Urban Green Space Soils: Not Critically Compacted but Shaped by a Human-Pressure Gradient—Evidence From Milan, Italy

Urban soils play a crucial role in supporting ecosystem services, yet they are often overlooked or perceived as degraded. This study provides an assessment of physical and chemical properties of soils in public green spaces in Milan, Italy-a representative medium-sized European city-with particular attention to soil compaction. Sixty georeferenced plots were sampled across five categories of publicly accessible green areas differing in vegetation cover, management intensity, and human pressure. Measurements included bulk density (BD), penetration resistance (PR), pH, organic carbon (SOC), total nitrogen, available phosphorus (AvP) and texture. Milan's soils generally retained favourable ecological properties. BD was low (mean +/- sd: 1.03 +/- 0.13 g cm-3), below thresholds limiting root growth and soil biota, and PR profiles showed no critical compaction. However, BD and PR varied across categories: values were lowest in peri-urban forests and highest in central parks and urban green islands, reflecting vegetation, management, and recreational pressure differences. SOC was relatively high in the topsoil (mean +/- sd: 3.23% +/- 0.75%), supporting fertility and carbon storage, with no significant differences among categories. Conversely, pH and phosphorus varied: peri-urban sites had acidic to sub-acidic conditions and moderate AvP levels, while central parks and urban islands showed near-neutral to slightly alkaline pH and elevated AvP, indicating stronger anthropogenic influence. These findings challenge the widespread assumption that urban soils are uniformly compacted and degraded. Soils in Milan's green spaces preserve properties that sustain ecosystem services, with differences reflecting management intensity, recreational use and land-use history. The framework adopted here can be applied in other cities to guide soil protection and support sustainable urban planning.