短期放牧强度对典型草原土壤有机碳及pH值的影响

Effects of Short-term Grazing Intensities on Soil Organic Carbon and pH Value in the Typical Steppe

选择克氏针茅典型草原放牧的西门塔尔牛为研究对象，分析研究短期不同放牧强度（零放牧、轻牧、中牧、重牧）对草地土壤有机碳及pH值的影响，以探索典型草原适宜的载畜率。结果表明：①0～20 cm土层，有机碳含量随着放牧强度的增大而降低，且在重度放牧条件下呈显著差异；而20～30 cm土层，有机碳含量大小顺序为重牧＞中牧＞零放牧＞轻牧，且重牧与轻牧呈显著差异。②土壤pH值随着放牧强度的增大而显著增加。③垂直分布上，土壤有机碳含量随着土层深度的增加而减少，而pH值大小顺序均呈现为10～20 cm＞20～30 cm＞0～10 cm。由此可见，制定适宜的载畜率，维持土壤养分平衡，是遏制草地退化的必要措施。

Taking Simmental cattle grazed in the typical steppe of Stipa krylovii Roshev as the research object, the effects of different short-term grazing intensities （non-grazing, light-grazing, moderate-grazing and heavy-grazing）on the soil organic carbon and pH value in the typical steppe of Inner Mongolia were analyzed and the suitable stocking rate of the typical steppe was discussed, in order to alleviate the grassland soil degradation and enhance the sustained utilization of grassland. The results showed that the content of organic carbon in 0-20 cm soil layer decreased with the increase of grazing intensities and there was significant difference under the heavy-grazing conditions. The organic carbon content in 20-30 cm soil layer was heavy-grazing〉moderate-grazing〉non-grazing〉light-grazing and there was significant difference between the heavy-grazing and light-grazing. The soil pH value significantly increased as the grazing intensities decreased. The organic carbon content in soil decreased as the soil depth increased and the order of pH value was 10-20 cm〉20-30 cm〉0-10 cm in the vertical distribution. Therefore it was essential for preventing the grassland degradation to find out the appropriate grazing intensity and sustain the balance of soil nutrients.