In soil science, mineralisation term refers to the process of decomposition of organic matters by microorganisms to release nitrogen, sulphur, phosphorus and other inorganic compounds that can be readily assimilated by plants.
The rate of mineralisation depends on various factors such as:
- The mineral content and organic matter present in the soil
- Temperature, pH, the water content of the soil
- Soil type
- Mineralisation process is slow in an acidic environment
- Rate of mineralisation increases in a warm environment and varies with seasons
- Legume crops increase the process of mineralisation due to nitrogen-fixing bacteria present in the root nodules
Mineralisation and Immobilisation
Mineralisation and immobilisation are two opposite terms.
Mineralisation refers to the conversion of organic matter to mineral nutrients, which are readily absorbed by plants, whereas immobilisation refers to mineral uptake by soil microbes and conversion to organic matter, which is unavailable to plants.
Carbon to mineral ratio decides whether decomposition will result in mineralisation or immobilisation.
E.g. if C/N ratio is high, then immobilisation is preferred and microbes may take up ammonia and nitrates present in the soil. On the other hand, if the C/N ratio is comparatively low, then it results in mineralisation of organic N.
To conclude, mineralisation proceeds when the concentration of an element is more than what is required by microbes or decomposers for their own metabolic processes.
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