短花针茅荒漠草原土壤氮对不同放牧方式的响应

为揭示荒漠草原土壤氮素对不同放牧方式的响应，以短花针茅荒漠草原为研究对象，采用自由放牧(CG)、禁牧(BG)、休牧40天(DG1)、休牧50天(DG2)和休牧60天(DG3)试验处理，于2008年8月对各处理区内土壤全氮和速效氮含量进行同一土层间的分布差异和处理区内的垂直分布变化进行研究。结果显示：CG区土壤全氮含量最低，其各层含量均值为0.76 g/kg；速效氮含量相对其他处理区在0~10 cm和10~20 cm层含量较高，其含量分别为87.41 mg/kg和131 mg/kg。BG区速效氮含量在20~30 cm和30~40 cm层较低，含量分别为56.82 mg/kg和51.59 mg/kg。在垂直分布上，土壤全氮在0~10 cm和30~40 cm层含量较高，平均含量分别为1.33 g/kg和1.09 g/kg；土壤速效氮含量在10~20 cm层含量较高，各处理区平均为91.86 mg/kg。休牧相对于自由放牧有利于草地土壤氮素的保持与稳定。

Response of Soil Nitrogen to Different Grazing in Stipa breviflora Desert Steppe

In order to identify the response of soil nitrogen to different grazing systems in Stipa breviflora desert steppe, continuous grazing (CG), banning grazing (BG), deferred grazing for 40 days (DG1), deferred grazing for 50 days (DG2), deferred grazing for 60 days (DG3) were chosen as different treatments, and the distribution of soil total nitrogen and available nitrogen content in different treatments and vertical distribution in each treatment were analyzed. The results were as follows: the soil total nitrogen content was lowest in CG treatment, the layers of content mean 0.76 g/kg. While available nitrogen content was higher in 0-10 cm and 10-20 cm soil layer compared with the other treatments, its contents were 87.41 mg/kg and 131 mg/kg. The available nitrogen in BG area was lower in 20-30 cm and 30-40 cm soil layer, the content 56.82 mg/kg and 51.59 mg/kg. As the vertical distribution, the soil total nitrogen was higher in 0-10 cm and 30-40 cm soil layers, average content were 1.33 g/kg and 1.09 g/kg. The available nitrogen was higher in 10-20 cm layer, each treatment area average 91.86 mg/kg. Deferred grazing was more prone to keep grassland soil nitrogen stable compared to continuous grazing.