What does subsoil mean?
Subsoil is the layer of soil lying directly beneath the topsoil, the cultivated and usually most fertile part of the ground. It commonly contains more clay and mineral material, together with some organic matter, and may be denser or less permeable than the surface soil. Farmers distinguish subsoil from topsoil when discussing drainage, erosion, tillage, and the depth of plant roots. The word also has a metaphorical use for a hidden supporting level beneath the visible surface of something such as an economy, organization, or community. In that sense, subsoil suggests a foundation that is less visible and often less immediately productive but can still influence what happens above it. The standard plural is subsoils.
The layer of soil lying immediately beneath the topsoil, typically denser and less fertile than the surface soil.
"Moisture retained in the subsoil helps sustain the orchard during dry periods."
Also used figuratively for a hidden underlying foundation or level.
To plough or break the subsoil, especially for aeration or drainage.
"The farmer subsoiled the field before sowing the winter crop."
This is a specialized agricultural verb and is relatively uncommon in general speech.
Used when referring to distinct layers of subsoil in different locations or geological contexts.
"Samples from the region's subsoils showed unusually high mineral content."
Subsoil is the soil's hidden middle layer: less glamorous than topsoil, but often where water and roots find their way.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does subsoil come from?
Subsoil was formed within English by combining the Latin prefix sub- meaning “under” with soil. The prefix sub- appears in many English borrowings from Latin and is also the source of English words such as submarine, subterranean, and subordinate. The compound emphasizes the soil located beneath the surface layer.
Related word forms
How subsoil is actually used
The term is mainly used in agriculture, geology, and land management. In general writing, it may be used metaphorically for a hidden foundation or the less visible levels of a society or organization.
Easily confused with subsoil
Topsoil is the fertile uppermost layer of soil, whereas subsoil is the denser layer directly beneath it.