N2O Exchange Fluxes from Wheat-Maize Crop Rotation System in the North China Plain
华北平原玉米-小麦轮作农田N2O交换通量的研究

N2O exchange fluxes from the intensively cultivated winter wheat-summer maize crop rotation system in the North China Plain were measured by the static chamber technique under normal fertilization treatment and normal fertilization combined with straw returning treatment. The results indicated that the cumulative emissions of N2O from normal fertilization treatment and normal fertilization combined with straw returning treatment were 7.61 kg·hm-2 and 12.6 kg·hm-2, respectively. The increased N2O from the straw returning mainly occurred during the maize growing season. The N2O emission during the maize growing season from the two fertilization treatments accounted for 57%-86% of the annual N2O cumulative emission, which indicated that the annual emission of N2O mainly occurred during the maize growing season. Total N2O emission after 10 days of each fertilization accounted for about 71%-88% of the annual emission. It is obvious that the application of existing chemical fertilizers greatly promoted the N2O emissions in the North China Plain.