Several conditions must be fulfilled before nitrification can occur.
This result is partly due to their period of accumulation and growth extending even months after the period of collection by the ripening cereals has terminated, and at the season when nitrification within the soil is most active, and the accumulation of nitrates in it is the greatest.
In summer, when the temperature is about 24° C. (75° F.), nitrification proceeds at a rapid rate.
It is only when these conditions are attended to that decay and nitrification of dung, guano, fish-meal, sulphate of ammonia and other manures take place, and the constituents which they contain become available to the crops for whose benefit they have been applied to the land.
Fermentation, &c.: Warington, The Chemical Action of some Micro-organisms (London, 1888); Winogradsky, " Recherches sur les organismes de la nitrification," Ann.