The Secret World of Soil

The Secret World of Soil
Images by Carole Topalian

Images by Carole Topalian

By Andrea Bellamy -

Soil, in many ways, is a mystery even to those of us who spend a lot of time up to our wrists in it. We rub elbows with the most common—and visible—denizens of the world: the earthworms, millipedes, and grubs usually disturbed (sometimes fatally) by our trowels. And while we may harbour vague ideas of a richly layered subterranean world inhabited by countless microorganisms endlessly moving through the cycle of decay and regeneration, it’s hard to fathom just how much impact soil—and its occupants—has on the success of our gardens.

A garden’s success is typically measured in terms of utility and beauty, by bushels of tomatoes produced and spasms of pleasure evoked in passersby. But what if the pinnacle of achievement in a lifetime of gardening isn’t a glorious perennial border but the earth beneath it? What if, instead of weighing vegetables produced we should be counting earthworms?

Gardeners often talk about growing soil, not plants. There’s no faking good soil, and there are no shortcuts. If you garden—and particularly if you’re growing food—soil is way more than just the medium in which to sow your seeds. Soil feeds plants, and plant health is wholly dependent on it.

Chemical fertilizers are big business. Like Red Bull for plants, they provide energy (quick growth) but do nothing to build the long-term health of either plant or soil, and in fact have been shown to negatively impact soil life. On the other hand, organic-matter-based fertilizers such as manure and compost are the equivalent of whole foods, building soil quality and contributing to sustained growth by feeding the organisms that live in our soil. There’s just no substitute for soil that’s rich in organic matter.

I learned this the hard way, of course. I’m prone to busyness and “it’s good enough”-ness, which, as a container grower, led to disappointing results (container potting soil is typically poor in nutrients and organic matter, and needs to be supplemented to support plant growth, something I failed to grasp early on). Now that I grow mostly in the ground, where worms pick up the slack, I’ve learned to walk the line between too much intervention and too little. It comes down to this: protect your soil (from winter rains, over use, chemical fertilizers, and compaction) and feed it with nutrient-rich organic matter.

Part of this equation involves going easy on demand: don’t plant the same demanding crops such as broccoli in the same bed year after year and expect your soil to keep up. One traditional way to address this is to rotate groups of plants (growing roots, brassicas, and legumes in succession, for example) so that the same nutrients aren’t being depleted by the same crops.

Another way is to use a cover crop as part of your rotation. Cover crops (also known as green manure) are typically planted in empty beds or around overwintering vegetables in late summer or fall to protect exposed earth against winter rains that wash away soil and nutrients. In spring, these grasses and legumes can be tilled under to decompose in situ, infusing the soil with vital organic matter, or cropped short and smothered with a layer of compost or manure before planting annual veggie crops.

More and more I favour the latter: a low-till method of bed preparation that is said to be less disruptive to the microbe population in the soil. The more we dig, the no-till theory goes, the more we destroy existing organic matter and disrupt the slow-and-steady work of earthworms, fungi, and bacteria—which, let’s face it, are more skilled decomposers and soil-builders than humans.

Studies show that healthy soils are better at sequestering carbon dioxide. So caring for our soil may not be good only for our carrots and roses, but our species too. Next time you turn over a spadeful of earth, give thanks to the creatures you see (and those you don’t). And ask what they need to keep doing their good work.

Andrea Bellamy is the gardener behind and author of Small-Space Vegetable Gardens: Growing Great Edibles in Containers, Raised Beds, and Small Plots.