Alive and dead earthworms capture carbon during mineral weathering through different pathways

Enhanced rock weathering aims at capturing atmospheric carbon dioxide as inorganic carbon, while potentially stabilizing soil organic carbon. However, the role of soil biota in this process remains underexplored. Earthworms, being key soil engineers, may impact carbon dynamics both when alive, through mineral ingestion and casting activities, and when dead, through microbial processes. Using stable isotope tracing, we investigate how live and dead earthworms affect carbon dynamics during rock weathering. We demonstrate that both living and dead earthworms contributed to carbon capture, albeit through distinct pathways. Live earthworms enhanced the formation of organo-mineral associations via their dejections over time, promoting organic carbon persistence. Dead earthworms boosted microbial abundance and activity, enhancing organo-mineral associations and atmospheric-derived inorganic carbon capture between 60 and 120 days. We show that earthworms influence carbon cycling beyond their lifespan, with contrasting physico-chemical and biological pathways driving carbon capture through rock weathering throughout their life cycle. Both living and dead earthworms stabilize organic carbon, with the latter also enhancing inorganic carbon sequestration, through castings and microbial-driven activities, respectively, via rock weathering in a 120-day column experiment.