Effect of Nitrification Inhibitors on Nitrogen Leaching and Enzyme Activities

Nitrification inhibitors (Thiourea and nitrification inhibitor “A”) with urea fertilizer were used to enhance the nitrogen efficiency. Nitrification inhibitors and the amount of nitrogen were applied through urea fertilizer to rice seed in Column Lysimeters. The whole experiment was conducted with following treatments such as; urea application as a control at 2gN/10kg (200 kg N/ha), urea application 2gN/10kg (200 kg N/ha) added with 1.0%, 0.5%, 0.1%, 0.05% and 0.01% of thiourea (w/w) and urea application 2gN/10kg (200 kg N/ha) added with 1.0%, 0.5%, 0.1%, 0.05% and 0.01% of nitrification inhibitor “A” (w/w) alone and in combination form. Leachate samples were elicited from the Column Lysimeters and observed the NO and NO nitrogen after first, 3 2 second, third and fourth weeks. The activity of NO and NO reductase also observed using UV-visible 3 2 Spectrophotometer. It was found that all the treatments reduced nitrogen leaching and enzyme activities that involved in nitrification process. It was also observed that the 0.01% of thiourea, nitrification inhibitor “A” and thiourea with nitrification inhibitor “A” for decreased the NO and NO concentration in the leachating samples 3 2 and also reduced the activities of NO and NO reductase in the soil after the fourth week. 3 2