Effect of fertilizers with the new nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) on yield and quality of agricultural and horticultural crops

Abstract.

In 1997–1999, 136 field trials were conducted under various soil-climatic conditions in western and southern Europe in order to assess the effects of N fertilizers with the new nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP) on the yield and quality of various agricultural and horticultural crops. Results show that DMPP may increase the mean crop yield (grain yield, winter wheat +0.25 t ha^–1, wetland rice +0.29 t ha^–1, grain maize +0.24 t ha^–1; tuber yield, potatoes +1.9 t ha^–1; corrected sugar yield, sugar beets +0.24 t ha^–1; biomass, carrots +4.9 t ha^–1, lambs' lettuce +1.9 t ha^–1, onions +0.5 t ha^–1, radish +4.6 t ha^–1, lettuce +1.4 t ha^–1, cauliflower +5.2 t ha^–1, leek +1.7 t ha^–1, celeriac +2.2 t ha^–1) and/or improve crop quality (e.g. reduced NO₃ ^– concentration in leafy vegetables). In some crops, the same yield level as obtained with the control (fertilizer without DMPP) was achieved with one fewer applications of N, or with a reduced N application rate. The positive effect of DMPP on crop yield was especially pronounced at sites with a high precipitation rate or intensive irrigation, and/or light sandy soil. DMPP had a negative effect on the crude protein concentration of winter wheat and on the biomass yield of spring-grown spinach.