Agricultural fields are the largest source of anthropogenic emissions of the potent greenhouse gas nitrous oxide (N₂O), due to N fertilization. Formation and consumption of N₂O takes place at different depths in the soil profile, ultimately resulting in emissions from the soil surface. However, our understanding of where in the soil profile and where along water availability gradients the formation and consumption of N₂O takes place is still incomplete.

In this Ph.D. we will conduct several studies examining N₂O production and consumption in soil profiles and along different water availability gradients. In the spring of 2024, a soil column study will be commenced simulating different groundwater levels. N₂O concentrations will be measured at different levels, as well as the N₂O emissions from the soil surface. In addition, there will be measurements of O_2, water level and relevant soil biogeochemical properties (Fig.1). The set-up is also being developed to introduce stable isotope tracers.
In the spring of 2025, it is planned to commence field scale experiments and additional laboratory experiments are currently being planned and will be performed in 2024 and 2025.

As the studies in this Ph.D. have not yet commenced, it is not yet possible to display any results. However, for the column study illustrated above, it is hypothesized that:

1. N₂O production and consumption occurs near the surface of the groundwater where O₂ conditions fluctuate (Deurer et al., 2008)
2. A shallow ground water table (close to surface) promotes higher N₂O emissions from the soil surface (Dobbie & Smith, 2006).