- Decomposition is when a decomposer recycles / returns nutrients / nitrogen from dead organisms to the soil by eating those dead organisms
- If something is returned to a place then that something is added to that place
- So, decomposers add nitrogen to soil using decomposition

- High quality / rich / good soil has a high number of nutrients / amount of nitrogen
- Fertile soil is high in quality
- So, fertile soil is high in amount of nitrogen

- Decomposers add nitrogen to soil using decomposition
- Fertile soil is high in amount of nitrogen
- So, decomposers make fertile soil by adding nitrogen to soil

Therefore, decomposers make fertile soil by adding nitrogen to soil
Question
Decomposers increase the fertility of the soil and prevent dead organisms from building up in the environment. In which way do decomposers make the soil more fertile?

Context
- Decomposition is when a decomposer recycles / returns nutrients / nitrogen from dead organisms to the soil by eating those dead organisms 
- High quality / rich / good soil has a high number of nutrients / amount of nitrogen 
- If something is returned to a place then that something is added to that place 
- Fertile soil is high in quality