Soil profile

Soil profile 

Soil profile is a vertical section of the soil that is exposed by a soil pit. A soil pit is a hole that is dug from the surface of the soil to the underlying bedrock.

Types of the soil profile 

Horizon A (Topsoil)

This is the layer that we call "topsoil". It is usually dark in colour due to human presence. It is well aerated and well drained. It consists of good crumb structure and is highly weathered and fertile. It also contains soil living organisms and usually cultivated part of soil.

Horizon B (Sub-soil)

This is the layer that we call "sub-soil". It is located below Horizon A. It has clay and mineral deposits. It accommodates few plants roots and soil organisms. It is usually poorly drained and aerated. Leached plant nutrients from topsoil accumulate in subsoil. It is less susceptible to erosion and weathering. 

Horizon C (Parental material)

This is the layer that we call "parent material/semi-watered" and is located below the Horizon B, due to the process of weathering it produces topsoil and sub-soil. It contains pieces of rocks undergoing the water process. It may contain water, which can be excessive to very deep-rooted, contain little or no humus, it is not important to plant life.

Horizon D(Bedrock)

Is what we call"bedrock", located below Horizon C. It is the deepest of all layers. Contains unbroken rocks which intact. It is where soil formation originates, it is no use to plant use and it is normally reached by boreholes.