短期放牧强度对典型草原土壤理化性质的影响

THE EFFECTS OF SHORT TERM GRAZING INTENSITIES ON SOIL PHYSICAL AND CHEMICAL PROPERTIES IN THE INNER MONGLIA TYPICAL STEPPE

以克氏针茅典型草原放牧西门塔尔牛（2岁）为研究对象，分析研究了短期放牧强度（对照、轻度放牧、中度放牧、重度放牧）对草地土壤理化性质的影响，探索典型草原的适宜载畜率，为减少草地退化及其可持续利用提供参考依据。结果表明：（1）土壤表层含水量随着放牧强度的增大而降低，土壤表层容重变化则相反。中度、重度放牧对土壤含水量和土壤容重的影响显著；（2）放牧强度主要影响0—20em土层养分。轻度放牧显著降低全N、速效N含量。重度放牧显著降低速效N和速效K；（3）放牧强度对全P、速效P和全K的影响不显著；（4）垂直分布上，各处理养分基本上随着土层深度的增加而减少。因此，制定适宜的载畜率，是维持土壤养分平衡，遏制草地土壤退化的必要措施。

In order to define the most proper stocking rate which consider the protection and sustained utilization of grassland, it is of great importance to understand the relationship between the grazing intensities and soil. The present study evaluated the effects of the different grazing intensities （non - grazing, light - grazing, moderate - grazing, and heavy - grazing） on the soil characteristics in the Inner Mongolia Stipa krylovii Roshev grassland. The results showed that： （1）Soil water content decreased as grazing intensities in- creased, while opposite tendency was found for soil bulk density ; Moderate - grazing and heavy - grazing had significantly effect on the soil water content and soil hulk density （2）The grazing intensities effect on the soil of 0 -20cm depth. Light -grazing treatment sig- nificantly reduced the total N and available N. Heavy -grazing significantly reduce the available N and K. （3）Grazing intensities had no significant effect on the total P, total K and available P. （4）Almost all the chemicals properties of each treatment decreased as the soil depth increased ; So it is necessary measure to protect the soil of grassland that determine the appropriate intensity to sustain the balance of soil nutrients;