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 for multiple 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 in a cornfield using the DeNitrification-DeComposition (DNDC) model. The model was parameterized with field experimental data collected in Nashville, TN under various management treatments and run for a short term (3 yrs) and a long term (100 yrs). Results showed that the DNDC model could adequately simulate N2O emissions as well as soil and climate conditions under different tillage, alternative use of N fertilizer sources or application methods (i.e. nitrification inhibitor, chicken manure and split applications), given that the model was parameterized based on the measured crop growths for each treatment. The emissions of N2O significantly increased by 29% with tillage, and decreased by 26% with the use of nitrification inhibitor, compared with the no-tillage and normal N fertilization. Chicken manure amendment and split applications of N fertilizer had minor impact on N2O emissions in a short term, but over a long term (100 yrs) they might significantly alter N2O emission (+30%, -12%, respectively). Sensitivity analysis showed that N2O emissions were 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 the best management practice to maintain highly productive corn yield while reducing greenhouse gas emissions.