The ecological relevance of fast-cycling mineral-associated organic matter – a dynamic pool of 'persistent’ soil carbon and nitrogen

This is a Preprint and has not been peer reviewed. This is version 2 of this Preprint. You must log in to post a comment. There are no comments or no comments have been made public for this article. This is a Preprint and has not been peer reviewed. This is version 2 of this Preprint. Add a Comment You must log in to post a comment. Comments There are no comments or no comments have been made public for this article. Longstanding theories and models classify mineral-associated organic matter (MAOM) as the large (~60%) but slow-cycling and persistent portion of the soil organic matter (SOM) pool. Strong physico-chemical interactions and diffusion limitations restrict the turnover of MAOM, allowing carbon and nitrogen bound therein to persist in soil for as long as centuries to millennia. However, MAOM is a chemically and functionally diverse pool with a substantial portion cycling at relatively fast (i.e., minutes to years) timescales. Despite a growing body of evidence for the heterogenous and multi-pool nature of MAOM, we lack consensus on how to conceptualize and directly quantify fast-cycling MAOM and its ecological significance. We demonstrate the dynamic qualities of fast-cycling MAOM vary based on 1) the chemistry of the mineral particles and organic matter, 2) the complex set of interactions between OM and the mineral matrix, and 3) the presence and strength of destabilizing forces that lead to decomposition or loss of MAOM (i.e., plant-microbe interactions, land use change, agricultural intensification, and climate change). Finally, we discuss potential implications and research opportunities for how we measure, manage, and model the dynamic subfraction of this otherwise persistent pool of SOM. https://doi.org/10.32942/X2G64J Agriculture, Biogeochemistry, Soil Science, Terrestrial and Aquatic Ecology soil organic matter, carbon, nitrogen, mineral-associated organic matter, nutrient dynamics Published: 2025-05-08 14:23 Last Updated: 2025-05-08 14:25 CC BY Attribution 4.0 International Conflict of interest statement: The authors declare no conflicts of interest. Data and Code Availability Statement: Not applicable Language: English