A collective and general term for the layers of soil below the uppermost layer or topsoil. It can consist of sand, silt and clay but has little, if any, humus or other organic matter. Subsoil provides structure, holds moisture, and is a good foothold for rooting plants.
A layer of soil beneath the topsoil that has lower organic content and higher concentrations of fine mineral particles; often contains soluble compounds and clay particles carried down by percolating water.
That layer of soil normally below cultivation depth but which has a great effect on the performance of the topsoil. Subsoiling is an operation where a deep cultivator runs through the subsoil at a depth of around 450 mm when the soil is dry to shatter it.
Subsoil is the layer of soil under the topsoil on the surface of the ground. The subsoil may include substances such as clay and has only been partially broken down by air, sunlight, water, etc., to produce true soil. Below the subsoil is the substratum, which can be residual bedrock, sediments, or aeolian deposits, largely unaffected by soil forming factors active in the subsoil.