Several types of worms are commonly found in a home garden. Earthworms are scientifically classified as animals in the phylum Annelida. There are 1,800 species in this phylum. The most common worms in North America belong to the family Lumbricidae, which has 220 species. Of these, night crawlers and field worms are the most common. Red worms and manure worms are used in vermicomposting.
People pick night crawlers from fields and lawns at night and use them for fishing bait. They reproduce slowly and are not often used for commercial worm production. Worms are important in the garden because they burrow deep into the soil, bringing oxygen to communities of microorganisms that improve soil health. Worm waste materials (castings) improve the microbial activity in the soil, which improves nutrient content.
Field worms are garden worms frequently found when you lift a spade full of dirt from the ground. They burrow deeply, carrying their nutrient-rich castings to enrich the soil. Worms swallow soil or plant residue on the soil surface. Their strong muscles contract to digest the swallowed material and pass it through the digestive tract. They secrete enzymes, amino acids, sugars and other small organic molecules essential for soil health.
Red Worms and Manure Worms
Red worms are sometimes called red wigglers. Red worm and manure worms live from digesting decaying food and plants. They do not burrow deeply into the ground, as night crawlers and field worms do. Manure worms are used to make vermicompost, which is a form of compost very high in nutrients. Vermicompost has five times the levels of nitrogen as common garden soil. Red worms and worm bins are provided by many local recycling workshop programs.
Importance of Garden Worms
Garden worms in the soil and red worms in compost play important roles in the health of soil ecosystems. A University of California at Santa Cruz study on earthworm ecology states that "their feeding and burrowing activities incorporate organic residues and amendments into the soil, enhancing decomposition, humus formation, nutrient cycling, and soil structural development."
Encouraging Worms in the Garden
Red worms eat kitchen scraps that are put into a compost pile. Coffee grounds, pasta, stale bread, grass clippings and paper towels are also excellent food for red worms. Garden worms reproduce easily in dark, moist conditions. You can encourage worms by providing 2 to 3 inches of mulch as ground cover around flower beds. Some farmers set aside a small plot of land exclusively to breeding earthworms so they can be introduced into food-growing areas.