Glomalins and their relationship with soil carbon

5The activity of bacteria and fungi is a relevant issue in the process of humification of organic matter and physical stability of the soil, standing out the role of arbuscular mycorrhizal fungi (AMF). AMF synthesize a recalcitrant glycoprotein called glomalin, with hydrophobic characteristics. GSRP (glomalin soil-related protein) is the generic product of proteins extracted from soil. The aim was to quantify GSRP and evaluate its share in the total soil organic carbon (TOC). GSRP presented a direct and positive association with soil TOC (R²:0.73). The quantitative participation of GSRP regarding TOC (GSRP / TOC) revealed that as TOC content decreases, GSRP proportion increases. Within the TOC range explored in this paper (1.3 to 3.2%), the glomalin related protein pool of soil changes about 9%, representing between 27% and 36% of TOC. This behavior would indicate an increase of resistant carbon forms counteracting the effects of carbon loss