Soil vs dirt: What exactly is the difference? Although I'm not certain that there's a scientific distinction between the two, the general consensus among gardeners is that while dirt is something that stains your clothes, soil is alive. I’ve attended many great presentations on the critical role soil plays in creating a healthy, thriving garden, but one of the best explanations came from Dr. Elaine Ingham and the Soil Foodweb, Inc., who introduced me to the Poop Loop.
The Poop Loop describes the interactive cycle that occurs between plants, organic matter, and all the critters that exist in your garden – from the tiny soil predators that can’t be seen without a microscope to the earthworms we all love to uncover when we turn over a patch of dirt in our gardens.
How cool is that?
Of course, the Poop Loop explains only part of the story of the soil food web. In addition to all that decomposing, excreting and dying your soil’s tenants are busy doing, organisms like mychorrhizal fungi are forming complex mutually beneficial relationships with your plants' roots. In essence, the roots send out a message that beneficial mycorrhizae interpret as “come on over, the drinks are on me!” Why are plants willing to share some of their hard-won photosynthesized energy through their roots? Because when they belly up to the bar, the mycorrhizae occupy space that would otherwise be taken up by any disease-causing organisms that might be wandering by. Furthermore, mycorrhizae play a role in binding soil aggregates, thereby benefiting soil structure (sorry, can't think of a bar analogy for that part).
What I imagine a plant root looks like to a thirsty mycorrhizae
While many of us have come to understand that pesticides are bad for the longterm health of our gardens, we’ve tended to overlook the effect of fertilizers. When artificial nutrients are introduced, this amazingly complex series of relationships that are happening in a garden's soil are disrupted. Plants absorb the nitrogen and other nutrients stored and released via these organisms much more efficiently than from inorganic sources like fertilizer. A nutritionist will tell you whole foods are a superior fuel for our bodies than processed "health" foods like power bars and energy drinks – the same idea holds true for plants.
So if you want healthy plants, begin with healthy soil. And don’t automatically reach for the fertilizer box – organic compost is one of the best thing you can do to for your garden.