A nitrification inhibitor is a non-phytotoxic substance
which inhibits the conversion of ammonium ion to nitrate
ion (nitrification). Several chemicals inhibit
nitrification. Some of the best known nitrification
inhibitors are nitrapyrin or N-serve, AM (2-amino-4-
chloro-6-methyl pyridine), DCD (dicyandiamide),
thiourea, ATC (nine - 1,2,4 - triazole), potassium
azide, neem (Azadirachta indica) seed extract, etc.
Generally, 0.2 to 2.0 kg/ha of the inhibitor, when placed
near the stored nitrogen fertilizer, is sufficient for
retarding nitrification. This selectively inhibits the
activity of Nitrosomnas, and is safe to use. The added
inhibitor prevents rapid nitrification of fertilizers and
remains effective throughout the fertilizer-soil reaction
zone, thereby reducing the nitrogen loss (through
leaching and denitrification) and improving the recovery
of the applied nitrogen.
