Long Term Crop Rotation and Tillage Effects On Greenhouse Gas Emissions From Corn, Soybean and Wheat Systems in Illinois, USA.

Management practices within conventional row crop agriculture vary greatly, generating a wide range of effects on soils, crops and, consequently, greenhouse gas (GHG) emissions. Two common agricultural practices aimed at improving soil properties are long term crop rotations and no-tillage systems. The objective of this study was to determine the influence of tillage and crop rotation on GHG emissions on typical Mollisols in Monmouth, IL, USA. The tillage and rotation study plots were established 15 years ago; however, this was the initial year studying GHG emissions from the plots. The experimental design was a split-plot arrangement of rotation and tillage in an RCBD with four replications. The main plot was crop rotation: continuous corn (CCC), corn-soybean (CS), continuous soybean (SSS), and corn-soybean-wheat (CSW); with each phase of each crop rotation present every year. The subplot was tillage: conventional tillage (CT) and no-tillage (NT). We measured GHG emissions – nitrous oxide (N₂O), carbon dioxide (CO₂) and methane (CH₄) – throughout 2012 and into 2013 from the varying crop rotation and treatment combinations. Preliminary results indicate that CCC in the CT plots had the largest mean N₂O emissions throughout the year, while both CT and NT wheat phase of the CSW rotation had the smallest mean N₂O emissions. Likewise, preliminary results indicate that CCC in the CT plots had the largest mean CH₄ emissions throughout the year. Initial results indicate the CT soybean phase of the CS rotation had the largest mean CO₂ emissions, while the NT wheat phase of the CSW had the lowest mean CO₂ emissions.