Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/9/2000
Publication Date: N/A
Technical Abstract: Simulation models enable the prediction of water quality parameters in response to different agricultural management practices. The objective of this research was to use the Agricultural Non-Point-Source Pollution Model (AGNPS) to simulate concentrations and loads of water quality parameters in surface runoff from two watersheds with contrasting land use. The first site was a 33.5-ha watershed located at the Deep Loess Research Station near Treynor, IA. AGNPS was used to predict changes in runoff water quality by implementation of a corn (Zea mays, L.)-soybean [Glycine max L.(Merr.)]-3x alfalfa (Medicago sativa L.) rotation. The second site was a 147-ha watershed near Savoy, AR. The Savoy watershed has been in hardwood forest (57% of area) and pasture (43%) since the 1930's. AGNPS simulations of the Treynor watershed indicated reductions of 22, 53, 51 and 62% in runoff volume, sediment yield, and total N and P in sediment, respectively, when alfalfa replaced disk-till corn. For the Savoy watershed, AGNPS consistently predicted significantly greater runoff and soil loss than was measured. Model results reinforce the necessity of accurate characterization of surface hydrologic properties to achieve accurate water quality predictions.