Potentially Mineralizable Nitrogen as an Indicator of Biologically Active Soil Nitrogen

This chapter discusses the use of nitrogen (N) mineralization potential as an indicator of soil quality and the advantages and disadvantages of the various methods available. It utilizes the term active soil N to refer to the biologically dynamic, labile organic N fractions that can be mineralized in the course of one growing season. Numerous chemical and biological methods have been developed for determination of N mineralization potential. Chemical methods for estimating potentially mineralizable N range from fairly mild treatments such as extraction of N with concentrated salt solutions, to drastic treatments that use acids to partially hydrolyze organic N compounds. Standford and S. J. Smith proposed a 30-wk aerobic incubation method to estimate soil N mineralization potential. Some have suggested that the anaerobic incubation method may serve as a substitute for microbial biomass determinations since it apparently involves killing and mineralizing the obligate aerobes.