Incorporating Nitrifier‐Denitrification Improves Simulation of Nitrous Oxide and Nitric Oxide Emissions Under Intensive Nitrogen Application

Nitrous oxide (N 2 O) and nitric oxide (NO) are key components of global biogeochemical nitrogen (N) cycle, contributing to global warming and atmospheric degradation. Process‐based models have been developed and applied to quantify N 2 O and NO fluxes from croplands. However, critical processes and controls influencing N 2 O and NO production and consumption are either missing or inadequately represented in existing models, limiting their ability to predict N 2 O and NO fluxes. In this study, we improved a widely used biogeochemical model, DeNitrification‐DeComposition, to simulate N 2 O and NO fluxes by incorporating the nitrifier‐denitrification process into its framework. The improved model can explicitly simulate soil nitrite (NO 2 − ) dynamics and N 2 O and NO emissions from nitrifier‐denitrification. When evaluated against field data from two corn fields, the model successfully captured soil mineral N contents and N 2 O and NO fluxes under different N application treatments. Simulations of soil NO 2 − dynamics and N 2 O and NO fluxes from nitrifier‐denitrification improved the model's overall performance in simulating fluxes of N gases under intensive N applications, primarily by capturing NO 2 − peaks and associated fluxes driven by transient NO 2 − accumulations. We also explored impacts of environmental factors, farming management practices, and kinetic parameters on simulated N 2 O and NO emissions. Results highlighted that N application rates were the most influential factor controlling these fluxes. Ammonium oxidation and nitrite oxidation rates also exerted considerable impacts on the N 2 O and NO emissions, primarily through regulating soil NO 2 − dynamics. This emphasizes the importance of considering soil NO 2 − dynamics in models to accurately estimate N 2 O and NO fluxes.