Soil Horizon refers to the layers of soil that are formed over time through various natural processes. These layers, also known as soil horizons, are parallel to the earth's surface and can be distinguished based on their physical and chemical properties. Each horizon has a distinct composition, color, texture, and organic matter content, which differentiate it from the other layers.

Layers of Soil:

1. O Horizon:
The topmost layer, known as the O horizon, consists of organic matter such as decomposed leaves, twigs, and other plant materials. This layer is rich in nutrients and provides a favorable environment for the growth of plants.

2. A Horizon:
The A horizon, also called the topsoil, is the layer where most of the organic matter accumulates. It is usually dark in color and has a crumbly texture. This layer is crucial for plant growth as it contains essential nutrients and minerals.

3. E Horizon:
The E horizon is commonly found in some soils and is characterized by leaching. Leaching refers to the process where minerals and nutrients are washed away by water, leaving behind a light-colored layer.

4. B Horizon:
The B horizon, also known as the subsoil, lies beneath the A and E horizons. It is rich in clay and minerals that have been leached from the above layers. The B horizon often has a reddish or yellowish color due to the presence of iron and other compounds.

5. C Horizon:
The C horizon is the layer of weathered parent material that has not undergone any significant changes. It consists of partially broken rocks and minerals and serves as a transition zone between the soil and the underlying bedrock.

6. R Horizon:
The R horizon is the bedrock layer, which is made up of solid rock. This layer is not considered part of the soil and is usually not directly accessible to plant roots.

Importance of Soil Horizons:

Understanding soil horizons is crucial for various purposes, including agriculture, construction, and environmental management. The different layers have varying water-holding capacities, nutrient levels, and drainage characteristics, which influence plant growth and ecosystem functioning. By studying soil horizons, scientists and farmers can determine the suitability of a soil for specific crops, identify potential issues such as nutrient deficiencies or excesses, and implement appropriate soil management practices.

In conclusion, soil horizon refers to the layers or horizons of soil that are formed over time. These layers are distinguished based on their physical and chemical properties, and each plays a significant role in supporting plant growth and ecosystem functioning.

The layers of the soil are called Horizons.