近来,国内外应用~(15)N标记肥料研究氮肥利用率和氮素去向的报告很多[1—4]。迄今,国内有关石灰性旱地土壤上应用~(15)N的研究尚不多见。Fenn[5]等认为铵态氮肥在石灰性土壤上利用率低与氨的挥发损失严重有密切关系,并对影响氨挥发损失的各种因子做了很多室内研究。我国北方分布着大面积的石灰性土壤,如黄土高原,黄淮海平原等,是我国重要的粮、棉、油产地,但目前大多数仍是中低产水平。氮肥利用率低, Recently, there have been many reports on the application of ~ (15) N labeled fertilizers to study nitrogen use efficiency and nitrogen source at home and abroad [1-4]. So far, the research on the application of ~ (15) N in calcareous soils in China is still rare. Fenn et al. [5] considered that the low utilization rate of ammonium nitrogen fertilizer in calcareous soil is closely related to the serious loss of ammonia volatilization, and many laboratory studies have been done on various factors affecting ammonia volatilization loss. Large areas of calcareous soil distributed in northern China, such as the Loess Plateau, the Huang-Huai-Hai Plain and so on, are important grain, cotton and oil producing areas in China. However, most of them are still in the middle-low yield level. Nitrogen utilization rate is low,