Nutrient cycling in soils involves biochemical, chemical, and physiochemical reactions, with the biochemical processes being mediated by microorganisms, plant roots, and soil animals. It is well known that all biochemical reactions are catalyzed by enzymes, which are proteins with catalytic properties owing to their power of specific activation. Enzymes are catalysts,
that is, they are substances that without undergoing permanent alteration cause chemical reactions to proceed at faster rates.