The process by which bacteria in soil and water oxidize ammonia and ammonium ions and form nitrites and nitrates. Because the nitrates can be absorbed by more complex organisms, as by the roots of green plants, nitrification is an important step in the nitrogen cycle .
Several conditions must be fulfilled before nitrification can occur.
In summer, when the temperature is about 24° C. (75° F.), nitrification proceeds at a rapid rate.
By nitrification this substance rapidly becomes available to succeeding crops.
But research showed that this process of nitrification is dependent on temperature, aeration and moisture, as is life, and that while nitre-beds can infect one another, the process is stopped by sterilization.
Mintz and others had proved that nitrification was promoted by some organism, when Winogradsky hit on the happy idea of isolating the organism by using gelatinous silica, and so avoiding the difficulties which Warington had shown to exist with the organism in presence of organic nitrogen, owing to its refusal to nitrify on gelatine or other nitrogenous media.