Location: Agroecosystem Management Research
Title: Greenhouse gas fluxes in response to corn stover harvest Authors
Submitted to: Sungrant Initiative
Publication Type: Proceedings
Publication Acceptance Date: October 2, 2012
Publication Date: November 19, 2012
Citation: Jin, V.L., Baker, J.M., Johnson, J.M., Karlen, D.L., Lehman, R.M., Osborne, S.L., Sauer, T.J., Stott, D.E., Varvel, G.E., Venterea, R.T. 2012. Greenhouse gas fluxes in response to corn stover harvest. In: Proceedings of the Sun Grant National Conference. Science for Biomass Feedstock Production and Utilization, October 2-5, 2012, New Orleans, Louisiana. Available: http://sungrant.tennessee.edu//NatConference/ConferenceProceedings/. Interpretive Summary: Corn stover is an important livestock feed and will probably be a major source of renewable bioenergy, especially in the U.S. Corn Belt. Overly aggressive removal of stover, however, could lead to greater soil erosion and hurt producer yields in the long-run. Good residue management practices could help prevent erosion of valuable topsoil while still providing a revenue source for producers, either as livestock feed or for use in renewable bioenergy. Good residue management could also help control the loss of greenhouse gases from agricultural soils that could add to already increasing levels of atmospheric greenhouse gases contributing to global climate change. To date, there is no regional study on how residue management affects gas emissions from agricultural soils. This study presents preliminary results from nine sites across the U.S. Corn Belt. We found that maximum rates of residue removal decreased soil gas emissions compared to when no residue was removed. The decision of how much residue to remove, however, will depend on local conditions and other agronomic management practices (ex. irrigation, tillage).
Technical Abstract: Agricultural soils play a critical role in the mitigation of increasing levels of atmospheric greenhouse gases (GHGs) such as carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). Identifying management strategies (fertilization, tillage, irrigation) that optimize corn stover removal rates for livestock feed and for cellulosic bioenergy is key to enhancing the long-term sustainability of yield and biomass, increasing soil carbon storage, minimizing erosion, and reducing agricultural GHG emissions. In-field measurements of management effects on GHG emissions provide critical data for quantifying the net energy efficiency and economic feasibility of bioenergy production systems. This assessment reviews GHG fluxes in corn stover removal systems under different management regimes for nine corn stover team sites in the SunGrant Regional Partnership and the USDA-ARS’s Renewable Energy Assessment Project (REAP). Cumulative GHG emissions varied widely across locations, by management, and from year-to-year. Despite this high variability, maximum stover removal averaged across all sites, years, and management resulted in lower total emissions of CO2 (-12 ± 11%) and N2O (-13 ± 28%) compared to no stover removal. Decreases in total CO2 and N2O emissions in stover removal treatments were attributed to decreased availability of stover-derived C and N inputs into soils, as well as possible microclimatic differences. Soils at all sites were CH4 neutral or small CH4 sinks. Exceptions to these trends occurred for all GHGs, highlighting the importance of site-specific management and environmental conditions on GHG fluxes in agricultural soils.