A Review of the Main Process-Based Approaches for Modeling N2O Emissions from Agricultural Soils

Modeling approaches have emerged to address uncertainties arising from N2O emissionsvariability, representing a powerful methodology to investigate the two emitting processes (i.e., nitrification and denitrification) and to represent the interconnected dynamics among soil, atmosphere,and crops. This work offers an extensive overview of the widely used models simulating N2O underdifferent cropping systems and management practices. We selected process-based models, prioritizing those with well-documented algorithms found in recently published scientific articles or havingpublished source codes. We reviewed and compared the algorithms employed to simulate N2Oemissions, adopting a unified symbol system. The selected models (APSIM, ARMOSA, CERES-EGC,CROPSYST, CoupModel, DAYCENT, DNDC, DSSAT, EPIC, SPACSYS, and STICS) were categorizedby the approaches used to model nitrification and denitrification processes, discriminating betweenimplicit or explicit consideration of the microbial pool and according to the formalization of the mainenvironmental drivers of these processes (soil nitrogen concentration, temperature, moisture, andacidity). Models' setting and performance assessments were also discussed. From the appraisal ofthese approaches, it emerged that soil chemical-physical properties and weather conditions are themain drivers of N cycling and the consequent gaseous emissions.