Several chemicals used as nitrification inhibitors were tested to determine their effect on dentrification by a Pseudomonas sp. and in soil. Denitrification by the bacterium was suppressed by 2-chloro-6(-trichloromethyl)-pyridine (N-Serve) at a concentration of 50 ppm, while 2,5-dichloroaniline caused the accumulation of nitrite in the culture medium. The nitrification inhibitors had little effect on the denitrifying activity in soil under anaerobic conditions. 2-Sulfanilamidothiazole inhibited denitrification to some extent and samples supplied with potassium azide produced N2O rather than N2 as the predominant gas.
