Wj. Gburek et An. Sharpley, HYDROLOGIC CONTROLS ON PHOSPHORUS LOSS FROM UPLAND AGRICULTURAL WATERSHEDS, Journal of environmental quality, 27(2), 1998, pp. 267-277
Development of strategies for controlling P loss from upland agricultu
ral watersheds requires an ability to identify specific source areas o
f P at field and farm scales, and to predict their resultant effects a
t the watershed scale. Key to identification of P source areas is defi
ning 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 spe
cific zones of runoff and erosion within a watershed, that is, source
areas for the P transport mechanisms. Research results from a series o
f studies within a small, upland agricultural watershed in fast-centra
l Pennsylvania show that the zones of runoff production, and consequen
tly the areas ultimately controlling most P transport, are often a lim
ited and identifiable portion of the landscape. Quantifying the hydrol
ogic controls on P transport within and from a watershed in this way a
llows us to focus management options on small and definable portions o
f the total watershed that contribute most P export.