Efficiency of N-(n-butyl) thiophosphoric triamide in retarding hydrolysis of urea and ammonia volatilization losses in a flooded sandy loam soil amended with organic materials

Using a forced-draft chamber technique, the suppression of NH3 volatilizati on losses by applying N-(n-butyl) thiophosphoric triamide (NBPT) was studie d in an alkaline sandy loam soil amended with green manure or wheat straw. Applied urea was completely hydrolysed in 12, 8 and 6 days in unamended? gr een manure and wheat straw amended soil, respectively. By applying 0.5% (w/ w of urea) NBPT, complete hydrolysis of urea was delayed up to 16 days in t he unamended soil, whereas in wheat straw amended soil urea hydrolysis was completed by the 12th day even when it was treated with 2% NBPT. Applied at 1 or 2% level? NBPT delayed the NH3 volatilization to the 4th day after ap plication of urea in green manure or wheat straw amended soil. Hydrolysis o f urea was more effectively retarded by applying NBPT in the unamended soil than in soil amended with green manure or wheat straw. In the unamended so il, 7.1% of the applied urea was lost through NH3 volatilization. The losse s were reduced to 1.2 and 0.7% by applying 0.5 and 1% NBPT, respectively. E nhanced NH3 volatilization caused by the green manure or wheat straw was co unteracted by applying NBPT.