10.3. SOIL FORMATION

Soil is the top fertile layer of the Earth's surface where plants grow. Soil is also an ecosystem with its own biocenosis and biotope which change often. Soil consists of: 45% mineral matter, 25% water, 25% air and 5% organic matter.

A biocenosis develops within the soil, eventually transforming it into a true ecosystem.
1. Rocks are gradually broken down by the action of water and wind. The rock particles mix with other sediments.	2. Fungi, lichen and some bacteria accelerate the breakdown of rocks, creating moist clay with nutrients.	3. Herbaceous plants colonize the area, along with many invertebrates that live in the soil, like worms.	4. Tree and shrub roots penetrate the soil making it more porous, increasing soil fertility and the amount of nutrients.