Abstract: Methanogens,methanotrophs,nitrifiers and denitrifiers are the important microorganisms in the production and consumption of CH₄ and N₂O in soil. In order to understand the microbial processes related to the two greenhouse gases in paddy soil,the four bacteria groups in phaeozem (Hailun) and burozem (Shenyang) were surveyed during rice growth season by using MPN counting technique. The CH₄ and N₂O emissions were measured with closed chamber method. Two different water management regimes,i.e.,continual irrigation and intermittent irrigation,were used for the two paddy soils. The results of multiple regression analysis showed that there was a significantly positive correlation between CH₄ emission and methanogen population in both phaeozem and burozem under two water management regimes. In the soil of Shenyang,there was a significantly positive correlation between CH₄ emission and methanotroph population. The N₂O emission was significantly correlated to the denitrifier population in both phaeozem and burozem under intermittent irrigation,and in the soil of Shenyang,there was a significantly positive correlation between N₂O emission and nitrifier population under two water managements.

Key words: Methanogens, Methanotrophs, Nitrifiers, Denitrifiers, CH₄, N₂O