DNDC (Li et al., 1992) is a process-based model simulating soil C and N biogeochemistry: decomposition, nitrification, denitrification, fermentation (CH₄ in paddy), and plant growth. It uses weather, soil, vegetation, and management inputs to predict N₂O, CH₄, CO₂ emissions and crop yields under different scenarios. It is widely used for national GHG inventories, climate-smart agriculture planning, and designing mitigation strategies for agricultural emissions.