ARS | Publication request: CRITICAL AREAS OF PHOSPHORUS EXPORT FROM AGRICULTURAL WATERSHEDS

Submitted to: Chesapeake Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 1, 1999
Publication Date: N/A

Technical Abstract: Phosphorus (P)-focused management of all fields having high soil P levels or high rates of P input via fertilizer or manure is not necessary to reduce P export from a watershed. Rather, management should focus on the areas representing the intersections of high P source-areas with areas of actual or potential transport mechanisms, primarily surface runoff and erosion. These intersections define the critical source areas (CSAs) controlling P export. In this paper, we extend the generalities of phosphorus soil chemistry and pathways of transport addressed in previous papers in this symposium to the watershed scale. Based on the watershed- scale findings, we suggest modifications to the Phosphorus Index, a user- oriented tool for identification of CSAs controlling P export from agricultural watersheds and evaluation of management options available.