PNNL

Abstract

Soil organic matter (SOM) is a reservoir for global carbon (C) that maintains soil fertility and prevents the release of greenhouse gases. Microbial necromass, consisting of dead cells and cellular components, is considered a major contributor to SOM formation; yet methods for enhancing the accumulation of microbial necromass in soil are still unknown. Here, we demonstrate the importance of fine amorphous minerals in accumulating microbial necromass in sandy and silty loam soils. We used 13C to trace microbial necromass persistence in a year-long laboratory incubation of soils from two agricultural research sites differing in texture and mineralogy. Isotopic tracing revealed that for both silty and sandy loams, approximately 88% of the microbial necromass was recovered in the fine (