1. O Horizon (Organic Layer):
* Found at the surface, this layer consists mainly of decomposed plant and animal matter (humus). It's rich in nutrients and dark in color.
* Types:
* O1 (Litter Layer): Freshly fallen leaves, twigs, and other organic debris.
* O2 (Decomposed Layer): Partially decomposed organic matter, still recognizable.
* O3 (Humus Layer): Highly decomposed organic matter, dark and crumbly.
2. A Horizon (Topsoil):
* The most fertile layer, a mixture of mineral particles, humus, and living organisms.
* It's where most plant roots grow and where nutrients are readily available.
* Characterized by:
* Dark color due to organic matter.
* Crumbly texture.
* High biological activity.
3. E Horizon (Eluviated Layer):
* Found in some soils, especially those with high leaching (movement of water and dissolved minerals).
* Characterized by:
* Lighter color due to the loss of organic matter and iron.
* Sandy texture.
* Often acidic.
4. B Horizon (Subsoil):
* Lies beneath the topsoil and contains more mineral particles than organic matter.
* Characterized by:
* Accumulation of clay, iron, and other minerals.
* Dense texture.
* Often red or yellow due to iron oxides.
5. C Horizon (Parent Material):
* Unconsolidated material from which the soil developed.
* Characterized by:
* Similar to the bedrock below.
* Less weathered and altered than the overlying horizons.
6. R Horizon (Bedrock):
* Solid, unweathered rock that lies beneath the soil.
* Characterized by:
* Hard and impenetrable.
Note:
* Not all soils have all these horizons. The presence and thickness of each horizon vary depending on factors like climate, parent material, vegetation, and topography.
* Soil profiles show the vertical arrangement of horizons, providing valuable information about soil development and fertility.
Understanding the different soil layers helps us better understand soil formation, fertility, and how to manage soil resources sustainably.
