Studies on Urea Hydrolysis in Typic Ustochrepts of Punjab

Urea hydrolysis did not follow any regular pattern with depth of soil samples. Urea hydrolysis was more rapid at field capacity than at 1: 1 of soil: water ratio in each depth of all the soil series. The time required for complete conversion of applied urea varied from less than 1 day to more than 10 days at 1: 1 of soil: water ratio and from less than 1 day to 7 days at field capacity. Urea hydrolysis seemed to follow zero and first order reaction kinetics. The average time for one-half of the hydrolysis to occur (t_l/2) ranged from 0.19 to 4.95 days. In some samples, the order of reaction could not be determined due to very fast urea hydrolysis.