Modelling of methane emissions from rice-based production systems in India with the denitrification and decomposition model: Field validation and sensitivity analysis

The DNDC (DeNitrification and DeComposition) model was calibrated and tested against experimental data on CH4 emission from rice fields of Central Rice Research Institute, Cuttack, India. There was good agreement between the simulated and observed values of grain yield, total biomass, N uptake and seasonal CH4 emission. Overall, the model satisfactorily simulated the seasonal variations of CH4 emission from flooded rice paddy. However, some discrepancies existed between observed and simulated seasonal patterns of CH4 emission. Large discrepancies between simulated and observed seasonal fluxes occurred at sites that used manual chamber flux measurements. Sensitivity test results indicate that soil texture and pH significantly influenced CH4 emission. Changes in organic C content had a moderate influence on CH4 emission at this site. Variation in the quantity of aboveground biomass returning to the soil was predicted to have little effect on short-term seasonal simulations. Increasing the length of mid-season aeration reduced CH4 emissions significantly, while addition of sulphate fertilizer reduced CH4 emissions. With continuous modifications and calibration, DNDC can become a powerful tool for estimation of greenhouse gas emissions, forecasting yield trends and studying the impact of climate change and policy formulations.