A healthy population of earthworms leads to a healthy garden

Story and Photos by Kristi Cook

I have worms. But I wish I had more. I’m talking about earthworms, some of nature’s most significant earth healers. These creatures can do everything from aerating garden soil and improving poor soil structure to fertilizing the garden. All they ask for in return is a bit of good food, a poison-free home, and cool, moist soil.

Perhaps the most recognized benefit of earthworms is their ability to aerate and loosen soil. Some earthworms, known as topsoil dwellers (endogeic), burrow horizontally as they consume debris and soil within the first several inches of topsoil, creating a fluffy layer that’s ready for garden plantings. Subsoil dwellers (anecic), on the other hand, prefer to burrow vertically, starting at the soil surface and traveling as much as 6 feet under, providing plenty of aerated growing space for nutrient seeking roots. And last, but certainly not least, litter dwellers (epigeic) enjoy traveling around in the floor litter, moving and turning debris into smaller and smaller pieces. 

All that munching and traveling not only gets the air, carbon, and roots to moving, it gets other stuff to moving, too – worm poop. If I could have only one fertilizer, this would be it. Referred to as “castings” in polite company, worm excrement is not only sterile, but has a neutral pH that helps neutralize soil and contains up to five times the nitrogen, seven times the phosphorus, and 11 times the potash as the surrounding soil. That’s a lot of free fertilizer! Earthworms are even considerate about where they leave their little gifts. Some leave trails along their burrows where roots can access the nutrients while others place piles around burrow openings or among the litter to be filtered down through the upper soil layers as it rains.

Adding organic kitchen scraps or surplus garden produce to a home composting pile creates the perfect food for hungry earthworms. They’ll happily turn this refuse into rich, fluffy soil and fertilizer to help you grow the healthiest garden possible.

This burrowing and fertilizing is akin to a gardener’s intention with tilling. We drag out the heavy tiller each spring to break up the ground and “aerate” the soil. Then, like any good gardener, we till again to incorporate fertilizer throughout the soil so the plants’ roots can access it easily. And finally, we till yet again to get that soil into a nice, fluffy texture. Then it rains. And undoes almost everything we just did. And what we basically did was undo all the hard work the earthworms had already done for us.

There is a better way. With fear of sounding corny, it’s the earthworm way. No-till, shallow-till, and broad forking provide sustainable alternatives to deep tilling and leave the majority of the earthworms’ aerating tunnels intact, their nutrient rich castings at both the root zones and the surface, all while keeping the loose topsoil they created where it belongs – at the surface. Left undisturbed and kept alive and well, this cycle continues season after season, creating a richer, darker, healthier soil full of the type of life that easily supports substantial crops and bountiful harvests. While it does take some getting used to – as I well know – the rewards of allowing the soil to remain intact are even farther-reaching than this article can encompass.

Leaving ground uncovered not only creates an ugly landscape, but also allows erosion to take hold, nutrients to leach away, soil to become hot and brittle, and ultimately destroys earthworm populations.

But what about weeds? That’s the most common initial complaint to the alternatives I have offered here. Yet, in keeping with the needs of the earthworm community – cool, moist soil rich in organic matter – the weed problem is solved as well. Gently working the typical 1-2 inches of compost and amendments into the top couple of inches with a broad fork or very shallow tillage provides both organic matter for the soil and earthworms as well as additional crop nutrients. Followed with organic mulch, these practices not only keep the soil and worms cool, moist, and well fed, but significantly reduce weeds as well. In fact, you will likely find your weeds are fewer than in previous years due to the undisturbed soil. And of course, don’t apply synthetic pesticides, fertilizers, or herbicides in the garden if you want to keep the earthworms healthy.

Living with worms is an organic gardener’s greatest accomplishment. If you have a substantial earthworm population, you will most often find you have healthy soil followed by healthy gardens. These little wigglers are just one more key ingredient to healthful, organic, and sustainable gardening.

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