Biomass Production of Switchgrass and Corn Grown for Biofuel

A long-term field study in large plots (18 x 30 m) was established in eastern Nebraska in 1998 to determine biomass crop responses and soil C sequestration of switchgrass (Panicum virgatum) and no-till corn (Zea mays) grown for biofuel production on marginal cropland. Two switchgrass cultivars (‘Cave-in-Rock' and ‘Trailblazer') and no-till corn were grown at three N-fertility levels, two harvest schedules for switchgrass, and two corn stover removal levels for corn. The study site is near Ithaca, NE on an Aksarben silty clay loam (fine, smectitic, mesic Typic Argiudoll). In the first 5 years, N-fertility increased switchgrass biomass, corn grain yield, stover yield, and total corn biomass. Removing 51% of available corn stover reduced corn grain yield by 6.1, corn stover yield by 4.4 and total biomass by 5.2%. These negative responses indicate removal of corn stover from rainfed, no-till fields may not be sustainable for biomass energy. Potential switchgrass ethanol yield equaled or was greater than total potential ethanol yield from the corn grain and its harvested stover at 120 kg N/ha. Biomass yield response of switchgrass and corn to treatments after 10 years is being summarized. Soil C storage under corn and switchgrass grown for biofuels in these trials is reported by Follett et al. (2008) in this symposium. This study will be maintained for monitoring long-term changes in soil C for bioenergy crops, including a new bioenergy type switchgrass cultivar established using a no-till soybean (Glycine max) conversion process developed by this program. Soil C will be measured before, during and after the no-till conversion process to quantify changes in soil C associated with converting switchgrass to oilseed or grain crops and back to switchgrass grown for bioenergy.