Major Process of organic matter decomposition
1. Mineralization Is the conversion of an element from organic form to an inorganic/mineral form is called mineralization. Mineralization occurs for each element present in the organic matter individually especially for N, P and S
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A. Nitrogen mineralization:
It is the conversion of organic nitrogen into inorganic Nitrogen NH4 and NO3 by microorganisms Organic N(proteins and amino acids) ----------> Proteose------------>Peptone-------------->Amino compounds- ammonia -----------> nitrite --------> nitrate
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Different steps involved in N-mineralization
1. Aminisation: proteins and other complex nitrogenous compounds are converted into amino acids and amino compounds by the action of enzymes and microorganisms, CO2 and energy is released. 2. Ammonification: it is the biochemical conversion of amino compounds and amino acids into ammonia by bacterial decomposition.

This process is governed by aminase and deaminase enzymes. The liberated NH3 is utilized by plants.
3. Nitrification :It is the biochemical oxidation of ammonia into nitrite and then finally into nitrate. This process carried out by by autotropic bacteria (Nitrosomanas and Nitrobacter) in aerobic condition. Two steps are involved

Rate of nitrification depends on suitable temperature, humidity, pH, season, aeration, addition of lime (increases), nature of organic matter etc.
4. Denitrification :It is the biochemical reduction of nitrate or nitrite to gaseous nitrogen (N2), either as molecular N or oxides of N.

Loss of nitrate by reduction and assimilation
B. Phosphorus mineralization

C. Sulphur mineralization

2. ImmobilizationThe conversion of an element from the inorganic to the organic form in microbial tissues or in plant tissues, thus rendering the element not readily available to other organisms or to plants.
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Last modified: Wednesday, 7 December 2011, 6:14 AM