【摘要】 利用土壤探头法和密闭气室法相结合 ,就黄土高原旱地土壤玉米生长期灌溉和降水对N2 O气态损失的影响进行了研究 ;并采用乙炔抑制原状土柱培养法 ,对土壤由湿变干和由干变湿过程中N2 O变化进行了模拟。试验结果表明 ,在旱地土壤上 ,N2 O的变化一般较小 ,但在降雨或者灌溉后无论是土壤N2 O通量或者土壤剖面中N2 O的浓度均呈现上升趋势 ,且这种变化趋势与同时期降雨量的变化趋势相同。培养结果说明 ,在相同的土壤孔隙水含量 (WFPS)条件下 ,土壤由湿变干过程产生的N2 O通量高于土壤由干变湿过程中的产生量 ;在土壤由干变湿过程中N2 O通量随土壤WFPS含量的增加而上升 ,但在土壤由湿变干过程中土壤N2 O通量在WFPS含量为 70 %时达到最大 ,而后随土壤WFPS含量的减少而下降。施肥处理与对照相比两者的变化趋势相同 ,但不施肥处理的变化幅度较小更多还原

【Abstract】 By using soil bores and closed chamber methods, field experiments were carried out in the semiarid area of dry land to study the effects of irrigation and rainfall on the N 2O loses. Meanwhile intact soil cores C 2H 2 incubation test was performed in the lab to study influences of wet and dry alternated on the N 2O emission so that further to explain the field results. The results showed that N 2O emission in the dry land usually is low but it will increase rapidly after irrigated or rainfall, the trend of N 2O concentration in the soil profiles and N 2O emission flux changes with the time were similar to that temporal rainfall variation pattern. Incubation test showed that when soils have same water filled pore space (WFPS) content, the influence on N 2O emission of soil from wet to dry is bigger than that from dry to wet. For the former, the biggest N 2O emission takes place at 70% soil WFPS instead at soil saturated, and after that N 2O emission will decrease with the soil WFPS decrease and for the latter, soil N 2O emission increases with the soil WFPS content increase. The control plot has the same tread as the fertilized plot but the curve is much more flatter than applied N treatment.更多还原