Which among the following are the properties of biofertilizers?

1. They liberate growth-promoting substances and vitamins and help to maintain soil fertility.

2. Increase the crop yield by 10-50%. N2 fixers reduce the depletion of soil nutrients and provide sustainability to the farming system.

3. Costly, pollution free, and based on non-renewable energy sources.

4. They improve the physical properties, tilth, and soil health.