The short-term effects of nitrification inhibitors on the abundance and expression of ammonia and nitrite oxidizers in a long-term field experiment comparing land management

Microcosms were set up to evaluate the effect of nitrification inhibitors (DCD, c-PTiO, and NaClO3) on the abundance and expression of ammonia-oxidizing bacteria (AOB) and archaea (AOA), as well as the nitrite-oxidizing bacteria (NOB) Nitrospira and Nitrobacter. Both DCD and NaClO3 inhibited the net nitrification rate, while c-PTiO had no significant effects, and NaClO3 had a much greater inhibitory effect (> 60%) in all soils than DCD. No significant changes in total microbial abundance were observed with DCD and NaClO3. DCD limited only the growth of AOB; however, NaClO3 inhibited growth of both AOA and Nitrospira-NOB with no significant effects on AOB and Nitrobacter-NOB. Probably NaClO3 inhibited both ammonia oxidation and nitrite oxidation. This is the first report to reveal the inhibitory effects of NaClO3 on a specific nitrification process, helping to clarify the ecological niche of nitrifiers and the potential of nitrification inhibitors applied to soil.