Submitted to: Canadian Journal of Soil Science
Publication Type: Book / Chapter
Publication Acceptance Date: June 6, 2005
Publication Date: January 20, 2008
Citation: Sharpley, A.N., Kleinman, P.J., Weld, J.L. 2008. Environmental soil phosphorus indices. In: Carter, M.R., Gregorich, E.G., editors. Soil Sampling and Methods of Analysis, 2nd Edition. Canadian Society of Soil Science. CRC Press, Boca Raton, FL. p. 141-159. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: The loss of phosphorus (P) in agricultural runoff and its input to freshwater bodies is known to accelerate eutrophication. As eutrophication of surface water impairs its use for recreation, drinking, and commercial fishing, several strategies have been put in place to minimize impairment by reducing the potential for P loss from agricultural operations via more stringent nutrient management planning. These Comprehensive Nutrient Management Planning (CNMP) strategies require many farms to address the land application of P in fertilizer and manure, as well as implement Best Management Practices (BMPs) that minimize runoff and erosion and conserve P where it is applied. Key components of implementing P-based nutrient management are the determination of soil P levels that are above those required for optimum crop growth, due to the continual application of P, and the identification of critical source areas where there is a high risk of P loss due to the coincidence of runoff and erosion with high soil P levels. The more prominent of these tests include water extractable soil P and P sorption saturation. Soil P sorption has also been used to estimate the potential of a soil to sequester proposed additions of P. In specific cases, a detailed assessment of the P sorption capacity of a soil is a planning requirement of proposed land applications of biosolids, in order to determine the potential for P leaching through a soil profile. Finally, most states have now adopted a P Indexing approach as part of P-based nutrient management planning requirements, so that areas at greatest risk of P loss can be targeted for remediation or more restrictive management. In this book chapter we detail the methods used to estimate water extractable soil P, P sorption saturation, P sorption capacity, and indexing P loss potential for a given site.