ARS | Publication request: Greenhouse gas fluxes in response to corn stover harvest

Submitted to: Sungrant Initiative
Publication Type: Abstract Only
Publication Acceptance Date: June 11, 2012
Publication Date: N/A

Technical Abstract: Agricultural soils play a critical role in mitigating the increasing levels of atmospheric greenhouse gases (GHGs) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Identifying optimal management strategies (tillage, irrigation, fertilization) for the removal of corn stover as a bioenergy feedstock is key to the long-term sustainability of grain yields and residue biomass while also minimizing erosion, enhancing soil carbon storage, and reducing agricultural GHG emissions. Further, empirical evaluations of management impacts on agricultural GHG emissions provide fundamental data needed to quantify 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 six corn stover team sites of the SunGrant Regional Partnership. Cumulative growing-season GHG fluxes varied widely among locations, by management treatment, and from year-to-year. Despite this high variability, maximum corn stover removal across all sites and all management practices tended to result in lower total emissions of CO2 (-10 to -35%) and N2O (-13 to -33%) compared to no-stover- removal treatments. Decreases in total CO2 and N2O emissions were attributable to the removal of potentially labile, stover-derived C and N inputs into soils due to stover harvest, as well as possible microclimatic differences. Soils at all sites also tended to be CH4 neutral or slight CH4 sinks, with no differences between residue removal treatments. Exceptions to these general trends occurred for all three GHGs, demonstrating the importance of site-specific management and environmental conditions on GHG fluxes in agricultural soils.