Methane Emissions from Rice Fields in the Chengdu Plain of China
成都平原稻田甲烷排放的实验研究

According to the measured data of four rice seasons between 1996 and 1999, characteristics of seasonal variation and annual variation of methane emission are analyzed for single-season rice in the Chengdu Plain. The results show a great variation in methane emission during the rice growing season, and the peak values appear during tillering period and fruiting period. A great inter-annual change is also observed and ranged from 2.35 mg m 2 h-1 to 33.95 mg m-2 h-1. The averaged value of CH4 emission for the four years is 12 mg m-2 h-1. Compared with 30 mg m-2 h-1 for the 7-year average of Leshan in Sichuan Province, there is an apparent regional difference. Methane emission from rice field is affected by several factors including temperaturc, ferlilization, rice variely, soil oxidation-reduction potential and water depth of rice field and so on. Results show that the average temperature during rice growing season in the Chengdu Plain has a little influence on annual CH4 emission. However, during the early growing season, the lemperature has a relatively significant influence on daily variation of CH4 emission from rice field. Another finding is that the weights of root, stalk and leaf of rice plant body have a signif-icant influence on CH4 emission. An oplimum combinalion of many effeclive factors is proposed in order to develop its potential of reducing CH4 emission.