Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: January 25, 2010
Publication Date: January 25, 2010
Citation: Mitchell, R., Vogel, K.P. 2010. Developing Switchgrass for Biofuels. Proceedings of Southern Weed Science Society. Abstract presented at 63rd Annual Meeting of the Southern Weed Science Society, Little Rock, AR, January 25-27, 2010. Technical Abstract: Switchgrass (Panicum virgatum L.) is a native warm-season grass that is a leading biomass crop in the US, but is not a new or novel crop. The USDA location in Lincoln, NE has conducted switchgrass research continuously since 1936. Plot-scale research has been conducted on switchgrass establishment, fertility requirements, and response to harvest date in numerous environments in the Great Plains and Midwest. Currently available plant materials and production practices can reliably-produce 5 tons per acre in the central Great Plains and Midwest, and 10 tons per acre in much of the Southeast. Weed control is essential during establishment, but with good management is typically not required again. Although stands can be maintained indefinitely, stands are expected to last at least 10 years, after which time the stand will be renovated and new, higher-yielding material will be seeded on the site. Fertility requirements are well understood in most regions, with about 12 to 14 pounds of N per acre required for each ton of expected yield if the crop is allowed to completely senesce before the annual harvest. Switchgrass production parameters such as economics, net energy, carbon sequestration, temporal and spatial biomass variation, and harvest and storage management have been evaluated at the field-scale on marginal land in the central and Northern Great Plains. Studies conducted on 10 farms over 5-years concluded that switchgrass biomass could be produced for an average farm gate cost of $60 per US ton. Switchgrass on these 10 farms produced 13 times more energy as ethanol than would be required as energy from petroleum and produced 5.4 times more renewable than non-renewable energy consumed when properly managed. After five production years, soil organic carbon was sequestered at a rate of 2,590 pounds of C acre-1 yr-1 in the top 48 inches of soil. The information from these studies on economic feasibility, net energy, C-sequestration, sustainability, and best agronomic production practices forms the basis on which large scale switchgrass production for bioenergy can be based. Nearly 75-years of research and field experience with switchgrass as a hay and forage crop suggests switchgrass will be productive and sustainable on rain-fed marginal land east of the 100th Meridian. Long-term plot trials and farm-scale studies in the Great Plains and plot trials in the Great Plains, Midwest, South, and Southeast indicate switchgrass is productive, protective of the environment, and profitable for the farmer. New cultivars and management practices will significantly increase yields similar to the corn yield increases achieved in the last 30 years. The availability of adequate acres of agricultural land and the profit potential provided to farmers for growing switchgrass in a region will determine the success of growing switchgrass for biomass energy. Production practices and plant materials are available to achieve sustainable and profitable biomass production, for both farmers and bio-refineries, to help meet the energy requirements of the nation and reduce our dependence on foreign oil.