Soil carbon and nitrogen cycle modeling for bioenergy crops
Due to the increase in the demands for bioenergy, considerable areas in the Midwestern United States (US) could be converted into croplands for second generation bioenergy, such as the cultivation of miscanthus and switchgrass. Study on the effect of the expansion of these crops on soil carbon and nitrogen dynamics is integral to understanding their long-term environmental impacts. We developed a coupled hydrological-soil nutrient model under identical field conditions and different harvest litter input scenarios. Our project simulation shows that there are critical harvest litter amounts for miscanthus (15% of above-ground biomass when harvested), and switchgrass (25%) to sequester significant quantities of atmospheric carbon dioxide (CO2) into the soil (up to 9.7 and 7.5 kg C m-2 accumulations in miscanthus and switchgrass, respectively, within the next 100 years), while reducing nitrogen (N) losses (approximately 98 % reduction in soil inorganic nitrogen), unlike corn-corn-soybean rotation. This finding resulted from an increase in the carbon/nitrogen (C:N) ratio of topsoil, deactivating soil microbes.
soil carbon, soil nitrogen, miscanthus, switchgrass, bioenergy crop
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign