Ammonium thiosulfate (ATS) significantly retarded the urea hydrolysis in the soil for 4-6 days when applied rates as high as 25,00 to 5,000 µg/g. After the 10 th day of application ATS loss their inhibition potential due increase in substrate concentration and structure confirmation . Yang and co-workers also reported that the synergistic effect of Azolla and urease inhibitor significantly reduced the NH3 emission by about 61.1-63.6% in the rice field .