Work

What can be done with de-sealed urban soil? A multidisciplinary case study in northern Germany

Year: 2026

Type: article

Abstract: Within urban settings, soil sealing is one of the most degrading forms of anthropogenic alteration, affecting all pedosphere ecosystem services. To address this issue, we present an interdisciplinary study in which physical, chemical, biological, and mechanical properties of soil sealed for 10 years were analyzed to evaluate the extend of anthropogenic impacts. Disturbed and undisturbed soil samples were collected from the edge and the center of a freshly de-sealed site, as well as from an adjacent green reference area, at depths of 15–20 cm and 40–50 cm. The analyses revealed an increase in soil pH from 6.0–6.4 in the reference profiles to 8.1–8.6 in the de-sealed soils. Electrical conductivity in the edge subsoil reached 341 µS cm−1, compared to 31–53 µS cm−1 in the reference. Total nitrogen declined from 1.31 mg kg−1 in the reference topsoil to 0.17–0.44 mg kg−1 under sealed conditions, while C/N ratios increased, reaching 78 at the edge compared to 15 in the reference. Organic carbon decreased in the lower layers from 0.44 mg kg−1 (reference) to 0.03–1.03 mg kg−1 (center). Bacterial and fungal counts dropped from 6.6×105 CFU g−1 (reference) to 9–51 CFU g−1, and from 8.2×104 CFU g−1 (edge) to 1–3 CFU g−1 (center), respectively. Bulk density increased in the de-sealed subsoil from 1.57 g cm−3 (reference) to 1.84 g cm−3 (center). Saturated hydraulic conductivity of the topsoil decreased from 1,157 (reference) to 543 cm d−1 (center). In the de-sealed subsoil field capacity decreased from 0.38 to 0.16 cm3 cm−3. CT imaging revealed extensive fracture networks and debris-rich matrices that differed between sampling locations. Exchange appeared at the edges, which served as a transitional zone, whereas the central part remained dense, isolated, and biologically inactive. The obtained data were used for modelling various scenarios aimed at restoring soil ecosystem services. Results show that lower water storage capacity in the de-sealed soil increases hydraulic stress, elevates percentage loss of conductivity (PLC), and may lead to drought-induced mortality under extreme conditions, while the reference soil supports higher transpiration and cooling potential. These findings suggest that soil hydraulic properties critically constrain early-stage vegetation establishment in de-sealed urban environments and should be considered in restoration strategies.

Source: Geoderma

DOI: 10.1016/j.geoderma.2026.117916