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United States Department of Agriculture

Agricultural Research Service

Research Project: Efficient Management and Use of Animal Manure to Protect Human Health and Environmental Quality

Location: Food Animal Environmental Systems Research

Title: Phosphorus indices and the 590 Revision: Why we need to take stock of how we are doing .

item Sharpley, Andrew
item Beegle, Doug
item Bolster, Carl
item Good, Laura
item Joern, Brad
item Ketterings, Quirine
item Lory, John
item Mikkelsen, Rob
item Osmond, Deanna
item Vadas, Peter

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2011
Publication Date: 10/19/2011
Citation: Sharpley, A., Beegle, D., Bolster, C.H., Good, L., Joern, B., Ketterings, Q., Lory, J., Mikkelsen, R., Osmond, D., Vadas, P.A. 2011. Phosphorus indices and the 590 Revision: Why we need to take stock of how we are doing .. ASA-CSSA-SSSA Annual Meeting Abstracts. Abstract Only.

Interpretive Summary:

Technical Abstract: Since its inception nearly 20 years ago, the phosphorus (P) Index has morphed from an educational tool to a Best Management Practice targeting and implementation tool, a manure-scheduling tool, and in many cases, a regulatory tool. A great deal of research has been conducted across the U.S. to derive, validate, and support components of the P Indexing concept, particularly those related to source factors. As different versions of the P Index have emerged, ostensibly to account for local topography, hydrology, soils, land use, and individual state policies and agendas, so too have differences in the P management recommendations that are made using the P Index. As a result, there are many variations in P Indices now in use as part of the NRCS 590 Nutrient Management Conservation Standard. This variation is both a strength and weakness of the P Indexing concept. However, the inconsistency among P Indices in terms of level of detail and scientific underpinnings among states, as well as in recommendations and interpretations based on site risk, prompted a review and possible revision of the 590 Standard and P-Indexing approach. The need for revision has been heightened by a slower than expected decrease in P-related water quality impairment and, in some cases, an increase in soil P to levels several fold greater than agronomic optimum due to the inability of the P Index to prevent the continued over-application of P to soils. While the basic scientific foundations of the P-Indexing approach are sound, these concerns are real. In this presentation, we propose the use of lower and upper boundaries of P Index use and describe an approach to evaluate individual State P Indices.

Last Modified: 09/18/2017
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