Our study aimed to observe how different earthworm species affect the transformation of labile litter-derived carbon into mineral associated organic matter (MAOM) across two soil types. We traced the amount of OC in casts using 13C-labeled litter in the laboratory and analyzed OC transformation from plant to microbial material using hemicellulosic sugar assays. Our findings highlight the crucial role of earthworms in sugar transformation and MAOM formation, showing that these processes are influenced by soil type and species interactions, which in turn impact the source, composition, and fate of plant litter.