O horizon

Definition

The O horizon, also known as the organic horizon, is the topmost layer of soil that consists mainly of organic matter such as decomposed leaves, twigs, and other plant materials. It is rich in nutrients and plays a crucial role in supporting plant growth.

Related terms

A horizon: The A horizon, or topsoil, is the layer below the O horizon that contains a mixture of organic matter and minerals. It is where most plant roots are found.

B horizon: The B horizon, or subsoil, lies beneath the A horizon and consists of accumulated minerals leached from above. It often has a different color or texture than the layers above it.

C horizon:

The C horizon represents the parent material from which soil forms. It consists of weathered rock fragments with little to no organic matter.