Submitted to: Soil and Tillage Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/4/2007
Publication Date: 9/20/2007
Citation: Omonode, R., Vyn, T., Smith, D.R., Hegymegi, P., Gal, A. 2007. Soil carbon dioxide and methane fluxes from long-term tillage systems in continuous corn and corn-soybean rotations. Soil and Tillage Research. 95:182-195. Interpretive Summary: Greenhouse gas emissions have been implicated in global climate change. While greenhouse gas emissions from industrial sources have been well documented, emissions from agriculture have yet to be completely characterized. This study was conducted to determine the effects of tillage operations on short-term greenhouse gas emission, and also to compare crop rotations and soil management on greenhouse gas emissions during the growing season. Gas emissions were calculated using flux measurements in continuous corn and corn/soybean plots that were established in 1975. The plots were cropped using no-till, chisel plow or moldboard plow management. Chisel plow resulted in greater short-term emissions of carbon dioxide than moldboard plow of no-till. During the growing season, carbon dioxide emissions were typically similar for the three tillage treatments, however, emission in 2004 and 2005 were greater from continuous corn than corn that was in rotation with soybeans. Methane emissions were minimal, and methane uptake by soils was even observed during both short-term and long-term studies. The impact of this work is to increase the body of knowledge regarding the emissions of greenhouse gases from agricultural lands in the Midwestern U.S.
Technical Abstract: Although the Midwestern United States is one of the world's major agricultural production regions, few research data are available to assess the possibly interacting effects of tillage and rotation practices on greenhouse gas emissions. This study was conducted in 2004 and 2005 on tillage and rotation experiments initiated 30 yrs ago in West-Central Indiana. Our objectives were to assess short-term chisel (CP) and moldboard plow (MP) effects on soil CO2 and CH4 fluxes relative to no-till (NT) and, determine how tillage and rotation interactions affect long-term gas emissions in continuous corn and corn-soybean rotations. Short-term gas emission was measured immediately before and hourly after tillage for 168 hrs. For long-term effects, fluxes were measured weekly for up to 14 weeks in the growing season. CO2 and CH4 emissions were significantly affected by tillage in the short-term and by rotation in the growing season, but tillage x interaction had significant effects only on CH4 fluxes. In the short-term, CO2 emission was lowest for NT relative to CP and MP but was significantly higher for CP than MP. On average, CO2 emission was 3479, 3356, and 3093 mg m-2 hr-1, respectively, for CP, MP and NT. Tillage resulted in low but net CH4 uptake for CP and MP and net emission under NT. Emission under continuous corn was significantly higher than rotation corn in all the period of measurements. Long-term chisel plowing may contribute more to the greenhouse gas effects than either moldboard or no-till and continuous corn emits more greenhouse gases from the soil surface than corn-soybean rotation systems.