Worm castings are rich in

Options

A. Nitrogen
B. Phosphorus
C. Calcium
D. All the above

Answer

**Step-by-Step Solution:**

1. **Understanding Worm Castings**: Worm castings, also known as vermicast, are the organic matter excreted by earthworms. They are known for their rich nutrient content and are often used as a natural fertilizer in gardening and agriculture.

2. **Nutrient Composition**: Worm castings are particularly noted for being rich in water-soluble nutrients. This means that they can easily be absorbed by plants, making them an excellent addition to soil.

3. **Key Nutrients**: The key nutrients found in worm castings include:
- **Nitrogen (N)**: Essential for plant growth and development, particularly for leaf and stem growth.
- **Phosphorus (P)**: Important for root development and flowering.
- **Calcium (Ca)**: Vital for cell wall structure and growth.
- Additionally, worm castings also contain potassium (K) and magnesium (Mg), among other minerals.

4. **Comparative Analysis**: It is noted that worm castings contain more than 50% humus compared to what is typically found in topsoil. Humus is crucial for soil health as it improves soil structure, water retention, and nutrient availability.

5. **Conclusion**: Since worm castings are rich in all the mentioned nutrients (nitrogen, phosphorus, calcium, and others), the correct answer to the question is option D: All of the above.

**Final Answer**: D. All of the above.

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