Organic fertilizer was widely used to enhance the buildup of soil organic carbon (SOC) and microbial necromass C. Iron and aluminum (Fe/Al) oxides serve as critical factors influencing SOC by controlling microbial necromass C. Nevertheless, the alterations and dynamics of microbial necromass C alongside Fe/Al oxides in the presence of organic fertilizer remain poorly elucidated. To evaluate the effect of organic fertilizer substitution for chemical fertilizer on Fe/Al oxides and its relationship to microbial necromass C, a site experiment was initiated in 2010 including three treatments: chemical fertilizer (CF), 50 %CF+ 50 % organic fertilizer (50 % OF), and 100 % organic fertilizer (100 %OF). The data were collected after 4, 8, and 13 years of experiments in 2014, 2018, and 2023, respectively. The results showed that organic fertilizer substitution decreased C loss from microbial mineralization and increased microbial necromass C, and thus contributed to SOC accumulation. With experiment duration, SOC content did not increase from 2018 to 2023 under 100 %OF may be due to C saturation, while microbial necromass still had an increasing trend. In 2023, bacterial and fungal necromass C was increased by 157.4 % and 178.5 % under 50 %OF, and by 230.7 % and 337.8 % under 100 %OF compared with CF, respectively. This suggests that prolonged use of organic fertilizer can enhance the stable SOC. Organic fertilizer increased microbial necromass C mainly through promoting the formation of Fe/Al oxides, and Fe oxides had a more important effect than Al oxides. Overall, we concluded that organic fertilizer substitution increased stable SOC sequestration through the association of microbial necromass C with iron oxides.

中文翻译：

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有机肥替代通过微生物坏死质量 C 与氧化铁的结合增加土壤有机碳


有机肥料被广泛用于增强土壤有机碳 （SOC） 和微生物坏死质量 C 的积累。铁和铝 （Fe/Al） 氧化物通过控制微生物坏死质量 C 成为影响 SOC 的关键因素。然而，在有机肥料存在下，微生物坏死团 C 与 Fe/Al 氧化物的变化和动力学仍然难以阐明。为评价有机肥替代化肥对 Fe/Al 氧化物的影响及其与微生物坏死体 C 的关系，2010 年启动了一项现场试验，包括三种处理：化肥 （CF）、50 %CF+ 50 % 有机肥 （50 % OF） 和 100 % 有机肥 （100 %OF）。数据是分别在 2014 年、2018 年和 2023 年经过 4 年、 8 年和 13 年的实验后收集的。结果表明，有机肥替代减少了微生物矿化引起的 C 损失，增加了微生物坏死质量 C，从而促进了 SOC 的积累。随着实验时间的延长，2018—2023 年 SOC 含量在 100 %OF 下未增加可能是由于 C 饱和，而微生物坏死量仍呈增加趋势。2023 年，与 CF 相比，细菌和真菌坏死量 C 在 50 %OF 下分别增加了 157.4 % 和 178.5 %，在 100 %OF 下分别增加了 230.7 % 和 337.8 %。这表明长期使用有机肥可以增强稳定的 SOC。有机肥主要通过促进 Fe/Al 氧化物的形成来增加微生物坏死质量 C，且 Fe 氧化物的作用比 Al 氧化物更重要。总体而言，我们得出结论，有机肥替代品通过微生物坏死团 C 与氧化铁的结合增加了稳定的 SOC 封存。