ESTIMATE GREENHOUSE GAS EMISSION FROM RICE FIELD IN CAI BE DISTRICT, TIEN GIANG PROVINCE WITH DNDC

Abstract

In Vietnam, rice cultivation plays an important role in the national greenhouse gas emission. Re-cently, using models to simulate and estimate emission from rice paddies has been received atten-tion from scientists due to the low labor-demand and fewer difficulties comparing to field meas-urements. DeNitrification & DeComposition (DNDC) model is commonly used to model green-house gas emissions from rice fields and several countries have developed their own DNDC models. However, the DNDC model version, which can simulate the emission from paddy field specified for Vietnam is not yet available. This study focuses on using the DNDC model to estimate greenhouse gas emissions from irrigated rice cultivation in Mekong Delta, Vietnam. The site study of this research is Hậu Mỹ Bắc B commune (HMBB), Tien Giang province - a typical rice production area with 3 crops per year in Mekong Delta. To conduct this study, the information on local  climate and farming practices in the site study in one year from 05/03/2017 to 04/03/2018 were collected as model input data. The DNDC model was adjusted according to the conditions found in the local rice paddies. This model was used to simulate and estimate green-house gas emissions from rice cultivation in 1 year. This study also analyzed the sensitivity of the model to the variations of different factors including climate data, soil textures, and farming methods. The simulated results show that the 1 year CH4 and N2O emission from the rice field in HMBB was 8311 kg CO2eq/ha and 8208 CO2 eq/ha respectively. Sensitivity analysis indicated that CH4 emissions were significantly influenced by temperature and flooding time while N2O emission was influenced by soil characteristics including soil pH, soil organic carbon and soil texture. Daily precipitation and the total amount of mineral fertilizer used per year have negligible effects on green-house gas emissions from the rice field. Further research is needed to develop the Vietnam-DNDC model..