Do Earthworms Affect Plant Growth?
- Earthworms supply the soil with nutrients from their feces, also known as casts. The worm moves throughout the soil feeding on grass, decaying roots, manure, or whatever is available. Its digestive system breaks down the organic material. The casts it leaves behind is rich in beneficial nutrients for plant life. The worm works similar to a compost heap, turning organic matter into fertilizer for the soil. Earthworms that burrow deep channels make it easier for roots to obtain additives and maintain a deep-rooted system. Dead earthworms also decay quickly, providing even more nutrients to the soil.
- The constant tunneling of earthworms creates channels and permanent burrows that turn into a natural water irrigation system. This irrigation system allows water to drain down to the plant roots. It also cuts down on soil erosion. Heavy rainfall is naturally directed into the soil through the earthworm's tunnels rather than running off.
- Earthworms continually mix top soil with lower layers as they move through the ground. The constant mixing of soil, along with the casts, distributes nutrients and contributes to a well-nourished root system. Charles Darwin estimated that it takes about 10 to 20 years for earthworms to turn over 6 inches of top soil.
- Epigeic, or surface earthworms, are small and adapt to varying temperatures and moisture conditions. Surface worms are commonly found in compost piles. Endogeic, or upper soil worms, do not make permanent burrows but live near the top of the soil. They feed on organic matter which quickly fills their channels as they move through the soil. Anecic, or deep-burrowing earthworms, are also known as "night crawlers." It will burrow several feet below the surface. They carry surface litter into the burrows and enrich the soil with trails of casts.
