Data for "<b>Microbial extracellular residues contribute to the buildup of long-term carbon storage</b>"

Soil microbes play a critical role in supporting carbon stocks through the accumulation of cellular and extracellular residues. Strikingly, while the contribution of cellular residues to carbon stocks is well established, that of extracellular residues is far less understood. Here, we combined a continental-scale survey with microcosm experiments and found that microbial extracellular polymeric substances (EPS) largely explain soil carbon sequestration, particularly mineral-associated carbon, which is expected to be less vulnerable to environmental disturbances. Remarkably, the production rate of EPS carbon significantly exceeded that of cellular residues, and was further capable to explain mineral-associated carbon. Microcosm experiments further demonstrated that a significantly higher proportion of EPS carbon, relative to cellular residue, was incorporated into the mineral pool, corroborating the overriding role of EPS carbon in explaining soil organic carbon sequestration. Our work provides new mechanistic insights into how soil microbiomes shape the fate of soil carbon and highlights the fundamental importance of EPS in guiding carbon sequestration under global change.