Study on C0₂ emimion from soil of typical farmland in North China Plain

CO₂ emission fluxes from soil were measured during the growing season of summer maize in Luancheng Agricultural Ecology Experiment Station of the Chinese Academy of Sciences ．The results show that CO₂ emision flux from soil covered with stalk increases by 10％ compared with that of no stalk-eover．The diurnal change of the C0₂ emision flux from soil can be shown with single peak curve．The maximum value appears from 12：00 tO 16：00 and the variation ranges from 109 to 170 ug/m²·s for stalk-covered one and from 97 to 128／ug/m²·S for no stalk-covered one．CO₂ emision flux from soil has a correlativity with soil temperature of 5cm ，but the relationship between CO₂ emision flux from soil and soil moisture is complex．During the prosperously growing stage of summer maize，C0₂ emision flux from soil is bigger than that during other stages,the flux of 2 on August is 1．42 and 1．32 times of 15 on September separately for stalk-covered and no stalk-covered ones ．And the flux amount of daytime is 63．5％ for stalk-covered one and 57．9％ for no stalk-covered one of whole day．