Managing agricultural phosphorus for protection of surface waters: issues and options

• Published in: Journal of environmental quality Vol. 23; no. 3; pp. 437 - 451
• Main Authors: Sharpley, A.N, Chapra, S.C, Wedepohl, R, Sims, J.T, Daniel, T.C, Reddy, K.R
• Format: Journal Article
• Language: English
• Published: Madison, WI American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America 01.05.1994; Crop Science Society of America; American Society of Agronomy
• Subjects: ABONOS ORGANICOS; Agricultural management; Agronomy. Soil science and plant productions; AMENAGEMENT DE BASSIN VERSANT; Applied sciences; Biological and medical sciences; CONDUITE DE LA CULTURE; Continental surface waters; CONTROL DE LA CONTAMINACION; EAU DE RUISSELLEMENT; ENGRAIS ORGANIQUE; EROSION; ESCORRENTIA; EUTROFIZACION; EUTROPHISATION; Exact sciences and technology; FERTILIDAD DEL SUELO; FERTILITE DU SOL; FOSFORO; Fundamental and applied biological sciences. Psychology; LUTTE ANTIPOLLUTION; MANEJO DEL CULTIVO; MANEJO DEL SUELO; MISE EN VALEUR DU SOL; Natural water pollution; ORDENACION DE CUENCAS; PHOSPHORE; POLLUTION; POLUCION; Surface water; Water treatment and pollution; Waste management; Surface water; Phosphorus; Agriculture; Water pollution; Runoff water; Farmyard manure; Environmental management; Eutrophication
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq1994.00472425002300030006x

The accelerated eutrophication of most freshwaters is limited by P inputs. Nonpoint sources of P in agricultural runoff now contribute a greater portion of freshwater inputs, due to easier identification and recent control of point sources. Although P management is an integral part of profitable agrisystems, continued inputs of fertilizer and manure P in excess of crop requirements have led to a build-up of soil P levels, which are of environmental rather than agronomic concern, particularly in areas of intensive crop and livestock production. Thus, the main issues facing the establishment of economically and environmentally sound P management systems are the identification of soil P levels that are of environmental concern; targeting specific controls for different water quality objectives within watersheds; and balancing economic with environmental values. In developing effective options, we have brought together agricultural and limnological expertise to prioritize watershed management practices and remedial strategies to mitigate nonpoint-source impacts of agricultural P. Options include runoff and erosion control and P-source management, based on eutrophic rather than agronomic considerations. Current soil test P methods may screen soils on which the aquatic bioavailability of P should be estimated. Landowner options to more efficiently utilize manure P include basing application rates on soil vulnerability to P loss in runoff, manure analysis, and programs encouraging manure movement to a greater hectareage. Targeting source areas may be achieved by use of indices to rank soil vulnerability to P loss in runoff and lake sensitivity to P inputs