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United States Department of Agriculture

Agricultural Research Service


item Sharpley, Andrew
item Tunney, Hubert

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Phosphorus is an essential element for plant and animal growth and its input has long been recognized as necessary to maintain profitable crop and animal production. Phosphorus inputs can also accelerate the eutrophication of fresh waters around the world. Eutrophication has been identified as the main problem in surface waters having impaired water quality, restricting water use for fisheries, recreation, industry, and drinking. Recent outbreaks of the dinoflagellate Pfiesteria in the eastern U.S. have dramatically increased public awareness of eutrophication and the need for solutions. Although we have done a lot of research on phosphorus in the last 20 years, we are not able to answer many of the questions now being asked as to how agriculture impacts water quality and how changes can be made. Our current problems have been caused by the specialization and concentration of crop and animal farming in separate areas of the country and changes in farm economics which have become more sensitive to world market demands. Thus, there is a need for more information to help resolve farm and water quality issues and provide defensible recommendations for basing manure management on phosphorus as well as nitrogen. In this paper we identify four main areas of research needed to meet these challenges. These are developing soil tests that identify the risk for nonpoint source pollution and investigating the routes by which phosphorus moves within watersheds. We also need to develop and put in place farm practices which reduce phosphorus loss in surface runoff and provide incentives or rewards for farmers using environmentally sound management.

Technical Abstract: The accumulation, management, and transfer of phosphorus (P) in intensive farming systems has increased P export from agricultural watersheds and accelerated eutrophication of surface waters. Even though much research on P has been done in the last 20 years, there are still few answers to many of the questions now being asked regarding agricultural production and environmental quality. To address these concerns, four areas of research are suggested: Soil P testing for environmental risk assessment - in combination with an assessment of site vulnerability to P loss, threshold P levels in soil and water should be established, i.e., what losses are acceptable and whether these can be determined by plot or watershed-scale studies? Pathways of P transport - the relative importance of different flow pathways is needed at a watershed scale. Best Management Practice (BMP) development and implementation - overall, BMP's must attempt to bring ginto closer balance P inputs and outputs and should be targeted to critica source areas within a watershed. Alternative management recommendations, uses and market demand for manures must be developed. Strategic initiatives to manage P - to initiate lasting changes, research should focus on consumer driven programs that encourage farmer performance and stewardship to achieve agreed environmental goals.

Last Modified: 06/21/2017
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