|Veith, Tameria - Tamie|
|Fuka, Daniel - Virginia Polytechnic Institution & State University|
|Weld, Jennifer - Pennsylvania State University|
|Easton, Zachary - Virginia Polytechnic Institution & State University|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2016
Publication Date: 4/22/2016
Citation: Collick, A.S., Veith, T.L., Fuka, D.R., Kleinman, P.J., Buda, A.R., Weld, J.L., Bryant, R.B., Vadas, P.A., White, M.J., Harmel, R.D., Easton, Z.M. 2016. Improved simulation of edaphic and manure phosphorus loss in SWAT. Journal of Environmental Quality. 45(4):1215-1225. doi:10.2134/jeq2015.03.0135.
Interpretive Summary: Watershed modeling is critical to guiding strategies to mitigate non-point source pollution. Current watershed models generally lack explicit representation of surface application of nutrients, a potential problem when forecasting the effects of nutrient management strategies. We evaluated a new set of routines for surface applied manures and fertilizers within the Soil Water Assessment Tool (SWAT) watershed model. Results show that these new routines better simulate the effects of manure management on phosphorus runoff and therefore should be considered in all watershed models.
Technical Abstract: Watershed models such as the Soil Water Assessment Tool (SWAT) are widely used to assess the consequences of agricultural nutrient management practices on phosphorus (P) loss in runoff. Soil P cycling routines used in such models, 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 SWAT to simulate surface applied manure at field and subwatershed scales within Mahantango Creek watershed (Pennsylvania). We corroborated the new P version of SWAT against the standard P version and monitored data. Substantial differences were apparent between the standard and new P routines at both scales, with the new routine capturing short-term “wash off” processes that occur when precipitation immediately follows surface application of manures. Dynamic cycling between soil P pools, introduced in the new routine, greatly improved proportions of organic, sediment-bound, and soluble P in losses from disc-incorporated manure. The new routines provided insight into all aspects of the “4R” strategy for nutrient management (i.e., method, timing, rate, and form of application). Results demonstrated substantial improvements in simulating P runoff processes with the new routines in SWAT and support similar revisions to other agroecosystem watershed models.