Abstract: This study aims to assess how organic fertilizer dosage affects soil characteristics in two different slopes (sunny and shady) in restoring patchily degraded alpine meadows. Six commercial organic fertilization gradients of 0 g·m^-2 (CK),150 g·m^-2 (M₁),450 g·m^-2 (M₂),750 g·m^-2 (M₃),1050 g·m^-2 (M₄),1350 g·m^-2 (M₅) were set up in a patchily degraded alpine meadow in Duosong Township,Henan Mongol Autonomous County,Qinghai Province,so as to clarify the optimal organic fertilizer dosage for effective restoration of a patchily degraded alpine meadow and its influencing mechanism on the soil characteristics in the source zone of the Yellow River. We determined the changes in soil nutrients,microbial biomass,enzyme activity and microbial diversity in relation to fertilizer dosage. The results showed that:(1) The degraded alpine meadow soils on the sunny slope were weakly alkaline,and there was no significant change in soil physicochemical properties under different treatments of organic fertilization. The soil pH value of the degraded alpine meadow in the shady sample plots was neutral and the soil organic carbon,soil total nitrogen and soil total phosphorus contents were significantly higher in the M₄ treatment than the CK treatment. Soil microbial biomass carbon,microbial biomass nitrogen and microbial biomass phosphorus did not change significantly with the dosage of organic fertilizer. The activity of β-1,4-glucosidase in the soil of the sunny sample plots reached its maximum value in the M₅ treatment. The grey correlation analysis showed that the optimal application rate of commercial organic fertilizer was 450 g·m^-2 on the sunny slopes,and 1050 g·m^-2 on the shady slopes,which was effective in restoring the physicochemical properties,enzyme activities and microbial diversity of patchy degraded alpine meadow soils.

Key words: Organic fertilizer, Alpine meadows, Soil physicochemical properties, Microbial biomass, Enzyme activity, Microbial diversity, Grey correlation

摘要： 为研究有机肥施用量对黄河源区斑块化退化高寒草甸土壤特征的影响，我们在青海省河南蒙古族自治县多松乡阳坡和阴坡样地的斑块化退化高寒草甸，分别设置0 g·m^-2(CK)，150 g·m^-2(M₁)，450 g·m^-2(M₂)，750 g·m^-2(M₃)，1050 g·m^-2(M₄)，1350 g·m^-2(M₅)6个商品有机肥施用量梯度，测定土壤养分、微生物生物量、酶活性以及微生物多样性的变化特征。结果显示：阳坡退化高寒草甸土壤呈弱碱性，有机肥不同处理下的土壤理化性质无显著变化。阴坡退化高寒草甸土壤pH值呈中性，土壤有机碳、土壤全氮和土壤全磷含量M₄处理较CK处理显著提高。在试验样地中土壤微生物生物量碳、氮、磷含量在有机肥不同施用量下无显著变化。阳坡样地土壤β-1,4-葡萄糖苷酶在M₅处理下达到最大值。通过灰色关联度综合分析得出在阳坡样地最佳商品有机肥施用量为450 g·m^-2，阴坡样地有机肥最佳施用量为1050 g·m^-2，该用量在恢复斑块化退化高寒草甸土壤理化性质、酶活性和微生物多样性方面具有明显的效果。

关键词: 有机肥, 高寒草甸, 土壤理化性质, 土壤微生物生物量, 土壤酶活性, 微生物多样性, 灰色关联度