Microbial aerobic oxidation of methane in paddy soil

The microbial aerobic oxidation activity of methane, the population of aerobic methane oxidizers and the factors influencing the activity of methane oxidation were investigated in three types of paddy rice soil in Zhejiang Province, China. Methane oxidation activity was different among Huangsong paddy soil developed from fluvo-aquic soil, Old huangjinni paddy soil developed from quaternary red clay and Qingzini paddy soil developed from coastal saline soil. The Huangsong paddy rice soil showed the highest activity of methane oxidation. Different methane oxidation activity and populations of methane-oxidizing bacteria were found in various Huangsong soil samples that had different plant-cover. Methane oxidation returned to the same level after these soil samples were incubated and induced by extra added methane. The population of methane oxidizing bacteria was at maximum within the peak-tillering, heading and flowering stages, during which the largest population of methanogenic bacteria also appeared. Temperatures from 25 to 35 °C and pH from 6 to 8 were the optimum conditions for aerobic oxidation of methane in paddy rice soil. Soil particle size also affected the activity of methane oxidation.