Mineralization (soil science)

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Mineralization in soil science is the decomposition or oxidation of the chemical compounds in organic matter releasing the nutrients contained in those compounds into soluble inorganic forms that may be plant-accessible.[1][2] Mineralization is the opposite of immobilization.

The mineralization process results in increased bioavailability of the nutrients that were contained in the organic compounds being decompose most notably (because of their quantities), nitrogen, phosphorus and sulphur. Whether the decomposition of an organic compound will result in mineralization or immobilization is dependent on its concentration relative to that of carbon. If the concentration of the element in question exceeds the needs of the decomposer for biosynthesis or storage it will be mineralized.

Carbon to nitrogen ratio[edit]

Whether nitrogen is mineralized or immobilized depends on the Carbon-to-nitrogen ratio (C:N ratio) of the plant residues.[3] In general plant residues entering the soil have too little nitrogen to support the biosynthetic needs of the soil microbial population (decomposers). If the C:N ratio of the decomposing plant material is above about 30:1 the soil microbial population may take nitrogen in mineral form (e.g. ammonium, nitrate). This mineral nitrogen is said to be immobilized. This may reduce the concentration of inorganic N in soil and reduce the nitrogen available to plants growing in the soil.

As carbon dioxide is released via energy generation during decomposition (catabolism), the C:N ratio of the organic matter narrows. When the C:N ratio is less than about 25:1 further decomposition results in simultaneous release of inorganic nitrogen as ammonium, referred to as mineralization.

When decomposition of added organic materials is complete the soil mineral nitrogen will be increased as a result of the mineralization of the nitrogen contained in the added organic residues.

See also[edit]


  1. ^ White, Robert E. (October 2005). Principles and Practice of Soil Science: The Soil as a Natural Resource (4th ed.). Blackwell Publishing. ISBN 0-632-06455-2.  384 pages
  2. ^ Beare, M. H.; Hendrix, P. F.; Cabrera, M. L.; Coleman, D. C. (1994). "Aggregate-Protected and Unprotected Organic Matter Pools in Conventional- and No-Tillage Soils" (PDF). Soil Science Society of America Journal. Free PDF download. 58 (3): 787. doi:10.2136/sssaj1994.03615995005800030021x. Retrieved 13 July 2016. 
  3. ^ R.G. McLaren & K. Cameron Soil Science: Sustainable production and environmental protection (2nd edition), Oxford University Press, (1996) ISBN 0-19-558345-0