The ground around us is riddled with a hidden network of tunnels, crossing every which way mere inches below our feet.
While humans have been the creators of some elaborate tunnels including the Channel Tunnel linking England to France and the New York City subway system which costs millions of dollars a year just to maintain, we’re quite late to the party. In fact, some of the world’s oldest and most impactful diggers are well known to nature lovers and city slickers alike.
Earthworms of all shapes and sizes are constantly moving throughout much of the soil on Earth, working their way underneath garden and turf alike and improving the soil as they go. While some might negatively view worms based on their slimy and wriggly appearance, exercise restraint when judging them based on their wormy demeanor. If it wasn’t for earthworms, our soil and in effect the world as we know it would be very different indeed.
Earthworms are by and large the main contributors to soil tunneling, and the average yard in the U.S. is home to more than 900,000 earthworms. Earthworms are split up into three groups depending on where they live, with some living in leaf litter and compost at the very surface of the soil, some burrowing down into permanent burrows 6 feet deep, and the rest taking up residence in the first foot or so of soil.
Feeding on microscopic organisms and decaying matter in the soil, worms are constantly eating as they go and at the same time constantly pooping. This is a good thing, as the waste worms leave behind is incredibly high in nutrients. As these animals eat their way through their surroundings, particularly resilient foodstuffs are run through tiny gizzards to help grind them down.
Earthworms condense many of the nutrients in decaying matter such as leaf litter, leaving much of it behind in easily accessible forms. Earthworms are also chock full of microorganisms. As soil passes through them, it’s filled with these beneficial microbes, which then grow and enrich the surrounding areas. Some of these microbes are then later consumed by worms in a respectable form of sustainable food.
The tunnels that earthworms construct tend to be excellent locations for root growth as they are basically areas of loosened, nutritious soil. Stormwater is also able to percolate through the soil using earthworm tunnels, and studies have shown that having sufficient earthworms in an area contributes towards reducing and controlling stormwater runoff. Earthworms primarily feed in areas rich in decaying matter in the uppermost layers of soil.
A very easy way to promote populations of earthworms in your area is to leave leaf litter wherever possible. As the leaves decay over the following season, you will be surprised at the amount of earthworms showing up to provide your property with some free fertilization.
There are estimated to be more than 180 earthworm species found in the U.S., but there are also a large number of potentially destructive introduced species as well. For this reason I generally recommend against buying worms in stores or online in order to supplement your garden. Also avoid dumping any leftover fishing bait into surrounding environments. Maintaining areas of leaf litter will bring in worms from the surrounding environment to enrich your soils. Many North American native plants also have roots that grow especially deep, which can help establish underground worm hideouts.
Tilling the soil is also fairly destructive to local worm populations, not only by unearthing them but by disrupting fungal networks that they rely on for food.
Brannen Basham and his wife, Jill Jacobs, operate Spriggly’s Beescaping, a business dedicated to the preservation of pollinators. He can be reached at firstname.lastname@example.org.