EGU23-9140, updated on 10 Jan 2024
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Small scale soil heterogeneity shows stable subsoil preferential flow paths of water and DOC over a 5 year period in a Dystric Cambisol

Sebastian Socianu1, Hanna Böhme1, Timo Leinemann1, Patrick Liebmann1, Karsten Kalbitz2, Robert Mikutta3, and Georg Guggenberger1
Sebastian Socianu et al.
  • 1Leibniz University Hannover, Institute of Soil Science, Herrenhäuser Straße 2, 30451 Hannover, Germany (
  • 2Technical University Dresden, Institute of Soil Science and Site Ecology, Pienner Straße 19, 01737 Tharandt, Germany
  • 3Martin Luther University Halle-Wittenberg, Soil Science and Soil Protection, Von-Seckendorff-Platz 3, 06120 Halle (Saale), Germany

Preferential flow paths (PFPs) are intertwined soil regions that link top and subsoil and through which water and consequently nutrients flow across the soil profile. PFPs enable newly available carbon sources to reach deeper soil layers, enabling soil microorganisms to flourish in an otherwise substrate-poor subsoil. A reliable assessment of organic carbon (OC) translocation into the subsurface requires an understanding of the small scale variability of dissolved organic carbon (DOC) concentrations and fluxes into the subsoil.

Using segmented suction plates over a 5-year period, we measured DOC and water fluxes, and subsequently OC translocation, at three depths in three soil profiles down to 1.5 m in a sandy Dystric Cambisol in Lower Saxony (Germany). DOC fluxes and water fluxes were correlated and decreased with depth. Overall fluxes were dependent on seasonal fluctuations of precipitation, with the winter and spring months bearing the highest water fluxes. We found significant flux variability between suction plates and soil depths. Rank analysis showed stable regions of high and low water and DOC fluxes, suggesting stable subsoil PFPs over these five years. Furthermore, the significance of small scale spatial heterogeneity as estimated by intraclass correlation was higher than the seasonal variability in each hydrological year, strengthening the idea that PFPs in a soil profile persist over years. In addition, SUVA analysis showed a decrease in OM aromaticity with depth in all three profiles and it was moderately correlated with water fluxes, indicating selective retention of complex organic matter along the soil profile.

These findings highlight the potential for long-term stability of PFPs in subsoils and their significance for the development and maintenance of biogeochemical subsoil C hotspots, and that small scale soil heterogeneity plays a major role in controlling water and nutrient movements across the soil profile.

How to cite: Socianu, S., Böhme, H., Leinemann, T., Liebmann, P., Kalbitz, K., Mikutta, R., and Guggenberger, G.: Small scale soil heterogeneity shows stable subsoil preferential flow paths of water and DOC over a 5 year period in a Dystric Cambisol, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9140,, 2023.