The soil profile is a vertical section of the soil from the ground surface downwards until the soil meets the bedrock and the individual distinguishable layers are called soil horizons.
Soils vary in thickness and can extend for a considerable depth as much as 4 to 5m. The soil properties in terms of composition, texture, nutrient content is not uniform throughout the entire thickness of the soil.
There are numerous ways to classify the soil layers. But the simplest scheme in dividing the layers is as follows.
Soil profile
- Horizon O
- A layer of dust and debris (Leaf, litter, & decaying lifeforms)
- Not a part of Soil Proper
- Horizon A
- Horizon A, E, and B are part of soil proper and capable of supporting plant growth.
- Topmost zone and Root Zone
- Horizon A and E - Elluviated layer - Nutrients are leached out.
- Organic materials have incorporated with mineral matter nutrients and water
- Necessary for the growth of plants
- Horizon E
- Horizon A and E - Elluviated layer - Nutrients are leached out.
- Zone of transition
- Horizon B
- Subsoil
- Zone of enrichment - Nutrients are deposited here.
- Illuviated layer.
- transition zone
- Matter from below and above
- Horizon C
- The first stage in the soil formation process
- Loose parent material (weathered)
- Large stones, boulders, and pebbles.
- It is a part of the soil. But, it is not capable of supporting plant growth.
- Horizon R/D
- Unweathered parent rock / Bedrock
