CO(NH2)2(s) + 3H2O2(l) ??> 2NH+4(aq) + HCO-3(aq) + OH-(aq) (1) NH+4(aq) + 3/2 O2(g) ??> NO-2(aq) + 2H+(aq) + H2O(l) (2) NO-2(aq) + 1/2 O2(g) ??> NO-3(aq) (3) It is well known that the hydrolyzing activity of urease follows the Michaelis-Menten kinetics, and it is influenced by several factors including the soil type, organic matter content, temperature, soil moisture, pH and the amount of added N