A Soil Horizon is a distinct layer of soil that runs roughly parallel to the soil surface, each differing in physical, chemical, and biological characteristics from the layers above and below it. The vertical arrangement of these layers is called a soil profile.

Major Soil Horizons

• O Horizon - Organic layer composed of decomposed plant and animal matter (humus)

• A Horizon - Topsoil; rich in organic matter and minerals; most biological activity occurs here

• E Horizon - Eluviation layer; leached of clay, minerals, and organic matter

• B Horizon - Subsoil; accumulation of minerals, clay, and iron leached from above

• C Horizon - Partially weathered parent material; little biological activity

• R Horizon - Bedrock, the unweathered solid rock beneath all other layers

Importance of Soil Horizons:

• Helps in soil classification and mapping

• Indicates soil fertility and agricultural potential

• Guides land use planning and irrigation management

• Reflects the climate, vegetation, and geological history of an area

Understanding soil horizons is essential for sustainable agriculture, environmental science, and land management practices.