The Horse 2020/21

EDX 4.3 Soil Biodiversity Characteristics

Soil biodiversity is the variety of life that exists within the soil, including bacteria, fungi, earthworms, and termites. A teaspoon of topsoil typically contains a vast range of different species and up to 6 billion microorganisms.

The group of large organisms in the soil is visible to the human eye. (Macroscopic)
For example:

• Plants
• soil fauna
• worms (earthworms, pot worms)
• isopods, millipedes, centipedes

The group of small organisms in the soil isn't visible to the human eye. (Microscopic)
For example:

• Soil microbes - bacteria, fungi
• microfauna (nematodes)

If we take a look at an arable field or a grassland then we see, aboveground, a few plant species: one plant species in a monocrop and up to 50 species per square meter in species-rich grassland.

Now if we look at the number of different species or the diversity, we can see the smaller the organisms the more different species there are, ranging from 10 species of earthworms to thousands of species of bacteria and fungi.

Soil life is sensitive to disturbance and compaction of soil because that affects the amount of space and air available for plant roots and other soil biotas.

It is also sensitive to chemicals that end up in the soil water, or pollution like oil spills that block access to food, air, and water. Life in soil is also sensitive to temperature and soil acidity.
Soil organisms feed directly or indirectly on plant inputs and not all species like to eat the same thing. So the type of plant you grow, like the type of crop or green manure that you add to the soil, can all influence the abundance and diversity of the soil life.