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Title: Improved simulation of edaphic and manure phosphorus loss in SWAT and TopoSWAT

item Collick, Amy
item Veith, Tameria - Tamie
item FUKA, DANIEL R - Virginia Polytechnic Institution & State University
item Kleinman, Peter
item WELD, JENNIFER - Pennsylvania State University
item Vadas, Peter
item White, Michael
item Harmel, Daren
item EASTON, ZACHARY - Virginia Polytechnic Institution & State University

Submitted to: Soil and Water Assessment Tool International Conference
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2015
Publication Date: 10/14/2015
Citation: Collick, A.S., Veith, T.L., Fuka, D., Kleinman, P.J., Weld, J.L., Vadas, P.A., White, M.J., Harmel, R.D., Easton, Z.M. 2015. Improved simulation of edaphic and manure phosphorus loss in SWAT and TopoSWAT. Soil and Water Assessment Tool International Conference. p. 91.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: Watershed models such as the Soil Water Assessment Tool (SWAT) and (APEX) are widely used to assess the consequences of agricultural nutrient management practices on soluble and particulate phosphorus (P) loss in runoff. Soil P cycling routines used in SWAT2012, however, do not simulate the short-term effects of applying a concentrated source of soluble P, such as a manure, to the soil surface where it is most vulnerable to runoff. We added a new set of soil P routines to SWAT2012 to simulate surface applied manure at field and subwatershed scales within watersheds in Pennsylvania and Texas. We corroborated the new P version of SWAT against the standard SWAT P routine. Corroborative systems involved standard SWAT, a topographically driven version of SWAT (TopoSWAT), and five and 12 years of measured data under field-specific, historical management information in Pennsylvania and Texas, respectively. Short-term “wash off” processes resulting from precipitation immediately following surface application of manures were captured with the new P routine whereas the standard routines resulted in losses regardless of manure application. The new routines improved sensitivity to key factors in nutrient management (i.e., timing, rate, method, and form of P application). Only the new P routines indicate decreases in soluble P losses for manure applications at one, five and 10 days, respectively, before a storm event. Unlike with standard P routines, the new P routines exhibit greater variation among proportions of organic, particulate and soluble P corresponding to spreading method. Results suggest similar revisions to other agroecosystem watershed models would be appropriate.