- 1University of Copenhagen, Department of Geosciences and Natural Resource Management, Geography, København, Denmark (yliu@ign.ku.dk)
- 2Chair of Soil Science, Institute of Ecology, Technische Universität Berlin, Ernst-Reuter-Platz 1, 10587 Berlin, Germany
- 3Department of Renewable Resources, University of Alberta, Edmonton, Canada
- 4Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research (IMK-IFU), 82467 Garmisch-Partenkirchen, Germany
- 5Department of Plant and Environment Science, University of Copenhagen, 2630, Taastrup, Denmark
- 6CIRAD, UMR Eco&Sols, Montpellier, France
- 7Eco&Sols, University of Montpellier, CIRAD, INRAe, Institut Agro, IRD, Montpellier, France
Nitrous oxide emissions from agricultural land largely contribute to the greenhouse gas budget worldwide. Denmark’s glacial landscape has widespread small scale topographic depressions, typically flooded for 1-3 months per year. These depressions within agricultural land are considered as hotspots of N2O emissions, because of exposure to an increased nitrate availability and labile carbon due to fertilization and deposition of eroded soil material. Temporal waterlogging in these depression areas affects plant development, thus their ability to deplete available nitrogen in soil. Additionally, living plants provide substrates for denitrification through root exudates. However, the effect of living plants and roots on N2O emissions from glacial depressions is not very clear yet.
In this study, we aimed to elucidate how waterlogging influences nitrogen uptake and dissolved organic carbon (DOC) release from plants at different root growth stages, and to quantify how this would affect N2O emissions. We conducted a fully crossed mesocosm experiment with depression soils subjected to saturated or freely-drained water conditions, three different wheat growth stages to mimic possible different root N uptake, and an unplanted control. In order to differentiate how much N2O was produced from newly-added fertilizer, we applied a 15N tracer. For monitoring root development, roots were imaged through the translucent mesocosm walls on a weekly basis.
The growth stage of wheat significantly influenced the fate of mineral nitrogen and the dynamic of DOC in the soil solution, thereby affecting N2O emissions from these soil systems. The interaction between DOC and mineral nitrogen explained 53.9% of the variance in daily N2O fluxes. Therefore, these findings highlight the critical role of root development and soil water conditions in regulating N2O emissions from conditions representative for glacial depressions.
How to cite: Liu, Y., Kemmann, B., Ambus, P., Elberling, B., Dannenmann4, M., Thorup-Kristensen, K., W. Mueller, C., and M.N. Poultney, D.: How wheat root development can determine denitrification rates in soils of glacial depressions in Eastern Denmark, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7595, https://doi.org/10.5194/egusphere-egu25-7595, 2025.
