[4] Immobilization and mineralization are continuous processes that occur concurrently whereby nitrogen of the decomposing system is steadily transformed from an inorganic to an organic state by immobilization and from an organic to an inorganic state by decay and mineralization.
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. nitrate).
When the C:N ratio falls below about 25:1 further decomposition results in simultaneous mineralization of nitrogen which is in excess to that required by the microbial population.
Following the initial leaching of soluble materials from fresh detritus, exoenzymes depolymerize the detritus substrate producing reactive carbohydrates, phenolics, small peptides, and amino acids, this is a period whereby microbial growth is rapid, with microbes converting substrate nitrogen and exogenous nitrogen into microbial biomass and exuded products of microbial activity.
[citation needed] The dictionary definition of immobilization (soil science) at Wiktionary