Influence of Corn Residue Harvest Management on Grain, Stover, and Energy Yields

Economic, environmental, and energy independence issues are contributing to rising fossil fuel prices, petroleum supply concerns, and a growing interest in biomass feedstocks as renewable energy sources. Potential feedstocks include perennial grasses, timber, and annual grain crops with our focus being on corn (Zea mays L.) stover. A plot-scale study evaluating stover removal was initiated in 2008 on a South Carolina Coastal Plain Coxville/Rains-Goldsboro-Lynchburg soil association site. In addition to grain and stover yields, carbon balance, greenhouse gas (GHG) emissions and soil quality impact reported elsewhere in this issue, variation in gross energy distribution within various plant fractions - whole plant, below ear shank (bottom), above ear shank (top), cob, as well as leaves and stems of the bottom and top portions (n ((part, year)) = 20) was measured with an isoperibol calorimeter. Stalks from above the ear shank were the most energy dense, averaging 18.8 MJ/kg db, and when combined with other plant parts from above the ear shank, the entire top half was more energy dense than the bottom half - 18.4 versus 18.2 MJ/kg db. Gross energy content of the whole plant, including the cob, averaged 18.28 +/- 0.76 MJ/kg db. Over the 4 years, partial to total removal (i.e., 25 % to 100 %) of above-ground plant biomass could supply between 30 and 168 GJ/ha depending upon annual rainfall. At 168 GJ/ha, the quantity of corn stover biomass (whole plant) available in a 3,254-km(2) area (32 km radius) around the study site could potentially support a 500-MW power plant.