Nitrification in Soil

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Nitrification in Soil

	Nitrification in Soil -The oxidation of ammonia to nitrate is called nitirification. The process consists of two steps and is carried out by two specific group of organisms of the family Nitrobacteriaceae. These are strict autotrophs and obtain their energy from the oxidation of ammonia to nitrites and of nitrites to nitrates.
The first step, the oxidation of ammonia to nitrite, is called nitrosification. This is accomplished by bacteria of the genera Nitrosomonas, Nitrosococcus, Nitrosospira; and Nitrosocystis. The nitrites formed by these organisms are toxic to plants as well as to the organisms forming it., Fortunately, nitrites are removed by further oxidation to nitrates by bacteria of the genus Nitrobacter.
Nitrification proceeds very rapidly in well-aerated manure piles. The nitrates from such sources were used for the manufacture of gun powder during the Napoleonic wars, long before the microbial process 0 f nitrification was known. Nitrates are readily used by plants and many microorganisms.
Certain heterotrophic bacteria (e. g. Streptomyces and Nocardia) oxidize ammonia to nitrite. However, several species of fungi (e. g. Penicillium, Aspergillus, Cephalosporium) oxidize both ammonia to nitrite and nitrite to nitrate.

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Sulphur Cycle Ammonification in Soil Nitrification in Soil Nitrate Reduction in Soil Denitrification in Soil Nitrogen Fixation Symbiotic Nitrogen Fixation Rhizobium Specificity of Bacteria and Legumes Non-Symbiotic Nitrogen Fixation Non-symbiotic Nitrogen Fixing Microorganisms Mechanism of Nitrogen Fixation Oxidation of Sulphur and Sulphur Compounds by Bacteria