Liu Jie, Yang Lin, Adams Jonathan Miles, Zhang Lei, Wang Jie, Wei Ren, Zhou Chenghu
School of Geography and Ocean Science, Nanjing University, Nanjing, 210023, China.
School of Geography and Ocean Science, Nanjing University, Nanjing, 210023, China.
J Environ Manage. 2025 Aug;389:126179. doi: 10.1016/j.jenvman.2025.126179. Epub 2025 Jun 20.
Rice paddies serve as important reservoirs of soil organic carbon (SOC) and are hotspots for microbial-mediated carbon conversion. Understanding the regulatory mechanisms of SOC in rice paddies is important for carbon sequestration management under global warming. Most previous studies on the influencing factors of paddy SOC have focused on a single habitat, such as bulk soil (BS) or rhizosphere soil (RS). However, the divergence in SOC regulatory mechanisms between BS and RS, the mediating role of rhizoplane soil (RP) microbial communities on SOC in RS, and the interactive effects of multiple influencing factors on habitat-specific SOC remain poorly quantified, particularly at regional scales. Herein we used piecewise structural equation modeling and random forest model to explore the effects of biotic-abiotic factors on SOC between BS and RS of rice paddies in the Yangtze River Delta. Significant differences in SOC, soil physicochemical, and microbial community properties between BS and RS. Soil physical and chemical properties had the greatest effect on SOC, with a standardized total effect of 0.76 vs. 0.53 for BS, and 0.72 vs. 0.94 for RS, respectively. The direct effect of microbial communities on SOC in RS (standardized direct effect, 0.33) was significant and positive, while it was marginal in BS (standardized direct effect, 0.14). Methane microbial communities in RP on SOC in RS were also markedly important. Notably, soil metallic elements had a significant positive effect on SOC in BS with a standardized path coefficient of 0.30 (P < 0.05), but a negative effect on SOC in RS with a path coefficient of -0.18 (P < 0.05). Soil physical properties had a positive indirect effect on SOC in BS with an indirect effect of 0.39 through its effect on soil chemical properties, metallic elements, and microbial community properties, while a positive indirect effect on SOC in RS with an indirect effect of 0.66 mainly through its effect on soil chemical properties. The indirect effects of climatic factors and agricultural management on SOC between BS and RS were also nonnegligible. Our study reveals the complex interactive influence of various categories of biotic-abiotic factors with different functions on paddy SOC between BS and RS at a regional scale, as well as the contribution of microbial communities in RP to SOC in RS. This study improves our understanding of the regulatory mechanisms for SOC storage and offers valuable guidance for paddy soil carbon sequestration management.
稻田是土壤有机碳（SOC）的重要储存库，也是微生物介导的碳转化热点地区。了解稻田SOC的调控机制对于全球变暖下的碳固存管理至关重要。以往大多数关于稻田SOC影响因素的研究都集中在单一栖息地，如大田土壤（BS）或根际土壤（RS）。然而，BS和RS之间SOC调控机制的差异、根面土壤（RP）微生物群落对RS中SOC的介导作用以及多种影响因素对特定栖息地SOC的交互作用仍缺乏量化，特别是在区域尺度上。在此，我们使用分段结构方程模型和随机森林模型，探讨了长江三角洲稻田BS和RS之间生物-非生物因素对SOC的影响。BS和RS之间的SOC、土壤理化性质和微生物群落特性存在显著差异。土壤理化性质对SOC的影响最大，BS的标准化总效应分别为0.76和0.53，RS的标准化总效应分别为0.72和0.94。微生物群落对RS中SOC的直接效应（标准化直接效应，0.33）显著且为正，而在BS中则不显著（标准化直接效应，0.14）。RP中的甲烷微生物群落对RS中的SOC也非常重要。值得注意的是，土壤金属元素对BS中的SOC有显著正效应，标准化路径系数为0.30（P<0.05），但对RS中的SOC有负效应，路径系数为-0.18（P<0.05）。土壤物理性质对BS中的SOC有正间接效应，通过其对土壤化学性质、金属元素和微生物群落特性的影响，间接效应为0.39，而对RS中的SOC有正间接效应，间接效应为0.66，主要通过其对土壤化学性质的影响。气候因素和农业管理对BS和RS之间SOC的间接效应也不可忽视。我们的研究揭示了不同功能的各类生物-非生物因素在区域尺度上对稻田BS和RS之间SOC的复杂交互影响，以及RP中微生物群落对RS中SOC的贡献。本研究增进了我们对SOC储存调控机制的理解，并为稻田土壤碳固存管理提供了有价值的指导。
