Occurrence of added nitrogen interaction affected by nitrogen stabilizer and glucose additions in an Alfisol

Abstract Nitrogen (N) fertilizer application provides available N and affects indigenous soil N availability, inducing added N interaction (ANI). However, limited information is available on the impacts of inhibitors combined with organic substances on ANI. A microcosm experiment was conducted to examine the effects of the additions of nitrification inhibitor (dicyandiamide [DCD]), urease inhibitor (hydroquinone [HQ]), and glucose on ANI. In non-glucose treatments, positive ANI was observed at the initial stage of incubation. DCD addition generally increased ANI. Conversely, HQ addition decreased ANI. Glucose application led to a significantly negative ANI caused by net microbial immobilization at the beginning. ANI recovered because of the remineralization of immobilized N. Glucose combined with DCD and HQ further decreased ANI up to 24.4% and 30.7% and retarded the appearance of positive ANI by 2.6 and 6.0 days, respectively, compared with the corresponding treatment without inhibitor. ANI was primarily driven by biotic processes, and the contribution of abiotic processes, such as isotope displacement reaction in the fixed ammonium (NH4+) pool, to ANI ranged from 15.6% to 31.0%. This contribution increased with DCD and glucose additions, but decreased with HQ application. Generally, DCD addition tended to hold urea-derived N in soil and enhanced the availability of indigenous soil N, whereas HQ addition resulted in a reverse tendency. Glucose amendment remarkably induced the negative ANI and reduced the availability of N derived from either fertilizer or indigenous soil. These results can provide helpful implications for optimizing N management practices and remaining N availability.