Microbial mechanism of in-situ remediation of arsenic (As) in As-contaminated paddy fields by silicon (Si) fertilization has been rarely reported, especially under continuous rice cultivation and Si applications. In this study, two Si fertilizers were applied for three phases in five consecutive rice seasons to investigate the long-lasting impacts on in-situ remediation of As, and the underpinning microbial mechanism of root-associated compartments (bulk soil, rhizosphere and endosphere) was explored using the last double-cropping rice. Repeated application of Si fertilizers as base manure had a long-lasting effect on reducing As concentrations in rice grains. Application of Si fertilizer at an adequate amount resulted in an extended in-situ remediation effect from endosphere to rhizosphere. The microbial diversity and richness in rhizosphere soil and endosphere were significantly impacted by Si fertilization, the effects depending on application doses and prolonged seasons. Si fertilization can immobilize As in the root or rhizosphere, and Fe concentrations and the As- and Fe-transforming microorganisms (i.e. Geobacteraceae) are the determinants of As uptake in rice. We recommend more extensive supplementation of Si fertilizer at a higher rate to decrease grain As concentration for in-situ remediation. This study sheds light on the microbial-mediated mechanism underlying Si fertilization effect on decreased As uptake in paddy fields.

硅（Si）施肥对砷污染稻田中砷（As）原位修复的微生物机制鲜有报道，尤其是在水稻连作和施硅条件下。在这项研究中，在连续五个水稻季节中分三个阶段施用了两种 Si 肥料，以研究对 As原位修复的长期影响，以及根相关区室（散装土壤、根际和内圈）的支撑微生物机制使用最后的双季稻进行了探索。反复施用硅肥作为基肥对降低稻谷中的砷含量具有长期的作用。适量施用硅肥可延长原位从根际到根际的修复作用。施硅显着影响根际土壤和根际土壤中的微生物多样性和丰富度，其影响取决于施肥剂量和延长的季节。施硅可以将砷固定在根或根际，铁浓度和转化砷和铁的微生物（即地杆菌科）是水稻吸收砷的决定因素。我们建议以更高的比例更广泛地补充硅肥，以降低原位修复的谷物砷浓度。本研究揭示了微生物介导的硅施肥降低稻田吸收砷的机制。