Do NO, N₂O, N₂ and CO₂ fluxes differ in soils sourced from cropland and varying riparian buffer vegetation? An...

Riparian buffers are expedient interventions for water quality functions in agricultural landscapes. However, the choice of vegetation and management affects soil microbial communities, which in turn affect nutrient cycling and the production and emission of gases such as nitric oxide (NO), nitrous oxide (N₂O), nitrogen gas (N₂) and carbon dioxide (CO₂). To investigate the potential fluxes of the above-mentioned gases, soil samples were collected from a cropland and downslope grass, willow and woodland riparian buffers from a replicated plot scale experimental facility. The soils were re-packed into cores and to investigate their potential to produce the aforementioned gases via potential denitrification, a potassium nitrate (KNO₃ ^-) and glucose (labile carbon)-containing amendment, was added prior to incubation in a specialized laboratory DENItrification System (DENIS). The resulting NO, N₂O, N₂ and CO₂ emissions were measured simultaneously, with the most NO (2.9 ± 0.31 mg NO m^-2) and N₂O (1413.4 ± 448.3 mg N₂O m^-2) generated by the grass riparian buffer and the most N₂ (698.1 ± 270.3 mg N₂ m^-2) and CO₂ (27,558.3 ± 128.9 mg CO₂ m^-2) produced by the willow riparian buffer. Thus, the results show that grass riparian buffer soils have a greater NO₃ ^- removal capacity, evidenced by their large potential denitrification rates, while the willow riparian buffers may be an effective riparian buffer as its soils potentially promote complete denitrification to N₂, especially in areas with similar conditions to the current study.