Salinization and alkalization contribute significantly to soil degradation. Rice (Oryza sativa L.) cultivation is an effective approach to remediate saline‐alkali soil. However, how rice straw (RS), rice straw biochar (RSB), and rice straw ash (RSA) impact soil organic carbon (SOC) accumulation and stability in saline‐alkali soil remains unknown. Herein, SOC and SOC fractions contents in bulk soil and its particle‐ and aggregate‐size classes under RS, RSB, and RSA amendments and control with amendments (CK) were investigated by field experiment. Carbon‐13 nuclear magnetic resonance spectroscopy was used to evaluate bulk SOC chemical composition. The SOC and SOC fractions contents ranked as CK<RSA<RS<RSB. Aromatic C was higher whereas O‐alkyl C was lower in RSB relative to other treatments. The contents of SOC and SOC fractions in bulk soil were generally positively correlated with those in particle‐ and aggregate‐size classes as well as with aromatic C. Redundancy analysis showed that exchangeable sodium and electrical conductivity were the most significant factors in shaping SOC contents and chemical composition. The results indicated that RSB is more beneficial for SOC accumulation and stabilization as compared to RS and RSA. The primary mechanisms of SOC accumulation in RSB‐amended soil included physical protection afforded by aggregate classes, chemical protection mediated by silt and clay fractions, and biochemical protection with recalcitrant aromatic C. Our findings suggest that converting RS into RSB and the subsequent application of this biochar have the potential for improving soil quality in saline‐alkali paddy field.

中文翻译：

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盐碱土稻秸秆、灰分和生物炭改良作用下土壤有机碳积累及稳定性


盐碱化对土壤退化有很大影响。水稻 （Oryza sativa L.） 种植是修复盐碱土壤的有效方法。然而，水稻秸秆 （RS）、水稻秸秆生物炭 （RSB） 和水稻秸秆灰分 （RSA） 如何影响盐碱土壤有机碳 （SOC） 积累和稳定性仍然未知。本文通过田间试验研究了 RS、RSB 和 RSA 改良剂和对照 （CK） 下块状土壤及其颗粒和团聚体粒径类别的 SOC 和 SOC 组分含量。碳 13 核磁共振波谱用于评估体 SOC 化学成分。SOC 和 SOC 馏分含量排名为 CK<RSA<RS<RSB。相对于其他处理，RSB 中的芳香族 C 较高，而 O-烷基 C 较低。散装土壤中 SOC 和 SOC 组分的含量通常与颗粒和团聚体尺寸类别以及芳香族 C 的含量呈正相关。冗余分析表明，可交换钠和电导率是影响 SOC 含量和化学成分的最重要因素。结果表明，与 RS 和 RSA 相比，RSB 更有利于 SOC 的积累和稳定。RSB 改良土壤中 SOC 积累的主要机制包括骨料类别提供的物理保护、淤泥和粘土组分介导的化学保护以及顽固芳香族 C 的生化保护。我们的研究结果表明，将 RS 转化为 RSB 并随后应用这种生物炭有可能改善盐碱稻田的土壤质量。