Evaluating Yield and N-Removal in Sorghum Grown for Biofuel.

Increasing national demands for alternative fuels, especially cellulosic ethanol, creates the need to develop biofuel crops, such as sorghum, to meet the demand. Sorghum (Sorghum bicolor L. Moench) is drought-hardy, grows on marginal crop land, produces high yields, and has a high energy conversion ratio as a biofuel feedstock. Unlike grain sorghum, less is known regarding N fertilizer requirements for sweet or high biomass sorghum (HBS) and currently no N-fertilizer recommendations exist for potential Missouri growers to optimize sorghum dry matter (DM) and ethanol yields. A three-year study was conducted to evaluate the yield response of four sorghum cultivars (two sweet and two HBS) to five N rates ranging from 0-224 kg ha^-1. Final harvests of sweet sorghum (2009-2011) and of HBS (2010-2011) were taken and total DM, ethanol yield, and N-removal determined. Results will aid in determining optimal N fertilizer rates for DM yield and ethanol production and to calculate overall energy efficiency of sweet and HBS sorghums.