TY - JOUR T1 - Application of a calibrated/validated Agricultural Policy/Environmental eXtender model to assess sediment and nutrient delivery from the Wildcat Creek Mississippi River Basin Initiative-Cooperative Conservation Partnership Initiative JF - Journal of Soil and Water Conservation SP - 23 LP - 35 DO - 10.2489/jswc.70.1.23 VL - 70 IS - 1 AU - W. Francesconi AU - D.R. Smith AU - G.C. Heathman AU - J.M. Gonzalez AU - M.M. Benage Y1 - 2015/01/01 UR - http://www.jswconline.org/content/70/1/23.abstract N2 - Wildcat Creek, a tributary to the Wabash River, was identified by the USDA Natural Resources Conservation Service (NRCS) as a priority watershed for its high sediment and nutrient loading contributions to the Mississippi River. As part of the Mississippi River Basin Initiative (MRBI), the incorporation of conservation practices was implemented through a Cooperative Conservation Partnership Initiative (CCPI) agreement using existing USDA programs. The objective of this work was to evaluate the potential water quality benefits of conservation practices placed in the Wildcat Creek Watershed through the MRBI-CCPI. Specifically, seven output variables (surface runoff, tile flow, sediments, total phosphorus [P], soluble P, soluble nitrogen [N], and soluble N in tile) were compared for four different row crop conservation practices (residue and tillage management no-till, residue and tillage management mulch-till, cover crops, and forage and biomass planting), and two manure application scenarios. Using the Agricultural Policy/Environmental eXtender (APEX) model, calibrated and validated for a field within the St. Joseph River Watershed, a modeling assessment was developed for current conservation practices incorporated at a similar watershed, Wildcat Creek. Annual average values were estimated for each simulated scenario, and percentage reductions were reported. Cover crops consistently reduced sediment and nutrient loads in runoff by more than 50% compared to the tillage baseline scenario, and removal of the manure application in the waste utilization scenario reduced the predicted total and soluble P amounts by 75% and 92%, respectively. When extrapolating the edge-of-field values predicted by the model to the area occupied by each conservation practice throughout the duration of the contracts at the Wildcat Creek Watershed, the total reductions were estimated to be almost 7,000 Mg (7,700 tn) of sediment (68% decrease), 20,000 kg (44,092 lb) of total P (73% decrease), 4,000 kg (8,818.5 lb) of soluble N in runoff (50% decrease), and 185,000 kg (414,00 lb) of soluble N in tile flow (43% decrease). Agricultural Policy/Environmental eXtender modeling is a useful tool for predicting sediment and nutrient loading information at the field-scale, which can be used to calculate the relative impact of conservation practices at the watershed scale when monitoring data are not available. The modeling results confirm the positive impact of these conservation practices and of the MRBI-CCPI initiative at improving water quality at the edge-of-field, and potentially at the Wildcat Creek, the Greater Wabash River Basins, and ultimately the Mississippi River Basin. ER -