DMPSA and DMPP equally reduce N2O emissions from a maize-ryegrass forage rotation under Atlantic climate conditions

The increase of the global demand for dairy products is reflected in a rise of animal feed and forage productivity. In the coastal Atlantic climate conditions of northern Spain the maize-ryegrass rotation is a common management used to satisfy this forage demand. With the aim of mitigating greenhouse gases (GHG) emissions associated with fertilization in this type of intensive management, the use of nitrification inhibitors (NI) such as 3,4-dimethylpyrazol phosphate (DMPP) or the isomeric mixture of 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl) succinic acid (DMPSA) could be a useful strategy. Until now, the new NI DMPSA has only been evaluated under Mediterranean conditions. The objective of this study was to compare the efficiency of DMPSA with respect to DMPP reducing GHG emissions when applied in a maize-ryegrass rotation under Atlantic climate conditions. Nitrogen fertilizer was applied as ammonium sulphate, with and without both NIs, split into two applications of 80 and 100 kg N ha−1 in the case of maize and in three applications of 80, 60 and 60 kg N ha−1 in the case of ryegrass. An unfertilized control treatment was also included. Nitrous oxide (N2O) and methane (CH4) fluxes were measured using the closed chamber technique. The new NI DMPSA showed a similar behaviour to DMPP, mitigating N2O emissions down to the levels of the unfertilized soil. The effect of DMPSA reducing N2O losses lasted for the same time as for DMPP (l