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- Each quize will have 20 mcqs & 30 sec time to attempt each question
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📌 SOIL PROFILE 📌
✅The vertical section of the soil showing the various layers from the surface unaffected parent material is known as a soil profile.
✅The various layers are known as horizons. A soil profile contains three main horizons.
✅They are named as horizon A, horizon B and horizon C.
✅The surface layer of soil which is liable to leaching and from which some soil constituents have been removed is known as horizon A or the horizon of eluviation.
✅The intermediate layer in which the materials leached from horizon A have been re-deposited is known as horizon B or the horizon of illuviation.
✅The parent material from which the soil is formed is known as horizon C.
✅The layers resulting from the soil forming process are grouped under five heads: O, A, E,B & C and all these horizons in combination are called master horizons.
✅Horizon A, E & B together called Solum.
✅Regolith- The unconsolidated product of rock by weathering above the earth's surface i.e. bed rock (A+B+C horizon).
✅O-horizon:
It is called as organic horizon. It is formed in the upper part of the mineral soil, dominated by fresh or partly decomposed organic materials.
It is generally found in forest areas.
Such O-horizon is visible in virgin soil and absent in arable soils.
✅A-horizon:
Horizon of organic matter accumulation adjacent to surface and that has lost clay, iron and aluminium (Eluvial horizon).
☑️A-horizon having sub horizons:
☑️A1: It is top most mineral horizon, containing strong admixture of humified organic matter and darker in colour than that of lower horizons due to organic matter.
☑️E or A2: Horizon of maximum eluviation of clay, iron and aluminum oxides and organic matter.
☑️A3: A transitional layer between A and B horizons with more dominated properties of A1 or A2 above than the underlying B horizon. This horizon is sometimes absent.
✅B-horizon:
Horizon of maximum accumulation of materials such as clay, iron and aluminium oxide (Illuvial horizon).
This horizon some time also referred to as subsoil.
It can't be cultivated by tillage operation.
✅C-horizon:
It is unconsolidated material underlying the solum (A+B).
It is zone of least weathering.
It may contain accumulation of carbonates or sulphates, calcium and magnesium.
✅R- Horizon:
Underlying consolidated bed rock and it may or may not be like the parent rock from which the solum is formed.
You'll have 30 second to answer each MCQ.
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