LAUSR

Nitrification inhibitors have been proposed as a tool to mitigate nitrous oxide (N 2 O) emissions from agriculture, which are caused mainly by fertilization. The nitrification inhibitor 3,4-Dimethylpyrazole phosphate (DMPP) was tested in a winter rapeseed field after dairy slurry application in Central Estonia. N 2 O emissions were monitored using the closed chamber method. Soil and leachate chemical parameters were also analyzed. N 2 O emissions increased from pre-slurry application values of 316 and 264 µg m −2 h −1 for the control and treatment plot, respectively, to maximum values of 3130.71 and 4834 µg m −2 h −1 , with cumulative emissions during the study period of 12.30 kg ha −1 for the control plot and 17.70 kg ha −1 for the treatment plot. The intense precipitation period that began with the application of the slurry resulted in changes in soil moisture and water-filled pore space (WFPS), modifying the nitrification/denitrification balance. Positive significant correlations ( p = 0.016 and p = 0.037, for the control and treatment plot, respectively) were found between N 2 O fluxes and WFPS. Future studies should consider the role of nitrifier and denitrifier communities in order to better assess in-field nitrification inhibitor effectiveness.