What term is used to describe the layers of soil located below the topsoil?

Subsoil refers to the layer of soil situated beneath the topsoil. It is typically denser and contains more minerals than organic matter compared to the topsoil. The subsoil plays a crucial role in plant growth as it retains moisture and nutrients that plant roots can access. It is formed from the weathering of materials found in the underlying layers and can vary in texture, composition, and depth depending on the geographic region.

Bedrock, on the other hand, is the solid rock that lies beneath the subsoil and is not considered a soil layer. Loam describes a balanced mixture of sand, silt, and clay that is ideal for growing plants but does not specifically denote a layer within the soil profile. Clay is a type of soil texture characterized by fine particles and high water retention, but like loam, it does not refer to a specific layer below the topsoil.