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Résumé :
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Major known fractions of soil nitrogen are amino nitrogen (proteins, peptides), polymers of amino sugars, and NH4+ fixed in interlayers of 2:1 minerals. Only a small percentage of the total soil organic N is easily mineralizable and contributes to the pool of mineral soil N. Predominant sources of mineralization are amino-N and polymers of amino sugars present in the soil microbial biomass. Influx into this pool occurs with the application of organic matter (green manure, straw), organic carbon released by plant roots, N-2 assimilation by leguminous species and inorganic nitrogen. Microbial metabolization of green manure proteins results in a partial mineralization of the applied organic N, microbial metabolization of straw in the assimilation (immobilization) of inorganic nitrogen.
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