Back Forty: Why soil matters
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By Samuel Fromartz
About two years ago, in my inner-city plot, I began practicing no-till vegetable gardening — that is, minimizing the disturbance of the earth to build up soil carbon. Having gardened organically for more than two decades, I’d always added compost to my beds. I also planted cover crops that later decomposed where they grew, further building fertility. But now, with no till, I was taking the final step toward “regenerative agriculture.”
The results of this one change were dramatic and immediate. By following the principle of minimizing soil tillage in combination with compost and cover crops, I had fewer weeds and very healthy crops. I was also building up soil carbon in a way that fed microbes, which in turn were delivering nutrients to my plants.
By focusing on the soil, I was following a long tradition, one that reached back to those who articulated the principles of organic farming a century ago. First in Europe and later in the U.S., these organic pioneers linked healthy soil to healthy plants, healthy animals, and ultimately to healthy food. But while those early practitioners observed this connection, they didn’t know the precise processes at work, because science hadn’t caught up.
A seminal moment in this movement occurred in 1939, when a panel of British experts concluded that something was amiss in the English diet. Although people were living longer, they were less healthy, with maladies like bad teeth, rickets, anemia and digestive problems. The cause, the panel believed, was a diet heavy on refined white bread, tinned meat, jam, tea, sugar, and boiled vegetables. Fresh foods were lacking.
The experts also had observed that in areas of the then far-flung British Empire, where people ate traditional diets and avoided heavily processed foods, the populations had fewer health issues.
These early researchers noticed something else: Synthetic nitrogen, introduced in the late 19th century to boost crop production, did feed plants but it also depleted the soil. Nitrogen was then being widely adopted as the latest advance in progressive agriculture. But the soil proponents thought the approach was faulty. By eschewing chemical fertilizers and focusing instead on soil health, farmers would have healthier crops. One of the proponents, Eve Balfour, a founder of Britain’s Soil Association, concluded that “any Public Health system of the future would have to be based on soil fertility.”
The problem was that soil science was in its infancy, which meant that the more reductive framework held sway. More inputs, such as fertilizer, meant more output, such as bushels per acre. The organic pioneers were dismissed as charlatans who spurned the most progressive farming methods of the day, namely the widespread use of chemical inputs.
David Montgomery and Anne Biklé recount this history in their new book, “What Your Food Ate: How to Heal our Land and Reclaim our Health” (Norton), drawing the connections to regenerative farming today. Montgomery, a professor at the University of Washington, and Biklé, a biologist, say it took “decades for advances in soil microbiology to confirm links and fill in mechanisms for the favorable effects” that these soil pioneers observed. Then they explain in exquisite detail how it all works.
At the root of it, literally, is soil biology, where unseen networks of fungi and bacteria live in a symbiotic relationship with plants, each feeding the other — at least in healthy soil. One shovel full of soil can contain miles of mycorrhizal fungi filaments, “making for a vast underground nutrient mining and transportation system,” the authors write. Those soil workers and their networks deliver minerals and other nutrients to plants. In return, plants photosynthesize sunlight to produce carbon, feeding the microorganisms through their roots.
With this microbial workforce, plants ingest minerals and nutrients. Thus fortified, they produce phytochemicals that can repel pests and diseases and benefit human health when the crops are eaten. So far 50,000 phytochemicals have been identified, among them lycopene in tomatoes, anthocyanins in berries, and quercetin in onions and broccoli, just a few of those associated with health benefits.
But in farming, such a system has to be created intentionally. Forestlands have this closed symbiotic system in place, which is one reason farmers burn down trees, till the soil and plant crops. The soil — at least for the first few years — is quite rich. But without nurturing the soil, farmers must either add ever greater amounts of fertilizer or move on, burning more trees to establish new crop fields. That is one reason why farmers went west in the Colonial era — tobacco plantations had denuded soils in the mid-Atlantic and South — and why farmers are burning through the Amazon rainforest today.
These depleted farms can be brought back to health, but it takes time. I experienced the same thing in my garden, which was established on the site of a former playground. It took years and probably tons of compost to build up the soil to where it is today. I have a relatively high amount of 12 percent organic matter in the soil, essentially carbon and nutrient stores for microbes and plants.
This isn’t to say that all organic farming regimes build soil health, since not all farms employ the three-step regime of cover cropping, compost and no till, as Montgomery and Biklé point out. But if a farmer does follow the method — as well as crop rotation and crop diversity — soil microbes and their important networks will increase. And plant health will improve, as I’ve seen myself.
The problem, of course, is that such farms are still too few and far between. Elements of the healthy-soil regime have been taken up, but reduced tillage on conventional farms is combined with herbicide applications, which create a host of issues, such as herbicide-resistant weeds and drift. Cover crops, too, are used on only about 5 percent of U.S. farms. No-till is used on 21 percent, according to the USDA.
Toward the end of the book, Montgomery and Biklé tell an encouraging story about a dramatic shift in growing methods for the number-one staple food in the world, rice. Modern methods required flooded fields and copious amounts of nitrogen fertilizer, which led to pest pressures and high costs. But a method developed in Madagascar in the 1980s, called the System of Rice Intensification, relied on less water, fewer rice plants and compost instead. Although it was first derided in ag research circles, recent work has documented its ability to raise yields dramatically. Micronutrient levels in SRI crops also increased, with fungi and bacteria in the soil. Today, 20 million farmers around the world use the method.
These sorts of advances will become crucial if the world wants to keep feeding itself not only food, but nutritious food — lessons I’ve learned in my own modest garden.