Abstract: The effect of mid season aeration (in 8 days starting at the end of the rice tillage) on methane emission and the relations of soil moisture and oxidation reduction potential ( Eh ) to methane emission of rice fields were investigated in hilly area of Jurong, Jiangsu province in 1997. A peaked methane flux was observed at the beginning of the mid season aeration and the emission decreased rapidly to nil afterwards. The methane increased gradually after the recovering of floodwater layer, but the fluxes did not reach that before the aeration until harvesting. The decrease of methane fluxes was related significantly to the decrease of soil moisture and the increase of soil Eh after the start of the aeration. The fluxe peaks and the total emission during the mid season aeration were not significantly related to the N application rate, but related to the rice straw which was amended when the preceding winter wheat was sown The total methane emission during the mid season aeration accounted for 3.86%-13.92% of those emitted during the whole rice growth period. 

Key words: rice field, aeration, methane emission