EFFECT OF THE NITRIFICATION INHIBITOR DMPP APPLIED WITH MINERAL FERTILISER AND CATTLE SLURRY ON YIELD AND N UPTAKE FROM GRASSLAND

A field study was conducted to assess the effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on forage production and N uptake from slurry applications in comparison to mineral ones in grassland systems of the Basque Country. Two kinds of fertilisers were applied: mineral (M) as ammonium sulphate nitrate 26 % (19.5 % ammoniacal and 6.5 % nitric) and cattle slurry (S). DMPP (1 kg ha-1) was used or not with both types of fertiliser. Following each fertiliser application grassland yield was assessed. Grass was dried in a forced-air oven at 70ºC for at least 48 h, weighed, and then ground. Nitrogen concentrations were performed on dried and ground herbage using a Macro Kjeldahl method. In our expe-riment, the use of DMPP did significantly increase biomass yield and N uptake (Table 4) in mineral ferti-lization. Botanical composition was not affected by the use of DMPP