What happens to the soil under heavily concreted environments? | Soil | The Guardian
Readers reply: what happens to the soil under heavily concreted environments?
What most people think of as soil exists only near the ground surface and has terrible engineering properties: whatever gets built on top settles unevenly and rain ingress can lead to swelling and erosion. So all the organic stuff containing the worms and dead leaves tends to be excavated, leaving firmer soil below to build structures on. Sadly, removing all that soil organic matter is taking quite a toll ecologically and environmentally (globally, soil is our No 2 carbon sink, after the oceans) so we need to be doing more to ensure we always return the nutrients to the earth. Ted O’Hare
If you look at the challenges faced by urban street trees, that’s probably an indication of the soil quality under heavily concreted areas. City trees grow in soil that is very depleted in nutrients due to a lack of top soil and organic matter from fallen leaves and other plant and animal debris; the soil will be much more compacted and less aerated, and surrounding surfaces are largely impermeable to oxygen and rainwater, which is also likely to be more polluted. Urban areas also act as heat islands increasing moisture evaporation. Consequently urban trees have a much shorter lifespan than suburban or rural trees, reflected by the soil quality. Mrs Lessing
