W. W. Wilhelm, USDA-ARS, 117 Keim Hall, PO Box 830934, Lincoln, NE 68583-0934, Jane Johnson, USDA-ARS-NCSCRL, 803 Iowa Avenue, Morris, MN 56267, Douglas Karlen, National Soil Tilth Laboratory, USDA-ARS, 2110 University Blvd., Ames, IA 50011-3120, and David Lightle, USDA-NRCS, 16105 Saltillo Road, Bennet, NE 68317-2082.
Sustainable aboveground crop biomass harvest estimates for cellulosic ethanol production, to date, have been limited by the need for residue to control erosion. Recently, estimates of the amount of corn stover needed to maintain soil carbon, which is responsible for favorable soil properties, were reported (5.25 to 12.50 Mg ha-1). These estimates indicate stover needed to maintain soil organic carbon, and thus productivity, are a greater constraint to environmentally sustainable cellulosic feedstock harvest than that needed to control water and wind erosion. An extensive effort is needed to develop advanced cropping systems that greatly expand biomass production to sustainably supply cellulosic feedstock without undermining crop and soil productivity.