Effects of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate on Nitrification and Nitrifiers in Two Contrasting Agricultural Soils

Abstract

The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) is a powerful tool that can be used to promote nitrogen (N) use efficiency and reduce N losses from agricultural systems by slowing nitrification. Mounting evidence has confirmed the functional importance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in nitrification and N 2 O production; however, their responses to DMPP amendment and the microbial mechanisms underlying the variable efficiencies of DMPP across different soils remain largely unknown. Here we compared the impacts of DMPP on nitrification and the dynamics of ammonia oxidizers between an acidic pasture soil and an alkaline vegetable soil using a 15 N tracing and 13 CO 2 -DNA-stableisotope probing (SIP) technique. The results showed that DMPP significantly inhibited nitrification and N 2 O production in the vegetable soil only, and the transient inhibition was coupled with a significant decrease in AOB abundance. No significant effects on the community structure of ammonia oxidizers or the abundances of total bacteria and denitrifiers were observed in either soil. The 15 N tracing experiment revealed that autotrophic nitrification was the predominant form of nitrification in both soils. The 13 CO 2 -DNA-SIP results indicated the involvement of AOB in active nitrification in both soils, but DMPP inhibited the assimilation of 13 CO 2 into AOB only in the vegetable soil. Our findings provide evidence that DMPP could effectively inhibit nitrification through impeding the abundance and metabolic activity of AOB in the alkaline vegetable soil but not in the acidic pasture soil, possibly due to the low AOB abundance or the adsorption of DMPP by organic matter. IMPORTANCEThe combination of the 15 N tracing model and 13 CO 2 -DNA-SIP technique provides important evidence that the nitrification inhibitor DMPP could effectively inhibit nitrification and nitrous oxide emission in an alkaline soil through influencing the abundance and metabolic activity of AOB. In contrast, DMPP amendment has no significant effect on nitrification or nitrifiers in an acidic soil, potentially owing to the low abundance of AOB and the possible adsorption of DMPP by organic matter. Our findings have direct implications for improved agricultural practices through utilizing the nitrification inhibitor DMPP in appropriate situations, and they emphasize the importance of microbial communities to the efficacy of DMPP.

Nitrification inhibitors effectively target N2O‐producing Nitrosospira spp. in tropical soil

“…The limitation of Nitrosospira but not Nitrososphaera by DCD has been shown also in a paddy field soil and in microcosms of Nitrosospira multiformis but not Nitrososphaera viennensis (Shen et al, 2013;Fu et al, 2018). In studies of nitrification in agricultural soils, DMPP inhibited AOB expression under neutral pH conditions (Shi et al, 2016(Shi et al, , 2017. In a Chinese vegetable soil, DMPP rather than DCD was revealed to be the more effective inhibitor of N 2 O-producing AOB rather than AOA, although the N source urea was also amended with manure (Kou et al, 2015).…”

Microbial N Transformations and N 2 O Emission after Simulated Grassland Cultivation: Effects of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate (DMPP)

“…Understanding their response to NIs and residue incorporation is key to devising effective management strategies. NIs have been shown to reduce potential ammonia oxidation (PAO) and to inhibit the growth of AOB more than that of AOA (21)(22)(23). A recent study further revealed that DMPP inhibits the transcription of AOB amoA genes (24).…”

“…A recent study further revealed that DMPP inhibits the transcription of AOB amoA genes (24). Few studies have examined the effects of NIs on denitrifiers, but based on the limited information available, DMPP appears to have little effect on the abundance of denitrifiers (23). Also, NIs do not seem to affect denitrifying enzyme activity (DEA) (25,26).…”

Effect of urease and nitrification inhibitors on ammonia volatilization and abundance of N‐cycling genes in an agricultural soil

“…The addition of NBPT either decreased the activity and abundance of the bacterial and archaeal amoA gene ( Shi et al., ) or did not affect it at all ( Giovannini et al., ). The application of DMPP reduced the abundance of the amoA gene of ammonia‐oxidizing bacteria ( Yang et al., ; Ruser and Schulz , ; Duan et al., ) and ammonia‐oxidizing archaea ( Kleineidam et al., ; Shi et al., , ). Further, urease and nitrification inhibitors can also affect denitrification, the process by which is sequentially reduced to nitrite ( ), NO, N 2 O, and, finally, N 2 by the nitrate‐, nitrite‐, nitric oxide‐, and nitrous oxide‐reductase enzymes encoded by the napA / narG, nirK / nirS, norB , and nosZ genes, respectively ( Bueno et al., , and references therein).…”