【摘要】 以华北地区冬小麦-夏玉米轮作农田为研究对象,在玉米整个生长季,运用静态箱法针对正常施肥及正常施肥结合秸秆还田处理进行了为期3年N2O排放通量的连续观测,并开展了1季CO2和CH4交换通量的研究.在玉米整个生长过程中施肥阶段N2O的排放量占到了总排放量的83%—96%,表明现有化肥的使用明显导致了农田N2O排放增加.与控制地相比,施肥和耕种可导致玉米田CO2排放明显增加,且正常施肥及秸秆还田样地CO2排放主要集中在苗期至吐丝期.控制地、正常施肥样地及施肥结合秸秆还田样地CH4的累积排放量均为负值,说明旱地土壤是CH4的一个汇.秸秆还田在一定程度上增加了玉米季N2O和CO2的排放量,但对CH4的吸收有所抑制.正常施肥样地和秸秆还田样地全球净增温潜势分别为-1392.8 kg C.hm-2和-179.2 kg C.hm-2,表明华北农田在现有耕作方式下是大气温室气体的一种重要汇.更多还原

【Abstract】 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.更多还原