Use of urease and nitrification inhibitors to reduce gaseous nitrogen emissions from fertilizers containing ammonium nitrate and urea

Nitrogen (N) fertilizers increase agricultural yields, but also lead to the release of the greenhouse gases nitrous oxide (N2O) and ammonia (NH3). This not only reduces the efficiency of N use, but also results in climate change and loss of biodiversity. The use of nitrification inhibitors may improve the efficiency of N use and reduce the emission of greenhouse gases. We tested three inhibitors (NZONE MAX, Piadin and N-(n-butyl) thiophosphoric triamide (NBPT)) added to two common N fertilizers (urea and urea ammonium nitrate (UAN)) and determined emissions of CO2, N2O and NH3 to evaluate the effectiveness of these three inhibitors and to improve our understanding of the soil nitrogen cycle. NBPT effectively reduced NH3 volatilization by 50% (from 3.0 g NH3-N m−2 in urea alone to 1.4 g NH3-N m−2 in urea + NBPT). Piadin decreased N2O emissions (from 0.98 g N2O-N m−2 in urea alone to 0.15 g N2O-N m−2 in urea + Piadin and from 0.81 g N2O-N m−2 in UAN alone to 0.39 g N2O-N m−2 in UAN + Piadin) by inhibiting the conversion of NH4+ to NO3−. However, although Piadin was found to be an effective nitrification inhibitor, the risk of higher NH3 emissions (from 3.0 g NH3-N m−2 in urea alone to 4.5 g NH3-N m−2 in urea + Piadin) with the addition of Piadin cannot be neglected in environmental and economical evaluations.