Distinct regulation of microbial processes in the immobilization of labile carbon in different soils

A process-based understanding of soil carbon (C) sequestration and stabilization has not been precisely characterized due to the lacking of linkage between microbial proliferation and mortality. In this study, stable isotope probing of phospholipid fatty acids and amino sugars were used to determine the microbial responses and microbial residue retention in two soils (Mollisol and Ultisol) with 13C-labeled glucose addition. The microbial responses stimulated by glucose were greater in C-poor Ultisol than in C-rich Mollisol. However, the transformation of labile C to microbial residues in Mollisol was more rapid. Therefore, the starvation effect may control microbial growth and microbial residue production, and thus resulting in distinct sequestration and stabilization process of labile C in different soils.