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United States Department of Agriculture

Agricultural Research Service


item Weld, Jennifer

Submitted to: Water Environment Federation
Publication Type: Proceedings
Publication Acceptance Date: 12/12/2002
Publication Date: 2/19/2003
Citation: Weld, J.L. 2003. Development of the national P index - The potential role of WTR. Water Environment Federation. Paper No. 94.

Interpretive Summary:

Technical Abstract: The primary water quality concern surrounding phosphorus (P), especially in freshwater bodies, is accelerated eutrophication. The natural aging process of a body of water, eutrophication, can be accelerated by increased nutrient and sediment loadings. Accelerated eutrophication results in excessive algal growth on the water body surface that inhibits light penetration and depletes available oxygen as the aquatic plant material decomposes. This limits water use for fisheries, recreation, and industry, and can contribute to fish kills. As a result of increasing water quality concerns associated with nonpoint contributions of P, increased attention by federal and state agencies has been focused on minimizing P contributions from these sources. In 1999, the U.S. Department of Agriculture and U.S. Environmental Protection Agency jointly issued the Unified National Strategy for Animal Feeding Operations that outlined three P-based nutrient management strategies, one of which was the P Index. The P Index is a tool that was developed for the purpose of identifying areas of P movement from agricultural fields by ranking site vulnerability to P loss. It accounts for both source and transport processes associated with P loss, and allows for targeted management. In a P Index evaluation, areas requiring additional management to minimize vulnerability to P loss are identified, and appropriate management practices are recommended. Often these practices involve soil conservation, but management practices that have the potential to control dissolved P loss, such as the use of water treatment residuals (WTRs), also have the potential to make a contribution to the P Index process. Finally, there is great potential to establish mutually beneficial relationships between the agricultural community and the industries by exploring beneficial uses for P binding by-products to control non-point losses of P from agricultural lands.

Last Modified: 08/17/2017
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