中文摘要：

为明确外源硝态氮添加对典型耕作土壤冻结过程N2O排放的影响,应用室内冰柜模拟土壤冻结过程,研究在室温-冻结过程中硝态氮添加（0、80、200和500 mg/kg）对3种典型耕作土壤（黑土、潮土和黄土）N2O排放影响的特征.结果表明：外源硝态氮的添加促进了黑土和潮土的N2O排放,在200 mg/kg硝态氮添加处理下,黑土和潮土的N2O排放通量比CK（对照）分别增加了849%和676%;但在添加高浓度（500 mg/kg）硝态氮时,黑土和潮土的N2O排放通量分别比200 mg/kg处理降低39.3%和21.2%,表现为显著抑制.随冻结过程的进行,黑土和潮土的N2O排放通量均逐渐降低并接近零排放.黄土N2O排放通量在室温-冻结过程中变化范围很小,甚至出现负排放.多因素方差分析结果表明,土壤类型显著影响N2O累计排放量,而土壤pH和C/N是其中重要的影响因子.根据室内培养试验结果,为减排N2O,建议在深秋整地施肥时期尽量避免在潮土和黑土中施用硝态氮肥.黄土的N2O排放似乎对外源硝态氮的添加反应不明显,这有待在大田气候-植物-土壤综合条件下进一步验证.

英文摘要：

Abstract： To understand the influence of nitrate nitrogen （NO3 --N） application on N2O emissions from different soil types during the freezing process, a lab-simulated experiment was conducted to investigate N2O production from black, fluvo-aquie and loess soils receiving different concentrations of NO3^ --N ： control （0） , 80, 200 and 500 mg/kg soil. The application of NO3^ --N significantly increased N2O emissions from the black and fluvo-aquic soils （ P 〈 0. 05 ）. Compared to the control treatment, the application of NO3^ --N with 200 mg/kg soil increased N2O emissions from the black and fluvo-aquie soils by 849% and 676% , respectively. However, N2O emissions from the 500 mg/kg NO3 ^--N treatment soil were reduced by 39.3% and 21.2% compared to 200 mg/kg NO3^ - -N treatment soil in the black and fluvo-aquic soils, respectively. As the freezing proceeded, the N2O fluxes from the black and fluvo-aquic soils gradually approached zero. Although there was no significant N2O flux found from the loess soil, N2O uptake occurred frequently in the soil. Multi- factor variance analysis showed that soil pH and soil C-to-N ratio were the most important factors driving N2O emissions. The results implied that management strategies aiming to mitigate N2O emissions from soil should avoid NO3^ --N fertilizer application in black and fluvo-aquic soils during late autumn fertilization. Further studies to investigate the comprehensive relationship between N2O emissions and variable field conditions involving climate, plants and soil conditions would be useful to expand this research.