Divergent carbon sequestration pathways in saline-alkali soils: Dual mechanisms of macroaggregate protection and chemoautotrophic compensation mediated by composted fermented straw amendments

Climate Smart Agriculture Pub Date : 2025-07-02 DOI:10.1016/j.csag.2025.100067

Tingliang Pan, Wenli Hao, Yunting Wang, Zhaoqi Qu, Yanhong Lou, Haojie Feng, Hui Wang, Quangang Yang, Yajie Sun, Zhongchen Yang, Hongjie Di, Hong Pan, Yuping Zhuge

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Abstract

Soil carbon sequestration mechanisms in saline-alkali ecosystems remain poorly understood, limiting precision management of organic amendments. We investigated composted fermented straw return (CFSR) versus conventional straw incorporation across salinity gradients (1.76 ‰ vs. 4.06 ‰) via controlled pot experiments. In lightly saline-alkali soils, CFSR elevated carbon accrual by 0.311 t ha⁻¹ yr⁻¹ (p < 0.05) via macroaggregate formation (+4.19 % mass proportion) and Acidobacteriota enrichment. Conversely, heavily saline-alkali soils exhibited CFSR-induced microaggregate stabilization (+29.32 % stability index) coupled with chemoautotrophic carbon fixation, supported by 48.38 % higher cbbL gene abundance. Microbial network analysis revealed salinity-dependent adaptations that lightly saline soils under CFSR developed Acidobacteriota-dominated networks with elevated connectivity (graph density: 0.269 vs. 0.202 control), while extreme salinity fostered resilient Actinobacteriota-centric consortia (622 edges vs. 562 control) through modular simplification. Structural equation modeling delineated dual pathways that dissolved organic carbon-mediated macroaggregate stabilization dominated in light salinity (λ = 1.902, p < 0.05), whereas chemoautotrophic carbon pump-driven microaggregate protection prevailed under high salinity (λ = 1.856, p < 0.05). These findings established a hierarchical framework linking aggregate architecture to microbial functional guilds, proposing a dual-mode carbon stabilization paradigm — physical protection in light salinity versus microbial-mineral interactions under heavy salinity. This mechanistic insight advanced salinity-adaptive organic amendment strategies to optimize carbon storage in global salt-affected croplands.

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盐碱地不同的碳固存途径：堆肥发酵秸秆改良剂介导的大团聚体保护和化学自养补偿双重机制

盐碱生态系统中的土壤固碳机制仍然知之甚少，限制了有机修正的精确管理。通过对照盆栽试验，研究了不同盐度梯度下（1.76‰vs. 4.06‰）堆肥发酵秸秆还还率与常规秸秆还还率的差异。在轻度盐碱土壤中，CFSR使碳累积增加0.311 t / h - 1 yr - 1 (p <；0.05)，通过形成大团聚体（+ 4.19%质量比例）和酸杆菌群富集。相反，重度盐碱土壤表现出cfsr诱导的微团聚体稳定（稳定性指数+ 29.32%）和化学自养碳固定，cbbL基因丰度高出48.38%。微生物网络分析显示，盐度依赖性适应表明，在CFSR下，轻度盐化土壤形成了以酸杆菌为主的网络，连性提高（图密度：0.269对0.202对照），而极端盐度通过模块化简化培养了具有弹性的以放线菌为中心的联合体（622条边对562条边对照）。结构方程模型描述了溶解有机碳介导的宏观团聚体稳定在轻盐度下占主导地位的双重途径(λ = 1.902, p <；0.05)，而高盐度条件下，化学自养碳泵驱动的微团聚体保护占优势(λ = 1.856, p <；0.05)。这些发现建立了一个层次框架，将聚集体结构与微生物功能协会联系起来，提出了一种双模式碳稳定范例-轻盐度下的物理保护与重盐度下微生物-矿物相互作用。这一机制的洞察力推进了盐度适应性有机修正策略，以优化全球受盐影响的农田的碳储量。

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Climate Smart Agriculture

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