Effects of land cover on subsoil physical and hydraulic properties

Land cover changes exert growing pressure on soils and can modify their physical structure and hydraulic behaviour. While the influence of land cover on erosion, compaction, and biological activity in the upper 30 cm is well documented, much less is known about how far these effects extend into deeper horizons. Here, we analyse depth-dependent variations in structural and hydraulic properties for soils of comparable texture under cropland, grassland, and forest. We used the EU-HYDI database, comprising 6,014 profiles and over 18,000 samples across Europe (36% with LUCAS land cover information). Samples were grouped by texture classes (using a modified version of the HYPRES texture triangle) and land cover independently of soil profile. For each texture X land cover combination, we fitted generalized additive models (GAMs) with depth, including random effects for data source to account for heterogeneity in analytical methods and sampling protocols. Results reveal significant differences in bulk density and θsat up to 60 cm, with consistent patterns (cropland > grassland > forest for bulk density; cropland < grassland < forest for θsat). These results show that land cover impacts are not restricted to the topsoil, highlight the lack of subsoil data, particularly for fine-textured soils and forested sites and underscores the importance of harmonized measurement procedures to improve comparability in soil hydrological studies.