Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2010
Publication Date: 7/1/2010
Citation: Smith, K.E., Runion, G.B., Prior, S.A., Rogers Jr, H.H., Torbert III, H.A. 2010. Effects of elevated CO2 and agricultural management on flux of greenhouse gases from soil. Soil Science. 175(7):349-356. Interpretive Summary: Three trace gases coming from agricultural land can potentially contribute to global climate change: these are carbon dioxide, nitrous oxide, and methane. Their rates of release are dependent on soil conditions. In our study, rates of release for these gases were measured from two crop systems (conventional tillage and no-till) that had been grown under either elevated or ambient carbon dioxide for 10 years. Gas emission from soil was generally greater under elevated carbon dioxide. Release of these trace gases tended to be lower under no-till conditions. Findings suggested that the increase in global warming potential (calculated from seasonal emissions) due to elevated carbon dioxide and conventional tillage was driven primarily by the release of carbon dioxide from the soil.
Technical Abstract: To evaluate the contribution of agriculture to climate change, flux of greenhouse gases from different cropping systems must be assessed. Measurement of soil efflux of greenhouse gases (CO2, N2O, and CH4) from conservation and conventional tillage systems that have been under the influence of elevated atmospheric CO2 for 10 years was conducted. Fluxes of all greenhouse gases were significantly greater under elevated vs. ambient CO2 regardless of tillage system effect. Carbon dioxide flux was generally greater in the conventional system. Methane fluxes were generally low, with the conservation tillage system being lower than the conventional system. In general, the conservation system acted as a greater sink for CH4 than the conventional system. A large flux of N2O, occurring over three summer sampling dates was observed in the conservation system under elevated atmospheric CO2 conditions. However, for ambient CO2 conditions, the conservation system generally had lower N2O fluxes. The flux of N2O from the conventional system remained low throughout the study period. Global warming potential, calculated from seasonal gas fluxes, was increased by elevated CO2 and by conventional tillage; these increases were driven primarily by soil CO2 flux. [GRACEnet Publication]