Nitrogen is a predominant plant nutrient where amendments are required for optimum production of most agricultural crops around the world. It is also a nutrient that can pose significant pollution of ground-and surface waters and air, and can contribute significantly to global warming. Soils differ considerably in their ability to supply nitrogen to crops such that methods are required to predict how much needs to be applied to individual  fields in order to grow crops efficiently without polluting the environment. Most currently used site-specific prediction methods involve either plant tissue testing or measuring nitrate in the soil, but their effectiveness is limited to specific crop and climate situations. Since most of the nitrogen in soil is organic and is available to plants when is mineralized to inorganic nitrogen, soil test methods that measure or predict potentially mineralizable nitrogen have been proposed. Tests based on a accumulation of inorganic nitrogen in samples incubated under laboratory conditions to determine mineralization of soil organic nitrogen have not been widely utilized probably because they require significant operational time and have not been  thoroughly  tested against actual field conditions. A number of chemical tests to predict potentially mineralizable nitrogen have been proposed but also have not been widely accepted. There appear to be analytical problems with many of these proposals, and these analytical issues need resolution before the chemical tests can be developed for soil nitrogen testing. Further sustained study is required for the development of site-specific and universal methods based on mineralizable nitrogen prediction to enhance agronomically and environmentally sound nitrogen management using soil tests.