The application of N-butyl Phosphorothioate Triamine and Dicyandiamide changes the soil N2O production path

This study aims to explore the effect of nitrification inhibitor combined with urease inhibitor on soil N2O emission under different nitrogen application depths. We carried out a soil column simulation test under 25°C. The combination of 1% N-butyl Phosphorothioate Triamine (NBPT) and 5% Dicyandiamide (DCD) was added to the soil. Anaerobically digested pig slurry (ADPS) was used as a nitrogen source and applied to four soil depths (soil surface (0 cm), 5 cm, 10 cm, and 15 cm, respectively). It was found that the inhibitory effects of NBPT and DCD on the soil N2O emission were significantly affected by different nitrogen application depths. When the ADPS was applied at 15 cm, 10 cm, and on the soil surface, the combination of 1% NBPT and 5% DCD could inhibit soil N2O emission by 46.1%, 21.7%, and 34.6%, respectively. Redundancy analysis (RDA) showed that the addition of inhibitors changed the microbial paths of soil N2O production. The dominant microbial path of soil N2O production after adding inhibitors was from ammonia oxidation dominated by AOB-amoA to denitrification dominated by nirS and nirK.