or store under 3 cm of mineral o i l . (Under mineral o i l , pH remains f a i r l y stable for 2 weeks). - I l l -P EXTRACTION METHOD NO.10 - Modified NH4HC03-DTPA M E T H O D : Soltanpour and Schwab (1977) ORIGINAL Procedure Followed: 1. Weigh 10 g s o i l into container 2. Add 20 ml extracting s o l u t i o n 3. Shake for 15 minutes, flasks open 4. F i l t e r 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml FF - 1 ml AP, EL - 4 ml CA, CM, TS - 2 ml CU, MI - 8 ml Modifications from O r i g i n a l Method Ex t r a c t i n g Solution: 1.0 M NHi+HC03 and 0.005 M DTPA and polyacrylamide - pH: 7.6 S o i l : S o l u t i o n Ratio: 10g:20ml (FF:5g) Container: 125 ml erlenmyer (FF:250 ml) Shaking - type: r e c i p r o c a l - time: 15 minutes F i l t e r Paper: Whatman #42 Size: 9 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: Bausch and Lomb - wavelength: 700 nm Comments/References 2. polyacrylamide instead of Soltanpour and Workman (1979) carbon black Inconveniences Noted: Major - troublesome because of efferverscence problem, need for color blanks and p r e c i p i t a t e s . FF reacts quite v i o l e n t l y , had to use 250 ml erlenmeyer. FF slow f i l t e r i n g . Post-greenhouse s o i l s could not be read on G i l f o r d due to efferverscence problems. Ca l c u l a t i o n : ppm P s o i l = (Linear regression using absorbance readings.) Reagents: Ex t r a c t i n g Solution: Add 1.97 g DTPA to 800 ml d i s t i l l e d H20,' add 2 ml 1:1 NHi+OH sol u t i o n (aids d i s s o l u t i o n and prevents effervescence i n next step), s t i r to dissolv e most of the DTPA. Add 79.06 g NHifHCOa and s t i r gently to di s s o l v e , add 5 ml 0.05% aqueous polyacrylamide. Adjust pH to 7.6 with NHt^OH and make to 1 l i t r e with d i s t i l l e d water. Use solution immediately or store under 3 cm of mineral o i l . (Under mineral o i l , pH remains f a i r l y stable for 2 weeks). - 112 -P EXTRACTION METHOD NO.11 - 0.01 N HCl ORIGINAL METHOD: Procedure Followed: Not known who f i r s t used this, reported by a number of studies. . 1. Weigh 2 g soil into container 2. Add 20 ml extracting solution 3. Shake for 5 minutes 4. Fil t e r 5. Refilter i f not clear 6. P determination volumes: Std - 2 ml FF - 2 ml AP, CM, CU, EL, TS - 10 ml CA, MI - 12 ml Extracting Solution: 0.01 N HCl - pH: not determined Soil:Solution Ratio: 2 g:20 ml Container: 50 ml erlenmyer Shaking - type: rotational - time: 5 minutes F i l t e r Paper: Whatman #42 Size: 92 cm P determined by: "Ascorbic Acid Method" - spectrophotometer: Gilford - wavelength: 700 nm Modifications from Original Method N/A Comments/References Inconveniences Noted: 11 cm f i l t e r paper would have been better. Calculation: ppm P s o i l = (ppm solution - blank) [20 m l U 2 ml std 1 2 g x ml sample a l i q u o t Reagents: Extracting Solution: 0.01 N_ HCl. - 113 -P EXTRACTION METHOD N O . 1 2 ( B ) * Mehlich (1978) ORIGINAL METHOD: Mehlich (1978) Procedure Followed: 1. Weigh 2.5 g s o i l into container 2. Add 25 ml extracting solution 3. Shake for 5 minutes 4. F i l t e r 5. R e f i l t e r i f not clear 6. P determination volumes: Std - 2 ml FF - 1 ml CM, TS - 2 ml AP, CA - 4 ml CU, EL, MI - 8 ml Extracting Solution: 0.2 N NH1+CL + 0.2 N HOAc + 0.015 N NHi+F + 0.012 N HCl - pH: approximately 2.5 S o i l : S o l u t i o n Ratio: 2.5 g:25 ml Container: 60 ml p l a s t i c b o t t l e Shaking - type: reci p r o c a t i o n (min, of 200/min; 3.5-4.0 cm) - time: 5 minutes F i l t e r Paper: Whatman #42 - Size: 9 cm P determined by: "Ascorbic Acid Method" - spectrophotometer:^ G i l f o r d - wavelength: 700 nm Modifications from O r i g i n a l Method Commen ts/References Inconveniences Noted: Ca l c u l a t i o n : ppm P s o i l = (ppm solu t i o n - blank) [25 ml][ 2 ml std 1 2.5g x ml sample a l i q u o t R e a g e n t s : E x t r a c t i n g Solution : 1. Dissolve 1.12 g NHu,F and 42.8 g NHHC1 i n about 1 l i t r e d i s t i l l e d water. 2. Add 2 ml cone. HCl and 23 ml g l a c i a l acetic acid 3. Dilute to 2 l i t r e s with d i s t i l l e d water and mix. *M12B = modification incorporating 50 ml erlenmyers and r o t a t i o n a l shaking. - 114 -APPENDIX 2: PHOSPHORUS TEST VALUE AND FRACTION CORRELATIONS FOR PODZOLIC SOILS ALONE IP r- 0) C N 0) O a O ro ai U> • T-O CO to T T T •' *- s CO ro o in C N o Q. T- O •»- o • O TJ C N O T- C N * -2 in r-~ to co C P O ) 01 CO CO O ro C N • Q . O C N o — O ) - £ CD cn in co C N o C N 01 01 00 r- • a C J co < N O co - 2 o in in 01 C N C O r- *- u> o a CO CO o C N - r-01 2 l/l 2 O 1— 01 C N r> in o 10 m CO < C N CO O a a C N O •»- • CO u. C O 2 a. a 0) C O GO < r- C N CO ro C O G O a a C O C O o • in r- at UJ _ i in . 02 o < 00 t- C J L O «-CO 01 10 O ) < II o C N C O u> a o n C O O w- -o C D 31 X o UJ *~ Z UJ . <& CO C N C O C O UJ a n C N w a *— C N C O . o < ip -^ - CO UJ r> in s co 00 1 1 r-a> z o in in C N o >-« ii CO u> u> 1— o to C O C N a < o «r O • CO - I m T 2 UJ O 1 OC a o o a: in C N r-ro C O in f* a r-- O O • C N ca co 2 in i 0) 14 C O in <T in CO * T o CO in C O C N CO CO C O C O a 5 in CO •<r C N a 01 *r 01 • C N 10 r- C O • »- •»- O • O in «-X o C N 2 2 a «. < a £ Ui - J Z m to O < (—t it CL a t- u . a a a a a a a O a < a < —J Ui U i < Ui Ui < _ J > < 14. u o < u . a. u a in r- C O <n C O 01 a ** ** *~ *" *~ O u - 115 -APPENDIX 3: PHOSPHORUS EXTRACTION DATA FOR GREENHOUSE STUDY Index Page 3-1 I n i t i a l Analysis Data (3 Soils) 116 3-2 Final Analysis Data (5 Soils) 117 Appendix 3-1- I n i t i a l Analysis Data (3 s o i l s ) Mod. Olsen Bray satment P Truog (880 nm) (700 nm) Pj - 1 min - 5 rain P 2 - 1 min ?2 - 5 min North Carolina Univ. of Fl o r i d a Mod. NH4HCO3 -DTPA(380 ran) 0.01S HCl New • Mehlich-Pollar P ppm P in 134.0 Soil 150.0 ZP .2093 111 138.0 139.0 90.4 99.4 130.0 146.0 114 .0 59.3 61.6 77.0 143.0 112 64.0 44.0 32.2 50.0 32.0 39.0 36.0 40.0 30.0 19.3 19.7 21.5 38.5 .1220 121 98.0 92.0 71.2 90.0 108.0 128.0 116.0 122.0 72.0 36.5 46.6 40.0 104.0 .2318 122 62.0 54.0 45.2 56.8 42.0 50.0 42.0 48.0 34.0 22.5 23.3 24 .0 ' 47.0 .0923 131 68.0 60.0 47.8 63.6 56.0 66.0 64.0 66.0 40.0 22.0 22.0 25.0 65.0 .3548 132 96.0 48.0 34.0 50.8 28.0 44 .0 34 .0 38.0 26.0 16.5 N.V.3 19.0 39.0 .1118 211 6.2 18.0 18.5 18.9 29.0 39.0 37.5 35.5 23 .0 5.9 11.6 8.0 40.5 .1580 212 .6 2.0 2.7 2.6 1.5 2.5 2.5 2.0 1.6 .5 1.0 .8 2.7 .0918 221 6.6 18.0 19.4 19.8 30.0 53 .0 43.0 34.0 24.0 6.0 13.1 10.0 42.0 .2459 222 .8 6.0 4.6 6.0 4.5 6.0 6.5 6.0 4 .3 1.0 1.6 1.8 7.0 .1226 231 5.3 16.0 17.8 18.4 31.0 39.0 40.0 31.0 22.5 4 .5 U.2 8.2 45.0 .2850 232 .5 2.0 2.8 3.8 2.0 2.0 3.0 3.0 1.9 .8 1.3 1.0 3.8 .0963 311 0.0 15.0 15.2 13.9 50.0 52.0 108.0 49.0 32.3 2.9 6.6 .5 28.0 .1020 312 0.0 10.0 14.2 13.3 46.0 50.0 100.0 45.0 33.0 2.3 5.7 .2 20.5 .1195 321 0.0 16.0 15.4 14.2 56.0 60.0 124 .0 54.0 39.0 3.3 7.3 .6 27.0 .0866 322 0.0 12.0 13.8 12.8 48.0 56.0 100.0 52.0 31.0 2.0 5.7 .2 25.0 .0811 331 0.0 16.0 17.0 15.6 52.0 52.0 120.0 52.0 36.0 3.5 7.0 .4 28.0 .1150 332 0.0 10.0 13.4 12.4 48.0 44.0 104.0 48.0 33.0 1.8 5.6 .2 21.0 .1050 ON * S o i l data from treatment composite samples; f o l i a r data represents means of Individual replicate analyses. "Treatment Codes are: 1 1 1 S o i l Species I Treatment 1 - FF 1 - LODGEPOLE PINE 1 - PADDED 2 - PA 2 - WESTERN HEMLOCK 2 - CONTROL 3 - TS 3 • DOUGLAS-FIR N.V. - no value obtained due laboratory complications with FF. - 117 -Appendix 3-2. F i n a l Analysis Data (5 S o i l s ) Bray 0.01 N Treatment 2 P L - 1 min HCl New-Mehlich F o l i a r P — ppm S o i l P %P 411 83.0 1.5 39.0 .1858 412 74.5 1.2 35.5 .1640 421 90.0 1.4 40.0 .2040 422 74.0 0.6 35.0 .1480 431 90.0 1.2 40.0 .3200 432 76.0 0.8 38.0 .3053 511 39.5 0.6 15.0 .1503 512 31.0 0.3 13.3 .1243 521 37.0 0.2 15.5 .0858 522 33.0 0.4 13.5 .0553 531 36.0 0.4 15.5 .2178 532 34.0 0.2 12.5 .1023 611 3.8 0.2 2.3 .1008 612 3.5 0.1 1.8 .0438 621 5.0 0.2 2.3 .0553 622 4.5 0.2 1.8 .0646 631 5.5 0.2 2.5 .0565 632 4.0 0.0 1.8 .0395 711 25.0 ( 0.3 13.8 .0820 712 18.0 0.1 7.5 .0710 722 17.5 0.2 9.5 .0991 731 24.5 0.2 12.5 .0720 73 2 17.5 0.0 6.0 .0560 821 0.7 3.6 29.0 .2540 822 0.3 3.0 24.0 .2010 831 1.0 2.8 28.0 .2707 832 0.3 2.0 21.0 .2123 " S o i l data from treatment composite samples; f o l i a r data represents means of i n d i v i d u a l r e p l i c a t e analyses. o Treatment Codes are: 411 S o i l Species Treatment 4 = CM 1 = LODGEPOLE PINE 1 = P ADDED 5 = AP 2 = WESTERN HEMLOCK 2 = CONTROL 6 - MI 3 = DOUGLAS-FIR 7 - CU 8 = AE - 118 -APPENDIX 4: ADDITIONAL STATISTICAL TESTS FOR EXPERIMENTAL DATA INDEX Page 4-1 Spearman Rank Correlation C o e f f i c i e n t s for the Relationships Among S o i l Phosphorus Test Values Obtained from 12 Extraction Methods 119 4-2 Spearman Rank Correlation C o e f f i c i e n t s for the Relationships Between Extractable Phosphorus and Phosphorus Fractions 120 4-3 Spearman Rank Correlation C o e f f i c i e n t s for the Relationships Among Phosphorus Fractions 121 4-4 Spearman Rank Cor r e l a t i o n C o e f f i c i e n t s for the Relationship Between S o i l Extractable Phosphorus and F o l i a r Phosphorus for 12 Methods and 3 S o i l s 122 4-5 Mann-Whitney U Test of Significance Between Two Bray P 2 - 1 Minute Extractions and C o r r e l a t i o n C o e f f i c i e n t s for Their Relationship with F o l i a r Phosphorus 124 4-6 Spearman Rank Correlation C o e f f i c i e n t s for the Relationship Between S o i l Extractable Phosphorus and F o l i a r Phosphorus for 3 Candidate Methods and a l l 8 S o i l s 125 4-7 Mann-Whitney U Test of Significance Between Two New-Mehlich Extractions D i f f e r i n g i n Ex t r a c t i o n Procedure and Cor r e l a t i o n C o e f f i c i e n t s for Their Relationship with F o l i a r Phosphorus 127 4-8 Spearman Rank Correlation C o e f f i c i e n t s for the Relationship Between S o i l Extracted by the Mehlich Method and F o l i a r Phosphorus for a l l Treatment Replicates 128 4-9 Analysis of Variance for F o l i a r Phosphorus on a l l Treatment Replicates 129 4-10 Analysis of Covariance for F o l i a r Phosphorus with New-Mehlich Phosphorus Values as the Covariate, on a l l Treatment Replicates 129 APPENDIX V A R I A B L E 2 M 1 P 119 -Spearman Hank C o r r e l a t i o n C o e f f i c i e n t s f o r the R e l a t i o n s h i p s Among S o i l Phosphorus Test Values Obtained from 12 E x t r a c t i o n Methods SPEARMAN'S V A R I A B L E G - K GAMMA V A U - B S E S1 UN I F RHO 3 . M 2 P . 1 2 0 0 . 1 1 3 2 . 2 9 8 2 . 9 0 4 9 . 1 6 3 6 4 M 3 P . 2 5 9 3 . 2 5 4 6 . 2 9 1 7 . 5 4 8 4 . 2 9 i j 4 5 . M 3 A P . 2 5 9 3 . 2 5 4 6 . 2 9 1 7 . 5 4 8 4 . 3 5 9 3 6 . M 4 P M i l . 1091 . 2 9 1 7 . 9 0 4 9 . I 5 S 7 7 . M 5 P . 1 1 1 1 . 1091 . 2 9 17 . 9 0 4 9 . 1 5 3 7 8 . M 6 P . 0 3 7 0 . 0 3 6 4 . 2 9 17 . 9 0 4 9 . 1 0 7 8 9 . M 7 P . 0 3 7 0 . 0 3 6 4 . 2 9 1 7 . 9 0 4 9 • . 1 0 7 8 10 . M S P . 1 1 1 1 . 1 0 9 1 . 2 9 1 7 . 9 0 4 9 . 1 9 1 6 1 1 . M 9 P . 1 1 1 1 . 1 0 9 1 . 2 9 1 7 . 9 0 4 9 . 1 3 1 7 12 . M 1 0 P . 2 5 9 3 . 2 5 4 6 . 2 9 1 7 . 5 4 8 4 . 4 0 7 2 1-1 M l I P . 6 2 9 6 . 6 1 8 3 . 2 9 1 7 . 0 6 1 0 . 7 4 2 5 15 . M 1 2 P . 1 8 5 2 . 1 8 1 8 . 2 9 1 7 . 7 195 . 2 7 5 5 4 . M 3 P . 8 4 6 2 . 8 154 . 2 9 5 0 . O 0 5 5 . 8 9 16 5 . M 3 A P . 6 9 2 3 . 6 6 7 1 . 2 9 5 0 . 0 3 1 2 . 8 5 5 5 6 . M 4 P . 5 3 8 5 . 5 189 . 2 9 5 0 . 1 0 8 7 . 4 0 9 7 7 . M 5 P . 5 3 8 5 . 5 1 8 9 . 2 9 5 0 . 1 0 8 7 . 4 0 9 7 8 • M 6 P . 4 6 15 . 4 4 4 7 . 2 9 5 0 . 1 7 8 9 . 3 8 5 6 9 . M 7 P . 4 6 1 5 . 4 4 4 7 . 2 9 5 0 . 1 7 8 9 . 3 8 5 6 10 . M B P . 5 3 8 5 . 5 1 8 9 . 2 9 5 0 . 1 0 8 7 . 5 3 0 2 1 1 . M 9 P . 8 4 6 2 . 8 154 . 2 9 S O . 0 0 5 5 . 9 2 7 8 12 . M 1 0 P . 6 9 2 3 . 6 6 7 1 . 2 9 5 0 . 0 3 1 2 . B 4 3 4 11 • M l I P . 5 3 8 5 . 5 1 8 9 . 2 9 5 0 . 1 0 8 7 . 6 9 8 8 15 M 1 2 P . 9 2 3 1 . 8 8 9 5 . 2 9 5 0 . 0 0 1 7 . 9 5 1 9 5 . M 3 A P . 7 1 4 3 . 7 1 4 3 . 2 8 8 7 . 0 1 4 1 . 8 8 10 6 . M 4 P . 7 143 . 7 1 4 3 . 2 8 8 7 . 0 1 4 1 . 7 6 1 9 7 . M S P . 7 1 4 3 . 7 1 4 3 . 2 8 8 7 . 0 1 4 1 . 7 6 19 8 . MGP . 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 1 2 . 7 3 8 1 9 M 7 P . 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 1 2 . 7 3 8 1 10 . M 8 P . 7 1 4 3 . 7 1 4 3 . 2 8 8 7 . 0 1 4 1 . 8 3 3 3 1 1 . M 9 P . 5 7 1 4 . 5 7 1 4 . 2 8 8 7 . 0 6 10 . 7 6 1 9 12 . M 1 0 P . 7 1 4 3 . 7 1 4 3 . 2 8 8 7 . 0 1 4 1 . 8 8 1 0 14 M 1 1 P . 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 1 2 . 7 8 5 7 15 . M I 2 P . 9 2 8 6 . 9 2 8 6 . 2 8 8 7 . 0 0 0 4 . 9 7 6 2 6 . M 4 P . 4 2 8 6 . 4 2 8 6 . 2 8 8 7 . 1 7 8 9 . 57 14 7 . M 5 P . 4 2 8 6 . 4 2 8 6 . 2 8 8 7 . 1 7 8 9 . 5 7 14 8 . M 6 P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 4 7 6 2 9 . M 7 P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 2 7 5 1 . 4 7 6 2 10 . M S P . 4 2 8 6 . 4 2 8 6 . 2 8 8 7 . 1 7 8 9 . 5 9 5 2 1 1 . M 9 P . 7 1 4 3 . 7 1 4 3 . 2 8 8 7 . 0 1 4 1 . 8 5 7 1 12 . M 1 0 P . 8 5 7 1 . 8 5 7 1 . 2 8 8 7 . 0 0 1 7 . 9 5 2 4 14 . M l I P . 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 12 . 7 8 5 7 15 . M 1 2 P . 7 8 5 7 . 7 8 5 7 . 2 8 8 7 . 0 0 5 5 . 9 2 8 6 7 . M 5 P 1 . 0 0 0 0 1.oooo . 2 8 8 7 . 0 0 0 0 1 . 0 0 0 0 8 . M 6 P . 9 2 8 6 . 9 2 8 6 . 2 8 8 7 . 0 0 0 4 . 9 7 6 2 9 . M 7 P . 9 2 8 6 . 9 2 8 6 . 2 8 8 7 . 0 0 0 4 . 9 7 6 2 10 . M B P . 8 5 7 1 . 8 5 7 1 . 2 8 8 7 . 0 0 1 7 . 9 5 2 4 1 1 . M 9 P . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 2 6 19 12 . M 1 0 P . 4 2 8 6 . 4 2 8 6 2 8 8 7 . 1 7 8 9 . 5 4 7 6 14 M l 1P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 4 5 2 4 1 5 . M 1 2 P , 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 1 2 . 6 4 2 9 8 . M 6 P . 9 2 8 6 . 9 2 8 6 . 2 8 8 7 . 0 0 0 4 . 9 7 6 2 9 . M 7 P . 9 2 8 6 . 9 2 8 6 . 2 8 8 7 . 0 0 0 4 . 9 7 6 2 10 M B P . 8 5 7 1 . 8 5 7 1 . 2 8 8 7 . O 0 1 7 . 9 5 2 4 1 1 . M 9 P . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 2 6 1 9 12 . M 1 0 P . 4 2 8 6 . 4 2 8 6 . 2 8 8 7 . 1 7 8 9 . 5 4 7 6 14 . M l I P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 4 5 2 4 1 5 . M 1 2 P . 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 1 2 . 6 4 2 9 9 . M 7 P 1 . 0 0 0 0 1 oooo . 2 8 8 7 . 0 0 0 0 1 . 0 0 0 0 1 0 . M 8 P . 9 2 8 6 . 9 2 8 6 . 2 8 8 7 . 0 0 0 4 . 9 7 6 2 1 1 . M 9 P . 2 1 4 3 . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 . 1 9 0 5 12 . M 1 0 P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 4 7 6 2 14 . M l I P . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 4 2 8 6 15 . M 1 2 P . 5 7 14 5 7 14 . 2 8 8 7 . 0 6 10 . ^ y b 2 1 0 . M 8 P . 9 2 8 6 . 9 2 8 6 . 2 8 8 7 0 0 O 4 . 9 7 6 2 1 1 . M 9 P . 2 1 4 3 . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 . 1 9 0 5 12 . M 1 0 P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 4 7 6 2 14 . M l I P . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 4 2 8 6 1 5 . M 1 2 P . 5 7 14 . 5 7 14 . 2 8 8 7 . 0 6 10 . 5 9 5 2 1 1 . M 9 P . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 " . 3 9 8 8 . 3 3 3 3 12 . M 1 0 P . 4 2 8 6 . 4 2 8 6 . 2 8 8 7 . 1 7 8 9 . 5 7 14 14 . M1 I P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 5 4 7 6 15 M 1 2 P . 6 4 2 9 . 6 4 2 9 , 2 8 8 7 . 0 3 1 2 . 7 1 4 3 12 . M 1 0 P . 5 7 14 . 5 7 1 4 . 2 8 8 7 . 0 6 10 . 8 0 9 5 14 . . M l I P . 5 0 0 0 . S O O O . 2 8 8 7 . 1 0 8 7 . 6 4 2 9 1 5 . M 1 2 P . 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 1 2 . 8 5 7 1 14 . M1 I P . 6 4 2 9 . 6 4 2 9 . 2 8 8 7 . 0 3 1 2 . 8 5 7 1 1 5 . M 1 2 P . 7 8 5 7 . 7 8 5 7 . 2 8 8 7 . 0 0 5 5 . 9 0 4 8 1 5 . M 1 2 P . 5 7 1 4 . 5 7 1 4 . 2 8 8 7 . 0 6 1 0 . 7 6 1 9 - 120 -APPENDIX 4-2 N= 8 V A R I A B L E V A R I A B L E 2 . M 1 P 1 6 . A L P 17 . F E P 18 . R E D P 1 9 . C A P 3 . M 2 P 1 6 . A L P 17 . F E P 1 8 . R E D P 1 9 . C A P 4 . M 3 P 16. . A L P 17 . F E P 1 8 . R E D P 1 9 . C A P 5 . M 3 A P 16 . A L P 17 . F E P 1 8 . R E D P 1 9 . C A P 6 . M 4 P 1 6 . A L P 1 7 . F E P 1 8 . R E D P 19 C A P 7 . M 5 P 1 6 . A L P 17 . F E P 1 8 . R E D P 1 9 . C A P 8 . M 6 P 1 6 . A L P 17 . F E P 1 8 . R E D P 1 9 . C A P 9 . M 7 P 1 6 . A L P 17 . F E P 1 8 . R E D P 1 9 . C A P 1 0 . M 8 P 16 . A L P 1 7 . F E P 1 8 . R E D P 1 9 . C A P 1 1 . M 9 P 1 6 . A L P 17 . F E P 1 8 . R E D P 1 9 . C A P 1 2 . M 1 0 P 1 6 . A L P 17 . F E P 1 8 . R E D P 19 C A P 1 4 . M 1 1 P 1 6 . A L P 1 7 . F E P 1 8 . R E D P 1 1 9 . C A P 1 5 . M 1 2 P 1 6 . A L P 1 7 . F E P 1 8 . R E D P 1 9 . C A P Spearman Rank Correlation C o e f f i c i e n t s for the Relationships Between Extractable Phosphorus and Phosphorus Fractions SPEARMAN'S K G A M M A T A U - B S E S I G N I F R H O - . 6 2 9 6 '- . 6 1 8 3 . 2 9 1 7 . 0 6 1 0 7 9 0 4 - . 5 0 0 0 4 6 19 . 3 0 0 1 . 1 7 8 9 5 4 0 0 - . 4 8 1 5 4 7 2 8 . 2 9 17 . 1 7 8 9 5 3 8 9 - . 0 3 7 0 0 3 6 4 . 2 9 1 7 . 9 0 4 9 2 2 7 5 0 0 . . 2 9 5 0 . 9 0 4 9 . 0 7 2 3 - . 0 4 3 5 0 3 9 2 . 3 0 3 5 . 9 0 4 9 . 1 1 1 1 - . 0 7 6 9 0 7 4 1 . 2 9 5 0 . 9 0 4 9 . 0 9 6 4 . 3 0 7 7 2 9 6 5 . 2 9 5 0 . 3 9 8 8 . 4 3 3 8 . 1 4 2 9 . 1 4 2 9 . 2 8 8 7 . 7 1 9 5 . 1 6 6 7 , 0 4 0 0 0 3 7 8 . 2 9 6 8 . 9 0 4 9 . 0 2 4 4 . 0 7 1 4 . 0 7 14 . 2 8 8 7 . 9 0 4 9 - . 0 4 7 6 . 0 7 14 . 0 7 14 . 2 8 8 7 . 9 0 4 9 . 1 6 6 7 0 0 . . 2 8 8 7 . 9 0 4 9 0 - . 2 8 0 0 . 2 6 4 6 . 2 9 6 8 . 5 4 8 4 - . 3 4 1 6 . 3 5 7 1 3 5 7 1 . 2 8 8 7 . 2 7 5 1 - . 4 5 2 4 - . 0 7 14 - . 0 7 14 . 2 8 8 7 . 9 0 4 9 - . 0 7 14 . 2 8 5 7 , 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 4 2 8 6 . 2 8 0 0 . 2 6 4 6 . 2 9 6 8 . 5 4 8 4 . 2 6 8 4 . 0 7 1 4 . 0 7 1 4 . 2 8 8 7 . 9 0 4 9 . 0 9 5 2 - . 2 1 4 3 . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 - . 2 3 8 1 . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 4 2 8 6 . 2 8 0 0 . 2 6 4 6 . 2 9 6 8 . 5 4 8 4 . 2 6 8 4 . 0 7 14 . 0 7 14 . 2 8 8 7 . 9 0 4 9 . 0 9 5 2 - . 2 1 4 3 - . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 - . 2 3 8 1 . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 4 7 6 2 . 3 6 0 0 . 3 4 0 2 . 2 9 6 8 . 3 9 8 8 . 4 1 4 8 . 1 4 2 9 . 1 4 2 9 . 2 8 8 7 . 7 1 9 5 . 2 6 19 - . 1 4 2 9 - . 1 4 2 9 . 2 8 8 7 . 7 1 9 5 - . 1 4 2 9 . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 4 7 6 2 . 3 6 0 0 . 3 4 0 2 . 2 9 6 8 . 3 9 8 8 . 4 1 4 8 . 1 4 2 9 . 1 4 2 9 . 2 8 8 7 . 7 1 9 5 . 2 6 1 9 - . 1 4 2 9 - . 1 4 2 9 . 2 8 8 7 . 7 1 9 5 - . 1 4 2 9 . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 3 8 10 . 2 8 0 0 . 2 6 4 6 . 2 9 6 8 . 5 4 8 4 . 2 9 2 8 . 0 7 14 . 0 7 14 . 2 8 8 7 . 9 0 4 9 . 1 6 6 7 - . 0 7 1 4 - . 0 7 1 4 . 2 8 8 7 . 9 0 4 9 - . 0 4 7 6 0 0 . 2 8 8 7 . 9 0 4 9 . 0 4 7 6 - . 2 0 0 0 - . 1 8 9 0 . 2 9 6 8 . 7 1 9 5 - . 2 6 8 4 - . 2 1 4 3 1 - . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 - . 2 8 5 7 . 2 1 4 3 . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 . 3 5 7 1 0 0 . 2 8 8 7 . 9 0 4 9 - . 0 2 3 8 - . 1 2 0 0 - . 1 1 3 4 . 2 9 6 8 . 9 0 4 9 - . 1 9 5 2 - . 2 1 4 3 - . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 - . 3 0 9 5 - . 0 7 1 4 - . 0 7 14 . 2 8 8 7 . 9 0 4 9 - . 0 7 14 - . 2 1 4 3 - . 2 1 4 3 . 2 8 8 7 . 5 4 8 4 - . 3 3 3 3 - . 2 0 0 0 - . 1 8 9 0 . 2 9 6 8 . 7 1 9 5 - . 2 4 4 0 . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 - . 3 0 9 5 0 . 0 . . 2 8 8 7 . 9 0 4 9 0 . 0 7 1 4 . 0 7 1 4 . 2 8 8 7 . 9 0 4 9 . 0 9 5 2 . 0 4 0 0 0 3 7 8 . 2 9 6 8 . 9 0 4 9 - . 1 2 2 0 . 1 4 2 9 1 4 2 9 . 2 8 8 7 . 7 1 9 5 - . 1 6 6 7 . 1 4 2 9 . 1 4 2 9 . 2 8 8 7 . 7 1 9 5 . 2 1 4 3 - 121 -APPENDIX 4-3 Spearman Rank Correlation C o e f f i c i e n t s for the Relationships Among Phosphorus Fractions N = 8 C O R R E L A T I O N S A C R O S S A L L 8 S O I L S SPEARMAN'S V A R I A B L E 1 6 . A L P 1 7 . F E P 1 8 . R E D P V A R I A B L E 1 6 . A L P 1 7 . F E P 1 8 . R E D P V A R I A B L E G - K G A M M A T A U - B S E S I G N I F R H Q 1 7 , F E P . 5 2 0 0 . 4 9 1 4 . 2 9 6 8 1 7 8 9 . 7 3 1 9 1 8 . . R E D P . 3 5 7 1 . 3 5 7 1 . 2 8 8 7 . 2 7 5 1 . 5 9 5 2 1 9 . C A P - . 0 7 1 4 - . 0 7 1 4 . 2 8 8 7 . 9 0 4 9 . 0 4 7 6 1 8 . R E D P . 9 2 0 0 . 8 6 9 3 . 2 9 6 8 . 0 0 5 5 . 9 5 1 5 1 9 . C A P . 2 0 0 0 . 1 8 9 0 . 2 9 6 8 . 7 1 9 5 . 2 1 9 6 1 9 . C A P . 2 8 5 7 . 2 8 5 7 . 2 8 8 7 . 3 9 8 8 . 4 5 2 4 L T I O N S A C R O S S P O D Z O L I C H O R I Z O N S S P E A R M A N ' S V A R I A B L E G - K G A M M A T A U - B S E S I G N I F R H O 17 , F E P - . 2 0 0 0 - . 2 0 0 0 . 4 0 8 2 . 8 1 6 7 0 . 1 8 R E D P - . 4 0 0 0 - . 4 0 0 0 . 4 0 8 2 . 4 8 3 3 - . 4 0 0 0 1 9 . . C A P - . 8 0 0 0 - . 8 0 0 0 . 4 0 8 2 . 0 8 3 3 - . 9 0 0 0 1 8 . R E D P . 8 0 0 0 . 8 0 0 0 . 4 0 8 2 . 0 8 3 3 . 9 0 0 0 1 9 . . C A P . 0 . 0 . . 4 0 8 2 . 8 1 6 7 -.lOOO 19 . C A P . 2 0 0 0 . 2 0 0 0 . 4 0 8 2 . 8 1 6 7 . 3 0 0 0 - 122 -APPENDIX 4-4 Spearman Rank. Co r r e l a t i o n C o e f f i c i e n t s for the Relationship Between S o i l Extractable Phosphorus and F o l i a r Phosphorus for 12 Methods and 3 S o i l s N= 11 ALL SPECIES VARIABLE 4 . M1P 5 . M2P G . M3P 7 . M3AP 0 . M4P 9.M5P 10.M6P 1 1 . M7P 12. M8P 13. M9P 15. M11P 16. M12P SPEARMAN'S VARIABLE G-K GAMMA TAU-B SE SIGNIF RHO 17 . FOLIARP . 3091 . 3091 . 2335 .2190 . 4545 17 . FOLIARP . 2830 . 2778 . 2365 . 2805 .4338 17 .FOLIARP . 3091 . 309 1 . 2335 . 2 190 .4545 17 .FOLIARP . 3091 .3091 .2335 . 2 190 .454 5 17 . FOLIARP . 38 18 . 3818 . 2335 . 1216 .5000 17 . FOLIARP .4231 .4114 . 2375 .0992 .6055 17 . FOLIARP .4909 .4909 . 2335 .0408 .6727 17 . FOLIARP . 2727 .2727 .2335 . 2835 .4273 17 . FOLIARP . 3091 . 3091 .2335 .2190 .4545 17 . FOLIARP . 2727 . 2727 . 2335 .2835 . 3727 17 . FOLIARP .3455 . 3455 . 2335 . 1652 .4909 17 . FOLIARP .4909 . 4909 . 2335 .0408 .6182 RANK-ORDER CORRELATION <1> SPEC IES :LPINE INITIAL ANALYSIS CORRELATION BY SPECIES VARIABLE 4 . M 1P 5.M2P 6 . MSP 7.M3AP 8 . M4P 9.M5P 10. M6P 11. M7P 12. MSP 13. M9P 15. M11P 16. M12P 18.M6BP VARIABLE 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP 17.FOLIARP GAMMA TAU-B SE SIGNIF SPEARMAN * S RHO 5714 .5521 .3608 . 2722 . 7537 7333 .7333 .3549 .0556 .8857 7333 .7333 . 3549 .0556 . 8857 7333 . 7333 . 3549 .0556 .8857 2000 . 2000 . 3549 . 7 194 . 4286 2857 . 2760 . 3608 . 7 194 .4638 3333 . 3333 .3549 . 4694 . 4857 20O0 .2000 . 3549 .7194 . 4286 3333 . 3333 . 3549 .4694 . 4857 7333 .7333 . 3549 .0556 .8857 4667 .4667 . 3549 . 2722 .7143 8667 . 8667 .3549 .0167 .9429 3333 . 3333 . 3549 . 4694 . 4857 Continued. - 123 -APPENDIX 4-4, continued R A N K - O R D E R C O R R E L A T I O N < 2 > S P E C I E S : W H E M I N I T I A L A N A L Y S I S C O R R E L A T I O N B Y S P E C I E S N= 6 V A R I A B L E 4 . M 1 P 5 . M 2 P 6 . M 3 P 7 . M 3 A P 8 . M 4 P 9 . M 5 P 1 0 . M 6 P 1 1 , M 7 P 1 2 , M 8 P 1 3 . M 9 P 1 5 . M1 1 P 1 6 . M 1 2 P 1 8 . M 6 B P V A R I A B L E 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P G - K G A M M A . 5 7 1 4 . 3 3 3 3 . 3 3 3 3 . 3 3 3 3 - . 2 0 0 0 - . 0 6 6 7 - . 2 0 0 0 - . 2 0 0 0 - . 0 6 6 7 . 3 3 3 3 . 6 0 0 0 . 3 3 3 3 - . 1 4 2 9 T A U - B . 5 5 2 1 . 3 3 3 3 . 3 3 3 3 . 3 3 3 3 • . 2 0 0 0 • . 0 6 6 7 • . 2 0 0 0 • . 2 0 0 0 • . 0 6 6 7 . 3 3 3 3 . 6 0 0 0 . 3 3 3 3 - . 1 3 8 0 S E . 3 6 0 8 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 6 0 8 SPEARMAN1S S I G N I F R H O . 2 7 2 2 . 4 6 9 4 . 4 6 9 4 . 4 6 9 4 . 7 1 9 4 1 . 0 0 0 0 . 7 1 9 4 . 7 1 9 4 1 . 0 0 0 0 . 4 6 9 4 . 1 3 6 1 . 4 6 9 4 1 . 0 0 0 0 . 6 9 5 7 . 4 2 8 6 . 4 2 8 6 . 4 2 8 6 . 2 5 7 1 . 0 8 5 7 . 2 5 7 1 . 2 5 7 1 . 1 4 2 9 . 4 2 8 6 . 7 1 4 3 . 4 2 8 6 . 1 7 3 9 R A N K - O R D E R C O R R E L A T I O N < 3 > S P E C I E S . D F I R I N I T I A L A N A L Y S I S C O R R E L A T I O N B Y S P E C I E S N= 6 V A R I A B L E 4 . M1 P 5 . M 2 P 6 , M 3 P 7 . M 3 A P 8 . M 4 P 9 . M 5 P 1 0 . M 6 P 1 1 . M 7 P 1 2 . M 8 P 1 3 . M 9 P 1 5 . M 1 1 P 1 6 . M 1 2 P 1 8 . M 6 B P V A R I A B L E 1 7 . F O L I A R P 1 7 . F O L I A R P 17 . F O L I A R P 17 . F O L I A R P 17 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P 1 7 . F O L I A R P G - K G A M M A . 2 8 5 7 . 7 1 4 3 . 7 3 3 3 . 7 3 3 3 . 6 0 0 0 . 5 7 1 4 . 3 3 3 3 . 4 6 6 7 . 4 6 6 7 . 7 3 3 3 . 4 6 6 7 . 8 6 6 7 . 3 3 3 3 T A U - B . 2 7 6 0 . 6 9 0 1 . 7 3 3 3 . 7 3 3 3 . 6 0 0 0 . 5 5 2 1 . 3 3 3 3 . 4 6 6 7 . 4 6 6 7 . 7 3 3 3 . 4 6 6 7 . 8 6 6 7 . 3 3 3 3 S E . 3 6 0 8 . 3 6 0 8 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 6 0 8 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 . 3 5 4 9 SPEARMAN'S S I G N I F R H O . 7 1 9 4 . 1 3 6 1 . 0 5 5 6 . 0 5 5 6 . 1 3 6 1 . 2 7 2 2 . 4 6 9 4 . 2 7 2 2 . 2 7 2 2 . 0 5 5 6 . 2 7 2 2 . 0 1 6 7 . 4 6 9 4 . 3 7 6 9 . 8 1 1 7 . 8 2 8 6 . 8 2 8 6 . 7 1 4 3 . 6 3 7 7 . 3 7 14 . 6 0 0 0 6 0 0 0 . 8 2 8 6 . 6 0 0 0 . 9 4 2 9 . 3 7 14 - 124 -APPENDIX 4-5 Mann-Whitney U T e s t of S i g n i f i c a n c e Between Two Bray P 2 - 1 Minute E x t r a c t i o n s and C o r r e l a t i o n C o e f f i c i e n t s f o r T h e i r R e l a t i o n s h i p w i t h F o l i a r Phosphorus . < T W 0 S A M P L E 0 P T 1 0 N S = P E R C E N T I L E . 0 U A N T I L E . D I F F E R E N C E VAR»M6 S T R A T - M 6 T Y P E L E V E L S - 9 9 S 9 9 > 1 W 0 - S A M P L E C O M P A R I S O N ' ' T E S T O F 2 . M S S I G N I F L O C A T I O N D I F F E R E N C E S 9 . 9 0 0 0 » . 9 5 0 O 9 . 9 9 0 0 M A N N - W H I T N E Y U- 1 0 2 . 5 0 . 0 5 9 6 L 3 . 0 0 0 0 - 2 . 5 0 0 0 - 1 7 . 0 0 0 C O R R E L A T I O N M A T R I X . I N I T I A L A N A L Y S I S C O R R E A L T I O N ( N O S T R A T A ) N - 1 1 DF = 9 R * . 0 1 0 0 " . 7 3 4 8 RO O S O O " . 6 0 2 1 R 9 . 1 0 0 0 ' . 5 2 1 4 V A R I A B L E 17 F O L I A R P . 2 6 6 8 . 3 2 7 8 . 3 8 5 2 . 3 7 3 8 . 4 4 2 1 . 4 8 1 5 . 5 0 5 1 . 4 2 9 0 . 3 7 7 6 . 2 7 2 5 . 2 9 0 1 . 4 9 3 4 4 - 5 6 - 7 . 8 . 9 . 1 0 . 1 1 . ' 1 2 . 1 3 . 1 5 . 1 6 . M 1 p M 2 P M 3 P M 3 A P M 4 P M 5 P M 6 P M 7 P M 8 P M 9 P M 1 1 P M 1 2 P 1 7 . F O L I A R P 1 8 . M 6 B P C O R R E L A T I O N M A T R I X <1> S P E C I E S : L P I N E I N I T I A L A N A L Y S I S C O R R E L A T I O N B Y S P E C I E S N - 4 O F " 2 R » . O l O O ' . 9 9 0 0 R«» . 0 5 0 0 - . 9 5 C O R» . l O O O - . 9 0 0 0 V A R I A B L E 1 7 . F O L I A R P 4 . M 1 P 5 . M 2 P . 8 8 4 5 6 . M 3 P 7 . M 3 A P 8 . M 4 P 9 . M 5 P 1 0 . M 6 P 11 . M 7 P 12 . M 8 P 13 . M S P 15 . M1 I P 1 6 . M 1 2 P 1 7 . F O L I A R P 18 M 6 B P C O R R E L A T I O N M A T R I X <2> S P E C I E S : W M E M N . 4 O F - 2 R » O l O O - . 9 9 0 0 R * 0 5 0 0 - . 9 5 0 0 R « . 1 0 0 0 - . 9 0 0 0 I N I T I A L A N A L Y S I S C O R R E L A T I O N B Y S P E C I E S V A R I A B L E 1 7 . F O L I A R P 4 . M 1 P 5 M 2 P 6 M 3 P . 5 9 9 5 9 . M 5 P . 5 8 3 6 1 0 . M 6 P 1 1 . M 7 P 12 . MBP 13 . M 9 P 15 . M1 1P 16 . M1 2 P 1 7 . F O L I A R P . 7 3 4 8 18 . M 6 B P C O R R E L A T I O N M A T R I X <3> S P E C I E S : O F I R . I N I T I A L A N A L Y S I S C O R R E L A T I O N B Y S P E C I E S N - 3 D F = 1 R » . O l O O - . 9 9 9 9 R » . 0 5 0 0 = . 9 9 6 9 R» . l O O O " . 9 8 7 7 V A R I A B L E 1 7 . F O L I A R P . 7 5 2 2 4 . M 1 P 5 . M 2 P 6 . M S P 7 . M 3 A P 8 . M 4 P 9 . M S P 1 0 . M 6 P . 9 7 7 5 12 M S P 13 . M90 15. M l IP 1 7 . F O L I A R P 18 . M 6 B P APPENDIX 4-6 Spearman Rank C o r r e l a t i o n C o e f f i c i e n t s for the R e l a t i o n s h i p Between S o i l E x t r a c t a b l e Phosphorus and F o l i a r Phosphorus for 3 Candidate Methods and a l l 8 S o i l s . S o i l s Species n Bray P i 0.01 N HCl New-Mehlich A l l A l l 45 .3413** .7362*** .7399*** A l l Lodgepole pine 14 .8110** .7850** .8330*** A l l Western hemlock 15 .0447 .7560** .6595* A l l D o u glas-fir 16 .5559* .7819*** ' .8961*** A l l but CA Lodgepole pine 14 .8110** .7850** .8330*** •• Western hemlock 13 .4215 .7283* .6850* •• D o u g l a s - f i r 14 .8549*** .8130*** .9131*** A l l but CU, CA Lodgepole pine 12 .7692** .7215* .8322** Western hemlock 12 .4667+ .8055** .7776** •• D o u g l a s - f i r 12 .8252** .7231** .9021*** A l l but FF Lodgepole pine 12 .7902** .7874** .8182** •• Western hemlock 13 -.0826 .8332** .7235* •• D o u g l a s - f i r 14 .4637+ .8108*** .9217*** A l l but FF, CA Lodgepole pine 12 .7902** .7874** .8182** •• Western hemlock 11 . .3470 .74 73* .7062* •• D o u g l a s - f i r 12 .8322** .8288** .9177*** A l l but FF, AP Lodgepole pine 10 .8182** .7927* .8424** Western hemlock 11 -.03 64 .8861** .7545* •• Douglas-fir 12 .4336 .8148** .9263*** A l l but FF, AP, CA Lodgepole pine 10 .8182** • .7927* .8424** •• Western hemlock 9 .4854 .83 94* .8333* •• Douglas-fir 10 .8303** .84 93** .9030*** Continued Appendix 4-6 continued Soils Species n Bray P i 0.01 N HCl New-Mehlich A l l but EL Lodgepole pine 12 .8601*** .8506*** .8112** •• Western hemlock 13 .2036 .7425** .7043* •• Douglas-fir 14 .5516* .8419*** .8820*** A l l but EL, CA Lodgepole pine 12 .8601*** .8506*** .8112** •• Western hemlock 11 .7745** .6802* .7654** •• Douglas-fir 12 .9231*** .9074*** .9212*** A l l but FF, EL, AP Lodgepole pine 8 .9048** .8555* .9048** •• Western hemlock 9 .0167 .8831** .7333* •• Douglas-fir 10 .4061 .8863** .9573*** Al l but FF, EL, AP, CA Lodgepole pine 8 .9048** .8555* .9048** •• Western hemlock 7 .8571* .7769 .8571* •'• Douglas-fir 8 .9762*** .9698** .9762*** Al l but CM Lodgepole pine 12 .6993* .7417** .7832** •• Western hemlock 13 .1846 .7329** .6080* - Douglas-fir 14 .3495 _ .84 64*** .8842*** Al l but CM, CA Lodgepole pine 12 .6993* .7417** .7832** •• Western hemlock 11 .1781 .6737* .5604 ** Douglas-fir 12 .7902** .8359** .9107*** +» *» **» *** significance at 10, 5, 1 and 0.1% levels, respectively. - 127 -Mann-Whitney U Test of S i g n i f i c a n c e Between Two New-Mehlich Extractions D i f f e r i n g in Extraction Procedure and C o r r e l a t i o n C o e f f i c i e n t s for Their Relationship with F o l i a r Phosphorus <TWOSAMPLE 0PTI0NS=PERCENT1LE,QUANTIL£.DIFFERENCE VAR=MI2 STRAI= MI2TYPE LEVELS TWO-SAMPLE COMPARISON TEST OF 2.M12 SIGNIF LOCATION DIFFERENCES <i>>.9000 <s».95O0 0.99OO MANN-WHITNEY U = 281.50 .1509 L -14.750 -15.750 -18.750 CORRELATION MATRIX FIANL ANALYSES CORRELATION N= 27 DF = 25 R* .0100= .4869 R»" .0500= .3809 R's> .1000= .3233 VARIABLE 8.FOLIARP .4499 .7 117 .8244 .8009 4 . 5. 6. I 7. 2 M4P M11P M12P M12BP CORRELATION MATRIX <1> SPECIES:LPINE . FINAL ANALYSES CORRELATION N= 8 DF = 6 R<5> .0100= .8343 R®> .0500= .7067 R«? .1000= .6215 VARIABLE 8.FOLIARP .8929 .8911 .8599 .8587 4. 5. 6. 7. M4P M11P M12P M12BP CORRELATION MATRIX <2> SPECIES:WHEM FINAL ANALYSES CORRELATION N= 9 DF« 7 Rs- .0100= .7977 R«» .0500= .6664 Rff .1000= .5822 o VARIABLE 8.FOLIARP .1455 .8936 .8077 .7452 4. 5. 6. 7. M4P M11P M12P M12BP CORRELATION MATRIX <3> SPECIES:DFIR FINAL ANALYSES CORRELATION N» 10 DF= 8 Rii» .0100= .7646 R*> .0500= .6319 R# .1000= .5494 VARIABLE 8.FOLIARP .6055 .6876 .9527 .9525 4. 5. 6. 7. M4P M11P M12P M12BP XM12P = 2M12BP NEW-MEHLICH WITH RECIPROCAL SHAKING (NORMAL PROCEDURE) = NEW-MEHLICH WITH ROTATIONAL SHAKING (MODIFIED PROCEDURE) - 128 -Appendix.4-8 Spearman Rank Correlation C o e f f i c i e n t s for the Relationship Between S o i l Extracted by the Mehlich Method and F o l i a r Phosphorus for a l l Treatment Replicates. S o i l Species n rho A l l A l l 176 .6736*** A l l but CA A l l 162 .7194*** A l l but FF A l l 152 .6812*** A l l but EL, CA A l l 145 .6849*** A l l Lodgepole pine 56 .7741*** A l l Western hemlock 56 .5687*** A l l Douglas-fir 64 .7938*** FF Lodgepole pine 8 .6747 FF Western hemlock 8 .8743* FF Douglas-fir 8 .6429 AP Lodgepole pine 8 .4762 AP Western hemlock 8 .3234 AP Douglas-fir 8 .9701* MI Lodgepole pine 8 .8729+ MI Western hemlock 8 -.3751 MI Douglas-fir 8 .7260 CM Lodgepole pine 8 .3516 CM Wes tern hemlock 6 - .5218 CM Douglas-fir 8 .2771 EL Lodgepole pine 8 .6205 EL Western hemlock 15 .6925* EL Douglas-fir 8 .7306 TS Lodgepole pine 8 .0549 TS Western hemlock ' 4 .2000 TS Douglas-fir 8 .4880 CU Lodgepole pine 8 .6747 CU Western hemlock (too few cases for analysis) CU Douglas-fir 8 .1437 CA Lodgepole pine 0 N/A CA Western hemlock 6 .6088 CA Douglas-fir 8 .4157 + »*.**,***significant at the 10, 5, 1 and 0.1% l e v e l s r e s p e c t i v e l y . APPENDIX 4-9 Analysis of Variance for Foliar Phosphorus on a l l Treatment Replicates ANALYSIS OF VARIANCE FOR FOLIAR P (L-SOI L&BLDCK T=TREE SPECIES P = P LEVEL: L IS RANDOM, T S P ARE FIXED FACTORS) Analysts for FOLP Analysis of variance table Sum of Mean Source squares OF square F-rat io Probab i 1 ity Test term L 0.62202 7 . 0.88860E-01 70.906 0.00000 RESIDUAL T 0.56469E -01 2. 0.28234E-01 2 .8223 0.09595 L*T P 0.18198 1 . 0.18198 10.024 0.01580 L*P L*T 0.13005 13. 0.1OO04E-01 7.9827 0.00000 RESIDUAL T*P 0.16635E -01 2 . 0.83174E-02 2.5000 0.1237 1 L-T-P L»P 0.12709 7 . 0.18155E-01 14.4B7 0.00000 RESIDUAL L*T*P 0.39924E -01 12 . 0.33270E-02 2.6547 0.00323 RESIDUAL Residual 0. 16417 131 . 0.12532E-02 Total 1.3532 175 . I APPENDIX 4-10 Analysis of Covariance for Foliar Phosphorus with 1 New-Mehlich Phosphorus Values as the Covariate, on a l l Treatment Replicates ANALYSIS OF COVARIANCE FOR MEHLICHP (L=SOIL&BLOCK T'TREE SPECIES P=P LEVEL: L IS RANDOM, T S P ARE FIXED FACTORS) Analysis for FOLP Analysis of variance table Sum bf Mean Source .squares DF square F-rat io Probab i 1 11 y Test term L 0.37603 7 . 0 .53719E -01 42.668 O.OOOOO RESIDUAL T 0.35726E -01 2 . 0 .17863E -01 1 .92-97 0.18528 L- T P 0.47609E -01 1 0 47G09E -01 4.6960 0.06691 L«P MEHLICHP 0.50344E -03 1 . 0 .50344E -03 0.39967 0.52826 RESIDUAL L*T 0.12065 13 . 0 92810E -02 7.37 18 0.00000 RESIDUAL T»P 0.94692E -02 2 . 0 47346E -02 1.6697 0.22921 L"T *P L*P 0.70967E -01 7 . 0 10138E -01 8.0527 0.OOOOO RESIDUAL L*T*P 0.34028E -01 12 . 0 .28356E -02 2.2523 0.01272 RESIDUAL Res idual 0.163G7 130. 0 .12590E -02 Total 1.3532 175. - 130 -APPENDIX 5 This study has provided useful information on s o i l testing for P i n B r i t i s h Columbia forest s o i l s . However, a few considerations regarding experimental design and procedures may be useful for s i m i l a r studies i n the future. This experiment involved a large f a c t o r i a l design (8 s o i l s x 3 species x 2 P lev e l s x 4 r e p l i c a t i o n s x 12 P methods) which required s i m p l i f i c a t i o n during analysis. This design provided some i n s i g h t into the various s o i l s and methods, but perhaps a d i f f e r e n t design might be preferable, considering that some of the s o i l s were s i m i l a r , and that an add i t i o n a l P l e v e l might have allowed better evaluation of methods. Growth of some tree species on some s o i l s i n the greenouse was,poor; perhaps more f e r t i l i z a t i o n (without P) would have been u s e f u l . In order to be consistent, a number of laboratory procedures (Appendix 1) were kept the same throughout. In another study on B r i t i s h Columbia forest s o i l s , the use of sw i r l i n g i n some methods might best be replaced by r e c i p r o c a l shaking to reduce v a r i a b i l i t y caused by hydrophobic samples. F i l t e r paper si z e should be matched to solu t i o n volumes and f a s t e r paper would be preferred for some methods. I t i s recommended that future s o i l P methods employ the ascorbic acid method for P determination i n extract solutions, following the method of John (1970) rather than Watanabe and Olsen (1965). 

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