Submitted to: Government Publication/Report
Publication Type: Government Publication
Publication Acceptance Date: 12/30/2004
Publication Date: 1/2/2005
Citation: Sharpley, A.N., Weld, J.L., Kleinman, P.J.A., Gburek, W.J. 2005. The phosphorus index. The Phosphorus Index. NRCS Technical Resources Manual. 12 p. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Phosphorus (P), an essential element for plant and animal production, can accelerate eutrophication, which has become one of the most ubiquitous water quality impairments in the U.S. This has forced many states to consider the development of recommendations for P applications and watershed management based on the potential for P loss in agricultural runoff. In response, a P Index has been developed to rank field vulnerability to P loss so that high risk areas may be identified for site-specific management. This publication documents the rationale behind the P Index, approach and calculations used, and interpretations of risk assessments, which was put together for the NRCS Technical Resources nutrient & pest management homepage (http://www.nrcs.usda.gov/technical/ECS/nutrient/pindex.html). The index accounts for and ranks transport (erosion, runoff, leaching, and landscape position) and source factors (added fertilizer and manure, soil P) controlling P loss and identifies sites where the risk of P movement is expected to be higher than others. Fields at high risk are those where areas of high P application or soil P coincide with zones of active surface runoff or erosion. A P Index has been developed to rank field vulnerability to P loss so that high risk fields may be identified for site-specific management. The Index provides a framework that can be regionally adapted to prevailing topography, geology, and climatic conditions and requires only readily available data.