Simulating agronomic management effects on greenhouse gas emissions in a subsurface drainage field in Southern Quebec using RZWQM2

Abstract. Greenhouse gas (GHG) emissions from agricultural soils are affected by many agronomic activities, such as tillage, fertilization, drainage, irrigation, crop rotation, cover crops, etc. The objective of this paper is to investigate the impact of nitrogen and water table management practices on N₂O and CO₂ emissions, subsequently to propose a few mitigation and adaptation suggestions based on the simulated results. In this study, the RZWQM2 was calibrated and validated for estimating the N₂O and CO₂ release from a subsurface drained field in Southern Quebec using measured data from 2012 to 2015. Then different agronomic management practices were applied in the model to study their impact on the GHG emissions. The preliminary results suggested that RZWQM2 simulated N₂O emission responds linearly to N fertilization application rate, while CO₂ release increases to the maximum at 150 kg/ha N application and reached to the minimum at 175 kg/ha N fertilization. The CO₂ emission has been reduced by 4.8% while N₂O emission has been enhanced by 3.9% on average under controlled drainage (CD) than free drainage (FD) due to higher soil water and lower O₂ in soil. Future study will be conducted for long-term simulation of tillage practice, water table management and N application effects on GHG emissions, and the mitigation of GHG emissions through agronomic practices.