Greenhouse gas emission under the treatments of fertilization and wheat straw returning during the maize growing seasons

The exchange fluxes of greenhouse gases from a winter wheat-summer maize crop rotation farmland during maize growing seasons in the North China Plain were investigated by static chamber method in this study.N2O fluxes were measured from normal fertilization and wheat straw returning treatments during three consecutive maize growing seasons,and the fluxes of CO2 and CH4 were investigated during one maize growing season.The cumulative N2O emission during the fertilization period accounted for 83%—96% of the total emission from the normal fertilization and wheat straw returning plots during the three maize growing seasons,indicating that the current fertilization management greatly promoted N2O emission.Compared with the control plot,fertilizer application and cultivation evidently simulated CO2 emission,especially during the period from seeding stage to silking stage.The cumulative CH4 emission from the control,normal fertilization and wheat straw returning plots were all negative values,indicating that the investigated soil was a sink of CH4.Returning straw back to the field could increase N2O and CO2 emission,and suppressed CH4 oxidation.The net global warming potentials of the normal fertilization and wheat straw returning plots were-1392.8 and-179.2 kg C · hm-2,respectively.Therefore,the prevailing cultivation practice in the North China Plain might act as an important sink for the greenhouse gases.