Abstract: A pot experiment was conducted with cadmium（Cd）‑contaminated cultivated soil as the test substrate to explore the effects of biochar at different application rates on soil microbial community structure and Cd availability. Four treatments were established：no biochar application（control，CK），biochar application at 2 g/kg （B1），4 g/kg （B2），and 8 g/kg（B3）.Soil physicochemical properties，available Cd concentration，soil enzyme activities，microbial biomass，and soil microbial community composition were determined. The results showed that soil pH value under B3 treatment increased by 0.25 compared with CK；the contents of soil organic matter，available phosphorus and available potassium increased by 35.90%，28.67% and 14.29%，respectively，while the concentration of soil available Cd decreased by 6.82%. Microbial biomass carbon under B1 and B2 treatments increased by 9.90% and 15.54% relative to CK，and microbial biomass nitrogen under B1，B2 and B3 treatments increased by 46.08%，21.77% and 62.05%，respectively.Compared with CK，soil catalase activity under B2 and B3 treatments increased by 19. 33% and 20. 72%，while soil acid phosphatase activity decreased by 43.25% and 42.25%. The dominant bacterial phyla in all treatments were Pseudomonadota，Bacillota，Bacteroidota and Acidobacteriota. Treatments B2 and B3 increased the relative abundances of Pseudomonadota and Acidobacteriota and reduced the relative abundance of Cyanobacteriota. The dominant fungal phyla across all treatments were Ascomycota and Unclassified_k_Fungi. Treatment B2 elevated the relative abundance of Ascomycota，and all biochar treatments reduced the relative abundance of Mortierellomycota. Soil catalase activity was positively correlated with the relative abundances of Pseudomonadota and Acidobacteriota，acting as a key factor affecting the bacterial community. Soil urease activity exhibited a significant negative correlation with the relative abundance of Rozellomycota，which was the key factor regulating the fungal community. In conclusion，biochar application could raise soil pH value and the contents of organic matter，available phosphorus and available potassium，enhance the activities of soil catalase，increase MBN，reshape the microbial community structure of Cd‑contaminated soil，improve the relative abundances of bacterial Pseudomonadota，Acidobacteriota and fungal Ascomycota，and reduce soil available Cd concentration；the optimal biochar application rate was 8 g/kg.

Key words: Soil, Biochar, Cadmium?contaminated soil, Microbial community, Soil enzyme activity, Cadmium availability

摘要： 为探究不同用量生物炭对镉（Cd）污染耕地土壤微生物群落结构及Cd有效性的影响，以Cd污染耕地土壤为供试基质开展盆栽试验，设置4个处理［不施生物炭（对照，CK）；施用生物炭2 g/kg（B1）；施用生物炭4 g/kg（B2）；施用生物炭8 g/kg（B3）］，测定土壤理化性质、有效态Cd含量、土壤酶活性、微生物生物量及土壤微生物群落组成。结果表明，B3处理土壤pH值较CK提升0.25，有机质、有效磷、速效钾含量较CK分别提高35.90%、28.67%、14.29%，土壤有效态Cd含量降低6.82%。B1、B2处理微生物生物量碳较CK分别增加9.90%、15.54%，B1、B2、B3处理微生物生物量氮较CK分别增加46.08%、21.77%、62.05%。B2、B3处理土壤过氧化氢酶活性较CK分别增加19.33%、20.72%，土壤酸性磷酸酶活性较CK分别降低43.25%、42.25%。各处理土壤细菌优势菌群均为变形菌门（Pseudomonadota）、厚壁菌门（Bacillota）、拟杆菌门（Bacteroidota）、酸杆菌门（Acidobacteriota）。其中，B2、B3处理均提高了变形菌门和酸杆菌门的相对丰度，降低了蓝细菌门（Cyanobacteriota）的相对丰度。各处理土壤真菌优势菌群为子囊菌门（Ascomycota）、Unclassified_k_Fungi。其中，B2处理提高了子囊菌门的相对丰度，各生物炭处理均降低了被孢霉门（Mortierellomycota）的相对丰度。土壤过氧化氢酶活性与变形菌门、酸杆菌门相对丰度正相关，是影响细菌群落的关键因素，土壤脲酶活性与罗兹菌门（Rozellomycota）相对丰度显著负相关，是影响真菌群落的关键因素。综上，生物炭可提高土壤pH值及有机质、有效磷和速效钾含量，增强土壤过氧化氢酶活性，提高微生物生物量氮，重塑Cd污染土壤微生物结构，提升细菌变形菌门、酸杆菌门和真菌子囊菌门相对丰度，降低土壤有效态Cd含量；施用量以8 g/kg效果最佳。

关键词: 土壤, 生物炭, 镉污染土壤, 微生物群落, 土壤酶活性, 镉有效性