. Measurement of soil enzyme activities
Knowing the sources of specific soil enzyme activities would greatly enhance
our understanding of which group(s) of organisms are directly accessing a given
nutrient resource particularly N and P, thus providing greater insight into the
pathways by which energy and nutrients flow through the soil food web. Activities
of alkaline and acid phosphatase were determined spectrophotometrically by
measuring intensity of yellow colour due to formation of p-nitrophenol from p-
nitrophenyl phosphate (Tabatabai, 1994); urease enzyme activity was measured by
Douglas and Bremner (1971) method which involves spectrophotometric estima-
tion of unhydrolyzed urea after an incubation period. Fluorescein diacetate (FDA)
hydrolysis assay was conducted spectrophotometrically by measuring formation of
fluorescein (fluorescent yellow-green) to assess the overall enzyme activity of total
microbial population (Adam and Duncan, 2001).