The invention is generally directed to a system and process for fluorometrically quantifying potentially mineralizable nitrogen for agricultural crop production. The soil analysis process measures potentially mineralizable nitrogen and calibrates the application of soil-based nitrogen for site or field specific management of nitrogen fertilizers for crops grown on a wide variety of soil textures including sandy loam, silt loam and clay soils. The spectrofluorometric system and process may be utilized for routine soil testing with a lower sample to sample variability, and the automation of the spectrofluorometric system and process allows for simultaneous determination of potentially mineralizable soil organic nitrogen, ammonium and nitrate
