呼伦湖流域3种利用方式草场水土及氮磷流失特征

Characteristics of soil erosion, nitrogen and phosphorous losses under three grassland use patterns in Hulun Lake watershed

为了研究不同利用方式草场水土和氮磷流失规律及原因,在呼伦湖流域选择传统放牧草场、草库伦草场、不放牧草场3种利用方式草场,用模拟降雨的方法进行了水土及氮磷随径流流失试验。结果表明:在40和75 mm/h 2种雨强下,传统放牧草场水土流失最严重。相同雨强下,总氮流失量:草库伦草场>传统放牧草场>不放牧草场;总磷流失量:传统放牧草场>草库伦草场>不放牧草场。同一种利用方式草场径流中总氮、总磷质量浓度与降雨强度关系不显著。草库伦草场可有效防止水土流失。传统放牧草场和草库伦草场的氮磷排放负荷与累积径流量之间存在线性关系,而不放牧草场的存在指数关系。该研究可为探讨呼伦湖流域草场合理利用、水环境的保护和面源污染的治理提供参考。

In order to analyze the law of soil erosion, nitrogen and phosphorous losses , the experiments of soil erosion, nitrogen and phosphorus losses with runoff production were conducted under three use pattern grassland （traditional use grassland, enclosed grassland, no grazing grassland） of Hulun Lake watershed by artificial rainfall simulator. The results showed that soil erosion in traditional grazing grassland was most serious among the three use pattern grassland with the rain intensity as 40 and 75 mm/h. Under the same rain intensity, loss amount of total nitrogen was highest in enclosed grassland followed by traditional grazing grassland and no grazing grassland, while loss amount of total phosphorous was highest in traditional grazing grassland, followed by enclosed grassland and no grazing grassland. It was also shown that the relationship between the loss amounts of the nitrogen and phosphorous and the rain intensities was not significant under the same use pattern grassland. Building more enclosed grassland could prevent soil erosion effectively. A linear relationship was found between the emission load of nitrogen and phosphorus and accumulated runoff in traditional grazing grassland and enclosed pasture. However, an exponential relationship was found in no grazing pasture. The research could provide reference for the reasonable utilization of grassland in Hulun Lake watershed, the protection of water environment and the control of non-point pollution of Hulun Lake.