Abstract
Microbial necromass is increasingly recognized as a major source of stable soil organic matter (SOM), and its persistence is often attributed to interactions with clay-sized minerals. However, the mechanisms underlying this mineral-mediated stabilization remain poorly understood. Here, we conducted an in situ dual-labeled (13C and 15N) microbial necromass experiment across a clay gradient to quantify how clay content and necromass origin (bacterial vs. fungal) regulate necromass persistence. We find that higher clay content markedly enhances necromass retention by strengthening mineral protection, suppressing microbial activity and diversity, and limiting leaching losses. NanoSIMS imaging shows that new necromass preferentially associates with organic matter coatings on the rough mineral surfaces, highlighting organo-organic interfaces as important stabilization pathways. Necromass origin exerts little effect on retention despite marked differences in C:N ratios and bulk chemical composition, indicating that finer-scale molecular features, rather than broad compositional differences, govern necromass stabilization in soils.
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Data availability
Microbial amplicon sequencing data have been deposited in the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) data repository under accession no. PRJNA1191639. All aggregated data supporting the findings of this study are available in the Figshare repository: https://doi.org/10.6084/m9.figshare.27896424.
Code availability
The main R code used in this study is available in the Figshare repository: https://doi.org/10.6084/m9.figshare.27896424.
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Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (42322306, 32201412), the National Key Research and Development Program of China (2022YFF1300501), the International Partnership Program of Chinese Academy of Sciences (064GJHZ2022054FN), Liaoning Revitalization Talents Program (XLYC2403021) and the Natural Science Foundation Program of Liaoning Province (2025JH6/101100019, 2023-MSBA-142), the Youth Innovation Promotion Association CAS to Chao Wang (Y2022064), and the CAS (Chinese Academy of Sciences) Project for Young Scientists in Basic Research (YSBR-108). We thank Guanghui Yu and Bohao Yin from Tianjin University for technical assistance and Jie Kang and Jiaxin Zhao from Huazhong Agricultural University) for NanoSIMS analysis. Additionally, we thank Weixing Zhu from Binghamton University for helpful discussions.
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X.W., C.W., and E.B. designed the study. X.W., C.W., and P.J. performed the experiment. X.W., C.P.S., and L.F.S. performed the laboratory analyses. X.W., Y.L., and C.W. analyzed the data. X.W., C.M.K., M.A., K.G., E.B., and C.W. wrote the manuscript. All authors contributed to the article and approved the submitted version.
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Wang, X., Kallenbach, C.M., Almaraz, M. et al. Clay-organic matter interactions drive microbial necromass preservation in soils. Nat Commun (2026). https://doi.org/10.1038/s41467-026-70156-1
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DOI: https://doi.org/10.1038/s41467-026-70156-1
