Mineral deficient soil of tropical rain forests is due to:

Options

A. Slow decomposition of humus
B. Excessive leaching
C. Alkalinity in soil
D. Excess of Cation

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: The question asks why mineral-deficient soil is common in tropical rainforests. It's essential to consider the environmental conditions of these regions, particularly the high levels of rainfall.

2. **Identifying the Process**: Tropical rainforests experience heavy rainfall, which can lead to soil erosion. This erosion primarily affects the top layer of soil, which is rich in minerals.

3. **Defining Leaching**: The process by which minerals are washed away from the soil by rainwater is known as leaching. In tropical rainforests, the excessive rainfall results in significant leaching, leading to a depletion of essential minerals in the soil.

4. **Evaluating Other Options**:
- **Slow Decomposition of Humus**: This option is incorrect because humus is already decomposed organic matter, and its decomposition does not significantly affect mineral content.
- **Alkalinity of Soil**: This option is also incorrect as alkalinity does not directly lead to mineral deficiency; it is more related to the presence of certain compounds in the soil.
- **Excess of Cations**: This option is incorrect as well since cations like potassium are essential nutrients and do not contribute to mineral deficiency.

5. **Conclusion**: The correct answer to the question is that excessive leaching due to heavy rainfall is the primary reason for mineral-deficient soil in tropical rainforests.

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