There is more life below the soil surface than there is above. This includes the burrowing animals such as moles and earthworms. Many soil creatures are not much bigger than the head of a pin. They include mites, springtails, nematodes, virus, algae, bacteria, yeast, actinomyetes, and protozoa. There are about 50 billion microbes in 1 tablespoon of soil. A typical soil may contain the following estimated number of organisms in each gram of soil:
| Bacteria | 3,000,000 to 500,000,000 |
| Actinnomycetes | 1,000,000 to 20,000,000 |
| Fungi | 5,000 to 1,000,000 |
| Yeast | 1,000 to 1,000,000 |
| Protozoa | 1,000 to 500,000 |
| Algae | 1,000 to 500,000 |
| Nematodes | 10 to 5,000 |
As soil life forms move through
the soil they create channels that improve aeration and drainage. Nematodes
and protozoa swim in the film of water around soil particles and feed
on bacteria. Mites eat fungi; fungi decompose soil organic matter. The
microorganisms' primary role is to break down organic matter to obtain
energy. They help release essential nutrients and carbon dioxide, perform
key roles in nitrogen fixation, the nitrogen and phosphorus cycles, denitrification,
immobilization and mineralization. Microbes must have a constant supply
of organic matter or their numbers will decline. Conditions that favor
soil life also promotes plant growth.
When the soil is tilled and left bare, soil life can be injured by high
temperatures. To promote soil organisms; incorporate organic matter, till
as little as possible, minimize soil compaction, maintain favorable soil
pH and fertility, and use an organic mulch on the soil surface.
Consumer Horticulture | Quick Reference
© Erv Evans, Consumer
Horticulturalist
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