“Be the kind of person who takes supplements – then skip the supplements.”

Michael Pollan, “Food Rules An Eater’s Manual”

The rules Michael Pollan devised to guide eating could apply just as well to nourishing soils. Pollan, the author of “In Defense of Food” and the pithier “Food Rules,” helped distill an oppressive glut of dietary guidance into just seven words:

Eat food, not too much, mostly plants.

That adage can guide us through a bewildering maze of nutritional counsel, seeing past evidence-free claims and dead-end diets. It can also point the way toward sustaining the subterranean ecosystems that indirectly feed us, the soils in which we grow vegetables, flowers, shrubs and trees.

When Pollan counsels “eat food,” he means the unadulterated kind that your great-grandparents would recognize, rather than the highly processed and packaged items that abound today. Soils are equally at risk of ingesting too many synthetic, chemical-laden products, particularly at this season when marketers push “fall feeding” of lawns and gardens. Dubious “soil conditioners” and “turf builders” – made to sound wholesome, even necessary – rarely represent genuine food for the soil.

Many of these chemical cocktails, far from nourishing the soil, disrupt its complex networks of mychorrizal fungi and beneficial bacteria. Recognizing the dangers of chemical pesticides and commercial fertilizers, I’ve always grown plants organically. But now, I’m even becoming skeptical of natural supplements like rock mineral powders, fish emulsifiers, and meals made from alfalfa, soybeans or kelp. I start to wonder if they might be the horticultural equivalent of protein powders, with unregulated labeling claims, unknown long-term effects and potential toxins.

Research suggests that even home-brewed compost teas, crafted from local plant material, are long on promise and short on results. As with nutritional supplements for humans, evidence of lasting benefits is at best thin.

Pollan’s admonition to “eat food,” while seemingly self-evident, is surprisingly hard to follow when surrounded by what he calls “edible foodlike substances.” Try finding, when traveling, anything that remotely resembles real food at a convenience store. A similar challenge exists for gardeners in a “weed ‘n’ feed” culture that pushes chemical remedies for problems we might not even have.

This fall, for example, a number of home gardeners going in search of straw bales (for winter mulch) were advised by store personnel to buy plastic-wrapped “straw mulch with tack.” Liz Stanley, a horticultural educator with University of Maine Cooperative Extension, told me she got several calls from gardeners wanting more information about this “manufactured” mulch. Tackifiers are compounds that make straw stick together, a questionable advantage in reseeding lawns and wholly unnecessary in vegetable patches or ornamental beds. Tack can be made from natural substances like guar gum or worrisome ones like polyacrylamides (which can contain residual acrylamides, known neurotoxins).

Pollan’s principle helps reduce chemical risks by steering us away from “garden products” altogether – leaving those bags, boxes and spray bottles (especially the ones with caution labels) on store shelves. Avoiding manufactured supplements leads effortlessly to the second concept, taming our enthusiasm to fortify soils.

Just as eating “not too much” can be hard at times, gardeners are tempted to pile on immoderate supplements. Stanley reports that “Extension staff are finding soil test results that indicate overdoses of compost, potentially leading to soil pH problems, nutrient imbalances and phosphorous contamination of water.”

Even the template of soil test reports signals the need for moderation. Every major nutrient and micronutrient, along with the “organic matter” so prized by gardeners, can register at an “above optimum” level. More is not always better, for our soil any more than for ourselves.

Committing to “not too much” in feeding soils could make our gardens more self-reliant and sustainable. As earlier generations did, we could provide all that our soils need from local sources – supplying woodstove ash in lieu of well-traveled lime, and household compost in place of plastic-wrapped commercial brands.

Local soil amendments can indeed be “mostly plants,” reducing the load of mineral supplements mined and transported great distances. To feed our soils primarily from plant matter, we can grow more cover crops and green fertilizers. Rather than buying bagged (and often dyed) bark mulch, we can rely for mulch on locally processed wood chips, fallen leaves, local hay and straw or washed-up seaweed.

Pollan, while not vegetarian or vegan, advocates for meat to be treated as a condiment, rather than as a centerpiece. Extending that idea to soil, we can offer vegetable beds occasional infusions of local animal manure while recognizing that even voracious annuals can be fortified primarily from decomposing plant material and the unwitting beneficence of soil microbes.

Our gardens, like ourselves, don’t need the horticultural equivalent of multivitamins or “nutraceuticals.” I plan to feed mine local amendments, mostly plants, in moderation. From seven words to six; try that gardening manifesto on for size.

ABOUT THE WRITER

MARINA SCHAUFFLER is a freelance journalist and editor (and a volunteer Master Gardener) whose work is online at www.naturalchoices.com.

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