Effect of Controlled Water Level on CH4 and N2O Emissions fromRice Fields in Indonesia

Several options to reduce methane (CH4) emission from rice fields have been reported including straw management,soil amended with Fe(OH)3 and iron slag, encapsulated calcium carbide, and water management by drainage-flooding. In the present paper, field experiments were conducted to determine whether controlled water level below 3 cm and 6 cm might affectCH4 and nitrous oxide (N2O) emissions compared to local rice farmer practice (water level mostly above 6 cm but basicallyuncontrolled) in Maros area, South Sulawesi, Indonesia. CH4 and N2O fluxes were measured at one-week intervals throughouttwo cropping seasons using a closed chamber method. Grain yield was determined at the end of cultivation. The results showedthat CH4 emission in the 1st cultivation was reduced by 36.5% and 33.8% in the plots with 3 cm and 6 cm water levels, respectively,whereas, in the 2nd cultivation, it was reduced by 63.6% and 44.6%, compared to farmer practice plots. N2O emission from paddyfields was not detected and tended to decrease in both cropping seasons. We concluded that controlled water level lower than thatin farmer practice could significantly reduce CH4 emission without affecting rice grain yield and N2O emission. Key words: CH4 and N2O emissions, Controlled water level, Indonesia, Rice fiel