Coupling Bioenergy Production and Precision Conservation Using a Spatially Distributed Modeling Approach.

Bioenergy production and precision conservation are reshaping the agricultural landscape. Due to the environmental risks of residue removal and other practices proposed for bioenergy production, precision conservation can play a crucial role at making bioenergy production environmentally sustainable. Trade offs exist, however, between bioenergy production, resources conservation, and the avoidance of on-site and off-site environmental degradation. In this research we apply a spatially distributed hydrological and cropping systems model, APEX, to assess different combinations of conservation practices and cropping systems in terms of productivity and environmental impacts. The virtual farm for this testing was built based on the USDA-ARS research station at Riesel, Texas. The farm (440 ha) was divided in 75 distinct and hydrologically connected subareas based on topographic attributes. Of the 75 subareas, 31 drain to the edge of field, 34 drain to lower slope positions within the field, and 10 subareas collect drainage from the 34 upland subareas and drain as edge of field or watershed outlets. It is shown that several options exist regarding optimal production (grain and biomass), and that targeted conservation practices have the most impact in reducing runoff and off-site transport of sediments and nutrients. Models, and in particular APEX, is a powerful tool for landscape-based agroecosystems design.