Denitrification And Associated Nitrogen Transformations In Soils

Rates of NO3- disappearance under anaerobic conditions, from six widely differing soils, gradually increased and then became relatively constant when glucose was added in increments supplying 0.04 to 1.5 mg of C/g of soil. Maximum rates of NO3- loss ranged from approximately 9.3 to 13.7 percent/hr. Increased production of NH4+ accompanied glucose additions in all soils. Results based on 13N-labeled Ca(NO3)2 showed that substantial amounts of NO3- were reduced to NH4+ after 4 hr of anaerobic incubation, and 15NH4+ continued to increase until all or most of the 15NO3- had been converted to NH4+, organic N, and gaseous forms (N2 and N2O). Results seriously challenge the prevalent view that denitrification accounts for essentially all NO3- dissimilation in anaerobic soils.