Cadmium (Cd) contamination in soil has posed a great threat to crop safety and yield as well as soil quality. Biochar blended with nitrogen fertilizer have been reported to be effective in remediating Cd-contaminated soil. However, the influence of co-application of biochar and nitrogen fertilizer on the Cd bioavailability, rice yield and soil microbiome remains unclear. In this study, eight different treatments including control (CK), 5% biochar (B), 2.6, 3.5, 4.4 g/pot nitrogen fertilizers (N1, N2 and N3), and co-application of biochar and nitrogen fertilizers (BN1, BN2, BN3) were performed in a pot experiment with paddy soil for observations in an entire rice cycle growth period. Results showed single N increased soil available Cd content and Cd uptake in edible part of rice, while the soil available Cd content significantly decreased by 14.8% and 7.4%–11.1% under the B, BN treatments, and the Cd content in edible part of rice was significantly reduced by 35.1% and 18.5%–26.5%, respectively. Besides, B, N and BN treatments significantly increased the yield of rice by 14.3%–86.6% compared with CK, and the highest yield was gained under BN3 treatment. Soil bacterial diversity indices (Shannon, Chao1, observed species and PD whole tree index) under N2, N3 were generally improved. Cluster analysis indicated that bacterial community structures under BN treatments differed from those of CK and single N treatments. BN treatments enhanced the abundances of key bacterial phylum such as Acidobacteria, positively associated with yield, and increased the abundance of Spirochaetes, negatively correlated to soil available Cd and Cd uptake of rice. Furthermore, the regression path analysis (RPA) revealed that pH, organic matter (OM), alkaline hydrolysis of nitrogen (AHN) and available Cd were the major properties influencing Cd content in edible part of rice. Redundancy analysis (RDA) revealed that pH and available Cd played key role in shaping soil bacterial community. Thus, BN is a feasible practice for the improvements of rice growth and remediation of Cd-polluted soil.

土壤中的镉（Cd）污染对作物安全和产量以及土壤质量构成了巨大威胁。据报道，生物炭与氮肥混合可有效修复受镉污染的土壤。然而，生物炭和氮肥共同施用对镉生物有效性、水稻产量和土壤微生物组的影响仍不清楚。本研究采用 8 种不同处理方法，包括对照（CK）、5% 生物炭（B）、2.6、3.5、4.4 g/盆氮肥（N1、N2 和 N3），以及生物炭和氮肥共施（BN1、 BN2, BN3) 是在水稻土盆栽试验中进行的，用于观察整个水稻周期生长期。结果表明，单施氮增加了水稻可食部分土壤速效Cd含量和Cd吸收量，而土壤速效Cd含量显着降低了14。B、BN处理分别降低了8%和7.4%~11.1%，水稻可食部分Cd含量分别显着降低了35.1%和18.5%~26.5%。此外，B、N和BN处理较CK显着提高水稻产量14.3%~86.6%，其中BN3处理的产量最高。N2、N3下土壤细菌多样性指数（Shannon、Chao1、观察种和PD整树指数）普遍提高。聚类分析表明BN处理下的细菌群落结构与CK和单N处理不同。BN处理提高了关键细菌门的丰度，例如 与CK相比，N和BN处理均显着提高水稻产量14.3%~86.6%，其中BN3处理的产量最高。N2、N3下土壤细菌多样性指数（Shannon、Chao1、观察种和PD整树指数）普遍提高。聚类分析表明BN处理下的细菌群落结构与CK和单N处理不同。BN处理提高了关键细菌门的丰度，例如 与CK相比，N和BN处理均显着提高水稻产量14.3%~86.6%，其中BN3处理的产量最高。N2、N3下土壤细菌多样性指数（Shannon、Chao1、观察种和PD整树指数）普遍提高。聚类分析表明BN处理下的细菌群落结构与CK和单N处理不同。BN处理提高了关键细菌门的丰度，例如酸杆菌，与产量呈正相关，螺旋体丰度增加，与土壤有效镉和水稻对镉的吸收呈负相关。此外，回归路径分析（RPA）表明，pH、有机质（OM）、碱解氮（AHN）和速效镉是影响水稻可食部分镉含量的主要因素。冗余分析 (RDA) 表明 pH 值和有效 Cd 在塑造土壤细菌群落中起关键作用。因此，BN 是改善水稻生长和修复 Cd 污染土壤的可行做法。