Soil organic carbon (SOC) is the key indicator of soil fertility, and its stabilization plays a significant role in terrestrial carbon cycling. The turnover of SOC often interacts with iron due to its active redox characteristics, especially in paddy soils. Zero-valent iron (ZVI) is highly reductive, while how its addition controls SOC turning over in soil received less attention and knowledge gap exists on soil C dynamics. Therefore, we investigated the influence of ZVI addition on soil and straw C dynamics in submerged soil over a period of 30 days in an incubation study. The results showed that ZVI addition enhanced the endogenous Fe(III) reduction, and the exogenous ZVI was oxidized mostly to Fe(II), resulting in substantial Fe(II) accumulation, with the content 33.39–164.9% higher than that in non-ZVI treatments after incubation. At the initial stage of incubation during day 0–10, ZVI addition showed a stimulated effect on OC accumulation as both the cumulative CO₂ emission and dissolved organic carbon (DOC) released were reduced in ZVI-amended treatments. This could be attributed to the O₂ limitation on OC mineralization caused by the lower oxidation-reduction potential (ORP) by ZVI addition. Besides, endogenous Fe(III) reduction boosted by ZVI addition could release fresh surfaces on Fe mineral for C accumulation by forming organics-Fe mineral complexes. During the latter stage of day 10–30, ZVI addition showed an inhibited effect on OC accumulation as both the cumulative CO₂ emission and DOC released were increased in ZVI-amended treatments, and CH₄ emission was vigorous after a 10-day lag phase. Labile OC was liberated and vulnerable to decomposition by microorganisms due to the dissolution of OC-Fe(III) oxide complexes as Fe(III) reduction was enhanced by ZVI addition. Furthermore, CH₄ emission was promoted by ZVI addition through lowering soil ORP and supplying electrons for methanogenesis. ZVI addition mitigated OC decomposition during the initial stage and stimulated that during the latter stage of incubation. Overall, ZVI addition increased straw C accumulation in the form of insoluble carbon (C_accumulated), but the different responses of C dynamic between days 0–10 and 10–30 led to a statistic insignificant positive effect. However, the association between iron oxides and OC was enhanced in ZVI addition treatments due to the anaerobic corrosion of ZVI, which may increase the stability of OC, indicating a potential to accumulate more straw C in the long term.

土壤有机碳（SOC）是土壤肥力的关键指标，其稳定在陆地碳循环中发挥着重要作用。由于其活跃的氧化还原特性，SOC 的周转经常与铁相互作用，特别是在水稻土中。零价铁（ZVI）具有高度还原性，但其添加如何控制土壤中SOC的转化却较少受到关注，并且在土壤碳动态方面存在知识差距。因此，我们在 30 天的孵化研究中研究了 ZVI 添加对沉水土壤和秸秆碳动态的影响。结果表明，ZVI的添加增强了内源Fe(III)的还原，而外源ZVI大部分被氧化为Fe(II)，导致Fe(II)大量积累，其含量比非ZVI高33.39%~164.9%。孵化后的 ZVI 处理。在孵化的第0-10天的初始阶段，ZVI的添加显示出对OC积累的刺激作用，因为ZVI修正处理中累积的CO ₂排放量和溶解的有机碳（DOC）释放量均减少。这可能归因于ZVI 添加降低氧化还原电位(ORP) 导致O _{2对OC 矿化的限制。}此外，ZVI添加促进的内源Fe(III)还原可以释放Fe矿物上的新鲜表面，通过形成有机物-Fe矿物复合物来积累C。在第 10-30 天的后期，ZVI 添加对 OC 积累显示出抑制作用，因为 ZVI 修正处理中累积 CO ₂排放量和 DOC 释放量均增加，并且在 10 天滞后期后 CH ₄排放量旺盛。由于添加 ZVI 增强了 Fe(III) 还原，OC-Fe(III) 氧化物复合物溶解，从而释放出不稳定的 OC，并且容易被微生物分解。此外， ZVI的添加通过降低土壤ORP和为产甲烷作用提供电子来促进CH _4排放。ZVI 的添加在初始阶段减轻了 OC 分解，并在孵化后期刺激了 OC 分解。_{总体而言，ZVI的添加增加了秸秆以不溶性碳（C累积}）形式积累的碳，但第0-10天和第10-30天之间碳动态的不同响应导致统计上不显着的积极影响。然而，由于ZVI的厌氧腐蚀，在ZVI添加处理中铁氧化物和OC之间的结合增强，这可能会增加OC的稳定性，表明从长远来看有可能积累更多的秸秆C。