Soil chemical properties affecting GHG emission from paddy rice field due to water regime and organic matter amendment

Paddy rice field is the main contributor of greenhouse gas (GHG) (CH4 and N2O) emissions in Indonesia. The actions to mitigate these emissions and maintain yield have being a serious concern. This study aims to investigate the emission of CH4 and N2O and determine the limiting factors of CH4 and N2O emission due to water regime and organic matter (OM) amendment in inceptisol soil. Treatments consist of two factors, the first factor was water regime, e.g., 1) continuously flooded, and 2) Alternate wetting-drying (AWD). The second factor was organic matter amendment, e.g., 1) with OM 3 t ha-1, and 2) without OM. The results showed that the addition of organic matter to the soils alongside managing its water regime with AWD resulted in low daily CH4 emissions compare to continuous flooded. No significant difference (p<0.05) in daily N2O emission between AWD and continuous flooded. The dynamic of C-org, Eh, Fe2O3, MnO2 in the soil due to water regime were affected daily CH4 emissions, while pH, NO3 and NH4 were affected daily N2O emissions. Results of this study can be used for further research and development of a model on CH4 emission from rice fields to determine feasible soil management in GHG mitigation.