Greenhouse gas emissions from Indian rice fields: calibration and upscaling using the DNDC model

The Denitrification and Decomposition ( DNDC) model was evaluated for its ability to simulate methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions from Indian rice fields with various management practices. The model was calibrated and validated for field experiments in New Delhi, India. The observed yield, N uptake and greenhouse gas (GHG) emissions were in good agreement with the values predicted by the model. The model was then applied for estimation of GHG emissions from rice fields in India using a newly compiled soil/climate/land use database. Continuous flooding of rice fields (42.25 million ha) resulted in annual net emissions of 1.07-1.10, 0.04-0.05 and 21.16-60.96 Tg of CH4-C, N2O-N and CO2-C, respectively, with a cumulated global warming potential ( GWP) of 130.93-272.83 Tg CO2 equivalent. Intermittent flooding of rice fields reduced annual net emissions to 0.12-0.13 Tg CH4-C and 16.66-48.80 Tg CO2-C while N2O emission increased to 0.05-0.06 Tg N2O-N. The GWP, however, reduced to 91.73-211.80 Tg CO2 equivalent. The study suggested that the model could be applied for estimating the GHG emissions and the influences of agronomic management, soil and climatic parameters on the GHG emissions from rice fields in India.