Additionally, the difference of CH4 emission in cropping
systems could also be attributable to the higher soil organic
carbon (SOC) in the wheat-rice systems. Studies have
demonstrated that wheat-rice systems experience over 200
days of dry soil per year in wheat season, once irrigation
commences in the rice season, the increasing decomposition
rate of SOC would increase CH4 concentration in the soil
(Huang et al. 2012), thus produced greater C for activating
methanotrophs.