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This article in JEQ

  1. Vol. 27 No. 2, p. 267-277
    Received: Feb 7, 1997

    * Corresponding author(s): wjg1@psu.edu
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Hydrologic Controls on Phosphorus Loss from Upland Agricultural Watersheds

  1. William J. Gburek * and
  2. Andrew N. Sharpley
  1. Pasture Systems and Watershed Management Research Laboratory, USDA-ARS, University Park, PA 16802.



Development of strategies for controlling P loss from upland agricultural watersheds requires an ability to identify specific source areas of P at field and farm scales, and to predict their resultant effects at the watershed scale. Key to identification of P source areas is defining the interaction between P availability over the landscape and its potential for movement to the watershed outlet by runoff and erosion. A current weakness in quantifying this interaction is determining specific zones of runoff and erosion within a watershed, that is, source areas for the P transport mechanisms. Research results from a series of studies within a small, upland agricultural watershed in east-central Pennsylvania show that the zones of runoff production, and consequently the areas ultimately controlling most P transport, are often a limited and identifiable portion of the landscape. Quantifying the hydrologic controls on P transport within and from a watershed in this way allows us to focus management options on small and definable portions of the total watershed that contribute most export.

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