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 (N 2 O) emissions. A field lysimeter study was conducted to determine the ability of the combination of the nitrification inhibitor dicyandiamide (DCD) and biochar to mitigate N 2 O emissions from a winter grazing forage crop soil. The results showed that over a 4 month period, applying cow urine at a rate of 700 kg N ha −1 increased N 2 O emissions from 0.7 kg N 2 O‐N ha −1 to 14.7 kg N 2 O‐N ha −1 . The application of DCD at 20 kg ha −1 reduced total N 2 O emissions by 65%. The application of biochar at 5 t ha −1 had no significant effect on N 2 O emissions. The combination of DCD with biochar did not lead to greater N 2 O reductions than DCD alone. These results indicated that DCD was highly effective whereas biochar was ineffective in reducing N 2 O emissions in the winter forage soil.