Microbial extracellular polymeric substances improve water retention in dryland biological soil crusts.

Biological Soil Crusts (BSCs) represent an important part of the living cover in drylands worldwide. BCSs change soil hydrology due to extracellular polymeric substances (EPS)-excreting species of cyanobacteria, dominant members of dryland-BSCs. The presence of EPS allowed matric potential (Ψ m ) to remain unchanged down to 20% water content, whereas, without EPS, Ψ m started decreasing at 80% water content. The EPS matrix improved the water retaining capacity of soil, suggesting that BSCs would delay onset of restrictive matric potential values due to its larger water holding capacity. [ABSTRACT FROM AUTHOR]