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As a small-scale farmer, I’m constantly looking for ways to fertilize my garden with on-farm inputs. This includes making my own compost from kitchen scraps, leaves, and chicken and rabbit manure. Despite my efforts, I still had to rely on some inputs from my local garden supply store, such as blood and kelp meal.
It didn’t take me long to realize that this method was unsustainable for me. Ever since I entered the world of farming, I’ve gravitated toward the idea that a closed-loop system — or at least as much of a closed-loop system as possible — is the best option. That means not running to the store whenever I need to feed my plants healthy, organic nutrients.
Over the course of a few months, I researched ways to feed my plants on my own, including compost teas, vermiculture, and kelp foliar sprays, but it wasn’t until I talked with a local farmer about my concerns that it all clicked.
“You could try water-soluble calcium, or a fish amino acid spray,” my neighbor David Baird told me. “Your plants will soak it right up.” David and his wife, Katie, run Bien-Aimé Farm, a no-till, biointensive market garden.
At first, I had no clue what he was talking about, but he explained that these techniques are part of a practice known as Korean Natural Farming (KNF). Popularized by Master Han-Kyu Cho in his book Natural Farming, KNF is a set of agricultural methods originating in Asia that date back hundreds of years. KNF practices are used to cultivate healthy plants without harmful pesticides or chemical inputs by creating a closed system that’s balanced with natural inputs from local environments. This is accomplished through the creation of fermented fertilizers and techniques that introduce indigenous microorganisms (IMOs) from the wild into a garden’s soil structure, which promotes hardy, robust plants. With KNF, virtually everything a healthy garden needs can be sourced from your surroundings. Right away, I knew this was my ticket to creating a closed-loop system on my own farm.
Promoting Plant and Soil Health
In my quest to learn more, I spoke with Aaron Englander, farm and program manager for the Erickson Fields Preserve in Rockport, Maine. Englander, who has a master’s degree in plant and soil science, studied KNF from Master Cho in Hawai'i through an intensive course in 2010.
“Korean Natural Farming promotes life,” Englander says. “And it encourages self-reliance and closed-loop systems. It fits in perfectly with and compliments other self-reliant, regenerative agricultural practices, such as permaculture, biodynamics, and no-till.”
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In 2011 and 2012, Koon-Hui Wang, associate professor in the department of plant and environmental protection sciences at the University of Hawai‘i at Mānoa, led a study that evaluated the benefits of KNF on tropical vegetable production in Hawai'i. One of the goals of the study was to analyze plant and soil health affected by KNF on three separate vegetable farms. On these farms, KNF practices were incorporated in addition to conventional farming practices to offer a comparison, which found that KNF generally improved plant health in all trials.
One farm, which was engaged in soybean production, showed the most improvement from KNF practices. At the end of the experiment, the farm saw an increased presence of omnivores and predatory nematodes, resulting in a more stabilized and less disturbed soil structure. According to a study progress report, “The root zones of soybeans in KNF plots were densely colonized by a whitish mycorrhizal mycelium, and occasionally, mushroom body can be found on the soil surface.” A thicker soil depth and increased presence of earthworms also supported a theory that KNF softens the physical structure of soil.
Englander has conducted his own research on KNF as well. In 2015, he published the paper “On-Farm Produced Microbial Soil Inoculant Effects on Bread Wheat (Triticum aestivum) Production,” which examined the effects of microbial soil inoculants on bread wheat in Maine. Englander’s results showed that mycorrhizal inoculants that are made on-farm can increase wheat [arbuscular mycorrhizal fungus] colonization, aboveground biomass, and phosphorus uptake. “I think that had to do with my guess that the microbial activity, either in the IMO itself or through the process of breaking down compost, makes nutrients more bioavailable for plants,” Englander says.
According to Englander, increased bioavailability is a big benefit of KNF. Nutrients are oftentimes locked in the soil and unavailable to plants, but KNF practices make these crucial nutrients more accessible, which is essential to sustainable soil health.
Englander teaches basic KNF principles through workshops, and he typically introduces folks to the practice via fertilizing techniques that supply nutrients and microorganisms to the soil. These include fermented plant juice, fish amino acid, water-soluble calcium phosphate, and water-soluble calcium. Focusing on this group of fertilizers is an excellent way to get started with KNF, because they’re relatively easy to make and apply, and they can provide much of the fertilizers your garden requires without many off-farm inputs.
Fermented Plant Juice. The simplest Korean Natural Farming fertilizer, fermented plant juice, is a liquid derived from a mixture of brown sugar and local plants.
“Select a plant that’s vigorous and healthy on its own without inputs,” Englander says. “For example, use nettles, seaweed, or comfrey. You’re looking for something that has pretty thick and robust leaves.” Harvest plants early in the morning, when they have the highest growth potential due to the large amount of moisture content, enzymes, and nutrients.
Cut the plants into small pieces, and then mix the plant material in a glass or ceramic jar with brown or cane sugar at a ratio of 1-to-1 by volume. Fill the jar two-thirds full, which allows space for fermentation to occur. Cover the jar, and let sit for one week.
At the end of the week, strain out the plant parts and compost them. Return the liquid to a clean jar, and store it in a cool, dark place, where it’ll last for years.
To apply fermented plant juice, dilute it with rainwater at a ratio of 1-to-500. (Don’t use municipal water sources that contain chlorine.) This fertilizer is most effective when used as a root drench or foliar spray on young plants that need more nitrogen, potassium, and healthy microbes. Englander sprays it on seedlings as a foliar mix after transplanting. The mixture is UV sensitive, so apply it early in the morning or on a day that’s cool and cloudy.
Photo by Jonathan Olivier
Fish Amino Acid. Fish has long been used as a natural fertilizer in many parts of the world, because it supplies a healthy and lasting supply of nitrogen and other nutrients. This KNF method incorporates fish into a fermented mixture that creates a blend rich in nitrogen, proteins, amino acids, and micronutrients.
The first step is to find fish; either whole fish or partial remains from processing will work. Avoid farm-raised fish and fish from contaminated bodies of water.
Cut up the fish and place the pieces in a 5-gallon bucket. Mix in brown sugar at a ratio of 1-to-1 by volume. Englander also adds local fruit to help the enzymes break down, and he often tops the mixture with hay or straw to act as a biofilter. Fill the bucket about two-thirds full, so there’s enough space for fermentation to occur. Cover the top with a permeable surface, and let the mixture sit for 3 to 6 months.
When it’s ready, the mixture should have a sweetish smell and be a light-brown color. Remove the fish and compost the remains, and then strain the juice into a clean bucket. Keep it in a cool, dark place, where it’ll last for years.
To apply fish amino acid, dilute it with rainwater at a ratio of 1-to-500. It’s ideal for young plants before they flower or fruit, which is when they need nitrogen. Englander applies it as a soil drench on young plants, uses it to soak seedlings before transplanting, and applies it as an early foliar feeding in the first stage of vegetative growth.
Water-Soluble Calcium Phosphate. As plants get older, their needs change. Once they enter the reproductive phase, when they’re flowering and fruiting, it’s important to provide less nitrogen and more phosphorus. Calcium phosphate is insoluble in water, but the compound becomes available in acids. This fertilizer is made by extracting the beneficial minerals of calcium phosphate from animal bones, such as chicken or beef, using vinegar.
First, you’ll need to cook the bones until they’re charred and devoid of any meat and fat. Englander does this by cooking them in a tin can in a barbecue pit until they’re blackened and brittle.
From there, mix the charred bones in a 5-gallon bucket with vinegar (white, apple cider, or rice vinegar work well) at a ratio of 10 parts vinegar to 1 part bones. Cover the top of the bucket with a cloth that'll allow gas and air to exchange. Let the mixture sit for two weeks, and then pour the liquid into another clean container for storage.
To apply water-soluble calcium phosphate, dilute it with rainwater at a ratio of 1-to-1,000. Use the mixture as a foliar spray on older plants when they’re flowering. According to Englander, the mixture also serves as an anti-pathogen, because it inhibits fungal growth.
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Water-Soluble Calcium. Calcium is an important element that plants need in the later stages of growth. Without an optimum supply, the quality of fruit can suffer. “That’s why sometimes you’ll see people adding Epsom salt or milk to their tomatoes to prevent end rot, which is a common symptom of calcium deficiency,” Englander says. In this KNF practice, calcium carbonate is changed to calcium, which can then be absorbed by plants.
First, you’ll need to roast egg shells to kill off their biologically active membranes; toasting them in a pan until they’re light-brown will suffice. Once they’re toasted, crush them up and add them to a 5-gallon bucket with vinegar at a ratio of 10 parts vinegar to 1 part eggshell. You’ll start to see the reaction immediately. “As the calcium starts to bind to the vinegar, it’ll release carbon dioxide,” Englander says. “You’ll see that in the form of bubbles.” For this reason, it’s very important not to seal the bucket with a lid, or else the mixture could explode under pressure. Simply cover the top of the bucket with a cloth to allow gas and air to exchange, and leave it alone until the mixture stops bubbling.
To apply water-soluble calcium, dilute it with rainwater at a ratio of 1-to-1,000. Use it as a foliar spray during the ripening stage of growth.
Jonathan Olivier is an independent journalist who primarily writes about the environment and how humans interact with the natural world. His work has appeared in Outside, Backpacker, Mother Earth News, and other national publications.