How Worms, Insects, Bacteria, Rodents and Large Mammals Help Soil

Worms

• Earthworms help create soil's structure, move its water, cycle its nutrients and create channels for plant roots to grow. They shred and move plant materials to deeper layers of soil. Earthworms eat and exude the microorganisms that create soil nutrients. Their shredding activity stimulates the microbe population by supplying their food. Worms improve soil drainage by burrowing horizontal tunnels that carry water and oxygen. Earthworms shed castings that are high in nitrogen and phosphorus, adding to the fertility of the soil. Ammonium nitrate synthetic fertilizer in soil reduces the earthworm population.

Insects

• Insects such as millipedes and sowbugs help soil by chewing and shredding plant material so it decomposes more quickly. Species such as oribatid mites feed on harmful bacteria and fungi that cause plant disease. Springtail insects are plentiful in the soil, as much as 250 million in 1 acre of land. They also prey on fungi and bacteria, converting them to minerals that are then deposited back into the soil. Insects improve soil structure by tunneling and by mixing plant materials into the layers they pass through.

Bacteria

• Bacteria are simple single-celled organisms that begin the process of decomposing plant and animal residue by beginning to dissolve it. They convert energy in organic matter into forms useful to the rest of the organisms in the soil. Some bacteria hold nitrogen in plant roots, making it available for growth. Some feed on other soil organisms, keep nutrients in the plant root zone and filter pollutants. Bacteria are capable of degrading the pollutants in soil that may harm food grown there. Composted soil transmutes pollutants such as wood preservatives, pesticides, and both chlorinated and nonchlorinated hydrocarbons.

Animals

• Moles, squirrels, rabbits, beavers, turkey and domesticated farm animals contribute to the life of soil by leaving manure and droppings on the land. Moles are insectivores that eat a variety of insects, helping to keep harmful insect pest populations under control. All burrowing mammals help incorporate essential oxygen into soil by digging tunnels. Poultry manure adds the highest nitrogen content to soil, with rabbits a close second. Large mammals in wild areas contribute to the decomposing process by walking on fallen plant materials, eating leaves and animals, and leaving their droppings.