Abstract: Based on incubation tests with labelled and unlabelled urea, this payer discussed the effects of hydroquinone on hydrolysis of urea, release and volatilization of ammonium, nitrification, denitrification and immobilization. It is concluded that hydroquinone not only delays the hydrolysis of urea and decreases the followed volatilization of ammonia, but more importantly, influences the process of further transformation of hydrolyzates of urea, increases the effective and sustained supply of urea-Nand decreases its total loss. The authors considered that in the study of urease inhibitors, objects in mind would not only be their direct effects, but also their influences on a series of processes of urea-Ntransformation. Only doing these, can we have a further understanding on the mechanism of their actions and give a fuller evaluation about their effects.

Key words: Urease inhibitor, Hydroquinone, Urea, Nitrification, Denitrifieation, Immobilization