Associations of iron (hydr)oxides (FeOx) with organic carbon are vital in regulating the stability of soil organic carbon (SOC). Like SOC, FeOx is chemically dynamic in soils, particularly under anaerobic conditions. However, previous research has not clarified how the stability of FeOx (goethite versus ferrihydrite) and the formation pathway of FeOx-OC associations (adsorption versus coprecipitation) affect the stability of FeOx-bound OC and, subsequently, the priming effect (PE) under anaerobic conditions. With an aim to bridge this gap, we incubated paddy soils for 80 d under anaerobic conditions after adding free C-glucose, ferrihydrite- or goethite-bound C-glucose formed by either adsorption or coprecipitation. Compared with the free glucose addition, the FeOx-bound glucose addition increased CO production by 8%–21% but reduced C–CH production by 7%–10%. Ferrihydrite-bound glucose was mineralised more than goethite-bound glucose; this is consistent with its lower crystallinity facilitating reduction and, thus, higher OC bioavailability. Glucose induced a negative priming effect (PE) for CO but a positive PE for CH, whereas FeOx-bound glucose showed the opposite trend. This may be because FeOx-bound glucose provides an energy source and electron acceptor for Fe-reducing bacteria; this promotes the dissimilating reduction of iron and combines with an aggravated microbial P limitation resulting from the FeOx input. The crystallinity of FeOx affected the amount of primed CH rather than its formation pathway. In conclusion, the crystallinity of FeOx controls the stability of FeOx-OC associations and the PE of SOC decomposition under anaerobic conditions.

中文翻译：

---

铁矿物类型控制厌氧条件下水稻土中有机质的稳定性和引发


铁（氢）氧化物（FeOx）与有机碳的结合对于调节土壤有机碳（SOC）的稳定性至关重要。与 SOC 一样，FeOx 在土壤中具有化学动态，特别是在厌氧条件下。然而，之前的研究尚未阐明 FeOx 的稳定性（针铁矿与水铁矿）以及 FeOx-OC 缔合的形成途径（吸附与共沉淀）如何影响 FeOx 结合的 OC 的稳定性以及随后的启动效应 (PE)。厌氧条件。为了弥补这一差距，我们在添加通过吸附或共沉淀形成的游离C-葡萄糖、水铁矿或针铁矿结合的C-葡萄糖后，在厌氧条件下将水稻土培养80天。与添加游离葡萄糖相比，添加 FeOx 结合葡萄糖使 CO 产量增加 8%–21%，但使 C–CH 产量减少 7%–10%。水铁矿结合葡萄糖的矿化程度高于针铁矿结合葡萄糖；这与其较低的结晶度有利于还原，从而具有较高的 OC 生物利用度是一致的。葡萄糖对 CO 产生负启动效应 (PE)，但对 CH 产生正启动效应 (PE)，而 FeOx 结合的葡萄糖则表现出相反的趋势。这可能是因为 FeOx 结合的葡萄糖为铁还原细菌提供了能源和电子受体；这促进了铁的异化还原，并与 FeOx 输入导致的微生物磷限制加剧相结合。 FeOx 的结晶度影响引发的 CH 的量而不是其形成途径。总之，FeOx 的结晶度控制着 FeOx-OC 缔合体的稳定性以及厌氧条件下 SOC 分解的 PE。