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

Abstract.

Mineral-N fertilization can lead to a short-term enhancement of N₂O emission from cultivated land. The aim of this field study was the quantitative determination 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 ¹⁵N in liquid and granulated form were used in specific fertilizer strategies. N fertilizers with higher NO₃ ^– contents caused higher N₂O emission than NH₄ ⁺ fertilizers. For fertilizers with NIs, used in simplified fertilizer strategies with fewer applications and an earlier timing of the N fertilization, the N₂O 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. Besides the fertilizer NO₃ ^–-N, the microbial available-N pool in the soil represented a further important source for N₂O losses. Compared to liquid fertilizers, the application in granulated form led to smaller N₂O emissions. For fertilizers with NIs, the decrease in the N₂O emission is mainly due to their low NO₃ ^–-N content and the possibility of reducing the number of applications.