Important role of Fe oxides in global soil carbon stabilization and stocks
Nan Jia, Lei Li, Hui Guo, Mingyu Xie
Abstract
Iron (Fe) oxides can interact with soil organic carbon (SOC) to form Fe-bound organic carbon (OC-Fe), which strongly promotes SOC protection, mitigating global climate change. However, the global patterns and factors controlling OC-Fe are unclear. Here, we conducted a meta-analysis of 3,395 globally distributed soil profiles to reveal the role of Fe-Al oxides in global soil carbon stabilization and stocks. The global OC-Fe stock in topsoil is 233 PgC, accounting for 33 ± 15% of the total SOC stock. A substantial OC-Fe deficit (difference between OC-Fe and OC-Femax) was observed at the equator and at mid-latitudes. Our findings suggest that mineral factors should be incorporated into soil carbon models to improve model predictions. Although there are uncertainties in current OC-Fe extraction method, the global distribution of OC-Fe and OC-Femax constitutes a vital resource for future research targeting carbon cycling issues and offers innovative strategies for global soil carbon sequestration initiatives. Iron oxides stabilize soil organic carbon globally, with OC-Fe accounting for 33 ± 15% of SOC in topsoil (233 PgC). A global OC-Fe deficit is evident at the equator and mid-latitudes, highlighting opportunities for carbon sequestration strategies