Hitting pay dirt
By Camille Wilson
Most people can detect the flavor difference between a tomato from their garden and one from a grocery store. That flavor difference also indicates a disparity in health benefits, and studies show that the nutrient density in commercially produced fruits and vegetables is declining.
In fact, some estimates show a drop of 30% or more, depending on the nutrient. One study, published in the “Journal of the American College of Nutrition,” looked at 43 different vegetables over a span of nearly 50 years and found declines in iron, calcium, vitamin C, protein, phosphorus and riboflavin (vitamin B2). The University of Texas scientists who conducted the study attribute the changes, in part, to commercial farmers opting for crop varieties that favor higher yield and faster growth—so fast that the plants cannot produce or take up needed nutrients from the soil. Other scientists believe the biggest issue is the soil itself.
Healthy, high-quality soil provides the nutrients plants require to grow and produce fruit and vegetables. Some plants need large amounts of potassium, nitrogen or phosphorus, all considered macronutrients, and smaller amounts of micronutrients, like manganese. Fertile soil makes enough of each nutrient available to plants without creating excesses that can leach into the groundwater or create a toxic environment for plants and soil microbes.
High-yield crops and the rise of monoculture—growing a single crop year after year without rotating what’s planted in a section of soil—has led to an overall decline in soil health, scientists say. Replanting in the same place depletes certain nutrients and doesn’t provide a way to replenish them. This prompts a heavy reliance on chemical fertilizers to replenish lost nutrients, but these may contain ammonium phosphate and other synthetic chemicals that are difficult to break down.
Nutrient-depleted soil is also less resistant to weeds and pests, increasing the need for pesticides and herbicides. Use of these chemicals is yet another contributor to the depletion of some micronutrients and organic content in agricultural soil, which in turn reduces the nutritional quality of crops. This is no small problem. In fact, the Centers for Disease Control and Prevention says at least half of children worldwide ages 6 months to 5 years suffer from one or more micronutrient deficiency, and globally more than 2 billion people are affected.
The decline of nutrients is most apparent in commercial produce, which gives home gardeners more incentive to rely on their own fruits and veggies. Take these steps to improve the nutrient density of the food you grow in your yard by improving the soil.
Understand Your Soil
Inexpensive soil tests administered by the Colorado State University Soil Testing Lab (soiltestinglab.colostate.edu) can tell you if the soil in your garden lacks specific nutrients. The results often include recommendations for specific ways to amend the soil to correct any deficiency. Mark Guttridge of Longmont’s Ollin Farms suggests starting there and testing several areas in your garden. Depending on which nutrients are lacking and the soil’s pH—both pieces of information are included in the test results—you can buy amendments in powdered rock form to add to the soil, such as limestone or gypsum for a calcium deficiency or clay for a phosphorous deficiency.
Local organic farmer Erin Dreistadt of Aspen Moon Farm says soil tests only show information about one place at one point in time, and suggests focusing on observation in the home garden. The Hygiene-based farm Dreistadt operates with her husband, Jason Griffith, is a Demeter-certified biodynamic farm that takes a holistic approach to agriculture.
If you observe yellowing leaves or stunted growth on a plant, for instance, this is likely a sign of overwatering, she says. “The soil really wants to have air; it needs to be aerobic. If it’s overwatered, it can’t have enough oxygen exchange, so the plants won’t thrive. Water it a little less and be sure it’s properly cultivated with a hoe or other tool.” Blossom-end rot, a mushy black spot on the bottom of tomatoes, peppers and squash, indicates a lack of calcium in the plant, caused by wide fluctuations in soil moisture or too much nitrogen fertilizer.
Dreistadt thinks the wisest solution for most growing issues is to feed both the soil and the plants throughout the season with organic compost and compost teas. The teas are made by steeping aged compost in water and then spraying or pouring the tea over the soil.
Feed Your Soil
Dreistadt views her land as a living, connected system and works hard to ensure healthy plants, animals, water and soil. There are many ways to return minerals to the soil that don’t involve chemical fertilizers, she says.
“Ultimately, it’s the soil that determines the health of everything that grows out of it,” she says. “For a newer garden, buying organic compost is OK…and then you can make compost from your own yard, which is going to be the best at building your own fertility. What you create in your own ecosystem is going to feed your soil better than anything you can purchase.”
Aspen Moon Farm (aspenmoonfarm.com)
Sells organic biodynamic seeds and starter plants
Farmstand: 7927 Hygiene Road, Longmont
Boulder County Farmers Market:
(Boulder) Wednesday and Saturday (Longmont) Saturday
Josephine Porter Institute (jpibiodynamics.org)
Source to purchase biodynamic preparations.
MASA Seed Foundation (masaseedfoundation.org)
Boulder-based source for organic produce seeds specifically adapted to Colorado.
Ollin Farms (ollinfarms.com)
Sells a cover-crop seed mix.
Farmstand: 8627 N. 95th St., Longmont (quarter-mile south of Colorado Highway 119 and Hover Street)
Boulder County Farmers Market:
(Boulder) Wednesday and Saturday (Longmont) Saturday
She would love to see more home gardeners apply biodynamic preparations to their soil. These are mineral, plant or animal manure extracts, usually fermented and applied after specific dilution and stirring procedures. Gardeners can make their own preparations or buy them, and the payoff is evident in a plant’s nutrient content and vibrancy, according to Dreistadt. “You can see it, you can taste it and you can feel it when you eat the food,” she says.
She also recommends covering the soil with cover crops—buckwheat for summer coverage, and rye, hairy vetch or oats in the winter. These feed the soil and keep it covered, and their roots keep topsoil from blowing away. Guttridge of Longmont’s Ollin Farms agrees cover crops are a critical part of soil health. He and his team use a specially blended seed mix containing winter rye and Austrian field peas, among other plants, on their family-run fields, and gardeners can buy this mix from their farmstand.
“Mulching with fall leaves is OK for the home garden, but using a cover crop gives your soil extra photosynthesis,” Guttridge says. “More diversity above the soil creates more diversity under the soil.”
In spring he suggests mowing the cover crop and leaving it to rest. This creates a green “manure” that further acts as its own amendment when tilled into the soil.
Feed Your Plants
Because nutrient-dense plants help maintain nutrient-dense soil, Guttridge says nutrient drenches and foliar (leaf) spraying at “critical points of influence” for plant success can, in turn, impact soil health. A drench is specially formulated by dissolving nutrients in water that are required for whatever plant is being grown. The drench is poured at the base of plants to provide targeted, deep penetraion. The content of his drenches vary, since different crops require different nutrients and are planted in different soils, but his farm often creates a general drench for seedlings before transplanting them to the fields.
The drench acts like a multivitamin, and Guttridge prefers it to fertilizers because it is more nutrient-specific and does not force-feed the plants. He also mists Ollin’s fields with a needs-specific foliar spray several weeks after planting when different species begin to flower. This technique compensates for identified deficiencies using minerals and microbial nutrients brewed into a liquid form and misted onto plants’ leaves, rather than poured on the soil.
Local heirloom varieties of fruits and vegetables are often slower growing, which allows them to establish better roots and higher nutrient content. They’re also better adapted to the particular climate and soil conditions in our area. Plant your own seeds from a previous season or purchase organic seeds from local farms and seed banks. If growing starter plants, avoid buying them from large chain stores because bee-harming chemicals (neonicotinoids) are already inside the stem and systems of these plants. Instead, opt for local organic starter plants available at the Boulder County Farmers Markets, Growing Gardens, on-site farmstands and elsewhere.