What are the Layers of Soil?
Bed rock Humus soil horizons Soil layers Sub-Soil Top Soil
Soil is a living, breathing, natural entity composed of soilds, liquids and gases. It has five major functions:
Ø Provides a habitat for organisms
Ø Filters water
Ø Provides a medium for plant growth
Ø Recycles waste products
Ø Serves as an engineering material
An Ideal soil for plant growth contains 50% pore space and 50% solids with the pore space filled with equal parts of air and water.
Given below is a vertical section of the soil that depicts all its horizons which extends from soil surface to parent material:
| S.No | Horizon | Layer Composition |
| 1 | O(humus/organic) | Surface horizon contain various organic matter mainly decomposing leaves and differs from place to place |
| 2 | A ( Top Soil ) | Surface horizon contains minerals such as sand, silt and clay and organic matter. Found mostly in the surface layer of Agricultural lands and grasslands. |
| 3 | E(eluviated horizon) | Sub-surface horizon where the soils are leached. Missing in some soil but mostly found in older and forest soils. |
| 4 | B(sub– soil) | Sub-surface horizon that holds the minerals leached from the above horizons. |
| 5 | C(parent material) | Sub-surface horizon, the deposits at earth’s surface from which the soil is developed |
| 6 | R (bedrock) | Mass of rocks such as granite, lime stone or sand stone that forms the parent material for some soils. |
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