Assessing the impacts of tillage and fertilization management on nitrous oxide emissions in a cornfield using the DNDC model

Quantification and prediction of N₂O emissions from croplands under different agricultural management practices are vital for sustainable agriculture and climate change mitigation. We simulated N₂O emissions under tillage and no-tillage,and different nitrogen (N) fertilizer types and application methods (i.e., nitrification inhibitor, chicken manure, and split applications) in a cornfield using the DeNitrification-DeComposition (DNDC) model. The model was parameterized with field experimental data collected in Nashville, Tennessee, under various agricultural management treatments and run for a short term (3 years) and a long term (100 years). Results showed that the DNDC model could adequately simulate N₂O emissions as well as soil properties under different agricultural management practices. The modeled emissions of N₂O significantly increased by 35% with tillage, and decreased by 24% with the use of nitrification inhibitor, compared with no-tillage and normal N fertilization. Chicken manure amendment and split applications of N fertilizer had minor impact on N₂O emission in a short term, but over a long term (100 years) the treatments significantly altered N₂O emission (+35%, -10%, respectively). Sensitivity analysis showed that N₂O emission was sensitive to mean annual precipitation, mean annual temperature, soil organic carbon, and the amount of total N fertilizer application. Our model results provide valuable information for determining agricultural best management practice to maintain highly productive corn yield while reducing greenhouse gas emissions.