3,4-Dimethylpyrazole phosphate / DMPP as new nitrification inhibitor

3,4-Dimethylpyrazole phosphate DMPP as new nitrification inhibitor

Quick Details

Classification: Chemical Auxiliary Agent
CAS No.: 202842-98-6
Other Names: 3,4-Dimethylpyrazole phosphate
MF: C5H11N2O4P
EINECS No.: Null
Purity: 98% Min.
Type: Adsorbent
Adsorbent Variety: Silica Gel
Usage: nitrification inhibitor, nitrification inhibitor
Model Number: DMPP 98%
Content (%): 98.0 Min.
Product name: 3,4-Dimethylpyrazole phosphate
Other Name: DMPP
key: inhibitor DMPP


•A sandy loam soil was exposed to DMPP at normal and ten-fold higher dose.
•Non-target soil functions and total microbial biomass were unaffected by DMPP.
•Minor trends in phospholipid fatty acid composition were not significant.
•The inhibition of potential ammonia oxidation was independent of DMPP dose.
•DMPP reduced cell-specific nitrification rates, but probably not populations.


The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) is widely used within agriculture to reduce nitrate leaching and improve nitrogen use efficiency of fertilizers, but few studies examined effects on non-target soil functions and microorganisms, i.e. other than the intended delay of ammonia oxidation. We investigated effects of DMPP amendment equivalent to 0 (Control), 1 (regular dose, RD) or 10 (high dose, HD) kg ha−1 in a sandy loam grassland soil at 50% water-filled pore space. Following incubation for 1, 7 or 14 d, soil was analyzed for fluorescein diacetate hydrolysis, dehydrogenase activity, phospholipid fatty acid composition and potential ammonia oxidation. DMPP showed no significant non-target effects (p > 0.05), but a possible stress response in HD was indicated by a factor analysis of phospholipid fatty acid composition. There was a strong DMPP inhibition on potential ammonia oxidation which was still significant (p < 0.05) in HD after 14 d. In separate treatments receiving 50 mg NH4+-N kg−1 dry soil in addition to DMPP, the inhibition of nitrate accumulation was similar in RD and HD at around 75%. Abundances of the gene amoA from ammonia oxidizing bacteria (AOB) and archaea (AOA) were quantified, and cell-specific nitrification rates were estimated. There was a general trend of increasing AOA and AOB abundance towards the end of incubation irrespective of DMPP treatment, whereas cell-specific activity of AOA and/or AOB was reduced in the presence of DMPP. Overall, this study indicated that DMPP effectively inhibited nitrification activity without effects on ammonia oxidizer populations, as well as non-target soil microorganisms or functions.