ABSTRACT
Any consideration of soil ecosystems requires inclusion of the living components. Soil microorganisms have central roles in all aspects of soil processes, including the initial formation of soils from mineral parent material, the establishment of soil structure, and the biogeochemical cycling of elements. It is in this last role that microorganisms most profoundly influence soil processes. The broad metabolic diversity exhibited by soil microbes enables them to participate in the oxidation and reduction reactions that comprise the natural cycles of carbon, nitrogen, sulfur, iron, manganese, and other elements. This microbially mediated cycling of biologically important elements in turn influences the useful properties of soils, such as their ability to support plant life.
