313-12 Greenhouse Gas Fluxes From Upper Midwest Corn As Mediated by Rotation.

Poster Number 618

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Management Impact On GHG Emissions and Soil C Sequestration: III
Wednesday, October 19, 2011
Henry Gonzalez Convention Center, Hall C
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Michael Lehman and Shannon Osborne, USDA-ARS, Brookings, SD

We used the flux chamber technique to measure greenhouse gas (carbon dioxide, nitrous oxide, methane) fluxes from replicated corn plots located in eastern South Dakota. The corn was grown within a randomized, complete block study that included both a two year (corn-soybean) rotation and a four-year (corn/field peas/winter wheat/soybean) rotation with plots containing the corn phase present in every year, 2006-2009. Annual carbon dioxide fluxes were between 1000 and 1500 kg CO2-C ha for three of the four years. In 2007, which had above-normal temperatures, CO2 fluxes were about 3500 kg/ha. CO2 fluxes generally tracked temperature and precipitation events. Nitrous oxide fluxes were less than <0.5 kg N2O-N/ha in 2006, about 1 kg/ha in 2007 and 0.7 kg/ha in 2008 and 2009. N2O fluxes peaked during spring thaw and following fertilization. Methane fluxes in 2006 were <0.5 kg N2O-N/ha with some plots serving as a small sink. In 2007, methane fluxes were neutral, while in 2008 and 2009 methane fluxes averaged about 0.6 kg CH4-C/ha. Methane fluxes varied with soil moisture. Relatively high variations were observed among chambers within the same plot and among plots within a single treatment. No significant differences in gas fluxes due to treatment (2 yr vs. 4 yr rotation) were observed. These ground-based data bound estimates of gas fluxes from corn grown in high organic matter (ca. 4%) Mollisols under rain-fed conditions in the sub-humid climate (58 cm mean annual precipitation) and mean annual temperature of 8C of the northwestern U.S. corn belt. This research is part of the USDA-ARS GRACEnet program.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Management Impact On GHG Emissions and Soil C Sequestration: III