To study the effect of substrate concentration on soil enzyme Urease in selected soils. Forty soil samples were assayed to measure the activity of the soil enzyme Urease among them four soil samples two Alfisols and two Vertisolssoils with high activity were selected for further study. Urease activities of the surface soils expressed as µg of NH4 + released g-1 soil h-1 ranged from to with an average value of enzyme Urease activity increased with an increase in substrate concentration in the beginning and almost reached a plateau at a substrate concentration of 30mM for all the four soils. With further increase in substrate concentration, minimal change in enzyme activity was observed.
