Corn. 2-chloro-6-trichloromethylopyridine (nitrapyrin) nitrification inhibitor was used during org. and org.-mineral fertilization in maize growing (field exps.). Increases in grain yield 5-8% at slurry fertilization and 12-20% at manure with urea fertilization were obsd. when compared to the same dose of fertilizers without any stabilizer.