Green manure is formed by

Options

A. decomposing green plants
B. decomposing algae
C. ploughing of leguminous plants into the soil
D. decomposition of the dead plants and animal wastes.

Explanation

**Step-by-Step Solution:**

1. **Definition of Green Manure**: Green manure refers to crops that are grown specifically to be plowed back into the soil to improve its fertility.

2. **Crops Used for Green Manure**: Certain crops, especially leguminous plants, are commonly used as green manure. These plants are known for their ability to fix nitrogen from the atmosphere into the soil.

3. **Role of Leguminous Plants**: When leguminous plants are grown, they not only add organic matter to the soil but also enhance the nitrogen content, which is essential for the growth of subsequent crops.

4. **Organic Matter Contribution**: Green manure is primarily composed of organic matter. It does not involve any inorganic substances, which distinguishes it from other types of fertilizers.

5. **Decomposition Process**: The process of creating green manure involves the growth of these plants, which are then plowed back into the soil while they are still green. This helps in enriching the soil with nutrients.

6. **Conclusion**: Therefore, green manure is formed by the cultivation of specific crops, particularly leguminous plants, which are then incorporated into the soil to enhance its fertility.