3,4-dimethylpyrazole phosphate reduces nitrous oxide emissions from grassland after slurry application

A field study was conducted to assess the effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), applied at a rate of 1 kg ha(-1), on nitrous oxide (N2O) emissions, forage production and N extraction from a grassland soil after cattle slurry applications in autumn and spring. Nitrous oxide emissions were measured daily or weekly using the closed chamber technique. DMPP efficiency after slurry application was lower in spring (16.7 degrees C mean soil temperature) than in autumn (11.4 degrees C mean soil temperature). Thus, DMPP was able to maintain soil mineral N in the ammonium form for 22 days and reduce cumulative N2O emissions by 69% in autumn, while in spring its effect on soil mineral N lasted for 7-14 days, reducing cumulative N2O losses by 48%. Furthermore, application of DMPP after slurry did not decrease biomass yield or N uptake.