Nitrous oxide emission from different fertilizers and its mitigation by nitrification inhibitors in irrigated rice

N2O emissions from a transplanted irrigated rice grown on a Typic Ustochrep t soil at New Delhi, India, were studied to evaluate the effect of N fertil izers, i.e. urea and (NH4)(2)SO4 alone and in combination with the nitrific ation inhibitors dicyandiamide (DCD) and thiosulphate. The addition of urea and (NH4)(2)SO4 increased N2O emissions considerably when compared to no f ertilizer N application (control). N2O measurement in the field was done by a closed-chamber method for a period of 98 days. The application of urea w ith DCD and thiosulphate reduced N2O fluxes considerably. The highest total N2O-N emission (235 g N2O-N ha(-1)) was from the (NH4)(2)SO4 treatment, wh ich was significantly higher than the total N2O-N emission from the urea tr eatment (160 g N2O-N ha(-1)). DCD reduced N2O-N emissions by 11% and 26% wh en applied with urea and(NH4)(2)SO4, respectively, whereas thiosulphate in combination with urea reduced N2O-N emissions by 9%. Total N2O-N emissions were found to range from 0.08% to 0.14% of applied N. N2O emissions were lo w during submergence and increased substantially during drainage of standin g water.