玉溪尖山河小流域N的输出特点研究

对澄江尖山河小流域不同土地利用类型径流小区进行监测，并对地表径流中氮素的流失特征进行研究。结果表明：随着降雨量的不断增大，径流中的总氮和氨氮的输出浓度也有上升的趋势；在相同降雨条件下，各地类年平均总氮输出浓度为：农地7．955mg／L、人工林7．4886mg／L、次生林6．9836mg／L、灌草丛4．5188mg／L；氨氮的年平均输出浓度为：农地0．8474mg／L、人工林0．7286mg／L、次生林0．6514mg／L、灌草丛0．4782mg／L。农地的总氮输出浓度和氨氮输出浓度最大，人工林次之，灌草丛和次生林较小。研究结果表明，灌草丛和次生林较高的植物覆盖有效地保持了水分和土壤，从而也减缓了氮素的输出。

The Output Characteristics of Nitrogen in Jianshanhe Watershed of Yuxi

The research is carried out to study the characteristics of the nitrogen loss in the surface runoff through monitoring the runoff under different land uses in Jianshanhe Watershed of Chengjiang. It shows that with increasing rainfall, the concentration of total nitrogen and ammonia nitrogen in the runoff are clearly rising up. Under the same conditions of the precipitation, the annual average concentration of the total nitrogen output for different land uses are as follows ： farmland ： 7.955 mg/1, plantation ： 7. 4886 rag/l, secondary forest land ： 6. 9836 mg/1, shrub and grass land： 4. 5188 mg/1. The annual average concentration of the ammonia nitrogen output is as follows： farm- land： 0. 8474 mg/1, plantation： 0. 7286 mg/1, secondary forest land： 0. 6514 mg/1, shrub and grass land： 0. 4782 mg/1. The concentration of total nitrogen and ammonia nitrogen in the farmland is the most, followed by the planta- tion, and the secondary forest land is even less. The results also show that the water and soil are effectively con- served by the shrubs and the taller plants in the secondary forest, thus these lands produces less nitrogen.