Abstract: Using the static chamber technique,in situ fluxes of methane from the soil of farmland in the North China Plain under different fertilization treatments and different crops(summer maize and winter wheat) were measured.Results showed that of the fertilized soil,with crops of summer maize and winter wheat,the mean methane flux was -79.8 and -21.6 μg·(m ²·h) ^-1 respectively,and -43.1 μg·(m ²·h) ^-1 for the year.And of the non fertilized soil with crops of summer maize and winter wheat,it was -110.0 and -88.2 μg·(m ²·h) ^-1 respectively,and -95.2 μg·(m ²·h) ^-1 for the year.All are negative values,which means that the soil is still a sink for methane.Non fertilized soil absorbed more methane than the other,and the soil under summer maize did more than the soil under winter wheat in the same treatment.Methane fluxes showed obvious variation with the season.During the period of May to mid September,the soil absorbed more methane than in the rest of the year.Fertilization could reduce consumption of methane significantly (about 27% to 76%).In the experiment area,higher precipitation stimulated consumption of methane in a certain period.

Key words: The North China Plain, agricultural soil, CH ₄ flux, in situ measurement