Abstract: By using continuous-automatic measurement system,the emission fluxes of different greenhouse gases from winter wheat fields in the North China Plain under typical climate conditions were continuously measured by the static chamber method.The process of emission flux changes of different greenhouse gases and closing time in the static chamber were analyzed.The results showed that the closing time in the static chamber should be within 25 minutes by measuring CO_2 emission,15~30 minutes by measuring N_2O emission and less than 30 minutes by measuring CH_4 emission respectively.These results have a significant reference to measurement of greenhouse gases emitted from cropland by using the static chamber method.

Key words: Static chamber method, Static chamber method, Greenhouse gas emission flux, Time of measurement, Dry cropland