Contribution of photosynthesized carbon to the methane emitted from paddy fields

Abstract

Emission rates of CH 4 from paddy soil with and without rice straw applications were measured with pot experiments to estimate the contribution of rice straw to total CH 4 emissions during the growing season. The CH 4 derived from rice straw was calculated to be 50.4% of the total emission. 13 CO 2 uptake experiments were carried out three times from Aug. 8 to Sept. 18 to estimate the contribution of photosynthesized carbon to CH 4 emission. The contribution percentages of photosynthesized carbon to the total CH 4 emitted to the atmosphere were 72–110% around Aug. 8, 29–36% around Aug. 30, and 13–17% around Sept. 18, 1993.