Fig. 6

Relationship between the soil-adsorbed organic carbon (SOC)–microorganism collocation factor, a, and soil clay content, c_c. Blue circles represent the averaged values of a and c_c for the different soil types in Supplementary Data 1. The horizontal bars represent the ranges of c_c, which was not given in the literature and instead estimated according to the US Department of Agriculture textural triangle⁷⁶ (see Supplementary Data 1); the vertical bars represent the ranges of a, which corresponds to the ranges of the optimum water content (see Fig. 5, Supplementary Fig. 5). The black line was derived via the linear least-square regression⁷⁷