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

抄録

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 affect CH₄ and nitrous oxide (N₂O) emissions compared to local rice farmer practice (water level mostly above 6 cm but basically uncontrolled) in Maros area, South Sulawesi, Indonesia. CH₄ and N₂O fluxes were measured at one-week intervals throughout two cropping seasons using a closed chamber method. Grain yield was determined at the end of cultivation. The results showed that CH₄ emission in the 1^st cultivation was reduced by 36.5% and 33.8% in the plots with 3 cm and 6 cm water levels, respectively, whereas, in the 2^nd cultivation, it was reduced by 63.6% and 44.6%, compared to farmer practice plots. N₂O emission from paddy fields was not detected and tended to decrease in both cropping seasons. We concluded that controlled water level lower than that in farmer practice could significantly reduce CH₄ emission without affecting rice grain yield and N₂O emission.