Technical basis for quantifying phosphorus transport to surface and groundwaters.
Decreasing the potential delivery of phosphorus in fertilizers or animal waste to surface and groundwater requires a knowledge of phosphorus's fate and transport mechanisms. The USDA Natural Resources Conservation Service has recently mandated each state to develop an assessment tool to estimate P transport to water bodies. The objective of this paper is to describe the processes involved with P transport to surface and groundwaters that must be accounted for in practical methods used to quantify the potential for P loss. Mechanistic models to assess P loss should account for: 1) P adsorbed to eroding sediments, 2) soluble P in runoff water, 3) soluble P in leaching water, and 4) P losses related to specific P sources. With sediment-bound P, the adsorbed P content in the eroded soil mass at the field edge must be quantified, whereas runoff volume and P concentration are needed to estimate soluble P loss in runoff water. Estimating P leaching potential requires calculation of drainage water volume and P concentration. When P is applied in animal waste, the specific source influences both soluble and particulate P loss because of differences in P solubility between waste types. In addition, the effects of conservation practices and other technologies on decreasing sediment, soluble, and leached P need to be included. Using these methods, a practical, quantitative P loss assessment tool can be developed that will enable technical service providers and other practitioners to estimate potential P loss and design best-management practices for land-applied waste management systems in order to minimize P transport to surface and groundwater.
Department of Soil Science, North Carolina State University, Raleigh 27695, USA. john_havlin@ncsu.edu <john_havlin@ncsu.edu>
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D000327:Adsorption; D000383:Agriculture / Q000379:methods / Q000592:standards; D000818:Animals; D003247:Conservation of Natural Resources / Q000379:methods; D018556:Crops, Agricultural / Q000254:growth & development; D005308:Fertilizers; D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry; D008372:Manure / Q000032:analysis; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D012987:Soil / Q000032:analysis; D014876:Water Pollution / Q000517:prevention & control
D005308:Fertilizers; D008372:Manure; D012987:Soil; D010758:Phosphorus