By using closed chamber methods, field experiments were carried out in the semiarid area of dryland to study the effects
of irrigation and rainfall on the N 2O loss. Meanwhile intact C 2H 2 inhibition soil cores incubation test were performed in the lab to study influences of
wetting and drying cycle on the
N 2O emission so that to further explain the field results. The results show that N 2O emission in the dryland is usually low but it increases rapidly after irrigating the land or rainfall, the trend N 2O flux changes with the time are similar to that of temporal rainfall pattern. N 2O flux for the fertilized plot and nonfertilized plot were 12.14 μg/(h·m 2) and 5.02 μg/(h·m 2) before irrigation, and those were 21.814 μg/(h·m 2) and 8.214 μg/(h·m 2) after irrigation, respectively. Incubation test shows that for the wetting to drying cycle the highest N 2O flux takes place at the soil WFPS 70%. After that N 2O flux would dramatically reduce with the decreasing of the soil WFPS content. For the drying to wetting cycle, soil N 2O emission flux increases with the soil WFPS content increases. However, when soils have same WFPS content, the influence of soil from wetting to drying cycle on N 2O flux is bigger than that from drying to wetting. The control plot has the same tread as the fertilized plot but the curve is much more flatter than applied N treatment.