Biofertilisers are prganisms that enrich the nutrient quality of the soil. Which of the following can be used as biofertilisers ?

Options

A. Nitrogen fixing cyanobacteria
B. Nitrogen fixing bacteria
C. Mycorrhizae
D. All of these

Answer

To determine which organisms can be used as biofertilizers, we need to analyze the given options based on their ability to enrich the nutrient quality of the soil. Biofertilizers are typically living organisms that enhance the availability of nutrients to plants, particularly nitrogen.

### Step-by-Step Solution:

1. **Understand the Definition of Biofertilizers**:
- Biofertilizers are organisms that improve soil fertility by increasing the availability of nutrients, especially nitrogen, to plants.

2. **Evaluate the First Option: Nitrogen Fixing Cyanobacteria**:
- Nitrogen-fixing cyanobacteria can convert atmospheric nitrogen into ammonia, a form of nitrogen that plants can use. This process enriches the soil and promotes plant growth.
- **Conclusion**: Nitrogen-fixing cyanobacteria can be classified as biofertilizers.

3. **Evaluate the Second Option: Nitrogen Fixing Bacteria**:
- Similar to cyanobacteria, nitrogen-fixing bacteria also convert atmospheric nitrogen into ammonia, enhancing soil nutrient quality.
- **Conclusion**: Nitrogen-fixing bacteria are also biofertilizers.

4. **Evaluate the Third Option: Mycorrhizae**:
- Mycorrhizae are fungi that form a symbiotic relationship with plant roots. They help plants absorb water and nutrients from the soil while receiving carbohydrates from the plants in return.
- **Conclusion**: Mycorrhizae can be considered biofertilizers due to their role in nutrient exchange.

5. **Final Conclusion**:
- Since all three options (nitrogen-fixing cyanobacteria, nitrogen-fixing bacteria, and mycorrhizae) enhance soil nutrient quality, they can all be classified as biofertilizers. Therefore, the correct answer includes all three.