Iron-driven fast decomposition of soil carbon under periodic anoxia

Soil organic carbon (SOC) decomposition underpins soil-atmosphere carbon exchange and is regulated by climate change-mediated variations in soil redox conditions. Periodic anoxia, commonly occurring following precipitation, soil flooding and erosion events, is assumed to preserve SOC. Yet, water saturation may also increase SOC decomposition relative to unsaturated conditions, and contradictory findings among previous studies remain unexplained. Here, using incubation experiments on 20 soils collected across a 24° latitude gradient in China, we show that 70% of the soils showed higher or similar anoxic decomposition rate of SOC compared to oxic treatment, indicating fast SOC loss under relatively short anoxia. Methane production was far lower than CO2 due to the presence of alternative terminal electron acceptors (TEAs). Variation in alternative TEAs and microbial community shows that fast anoxic decomposition was primarily driven by iron (Fe) reduction, which accounted for up to 90% of..., , # Iron-driven fast decomposition of soil carbon under periodic anoxia

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We have submitted our data on the following: soil properties (**Dataset 1 Soil properties of non-incubated soils.csv**), mean decomposition rate (**Dataset 2 Mean decomposition rate and response ratios within 90 days.csv**), instantaneous decomposition rate (**Dataset 3 Instantaneous CO2 and CH4 production rates.csv**), alternative TEA variations (**Dataset 4 Variation in alternative terminal electron acceptors and their reductive products.csv**), soil property variation (**Dataset 5 Variation in soil properties over time under different redox treatments.csv**), Fe-bound OC variation (**Dataset 6 Variation in Fe-bound OC after different redox treatments.csv**), random forest for rate response (**Dataset 7 Random forest for predicting mean RRCO2+CH4.csv**), random forest for Fe-bound OC loss (**Dataset 8 Random forest for predicting Fe-bound OC loss.csv**), and microbial communities (**Dataset_9_Microbial_communi...,