放牧对阿拉善荒漠草地土壤性状的影响

对阿拉善荒漠草地不同放牧条件下土壤理化性状的变化进行了研究,结果表明:在草地基况一致的条件下,经过连续6a不同强度的放牧,0~ 20cm土层土壤容重轻牧和重牧区低于中牧区。随着放牧强度的增加,土壤颗粒组成极粗砂、粗砂和中砂含量增加,细砂、极细砂、粉砂和粘粒含量减少,过度放牧加快了土壤风蚀沙化。0~20cm土层中土壤有机C、全P的含量和C/N随着放牧强度的增加而依次降低;全N、全K、pH末发生明显变化;速效N和速效K重牧区显著高于轻牧区和中牧区;速效P轻牧区高于中、重牧区。土壤有机C与全P、速效P呈显著正相关;全P与速效N和K呈显著负相关,与速效P呈显著正相关(P<0.05)。

Effects of Grazing on Soil Physical and Chemical Properties of Alxa Desert Grassland

Soil physical and chemical properties of desert grassland with different grazing management systems were studied at Alxa Prefecture, Inner Mongolian Autonomous Region. The results showed that started from the similar grassland conditions soil bulk density of medium grazed paddocks at 0~20 cm depth was higher than those of light and heavy grazed paddocks six years after grazed with different stock rates. As grazing intensity increased the proportions of extremely coarse, coarse and medium size sandy particles were increased, while the contents of fine and extremely fine sandy particles, silt particle and clay particle were decreased. This indicated that overgrazing accelerated the process of soil wind erosion and desertification. The contents of organic matter, total P and C/N at 0 ~ 20 cm depth decreased as the grazing intensity increased. No significantly differences in the contents of total N, total K and pH were detected among the paddocks with different grazing intensity. However, the contents of available N and available K in the soil of heavy grazed paddocks were higher than those in the light and medium grazed paddocks. On the other hand, the contents of available P in the light grazed paddock is the highest, which is followed by the medium and heavy grazed paddocks. Significantly positive correlations were found between soil organic matter and contents of total P, available P, and between contents of total P and available P. Significantly negative correlations were existed between the contents of total P and available N, and available K., respectively.