Which organism is most useful for soil fertility

Options

A. Algae
B. Fungi
C. Bacteria
D. Bacterio phage

Answer

**Step-by-Step Solution:**

1. **Understanding Soil Fertility**: Soil fertility refers to the ability of soil to provide essential nutrients to plants. It is crucial for agricultural productivity and ecosystem health.

2. **Identifying Organisms**: The question provides four options: algae, fungi, bacteria, and bacteriophage. We need to evaluate the role of each in enhancing soil fertility.

3. **Role of Bacteria**:
- Certain bacteria, particularly nitrogen-fixing bacteria, play a significant role in soil fertility.
- These bacteria can fix atmospheric nitrogen (which is inert and not usable by plants) into a more usable form, such as ammonia.
- This process enriches the soil with nitrogen, which is an essential nutrient for plant growth.

4. **Role of Algae**:
- Algae contribute to soil fertility by increasing organic carbon content when they decompose.
- However, their impact is not as direct or significant as that of nitrogen-fixing bacteria.

5. **Role of Fungi**:
- Mycorrhizal fungi form symbiotic relationships with the roots of higher plants.
- They help in nutrient absorption, including nitrogen, but their primary role is not direct nitrogen fixation.

6. **Role of Bacteriophage**:
- Bacteriophages are viruses that infect bacteria and do not contribute to soil fertility. Their role is more related to controlling bacterial populations rather than enhancing soil nutrient content.

7. **Conclusion**: After evaluating the roles of the organisms, the most useful organism for soil fertility is **bacteria**, particularly nitrogen-fixing bacteria.

**Final Answer**: Bacteria

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