Table 2: Conditions for assay of soil enzyme activities and their role in soil biogeochemical functioning.

Class/EC number Recommended name Role in soil function   Assay conditions     Reaction Substrate Optimum pH C cycling  3.2.1.21 -Glucosidase Cellulose degradation, produces glucose needed by plants and microorganisms Glucoside-R + H2OGlucose + R–OH p-Nitrophenyl--D-glucopyranoside (10 mM) 6 C and N cycling      3.2.1.30 -Glucosaminidase Chitin degradation, produces amino sugars, one of the major sources of mineralizable N R-N-acetyl--D glucosaminideR–OH + N-acetyl--D-glucosaminide p-Nitrophenyl-N-acetyl--D-glucosaminide (10 mM) 5.5 P cycling  3.1.3.2 Acid Phosphatase Produces plant available phosphates, predominant in acid soils RNa2PO4 + H2O R–OH + Na2HPO4 p-Nitrophenyl-phosphate (10 mM) 6.5  3.1.3.1 Alkaline Phosphatase Produces plant available phosphates, predominant in alkaline soils RNa2PO4 + H2O R–OH + Na2HPO4 p-Nitrophenyl-phosphate (10 mM) 6.5  3.1.4.1 Phosphodiesterase Produced from plants, animals, and microorganisms RNa2 2PO4 + H2O RNa2PO4 + R–OH bis-p-nitrophenyl phosphate (10 mM) 8 S cycling        3.1.6.1 Arylsulfatase Produces plant available sulfates Phenol sulfate + H2O phenol + sulfate p-Nitrophenyl-sulfate (10 mM) 5.8