Diane Miessler: The soil food web and why you love it
Special to The Union
Do you have any idea what’s living in your back yard? Microbes. Trillions of them. And protozoa and nematodes and worms and bugs and other crawly things.
Before you call the movers, consider this: A tablespoon of healthy soil contains more microbes than there are people on Earth. Microbes are part of the soil food web, which comprises all the things that live in and on the soil. All the members of the soil food web eat and are eaten by each other, and work together to feed plants. A thriving, diverse soil food web also competes with pathogenic microbes and destructive insects, limiting the damage they do.
Gardeners know what good soil looks like: dark brown, crumbly, moist, full of worms. What many don’t know, though, is that the best way to get good soil is to be sure there’s lots of life in it. “How do you do that?” you may ask. Excellent question, alert reader.
Rototilling, a ritual beloved by gardeners, actually destroys life in your soil. Granted, tilling can chop in the weeds and other green stuff growing there, but it also chops up the soil food web. That green matter gives soil bacteria a springtime binge; in the process, however, it causes the soil food web sorrow in many ways. To wit, tilling:
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Chops up worms, most of which live near the surface of the soil.
Destroys mycorrhizae, the fragile fungal filaments (nice alliteration, right?) that serve as soil’s circulatory system. Mycorrhizae intertwine with plant roots — think hair extensions — and bring water and nutrients from much farther away than those roots could grow.
Damages soil texture. Your soil doesn’t need to be “fluffy,” which is the end result of rototilling. Soil organisms put the “crumb” in crumbly soil — they glue together soil particles (sand, silt, and clay) into aggregates — tiny bits of nutritious goodness that allow air, water, and roots to penetrate the soil, while storing water and nutrients the plant needs. Tilling pulverizes those crumbs and dries them out.
Releases carbon into the atmosphere, where it binds with oxygen in a bigamist sort of way (CO2, get it?) and floats off into the atmosphere to destroy life as we know it.
For soil to be biologically active it needs to be fed and sheltered, not chopped up. You do this by keeping it covered with mulch, cover crops or other things you plant, and by feeding it lots of organic matter.
This spring, try just loosening your soil with a digging fork, pulling up and laying down anything growing in it, and mulching heavily with straw or alfalfa hay. The mulch will kill weeds by starving them of sunlight, while it slowly rots and provides organic matter to the worms and germs below.
This is also a good time to plant cover crops — fava beans and buckwheat are a couple of my favorites. Pull up any weeds growing in your planting area, shake off the dirt, and lay them down for mulch. Scatter your cover crop generously over the area and mulch just deeply enough to keep the soil moist — two inches of loosened straw is about right. Water daily until the seeds sprout, then every couple days to keep them green and growing. The roots of those plants feed the soil creatures that feed them, improving the soil in the root zone.
Besides enriching soil, cover crops will grow into and loosen your soil, add organic matter in the form of roots, and create spaces for air and water when you pull them out. When it’s time to plant, just scoot aside your mulch, pull up and lay down any cover crops and weeds growing there, and plant like you always do. Chop in a little compost for extra credit.
What about weed seeds, you ask? In a no-till garden you can easily pull weeds out of your soft, mulched soil and lay them down on top. They’ll eventually compost into the soil, feeding the community living there.
As you thumb through seed catalogs and envision your garden, envision buying a bale of straw or alfalfa hay and giving the soil food web a head start. Your plants, and your worms, will thank you.
Diane Miessler is a certified permaculture designer; her book, Grow Your Soil, is now available at The Bookseller and Harmony Books, as well as on Amazon. She lives in Nevada City with her husband and an ill-behaved, shoe-chewing but cute new dog.
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