Fertile soil has lots of humus. Why?

Fertile soil:

1. Fertile soil has a high concentration of humus because it contains microbes that decompose dead organic matter in the soil and humus formation takes place.
2. Humus is a mineral source that absorbs H₂O and allows plant roots to pass through the soil.
3. Humus is necessary for the binding of soil particles into crumbs.
4. Crumbs are important for hydration and aeration.
5. Humus contains chemicals for plant growth.