Soil organic matter (SOM) is the largest terrestrial organic carbon pool and a key lever for climate regulation, yet the mechanisms governing its dynamics and long-term persistence across contrasting scales remain debated. A paradigm shift over the last two decades has moved the field from viewing SOC persistence primarily as a function of intrinsic molecular recalcitrance towards a framework in which physical organization and microbial accessibility control turnover times. Resolving how carbon moves from fresh inputs through particulate (POM) to mineral-associated organic matter (MAOM), and where and why it is stabilized or lost, across ecosystems and along the soil–regolith profile, requires integrated, multi-proxy approaches combining methods from soil science, biogeochemistry and isotope geochemistry.
This session aims to bring together researchers working along the full SOC continuum and adopting multidisciplinary approaches to disentangle the formation and fate of SOC by investigating SOM chemistry, mineral soil characteristics, physical organization and mineralogy. We invite studies that (i) investigate SOC persistence across contrasting spatial and temporal scales; (ii) trace SOM formation and transformation using classical and non-traditional molecular and isotopic approaches; (iii) apply emerging non-traditional methods, including stable isotope systems of mineral elements, to trace mineral transformation and organo-mineral interactions along the critical-zone profile; and (iv) use models across contrasting scales to integrate data generated by different approaches.
We particularly encourage studies combining these complementary approaches to constrain mechanisms of long-term SOC preservation, including studies of Quaternary archives such as loess–paleosol sequences.
By bringing together communities from different disciplines, the session seeks to advance a unified, process-based understanding of SOC dynamics by integrating short-term turnover with long-term stabilization. Such an integrated perspective is essential for assessing the persistence of carbon across contrasting soil types and climates and its responses to environmental change, and for underpinning robust climate and land-management strategies. We particularly encourage submissions from early-career researchers and under-represented regions, and invite contributions that could form the basis of a topical collection in Biogeosciences or SOIL.