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How Earthworms Break Down Cellulose in Wood Chips

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You may think worms are gross, but several thousand species of earthworms benefit people in many surprising ways. Earthworms consume and break down organic matter, including plant cellulose such as that in wood chips, and the resulting waste provides a nutrient-rich environment for crops. Earthworms living in just 1 acre of land can recycle as much as 5 tons of soil per year. Earthworms also speed up the process of turning organic waste into usable compost.

Earthworm Digestion

In a compost bin, worms consumes both organic waste and wood chips if you use them for bedding. An earthworm doesn't have teeth; instead, the worm breaks down tough cellulose fibers with the assistance of bacteria and fungi in its digestive system. While the bacteria take care of digestion, the fungi break down the cellulose so it passes through the worm. The worm's gizzard grinds food into finer particles, which like a bird's gizzard contains hard sand grains and minerals. This efficient process enables the worm to consume as much as half his weight per day in organic material.

Garbage In, Garbage Out

Undigested material like soil passes through the worm's long intestine to be excreted as castings. Castings, also called worm manure, have great value to farmers and gardeners for soil enrichment. Each worm can produce castings equal to his own weight on a daily basis. Worm castings contain many nutrients that plants need for healthy growth, and may contain between 5 and 11 times more nitrogen, phosphorus and potassium than the earth in which crops are sewn.


Earthworms can be the most valuable physical decomposers in a vermicomposting system. The worms useful for composting aren't the usual earthworms you'd find in the garden. The best species for vermicomposting are brandling worms (Eisencia foetida) and red wrigglers (Lumbricus rubellus), which typically thrive in old piles of manure. Their efficient processing of agricultural and organic waste material produces a rich vermicompost that's useful both as mulch and in potting soil mixes. Vermicompost has a higher nutritional content than the average gardening soil mixes and is particularly helpful for starting new seedlings.

Energy Efficiency

The earthworm's unique process of breaking down cellulose prompted the U.S. Department of Energy to study the microbes and bacteria in earthworm digestive systems. Learning how an earthworm uses bacteria and fungi to break down cellulose could benefit the search for economical alternate energy resources. Plant cellulose could be used to produce ethanol, but this effort has been slowed by the expensive and inefficient processes used to break down cellulose. The potential to synthesize the process that worms use could increase the viability of cellulosic ethanol as an economic biofuel.