Abstract: With simulation test of insitu soil column,this paper studied the effects of urease inhibitor hydroquinone (HQ),nitrification inhibitors coated calcium carbide (ECC) and dicyandiamide (DCD),and their different combinations on the persistence,oxidation,and leaching of soil urea's hydrolyzed product ammonium.The results showed that compared with other treatments,the combination of HQ and DCD could effectively inhibit the oxidation of the ammonium,and make it as exchangeable form reserve in soil in a larger amount and a longer period.The inhibition of this oxidation not only decreased the accumulation of oxidized product NO₃^- in soil,but also decreased the potential of NO₃^- leaching,making the NO₃^- only leach to 5～10 cm in depth,and the leached amount significantly decreased.

Key words: Molecular responses, mRNA differential display, Oryza sativa L., UV-B radiation