Global stocks and capacity of mineral-associated soil organic carbon. ...

• Main Authors: Georgiou, Katerina, Jackson, Robert B, Vindušková, Olga, Abramoff, Rose Z, Ahlström, Anders, Feng, Wenting, Harden, Jennifer W, Pellegrini, Adam FA, Polley, H Wayne, Soong, Jennifer L, Riley, William J, Torn, Margaret S
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2022
• Subjects: Agriculture; Carbon; Carbon Sequestration; Minerals; Soil; permafrost
• Online Access: https://dx.doi.org/10.17863/cam.87155; https://www.repository.cam.ac.uk/handle/1810/339736

Soil is the largest terrestrial reservoir of organic carbon and is central for climate change mitigation and carbon-climate feedbacks. Chemical and physical associations of soil carbon with minerals play a critical role in carbon storage, but the amount and global capacity for storage in this form remain unquantified. Here, we produce spatially-resolved global estimates of mineral-associated organic carbon stocks and carbon-storage capacity by analyzing 1144 globally-distributed soil profiles. We show that current stocks total 899 Pg C to a depth of 1 m in non-permafrost mineral soils. Although this constitutes 66% and 70% of soil carbon in surface and deeper layers, respectively, it is only 42% and 21% of the mineralogical capacity. Regions under agricultural management and deeper soil layers show the largest undersaturation of mineral-associated carbon. Critically, the degree of undersaturation indicates sequestration efficiency over years to decades. We show that, across 103 carbon-accrual measurements ...