what is the importance of bacteria in soil ecosystems (simple answers)?

Answer 1

Bacteria breaks down organic materials ( leaves, twigs, grass, dead things, etc ) to enrich soil mixture.

Answer 2

In the soil:
1. Bacteria break down dead organic matter and organic wastes, returning the nutrients to the soil.
2. Bacteria fix nitrogen, taking nitrogen gas from the air and putting it into nitrogen compounds in the soil. This is the only way plants can get the nitrogen.
3. Some bacteria also take nitrogen from the ground and put it back into the air. It's not too helpful, but it is important.