Nitrous oxide emission from soil and from a nitrogen-15-labelled fertilizer with the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP)

Mineral-N fertilization can lead to a shortterm enhancement of N2O emission from cultivated land. The aim of this field study was the quantitative det ermination of the short-term N2O emission after application of a fertilizer with the new nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate ( DMPP) to winter wheat. NO3- and NH4+ fertilizers labelled with N-15 in liqu id and granulated form were used in specific fertilizer strategies. N ferti lizers with higher NO3- contents caused higher N2O emission than NH4+ ferti lizers. For fertilizers with NIs. used in simplified fertilizer strategies with fewer applications and an earlier timing of the N fertilization. the N 2O release was reduced by about 20%. Of the total N2O emission measured, 10 -40% was attributed to fertilizer N and 60-90% originated from soil N. Besi des the fertilizer NO3--N, the microbial available-N pool in the soil repre sented a further important source for N2O losses. Compared to liquid fertil izers, the application in granulated form led to smaller N2O emissions. For fertilizers with NIs, the decrease in the N2O emission is mainly due to th eir low NO3--N content and the possibility of reducing the number of applic ations.