Field validation of the DNDC model for greenhouse gas emissions in East Asian cropping systems

[ 1] Validations of the DeNitrification- DeComposition ( DNDC) model against field data sets of trace gases ( CH4, N2O, and NO) emitted from cropping systems in Japan, China, and Thailand were conducted. The model- simulated results were in agreement with seasonal N2O emissions from a lowland soil in Japan from 1995 to 2000 and seasonal CH4 emissions from rice fields in China, but failed to simulate N2O and NO emissions from an Andisol in Japan as well as NO emissions from the lowland soil. Seasonal CH4 emissions from rice cropping systems in Thailand were poorly simulated because of site- specific soil conditions and rice variety. For all of the simulated cases, the model satisfactorily simulated annual variations of greenhouse gas emissions from cropping systems and effects of land management. However, discrepancies existed between the modeled and observed seasonal patterns of CH4 and N2O emissions. By incorporating modifications based on the local soil properties and management, DNDC model could become a powerful tool for estimating greenhouse gas emissions from terrestrial ecosystems.