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United States Department of Agriculture

Agricultural Research Service

Title: Phosphorus Loss from Land to Water: Integrating Agricultural and Environmental Management

Authors
item Sharpley, Andrew
item Mcdowell, Richard - PENN STATE UNIVERSITY
item Kleinman, Peter

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 12, 2001
Publication Date: December 20, 2001
Citation: Sharpley, A.N., Mcdowell, R.W., Kleinman, P.J. 2001. Phosphorus loss from land to water: integrating agricultural and environmental management. Plant And Soil Journal. 237:287-307.

Interpretive Summary: Phosphorus (P) is an essential element for plant growth and its input has long been recognized as necessary to maintain profitable crop production. Phosphorus inputs can also increase the biological productivity of surface waters. Thus, reducing P loss in runoff is of prime importance in minimizing accelerated eutrophication of fresh waters. More intensive crop pand livestock production in many parts of the world, has generally increased the potential for P export from watersheds. Management strategies to minimize P loss to water may be brought about by optimizing P use-efficiency, refining animal feed rations, using feed additives to increase P absorption by the animal, moving manure from surplus to deficit areas, and targeting conservation practices, such as reduced tillage, buffer strips and cover crops, to critical areas of P export from a watershed. However, because farmers' decisions are influenced by regional and even global economics over which they have little control, we should explore the use of incentives to aid in implementation of innovative measures that minimize on-farm surpluses of P and reduce P losses.

Technical Abstract: Phosphorus (P), an essential nutrient for crop and animal production, can accelerate freshwater eutrophication, now one of the most ubiquitous forms of water quality impairment in the developed world. Repeated outbreaks of harmful algal blooms have increased society's awareness of eutrophication, and the need for solutions. Agriculture is regarded as an important source eof P in the environment. Specifically, the concentration of specialized farming systems has led to a transfer of P from grain- to animal-producing areas. This has created regional surpluses in P inputs as fertilizer and feed over outputs as crop and animal produce, built up soil P in excess of crop needs, and increased the loss of P from land to water. Recent research has shown that this loss of P in both surface runoff and subsurface flow originates primarily from small areas within watersheds during a few storms. These areas occur where high soil P, or P application nin fertilizer or manure, coincide with high runoff or erosion potential. We argue that the overall goal of efforts to reduce P loss to water should involve balancing P inputs and outputs at farm and watershed levels, while managing soil and P in ways that maintain productivity. Management strategies to minimize P loss to water may be brought about by optimizing P use-efficiency, refining animal feed rations, using feed additives to increase P absorption by the animal, moving manure from surplus to deficit areas, and targeting conservation practices to critical areas of P export from a watershed. However, because farmers' decisions are influenced by regional and even global economics over which they have little control, we should also explore the use of incentives to aid in implementation of innovative measures that minimize on-farm surpluses of P & reduce P losses.

Last Modified: 10/24/2014
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