Get the Dirt on Soil Health in Organic Farming

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Organic farming is more often touted for what it doesn’t do — such as using toxic chemicals to suppress pests and weeds — than for what it does do: value biodiversity as much as profit margins. Soil health is always at the top of an organic farm’s priority list, a practice that goes back to the early days of organic farming.

Organic Origins

Perhaps no other movement has done more to champion soil conservation and best management practices than organic agriculture. British agriculturist Sir Albert Howard, who’s 1943 book, An Agricultural Testament, is credited with initiating the organic farming movement, advocated for soil health as the single most important factor to maintaining human health. Howard lived during the rise of large-scale, intensive, and chemically dependent farming systems that paved the way for the industrial agriculture we know today. Intensive tilling and copious chemical inputs are damaging to the soil, eventually reducing its organic matter, mineral content & microbial populations, while lowering its water-holding capacity and making it more prone to erosion. Even when this kind of farming was in its infancy, Howard foresaw the devastating effects this kind of soil depletion could have on human and ecological health. In its place, Howard envisioned and experimented with an agricultural system founded on the annual incorporation of organic matter into the soil, thus coining the term organic farming.

The Soil Food Web

Even so, soil often takes a back seat in the public conversation about food quality and safety. This is in part because soil science, it turns out, is exceptionally complex. When most of us think of soil, we think of what we can see: grainy bits of minerals, pebbles and rocks, maybe a few bugs. Very little of that looks alive to us, and none of it in the way a meadow or a forest looks lush and living. But the soil is very much alive. As Howard recognized so long ago, the healthier and more vibrant the soil, the better it is at supporting plant life and, in turn, us. Soil life is often described as a web: a series of symbiotic relationships that transform and exchange nutrients and minerals. Each organism in the soil food web acts in its own interest — sourcing and mobilizing the food it needs — but, as is always the case in a balanced ecological system, what one organism sees as a waste-product is another organism’s favorite meal.

Mycorrhizae: The Root of Plant Nutrition

Roots are a good example of the soil food web at work. They are the primary doorway through which water and nutrients enter a plant, but they are not particularly good at that task. Equal opportunity imbibers, roots absorb whatever fluids they come in contact with. When the soil around them is low in nutrients or overly dry, they cannot take in enough nutrients or water to keep the plant alive. Enter the mycorrhizae, tiny fungal strands that form a sheath around plant roots and act as their gate-keeper, selecting and transporting essential growth nutrients (such as nitrogen and phosphorous) to the plant in exchange for carbohydrates the plant produces through photosynthesis. Mycorrhizae also significantly increase the surface area of a plant’s root system, increasing its absorption ability and drought tolerance. When farmers till repeatedly and deeply (such as in intensive conventional farming) or use fungicides (aimed at reducing harmful fungi, but which kill all fungal organisms they come into contact with), mycorrhizal populations are devastated, leaving plants to fend for themselves until the mycorrhizae come back. Not long after that the farmer will till again, repeating the cycle of destruction and making the farmer more reliant on concentrated chemical nutrients to make sure the plants get enough food to grow to a harvestable size.

Soil Health and Human Health

The soil food web contains millions of relationships as essential as this partnership between roots and mycorrhizae, most of them barely understood by scientists. Some are biological, some are chemical, some are mutually supportive, some derive their benefit through competition (such as that between beneficial and disease-causing bacteria—the more good bacteria there are, the less pathogenic bacteria populations can get out of control). Though there are many mysteries left to uncover in the soil food web, one factor remains irrefutably true: the more complex a soil’s food web, the more life it can support. Under the guidance of Sir Albert Howard, organic farming subscribes to the same principle, namely by incorporating organic matter in the form of composted plant material or manures, cover crops, plant residues and even weeds to feed the soil food web. Organic matter is amazingly useful, feeding beneficial organisms (including mycorrhizae), increasing the soil’s water-holding capacity, helping to balance the soil’s pH (improving the soil’s ability to transmit nutrients), and much more. When you look at it from the ground up, it’s not so hard to believe that organically grown foods might be healthier for you—they’ve eaten better, have stronger pest resistance, and have benefited from the partnerships of millions of invisible organisms. And when you buy organic, you’re investing in more than your own health. Your dollars also go to insuring that future generations get food from living soil.

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About The Author

Sarah West has worked on small farms and local food systems since 2008, a path that has taken her from pulling weeds on an organic garlic farm in northeastern Oregon to managing a vibrant farmers market in Portland. Along the way she earned an associate's degree in Horticulture and ran her own small farm, where she learned how hard it is to make a living growing organic food. She currently lives at the foothills of the Wallowa Mountains in northeast Oregon, where she and her husband recently bought a plot of land down the road from the garlic farm where it all started.

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