- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 10 Jan 2019
It is the weathered soil layer extending between the natural topsoil and the unweathered basal layer (geological parent material) below, or similar material on which topsoil can be spread. Subsoil has lower organic matter and plant nutrient content than topsoil. In most cases topsoils require a subsoil to perform one or a number of natural soil functions. Ref The HS2 London-West Midlands Environmental Statement, Glossary of terms and list of abbreviations, DETR 2013.
Typically, subsoil consists of the same variable mixture of minerals and small particles (e.g. sand, silt, clay) as the topsoil, but it has a much lower percentage of organic matter and humus (fine organic matter derived from the decomposition of plant and animal substances).
Subsoil tends to be paler than its overlying topsoil due to the lack of dark humus, and varies in colour from red to yellow.
The macro- and microscopic organisms that proliferate in topsoil are mostly lacking in the subsoil, although it may contain the deeper roots of some plants and trees. Water run-off results in minerals from the topsoil migrating down into the subsoil which can lead to mineral deficiencies in the topsoil. The knock-on effect of this is that roots have to dig deeper for nutrients.
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
Special educational needs: analysing the necessities for inclusion
Can we build cities that anticipate the future?
How to provide affordable, sustainable and healthy urban communities.
The government has launched an ‘Outsourcing Playbook’.
How can we ensure the benefits of off-site construction are realised?
A new theory for managing large complex projects
A vision for digital highways
Finding stone to conserve historic buildings.
If it is not planned properly even a simple activity can kill.
A disgruntled or ignored stakeholder can easily derail your hard work.
Next generation cementitious materials
Still going strong...one of the great buildings of the 20th century.