Effectiveness of three nitrification inhibitors on mitigating trace gas emissions from different soil textures under...

Nitrification inhibitors (NIs) and drip irrigation are recommended to mitigate trace gas emissions from agricultural soils. However, studies comparing the effect of different NIs on the release of trace gases from soils with contrasting textures under subsurface (SBD) and surface (SD) drip irrigation are lacking. Therefore, this study aimed to assess the effectiveness of three NIs in mitigating nitrous oxide (N₂O), carbon dioxide (CO₂), and methane (CH₄) emissions from two soils with different textures under SBD, with pipe buried in 10 cm depth, and SD. Two greenhouse experiments were carried out with silt loam and loamy sand soil textures cultivated with wheat under SBD and SD to assess the effectiveness of the NIs Dicyandiamide (DCD), 3,4-Dimethylpyrazole phosphate (DMPP), and 3-Methylpyrazol combined with Triazol (MP + TZ). Ammonium sulfate was applied at a rate of 0.18 g N kg soil^-1. The measured variables were daily and cumulative N₂O-N, CO₂-C, and CH₄-C emissions, as well as soil NH₄⁺-N and NO₃^--N concentrations. The NIs and SBD had additive effects on reducing N₂O-N emissions in the silt loam, but not in the loamy sand soil texture. Under SBD, total N₂O-N emissions were 44% and 52% lower than under SD in the silt loam and loamy sand soil textures, respectively. Moreover, DMPP kept the highest NH₄⁺-N concentrations and promoted the lowest N₂O-N release. CO₂-C and CH₄-C total emissions were not affected by the treatments. Our findings supported the hypothesis that SBD decreases N₂O-N emissions relative to SD. Among the investigated NIs, DMPP has the highest effectiveness in retarding nitrification and mitigating N₂O-N release under the studied treatments. Finally, in coarse-textured soils, the use of NIs could be sufficient to significantly abate N₂O-N emissions.