Abstract: To further evaluate the effects of cover crops on soil organic carbon fractions and microbial community structure in organic kiwifruit orchards（Actinidia chinensis）， a field experiment was conducted at an orchard from 2020 to 2023 in Baiheng， Yangling， Shaanxi Province， China. White clover （Trifolium repens） was sown as the cover crop， and clean tillage （CT） was served as the control. Soil organic carbon fractions， microbial residue carbon， and microbial community structure were analyzed in the 0-20 cm soil layer under three-year-old inter-row areas of white clover. The results showed that cover crop significantly increased soil microbial biomass carbon， microbial biomass nitrogen， β-1，4-glucosidase， and β-1，4-xylosidase activities （P<0.05）， while significantly decreased dissolved organic carbon content by 25.87% （P<0.01）. The evenness and diversity of soil bacteria significantly reduced （P<0.05）， leading to an increase in negative competitive relationships among bacterial species. There was a significant positive correlation between soil organic carbon， microbial residue carbon， and aggregate stability （P<0.05）. In conclusion， the use of white clover as a cover crop in organic kiwifruit orchards in the Guanzhong region not only enhanced the content of surface soil organic carbon fractions and carbon-cycling enzyme activities， but also promoteds soil carbon cycling and the stability of organic matter by optimizing the ecological structure and functional capacity of the soil microbial community.

Key words: Soil organic carbon, Microbial necromass carbon, Soil microbial community, Cover crops in orchard

摘要： 为进一步探究生草覆盖对有机猕猴桃（Actinidia chinensis）园土壤有机碳组分和微生物群落结构的影响，本研究于2020—2023年在陕西百恒有机猕猴桃园开展了连续三年的定位试验，以白三叶（Trifolium repens）生草覆盖为试验处理，以传统清耕为对照，对行间三年生白三叶耕层0~20 cm土壤的有机碳组分、微生物残体碳和微生物群落结构进行测定分析。结果表明，生草覆盖后土壤微生物碳、微生物氮、β-1，4-葡萄糖苷酶和β-1，4-木糖苷酶活性显著提高（P<0.05），水溶性有机碳极显著降低25.87%（P<0.01）；土壤细菌的均匀度和多样性显著降低（P<0.05），提高了细菌物种负向竞争关系；土壤有机碳、微生物残体碳和团聚体稳定性之间存在显著正相关（P<0.05）。综上认为，关中地区有机猕猴桃园采用白三叶作为生草覆盖不仅有助于提高表层土壤有机碳组分的含量和碳循环酶活性，而且可以通过优化土壤微生物生态结构及功能，进而促进土壤碳循环和有机质的稳定性。

关键词: 土壤有机碳, 微生物残体碳, 土壤微生物群落, 果园生草