黄河源区不同退化程度高寒草地土壤特征研究

研究了不同退化梯度的高寒草地不同层次（0～10cm，10-20cm和20-30cm）土壤理化性状变化特征。结果表明：随草地退化程度的加重，土壤含水量下降，土壤容重和pH值增加；土壤有机碳含量亦随退化程度加剧而降低，以0-10cm土层的降低最明显，轻度，中度和重度退化的“黑土滩”草地该土层有机碳含量与未退化草地相比，分别下降36．1％，66．79／6和73．5％；草地0-10cm土壤全氮、全磷含量大小顺序为轻度退化〉未退化〉中度退化〉“黑土滩”退化草地，全钾变化趋势不明显。轻度、中度、“黑土滩”退化草地0～10cm土层速效氮分别比未退化草地降低了21％，54％和64％，10-20cm土层中度退化草地和“黑土滩”分别降低了37％和21％；随草地退化程度加大，速效钾含量在各土层的变化趋势不同，但不同土层的最大速效钾含量均出现在轻度退化草地。

Characteristics of soil in different degraded pasture in the headwaters of the yellow Rivers

Physicochemical characteristics of soil in different degradation grassland were analyzed based on three soil layers(0～10 cm,10～20 cm,20～30 cm) in this study.The results showed that water content decreased,soil bulk density and soil pH increased gradually with the expansion of degradation degree.Content of SOC(0～10 cm) was highest in undegraded pasture,while 36.1%,66.7% and 73.5% decreased in light,moderately and heavy degraded pasture compared with undegraded pasture respectively.The tendency of total N and total P contents in different pastures as follows:light degraded pasture>un～degraded pasture>moderately degraded pasture>heavy degraded pasture at 0～10 cm,while total K content showed no significant difference.Available N content under light,moderately and heavy degraded pasture decreased 21%,54% and 64% at 0～10 cm;The highest available K content was obtained under light degraded pasture at three different depths although it varied with degradation of pasture.