Immobilization is the conversion of an element from an inorganic to organic form by microorganisms. If a particular nutrient is limiting to microbial metabolism, nutrients liberated by mineralization or nutrients available from other soil pools will be taken up and retained by the microbial biomass rendering these nutrients unavailable for plant uptake. Thus, under conditions of nutrient limitation, the microorganisms compete with plants for nutrient made available from mineralization, chemical weathering, and atmospheric deposition. Rates of immobilization are a function of labile organic matter concentrations, litter quality (especially nutrient concentrations), and availability of nutrients from other soil pools. The amount of nutrient made available for plant uptake is termed net mineralization which is equal to gross mineralization minus immobilization.