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Question
What is the soil profile? Explain the characters of different soil horizons.
Solution
| Horizon | Description |
| O-Horizon (Organic horizon) Humus SamacheerKalvi.Guru | It consists of fresh or partially decomposed organic matter. 01 - Freshly fallen leaves, twigs, flowers, and fruits. O2 - Dead plants, animals, and their excreta decomposed by micro-organisms. Usually absent in agricultural and deserts. |
| A-Horizon (Leached horizon) Topsoil - Often rich in humus and minerals. | It consists of topsoil with humus, living creatures, and in-organic minerals. A1 - Dark and rich in organic matter because of the mixture of organic and mineral matters. A2 - Light-colored layer with large-sized mineral particles. |
| B-Horizon (Accumulation horizon) (Subsoil - Poor in humus, rich in minerals) | It consists of iron, aluminum, and silica-rich clay organic compounds. |
| C - Horizon (Partially weathered horizon) Weathered rock Fragments - Little or no plant or animal life. | It consists of parent materials of soil, composed of a little amount of organic matter without life forms. |
| R Horizon (Parent material) Bedrock | It is a parent bedrock upon which underground water is found. |
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