Stimulated methane emission from a rice paddy under elevated atmospheric CO2



Flooded rice cultivation is considered to be one of the major sources of atmospheric methane. It is pointed out that recent increase in the rice production has contributed to the global warming by increasing methane emissions. Elevated CO2 in the atmosphere may have a positive effect on the emission increase through accelerating the rate of carbon turnover in rice-soil system.
We examined the effect of elevated CO2 on methane emission from a rice paddy using six computer-controlled growth chambers. The experiments were conducted for two entire growing seasons of rice in 1998 and 1999. The CO2 concentration was kept at 350 ppm (ambient) in three of the chambers, and at 650 ppm (elevated) in the other three chambers. Methane emission rates in the chambers were determined by an automated monitoring system.
Seasonal methane emission rates in ambient and elevated conditions were 18.4 and 21.8 g/m2 , respectively, in 1998. The rates in 1999 were 5.6 and 13.7 g/m2 , respectively, which were significantly lower than those in 1998, possibly caused by lower application rate of rice straw prior to transplanting rice plants. The results showed that elevated CO2 increased seasonal methane emission significantly (P<0.05). The increase in the emission rates was mainly observed after the middle growth stage. Elevated CO2 also increased aboveground biomass of the rice plant.


Japan International Research Center for Agricultural Sciences Biological Resources Division


Technical A

Term of research

FY2000 (FY1999-2000)

Responsible researcher

YAGI Kazuyuki ( Biological Resources Division )

LI Zhong ( Biological Resources Division )

SAKAI Hidemitsu ( National Institute for Agro-Environmental Sciences )

KOBAYASHI Kazuhiko ( National Institute for Agro-Environmental Sciences )

Japanese PDF

2000_06_A3_ja.pdf682.46 KB

Related Research Highlights