Table_1_Interaction between dissolved organic carbon and fungal network governs carbon mineralization in paddy soil under co-incorporation of green manure and biochar.DOCX

Legume crops in rice cultivation are typically rotated and incorporated into the soil as green manure to improve soil fertility. Biochar has recently been co-incorporated with green manure to simultaneously stimulate soil organic carbon (SOC) mineralization and increase carbon (C) sequestration. However, few studies examine the effects of the co-incorporation of biochar and green manure on C cycling and the underlying microbial mechanisms in paddy fields. In this study, the effects of the co-incorporation of green manure and biochar on C mineralization, dissolved organic carbon (DOC) characteristics, and microbial community structures were investigated. A pot study was conducted with three treatments: inorganic NPK (NPK), inorganic NPK + green manure (GM), and inorganic NPK + green manure + biochar (GMC). Organic amendments significantly increased cumulative C mineralization, with amounts in the order GMC (3,434 mg·kg−1) > GM (2,934 mg·kg−1) > NPK (2,592 mg·kg−1). Fertilizer treatments had similar effects on DOC concentrations, with amounts in the order GMC (279 mg·kg−1) > GM (255 mg·kg−1) > NPK (193 mg·kg−1). According to fluorescence spectra, the highest microbial humic acid-like fraction and biological index were also in GMC. Co-incorporation of green manure and biochar shifted the composition of bacterial and fungal communities but more importantly, increased fungal network complexity and decreased bacterial network complexity. The increase in fungal network complexity with the increase in DOC concentrations and microbially derived components was the dominant factor in promoting C mineralization. Overall, this study reveals the underlying biochemical mechanism, the interaction between DOC and fungal network of C cycling in paddy soil under the co-incorporation of green manure and biochar management, and provides fundamental knowledge for exploring effective approaches to improve soil fertility and health in the future.

豆科作物在水稻栽培中通常作为绿肥轮作并施入土壤，以提升土壤肥力。近期，生物炭与绿肥的共同施用已被纳入土壤有机碳（SOC）矿化和碳（C）固存增强的范畴。然而，鲜有研究探讨生物炭与绿肥共同施用于稻田中碳循环及微生物机理的影响。本研究旨在探究绿肥与生物炭共同施用对碳矿化、溶解有机碳（DOC）特性和微生物群落结构的影响。采用盆栽实验，设置三种处理：无机氮磷钾（NPK）、无机氮磷钾+绿肥（GM）以及无机氮磷钾+绿肥+生物炭（GMC）。有机改良剂显著提升了累积碳矿化量，其顺序为GMC（3,434 mg·kg−1）> GM（2,934 mg·kg−1）> NPK（2,592 mg·kg−1）。肥料处理对DOC浓度的效应相似，其顺序为GMC（279 mg·kg−1）> GM（255 mg·kg−1）> NPK（193 mg·kg−1）。根据荧光光谱分析，GMC处理中微生物腐殖酸类物质的比例和生物指数最高。绿肥与生物炭的共同施用改变了细菌和真菌群落的组成，更重要的是，提升了真菌网络复杂性并降低了细菌网络复杂性。真菌网络复杂性与DOC浓度及微生物衍生成分的增加共同成为促进碳矿化的主导因素。总体而言，本研究揭示了绿肥与生物炭共同施用管理下稻田土壤碳循环中DOC与真菌网络的相互作用及生化机制，并为未来探索提升土壤肥力和健康的有效途径提供了基础性知识。