Humus is formed in

Options

A. Horizon-A
B. Horizon-O
C. Horizon-B
D. Horizon-C

Answer

To answer the question "Humus is formed in," we need to understand the layers of soil and where the decomposition of organic matter primarily occurs. Here’s a step-by-step solution:

### Step 1: Understand Soil Horizons
Soil is typically divided into different layers known as horizons. The main horizons are:
- Horizon O: Organic layer, rich in organic matter.
- Horizon A: Topsoil, where organic matter mixes with minerals.
- Horizon B: Subsoil, which is less rich in organic matter.
- Horizon C: Parent material, which consists of weathered rock.

### Step 2: Identify Where Decomposition Occurs
Humus is formed through the decomposition of organic matter by microorganisms such as bacteria and fungi. This process is most active in the layers of soil that contain the highest concentration of organic material.

### Step 3: Analyze Each Horizon
- **Horizon O**: This layer is primarily composed of organic matter, including decomposed leaves and other plant materials. It is rich in microorganisms that facilitate decomposition.
- **Horizon A**: This layer, or topsoil, is where organic matter from Horizon O mixes with minerals. It also has a high concentration of microorganisms and is crucial for humus formation.
- **Horizon B**: This layer has less organic material and is primarily mineral-based, so humus formation is minimal here.
- **Horizon C**: This layer consists of weathered rock and does not contribute to humus formation.

### Step 4: Conclusion
Based on the analysis, humus is primarily formed in **Horizon O** and **Horizon A** due to the high levels of organic matter and microbial activity in these layers.

### Final Answer
Humus is formed in **Horizon O** and **Horizon A**.

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