Soil Profile – Microbz Soil

Microbz Soil

Soil structure

If you were to dig a big hole in the ground, you will be able to notice the various layers of soil types that are beneath us.

The cross-section view is called a soil profile which is made up of layers running parallel to the surface, called soil horizons. Each horizon can be very or slightly different to the layer that is above or below it but each one has an important part to play in the soil ecosystems. Most soils gave three major horizons; Horizon A, Horizon B and Horizon C. There is also Horizon O, E and Horizon R.

The O Horizon
The O horizon is very common in many surfaces with lots of vegetation cover. This is the layer which is made up of organic materials such as dead leaves and twigs. It has about 20% organic matter and it is the layer in which the roots of small grass are found. It is also often dark in colour being either black or dark brown.

The A Horizon The A Horizon can sometimes be visible when the O Horizon is not, and it is often referred to as topsoil and also known as the root zone. It is the top layer soils for many grasslands and agriculture lands. This layer is usually made up of sand, silt and clay with a large amount of organic matter. This layer is also the most vulnerable to wind and water erosion.

The E Horizon
The E Horizon is below the O and A Horizons and is rich in nutrients that are leached from the top two layers. It has a lower clay content and is common in forested lands. It is usually lighter in colour.

The B Horizon
The B Horizon is similar to the E Horizon and contains high levels of silicate clay, iron, aluminium and carbonates. This layer is formed below the O, A and E Horizons and if also known as the illuviation zone due to the accumulation of minerals. This is the layer in which the roots of big trees end.

The C Horizon
This layer is mainly made up of broken bedrock and no organic material meaning it lacks all the properties of the layers above it. It has cemented sediment and geologic material. Little activity takes place here although additions and losses of soluble material occur here. This layer is also called saprolite.

The R Horizon
This layer is bedrock, material, compacted and cemented by the weight of the above layers. This layer is the unweathered parent material and certain rock types are found here such as granite, basalt and limestone.