Lesson 5: The Functions of Soils in an Ecosystem

First, soil acts as a medium for plant growth. It acts as physical support for the plant, keeping it upright. Deeper soils provide better support to plants. Trees planted in shallow soils are often uprooted by winds. 

Second, soil stores water for plants to use when they need it. The leaves of green plants produce food through photosynthesis. During this process, the leaves lose water to the atmosphere. Plants need a continuous supply of water to replace the water they lose so that photosynthesis can continue.

Third, the soil acts as a ventilation shaft that allows carbon dioxide to leave, and oxygen to enter, the soil. Most plant roots give off carbon dioxide and take up oxygen.

Soil also controls temperature fluctuations. In hot weather, the temperature at the surface of the soil may exceed 40ºC, which would kill most plant roots. The temperature a few centimetres down into the soil is lower, which allows the roots to function better than they can at high temperatures.

Last, the soil acts as a habitat for living things (organisms). Soil contains millions of organisms from thousands of species, including earthworms, nematodes, fungi, algae, and microorganisms. These organisms break down dead plant and animal material to form humus, which makes soil more fertile.