Assessing soil phosphorus for crop production by soil testing

Phosphorus: Agriculture and the Environment

Volumn , Issue , 2015, Pages 123-143

  Beegle, Douglas ^a  

^a PENNSYLVANIA STATE UNIVERSITY   (United States)

Author keywords

Crop production; Fertility recommendation; Soil analysis; Soil extraction; Soil phosphorus assessment; Soil sampling; Soil test extractants; Soil testing

Indexed keywords

EID: 85103030912     PISSN: None     EISSN: None     Source Type: Book    
DOI: 10.2134/agronmonogr46.c5     Document Type: Chapter

References (116)

1. 32P equilibration. Plant Soil 6: 391-408.
2. Amrani, M., D.G. Westfall, and L. Moughlii. 1999. Improving the soil test phosphorus calibration for calcareous soils. Commun. Soil Sci. Plant Anal. 30: 129-144.
3. Anderson-Cook, C.M., M.M. Alley, R. Noble, and R. Khosla. 1999. Phosphorus and potassium fertilizer recommendation variability for two mid Atlantic Coastal Plain fields. Soil Sci. Soc. Am. J. 63: 1740-1747.
4. Andreis, H.J. and J.M. McCray. 1998. Phosphorus soil test calibration for sugarcane grown on Everglades Histosols. Commun. Soil Sci. Plant Anal. 29: 741-754.
5. Aquino, B.E., L.F. Sobral, and F.R. Cox. 1998. Properties of Ultisols and Oxisols related to Mehlich 3 phosphorus buffer coefficients. Commun. Soil Sci. Plant Anal. 29: 1155-1166.
6. Barber, S.A. 1995. Soil nutrient bioavailability. 2nd ed. John Wiley & Sons. New York.
7. Bartholomew, W.V. 1972. Soil nitrogen supply processes and crop requirements. Int. Soil Testing Ser. Tech. Bull. 6. North Carolina State Univ., Raleigh.
8. Beegle, D.B. 2003. Soil fertility management. In E. Martz (ed) The agronomy guide 2003. College of Agric. Sci., The Pennsylvania State Univ., University Park.
9. Beegle, D.B., and T.C. Oravec. 1990. Comparison of field calibrations for Mehlich 3 P and K with Bray Kurtz P1 and ammonium acetate K for corn. Commun. Soil Sci. Plant Anal. 21: 1025-1036.
10. Black, C.A. 1993. Soil fertility evaluation and control. Lewis Publ., Boca Raton, FL.
11. Blanchar, R.W., and A.C. Caldwell. 1964. Phosphorus uptake by plants and readily extractable phosphorus in soils. Agron. J. 56: 218-221.
12. Bowman, R.A., and C.V. Cole. 1978. An exploratory method for fractionation of organic phosphorus from grassland soils. Soil Sci. 125: 95-101.
13. Bray, R.H., and L.T. Kurtz. 1945. Determination of total, organic, and available forms of phosphorus in soils. Soil Sci. 59: 39-45.
14. Cate, R.B. and L.A. Nelson. 1965. A rapid method for correlation of soil test analysis with plant response data. Int. Soil Test Ser. Tech. Bull. 1. North Carolina State Univ. Agric. Exp. Stn., Raleigh.
15. Chang, S.C., and M.L. Jackson. 1957. Fractionation of soil phosphorus. Soil Sci. 84: 133-144.
16. Colwell, J.D. 1963. The estimation of phosphorus fertilizer requirements of wheat in southern New Wales by soil analysis. Aust. J. Exp. Agric. Anim. Husb. 3: 190-197.
17. Corey, R.B. 1987. Soil test procedures: Correlation. p. 15-22. In J.R. Brown (ed.) Soil testing: Sampling, correlation, calibration, and interpretation. SSSA Spec. Publ. 21. SSSA, Madison, WI.
18. Cox, F.R. 1992. Range in soil phosphorus critical levels with time. Soil Sci. Soc. Am. J. 56: 1504-1509.
19. Cox, F.R. 1994. Predicting increases in extractable phosphorus from fertilizing soils of varying clay content. Soil Sci. Soc. Am. J. 58: 1249-1253
20. Crozier, C.R., G.C. Naderman, M.R. Tucker, and R.E. Sugg. 1999. Nutrient and pH stratification with conventional and no till management. Commun. Soil Sci. Plant Anal. 30: 65-74.
21. Dahnke, W.C., and R.A. Olsen. 1990. Soil test correlation, calibration and recommendation. p. 45-71. In R.L. Westerman (ed.) Soil testing and plant analysis. 3rd ed. SSSA Book Ser. 3. SSSA, Madison WI.
22. Daubeny, C.G.B. 1845. Memoirs on the rotation of crops and on the quantity of inorganic matters abstracted from the soil by various plants under different circumstances. R. Soc. (London) Phil. Trans. 135: 179-253.
23. Dunbar, A.D., and D.E. Baker. 1965. Use of isotopic dilution in a study of inorganic phosphorus fractions from different soils. Soil Sci. Soc. Am. Proc. 29: 259-262.
24. Eckert, D.J., and M.E. Watson. 1996. Integrating the Mehlich-3 extractant into existing soil test interpretation schemes. Commun. Soil Sci. Plant Anal. 27: 1237-1249.
25. Egner, H., H. Riehm, and W.R. Domingo. 1960. Untersuchungen uber die chemishe bodenanalyse als gurndlage fur die beurteilung des nahrstoffzustandes der boden. II. Chemische extraktionsmethodenzur phosphor-undkalimbestimmungkungl. Lantbrukshoegsk. Ann. 26: 204-209.
26. Eliason, R., J.L. Lamb, and G.W. Rehm. 2001. Colorimetric and ICP measurement of P extracted by the Mehlich 3 procedure. In Annual meetings abstracts [CD-ROM]. ASA, CSSA, and SSSA, Madison, WI.
27. Fixen, P.E., B.G. Faber, and M. Vivekanandan. 1987. Phosphorus management as influenced by tillage systems in eastern South Dakota. p. 201-212. In J.T. Batchelor (ed.) Proc. Symp., Clearwater Beach. FL. 16-18 Mar. 1987. Natl. Fert. Solutions Assoc., St. Louis, MO.
28. Fixen P.E., and J.H. Grove. 1990. Testing soils for phosphorus. In R.L. Westerman (ed.) Soil testing and plant analysis. 3rd ed. SSSA Book Ser. 3. SSSA, Madison, WI.
29. Follett, R.F., and G.A. Peterson. 1988. Surface soil nutrient distribution as affected by wheat-fallow tillage systems. Soil Sci. Soc. Am. J. 52: 141-147.
30. Frank, K., D. B. Beegle, and J. Denning. 1998. Phosphorus. In J.R. Brown (ed.) Recommended chemical soil test procedures for the North Central Region. North Central Regional Res. Publ. 221 (revised). Missouri Agric. Exp. Stn., Columbia.
31. Franzen, D.W., L.J. Cihacek, V.L. Hofman, and L.J. Swenson. 1998. Topography based sampling compared with grid sampling in the northern Great Plains. J. Prod. Agric. 11: 364-370
32. Gavlak, R.G., D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2003. Plant, soil, and water reference methods for the Western Region. 2nd ed. WREP 125. Utah State Univ., Logan.
33. Goedeken, M.W., G.V. Johnson, W.R. Raun, and S.B. Phillips. 1998. Soil test phosphorus crop response projections to variable rate application in winter wheat. Commun. Soil Sci. Plant Anal. 29: 1731-1738
34. Hanlon, E.A. 2001. Procedures used by state soil-testing laboratories in the Southern Region of the United States. So. Coop. Ser. Bull. 190-C. Univ. of Florida, Inst. of Food and Agric. Sci., Immokalee, FL.
35. Hoffman, L.D., W.S. Harkcom, and D.B. Beegle. 1999. Soil Fertility trends in a long term crop rotation- soil fertility trial. In Proc. of the 29th North Central Extension-Industry Soil Fertility Conf. Potash & Phosphate Inst., Brookings, SD.
36. Holanda, F.S.R., D.B. Mengel, M.B. Paula, J.G. Carvaho, and J.C. Bertoni. 1998. Influence of crop rotations and tillage systems on phosphorus and potassium stratification and root distribution in the soil profile. Commun. Soil Sci. Plant Anal. 29: 2383-2394.
37. Honeycutt, C.W., R.D. Heil, and C.V. Cole. 1990. Climatic and topographic relations of three Great Plains soils. II. Carbon, nitrogen, and phosphorus. Soil Sci. Soc. Am. J. 54: 476-483.
38. Hooker, M.L., R.E. Gwin, G.M. Herron, and P. Gallagher. 1983. Effects of long-term annual application so N and P on corn grain yields and soil chemical properties. Agron. J. 75: 94-99.
39. 2 as a single extraction solution for the assessment of the nutrient status of soils and other diagnostic purposes. Commun. Soil Sci. Plant Anal. 21: 2281-2290.
40. Hylander, L.D., H.I. Svensson, and G. Siman. 1996. Different methods for determination of plant available soil phosphorus. Commun. Soil Sci. Plant Anal. 27: 1501-1512
41. Ibrikci, H., E.A. Hanlon, and J.E. Rechcigl. 1992. Initial calibration and correlation of inorganic phosphorus soil test methods with a bahiagrass field trial. Commun. Soil Sci. Plant Anal. 23: 2569-2579.
42. Ivanoff, D.B., K.R. Reddy, and S. Robinson. 1998. Chemical fractionation of organic phosphorus in selected histosols. Soil Sci. 163: 36-45.
43. Jokela, W.E., F.R. Magdoff, and R.P. Durieux. 1998. Improved phosphorus recommendations using modified Morgan phosphorus and aluminum soil tests. Commun. Soil Sci. Plant Anal. 29: 1739-1749.
44. Jones, J.B. 1998. Soil test methods: Past, present, and future use of soil extractants. Commun. Soil Sci. Plant Anal. 29: 1543-1552.
45. Kamprath, E.J. 1999. Changes in phosphate availability of ultisols with long term cropping. Commun. Soil Sci. Plant Anal. 30: 909-919.
46. Kamprath, E.J., and M.E. Watson. 1980. Conventional soil and tissue tests for assessing phosphorus status of soils. p. 433-469. In F.E. Khasawneh et al. (ed.) The role of phosphorus in agriculture. ASA, CSSA, and SSSA, Madison, WI.
47. Kim, S. 1996. Phosphorus. p. 869-919. In D.L. Sparks (ed.) Methods of soil analysis. Part 3. SSSA Book Ser. 5. SSSA, Madison, WI.
48. Kitchen, N.R., J.L. Havlin, and D.G. Westfall. 1990. Soil sampling under no-till banded phosphorus. Soil Sci. Soc. Am. J. 54: 1661-1665.
49. 3) extractable phosphorus and potassium and fertilizer recommendations. Commun. Soil Sci. Plant Anal. 31: 375-386.
50. Kovar, J.L., S.A. Barber, E.J. Kladivko, and D.R. Griffith. 1992. Characterization of soil temperature, water content, and maize root distribution in two tillage systems. Soil Tillage Res. 24: 11-27
51. LeClerg, E.L., W.H. Leonard, and A.G. Clark. 1962. Field plot technique. 2nd ed. Burgess Publ. Co., Minneapolis, MN.
52. Lee, Y.S., and R.J. Bartlett. 1977. Assessing phosphorus fertilizer needs based on intensity/capacity relationships. Soil Sci. Soc. Am. J. 41: 710-712.
53. Lindsay, W.L. 1979. Chemical equilibria in soils. John Wiley & Sons, New York.
54. Mackay, A.D., E.J. Kladivko, S.A. Barber, and D.R. Griffith. 1987. Phosphorus and potassium uptake by corn in conservation tillage systems. Soil Sci. Soc. Am. J. 51: 970-974.
55. Magdoff, F.R., C. Hryshko, W.E. Jokela, R.P. Durieux, and Y. Bu. 1999. Comparison of phosphorus soil test extractants for plant availability and environmental assessment. Soil Sci. Soc. Am. J. 63: 999-1006.
56. Mahler, R.L. 1990. Soil sampling fields that have received banded fertilizer applications. Comm. Soil Sci. Plant Anal. 21: 1793-1802.
57. Mallarino, A.P., and A.M. Blackmer. 1992. Comparison of methods for determining critical concentrations of soil test phosphorus for corn. Agron. J. 84: 850-856.
58. Mallarino, A.P., and J.S. Schepers. 2005. Role of precision agriculture in phosphorus management practices. p. 881-908. In J.T. Sims and A.N. Sharpley (ed.) Phosphorus: Agriculture and the environment. Agron. Monogr. 46. ASA, CSSA, and SSSA, Madison, WI.
59. Mallarino, A.P., J.R. Webb, and A.M. Blackmer. 1991. Corn and soybean yields during 11 years of phosphorus and potassium fertilization on a high-testing soil. J. Prod. Agric. 4: 312-317.
60. McCollum, R.E. 1991. Buildup and decline in soil phosphorus: 30-year trends on a Typic Umprabuult. Agron. J. 83: 77-85.
61. McIntosh, J.L. 1969. Bray and Morgan soil test extractants modified for testing acid soils from different parent materials. Agron. J. 61: 259-265.
62. McLean, E.O. 1984. Improved lime, phosphorus, and potassium recommendations based on double equilibration soil test methods for assessing buffering or fixation tendencies of individual soils. Commun. Soil Sci. Plant Anal. 16: 1229-1257.
63. McLean, E.O., T.O. Oloya, and J.L. Adams. 1979 Soil test to inventory the initially available levels and to assess the fates of added P and K as basis for improved fertilizer recommendations. Commun. Soil Sci. Plant Anal. 10: 623-630.
64. McLean, E.O., T.O. Oloya, and S. Mostaghimi. 1982. Improved corrective fertilizer recommendations based on a two-step alternative usage of soil tests: I. Recovery of soil-equilibrated P. Soil Sci. Soc. Am. J. 46: 1193-1197.
65. McPharlin, I.R., R.C. Jeffrey, and R.C. Weissberg. 1994. Determination of the residual value of phosphate and soil test phosphorus calibration for carrots on a Karrakatta sand. Commun. Soil Sci. Plant Anal. 25: 489-500.
66. McPharlin, I.R., W.J. Robertson, R.C. Jeffrey, and R. Weissberg. 1995. Response of cauliflower to phosphate fertilizer placement and soil test phosphorus calibration on a Karrakatta sand. Commun. Soil Sci. Plant Anal. 26: 607-620
67. 4. Mimeo. North Carolina Soil Testing Div., Raleigh, NC.
68. Mehlich, A. 1978. Influence of fluoride, sulfate, and acidity on extractable phosphorus, calcium, magnesium, and potassium. Commun. Soil Sci. Plant Anal. 9: 455-476.
69. Mehlich, A. 1984. Mehlich 3 soil test extractant: A modification of Mehlich 2 extractant. Commun. Soil Sci. Plant Anal. 15: 1409-1416.
70. Menon, R.G., S.H. Chien, and W.J. Chardon. 1996. Iron oxide filter paper (Pi test). II. A review of its application. Nutr. Cycl. Agroecosyst. 47: 7-18.
71. Menon, R.G., S.H. Chien, and L.L. Hammond. 1990. Development and evaluation of the Pi soil test for plant available phosphorus. Commun. Soil Sci. Plant Anal. 21: 1131-1150.
72. Menon, R.G., S.H. Chien, L.L. Hammond, and H.H. Sissing. 1988. A determination of plant available phosphorus by the iron hydroxide impregnated filter paper (Pi) soil test. Soil Sci. Soc. Am. J. 52: 110-115.
73. Miller, R.O. 2002. North American proficiency testing program. 1st quarter report, June 2002. SSSA, Madison, WI.
74. Morgan, M.F. 1941. Chemical soil diagnosis by the universal soil testing system. Bull. 450. Connecticut Agric. Exp. Stn., New Haven.
75. Murphy, J., and J.P. Riley. 1962. A modified single solution method for the determination of phosphate in natural waters. Anal. Chem. Acta 27: 31-36.
76. Nelson, L.A., and R.L. Anderson. 1977. Partitioning of soil test crop response probability. p. 19-38. In T.R. Peck et al. (ed.) Soil testing: Correlating and interpreting the analytical results. ASA Spec. Publ. 29. ASA, CSSA, and SSSA, Madison, WI.
77. Nesse, P., and J. Grava. 1986. Correlation of several tests for phosphorus with resin extractable phosphorus on alkaline soils. p. 218-220. In A report on field research in soils. Publ. 2 (revised). Univ. of Minnesota Agric. Exp. Stn., St. Paul.
78. Olsen, R.A., F.N. Anderson, K.D. Frank, P.H. Grabouski, G.W. Rehm, and C.A. Shapiro. 1987. Soil testing interpretations: Sufficiency vs. build-up and maintenance. p. 41-52. In J.R. Brown (ed.) Soil testing: Sampling, correlation, calibration, and interpretation. SSSA Spec. Publ. 21. SSSA, Madison, WI.
79. Olsen, S.R., C.V. Cole, F.S. Watanabe, and L.A. Dean. 1954. Estimation of available phosphorus in soils by extraction with sodium bicarbonate. USDA Circ. 939. U.S. Gov. Print. Office, Washington, DC.
80. Olsen, R.A., K.D. Frank, P.H. Grabouski, and G.W. Rehm. 1982. Economic and agronomic impacts of varied philosophies of soil testing. Agron. J. 74: 492-499.
81. Olsen, S.R., and F.E. Khasaweneh. 1980. Use and limitation of physical-chemical criteria for assessing the status of phosphorus in soils. p. 361-410. In F.E. Khasawwneh et al. (ed.) The role of phosphorus in agriculture. ASA, CSSA, and SSSA, Madison, WI.
82. Peck, T.R., L.T. Kurtz, and H.L.S. Tandon. 1971. Changes in Bray P-1 soil phosphorus test values resulting from applications of phosphorus fertilizer. Soil Sci. Soc. Am. Proc. 35: 595-597.
83. Peck, T.R., and P.N. Soltanpour. 1990. The principals of soil testing In R.L. Westerman (ed.) Soil testing and plant analysis. SSSA Book Ser. 3. SSSA, Madison, WI.
84. Pierzynski, G.M., R.W. McDowell, and J.T. Sims. 2005. Chemistry, cycling, and potential movement of inorganic phosphorus in soils. p. 53-86. In J.T. Sims and A.N. Sharpley (ed.) Phosphorus: Agriculture and the environment. Agron. Monogr. 46. ASA, CSSA, and SSSA, Madison, WI.
85. Randall, G.W., S.D. Evans, and W.W. Nelson. 1986. High phosphorus and potassium rates in a cornsoybean rotation. p. 153-164. In A report on field research in soils. Misc. Publ. 2. Univ. of Minnesota Agric. Exp. Stn., St. Paul.
86. Randall, G.W., T.K. Iragavarapu, and S.D. Evans. 1997. Long term P and K applications. I. Effect on soil test incline and decline rates and critical soil test levels. J. Prod. Agric. 10: 565-571.
87. Rehm, G.W., G.W. Randall, A.J. Scobbie, and J.A. Vetsch. 1995. Impact of fertilizer placement and tillage system on phosphorus distribution in soil. Soil Sci. Soc. Am. J. 59: 1661-1665.
88. Rouse, R.D. 1968. Soil test theory and calibration for cotton, corn, soybeans, and coastal bermudagrass. Bull. 375. Auburn Univ. Agric. Exp. Stn., Auburn, AL.
89. Sagger, S., M.J. Hedley, and R.E. White. 1990. A simplified resin membrane technique for extracting phosphorus from soils. Fert. Res. 24: 173-180.
90. Sample, E.C., R.J. Soper, and G.J. Racz. 1980. Reactions of phosphate fertilizers in soils. p. 263-310. In F.E. Khasawwneh et al. (ed.) The role of phosphorus in agriculture. ASA, CSSA, and SSSA, Madison, WI.
91. Schmidt, J.P., S.W. Buol, and E.J. Kamprath 1996. Soil phosphorus dynamics during seventeen years of continuous cultivation: Fractionation analyses. Soil Sci. Soc. Am. J. 60: 1168-1172.
92. Schoenau, J.J., and W.Z. Huang. 1991. Anion exchange membrane, water, and sodium bicarbonate extractions as soil tests for phosphorus. Commun. Soil Sci. Plant Anal. 22: 465-492.
93. Sharpley, A.N. 1985. Phosphorus cycling in unfertilized and fertilized agricultural soils. Soil Sci. Soc. Am. J. 49: 905-911.
94. Sharpley, A.N. 1991. Soil phosphorus extracted by iron-aluminum oxide impregnated filter paper. Soil Sci. Soc. Am. J. 55: 1038-1041.
95. Sharpley, A.N. 1993. An innovative approach to estimate bioavailable phosphorus in agricultural runoff using iron oxide impregnated paper. J. Environ. Qual. 22: 597-601.
96. Sharpley, A.N., and S.J. Smith. 1985. Fractionation of inorganic and organic phosphorus in virgin and cultivated soils. Soil Sci. Soc. Am. J. 49: 127-130.
97. Sharpley, A.N., S.J. Smith, B.A. Stewart, and A.C. Mathers. 1984. Forms of phosphorus in soil receiving cattle feedlot waste. J. Environ. Qual. 13: 211-215.
98. Sibbesen, E. 1977. A simple ion exchange resin procedure for extracting plant available elements from soil. Plant Soil 46: 665-669.
99. Sibbesen, E. 1978. An investigation of the anion-exchange resin method for soil test phosphate extraction. Plant Soil 50: 305-321.
100. Simonis, A.D., and H.B. Setatou. 1996. Assessment of available phosphorus and potassium in soils by the calcium chloride extraction method. Commun. Soil Sci. Plant Anal. 27: 685-694.
101. Skogley, E.O., S.J. Georgitis, J.E. Yang, and B.E. Schaff. 1990. The phytoavailability soil test. Commun. Soil Sci. Plant Anal. 21: 1229-1243
102. Smith, F.W., B.G. Ellis, and J. Grava. 1957. Use of acid fluoride solutions for the extraction of available phosphorus in calcareous soils and in soils to which rock phosphate has been added. Soil Sci. Soc. Am. Proc. 21: 400-404.
103. Smyth, T.J., and P.A. Sanchez. 1982. Phosphate rock and superphosphate combinations for soybeans in a cerado oxisol. Agron. J. 74: 730-735.
104. Sobral, L.F., B.F. Aquino, and F.R. Cox. 1998. Mehlich 3 phosphorus buffer coefficients. Commun. Soil Sci. Plant Anal. 29: 1751-1761.
105. Soltanpour, P.N., and A.P. Schwab. 1977. A new soil test for simultaneous extraction of macro- and micro-nutrients in alkaline soils. Commun. Soil Sci. Plant Anal. 8: 195-207.
106. Stewart, J.W.B., and A.N. Sharpley. 1987. Controls on dynamics of soil and fertilizer phosphorus and sulfur. p. 101-121. In R.F. Follett et al. (ed.) Soil fertility and organic matter as critical components of production systems. SSSA Spec. Publ. 19. SSSA, Madison, WI.
107. Thomas, G.W., and W.W. Frye. 1984. Fertilization and liming. p. 87-126. In R.E. Phillips and S.H. Phillips (ed.) No-tillage agriculture principles and practices. Van Nostrand Reinhold, New York.
108. Thomas, G.W., and D.E. Peaslee. 1973. Testing soils for phosphorus. In L.M. Walsh and J.D. Beaton (ed.) Soil testing and plant analysis. Revised ed. SSSA, Madison, WI.
109. Tran, T.S., R.R. Simard, and M. Tabi. 1992. Evaluation of the electro-ultrafiltration technique (EUF) to determine available P in neutral and calcareous soils. Commun. Soil Sci. Plant Anal. 23: 2261-2281.
110. Tyner, E.H., and J.G. Davide. 1962. Some criteria for evaluating phosphorus tests for lowland rice soils. p. 625-634. In G.J. Neale (ed.). Trans. Commun. IV and V Int. Soc. Soil Sci. Nov. 1962, Palmerston North, NZ. Soil Bureau, P.B., Lower Hutt, NZ.
111. van Raij, B. 1998. Bioavailability tests: Alternatives to standard soil extractions. Commun. Soil Sci. Plant Anal. 29: 1553-1570.
112. van Raij, B., and J.A. Quaggio. 1990. Extractable phosphorus availability indexes as affected by liming. Commun. Soil Sci. Plant Anal. 21: 1267-1276.
113. von Liebig, J. 1855. Principles of agricultural chemistry, with special reference to the late researches made in England. (English translation of original work in German). Walton & Maberly, London.
114. Voss, R. 1998. Fertility recommendations: Past and present. Commun. Soil Sci. Plant Anal. 29: 1429-1440.
115. Wolf, A.M., and D.B. Beegle. 1995. Recommended soil tests for macronutrients: Phosphorus, potassium, calcium, and magnesium. In J.T. Sims and A.M. Wolf (ed.) Recommended soil testing procedures for the northeastern United States. Northeast Regional Bull. 493. Univ. of Delaware, Newark.
116. Zhang, H., and J.L. Kovar. 2000 Phosphorus fractionation In G.M. Pierzynski (ed.) Methods of phosphorus analysis for soils, sediments, residuals, and waters. SERA-17, South. Coop. Ser. Bull. 396. North Carolina State Univ., Raleigh.