Management of Biofuel Crops in Southern Wisconsin to Reduce Soil and Nutrient Losses From Surface Runoff.

Increased production of biofuel crops such as corn (Zea mays L.) is a questionable alternative energy source to fossil fuels as current management practices results in losses of sediment and nutrients from surface runoff on sloped land, leading to decreased soil fertility and long term environmental degradation.

Sustainable management practices maintaining high yields of corn while limiting surface runoff must be developed. Another promising practice is growing switchgrass (Panicum virgatum L.) as a biofuel source. Requiring little nutrient inputs and non-intensive field maintenance, switchgrass is considered to be more protective of soil. However there is little, if any, research on surface runoff from the production of switchgrass. The objectives of this study were to assess the impact of growing corn under varying management practices on sloping land as compared to switchgrass by quantifying sediment and nutrient losses in surface runoff.

The study design included twenty-one plots representing three replicates of one treatment of switchgrass and three planting treatments of no-tillage continuous corn. Switchgrass was planted using the drill-seed method. Corn was planted at standard 30-in row spacing at standard and high densities, and narrow 15-in row spacing at standard density. Mini-erosion frames (0.5-m wide by 1.0-m long) were installed in each plot for the collection of surface runoff. Results indicate high yields for all corn treatments while runoff volume was highest for corn at standard row spacing and standard density and lowest for standard row spacing and high density. Sediment loads and nutrient losses have not yet shown a significant difference between treatments. Runoff volume was initially high for switchgrass during establishment yet greatly decreased near the end of the season. In varying management of biofuel crops surface runoff was reduced and high yields maintained, yet to fully assess benefits continued monitoring is needed.