3,4‐Dimethylpyrazol Phosphate Effect on Nitrous Oxide, Nitric Oxide, Ammonia, and Carbon Dioxide Emissions from Grasslands

Intensively managed grasslands are potentially a large source of NH 3 , N 2 O, and NO emissions because of the large input of nitrogen (N) in fertilizers. Addition of nitrification inhibitors (NI) to fertilizers maintains soil N in ammonium form. Consequently, N 2 O and NO losses are less likely to occur and the potential for N utilization is increased, and NH 3 volatilization may be increased. In the present study, we evaluated the effectiveness of the nitrification inhibitor 3,4‐dimethylpyrazol phosphate (DMPP) on NH 3 , N 2 O, NO, and CO 2 emissions following the application of 97 kg N ha −1 as ammonium sulfate nitrate (ASN) and 97 kg NH 4 + –N ha −1 as cattle slurry to a mixed clover–ryegrass sward in the Basque Country (northern Spain). After slurry application, 16.0 and 0.7% of the NH 4 + –N applied was lost in the form of N 2 O and NO, respectively. The application of DMPP induced a decrease of 29 and 25% in N 2 O and NO emissions, respectively. After ASN application 4.6 and 2.8% of the N applied was lost as N 2 O and NO, respectively. The application of DMPP with ASN (as ENTEC 26; COMPO, Münster, Germany) unexpectedly did not significantly reduce N 2 O emissions, but induced a decrease of 44% in NO emissions. The amount of NH 4 + –N lost in the form of NH 3 following slurry and slurry + DMPP applications was 7.8 and 11.0%, respectively, the increase induced by DMPP not being statistically significant. Levels of CO 2 emissions were unaffected in all cases by the use of DMPP. We conclude that DMPP is an efficient nitrification inhibitor to be used to reduce N 2 O and NO emissions from grasslands.