Long Term Crop Rotation and Tillage Effects on Greenhouse Gas Emissions in Illinois, USA.

Conventional row crop agriculture varies greatly due to the numerous different management practices implemented by growers. These management practices create 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, only the past four years were studied for GHG emissions: 2012, 2013, 2014, and 2015. 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) – in 2012, 2013, 2014, and 2015 from the varying crop rotation and treatment combinations. Results from 2012-14 indicate that CCC in the CT plots had the largest mean N₂O emissions (7.06±0.76), while both CT and NT wheat phase of the CSW rotation had the smallest mean N₂O emissions. The CO₂ and CH₄ results were not as evident and varied from year to year.