How does biofertilizers enrich the fertility of soil?

Explanation

### Step-by-Step Solution:

1. **Definition of Biofertilizers**: Biofertilizers are natural fertilizers that contain living microorganisms. They enhance the availability of nutrients to plants by promoting soil fertility.

2. **Role of Bacteria and Cyanobacteria**:
- Bacteria and cyanobacteria (also known as blue-green algae) are significant components of biofertilizers.
- These organisms are capable of fixing atmospheric nitrogen, which is not directly usable by plants.

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