Effectiveness of the nitrification inhibitor dicyandiamide and biochar to reduce nitrous oxide emissions

Animal urine from grazing animals is responsible for the majority of New Zealand's nitrous oxide (N2O) emissions. A field lysimeter study was conducted to determine the ability of the combination of the nitrification inhibitor dicyandiamide (DCD) and biochar to mitigate N2O emissions from a winter grazing forage crop soil. The results showed that over a 4 month period, applying cow urine at a rate of 700kgNha(-1) increased N2O emissions from 0.7kgN(2)O-Nha(-1) to 14.7kgN(2)O-Nha(-1). The application of DCD at 20kgha(-1) reduced total N2O emissions by 65%. The application of biochar at 5tha(-1) had no significant effect on N2O emissions. The combination of DCD with biochar did not lead to greater N2O reductions than DCD alone. These results indicated that DCD was highly effective whereas biochar was ineffective in reducing N2O emissions in the winter forage soil.