It’s a Microbial World

By Valentin Kostelnik

There’s a world just beyond our eyesight that powers everything we see: the world of microbes. Most plants you see in nature are not capable of living alone, and are sustained and protected by the microbial world. In the bustling zone called the rhizosphere, where soil meets root, billions of diverse microbes create complex support systems for plants.

Dennis Dierks is a farmer in Northern California who for 50 years has experimented with the microbial world to achieve self-sufficiency, replacing synthetic fertilizers and pesticides with natural processes. “I always wanted to feed the microbes in the soil, not the plants that I will put in the ground. The microbes break the [compost and fertilizer] down and feed the plants.”

At the farmer’s market, his fresh produce is vibrant, nutritious, and stays fresher longer than that of other vendors. With his farm of about five acres, he has been met with considerable success, which he attributes to the superiority of his products: “The flavors and the nutrients are there, and we’ve got this big following of customers that were very loyal. And the restaurants started picking up on it, so we had these lines of chefs. And it’s all because…most of our focus was feeding the soil before the plants that go in it.”

Despite his future success, Dennis began with almost no background in farming. He got a degree from the San Francisco Art Institute and illustrated textbooks before turning to farming. In those first years, he often asked himself, “am I an artist farming or a farmer who paints?” But, Dennis considers his unlikely background a blessing, saying “if I went to ag school instead of art school, I’d be buying bags of chemical fertilizer!”

Dennis’s current methods are adapted from those of Dr. Han Kyu Cho, a Korean farmer and researcher who developed ways of obtaining and sustaining nutrients and microbes from the environment. Dr. Cho designed these techniques to be implemented by small farms in developing countries, but they work almost anywhere.

Dennis’s farm is in a small valley an hour north of San Francisco, surrounded by forest and streams. Using tools picked up from Dr. Cho and other farmers, Dennis has tried to replicate the processes he sees working well for plants in nature. Although he admits “it was a long learning curve,” his methods have drawn acclaim within the sustainable agriculture community.

Once, he even received a visit from Prince Charles. The now-King Charles, who has long been alarmed by the effect of industrial agriculture on England, toured Dennis’s farm to learn about Dennis’s microbial brews while visiting the Bay Area. I also had the chance to tour his farm, and see firsthand the microbial world at work in Dennis’s fields.

Dennis beckons me over to a covered plastic blue 50-gallon tank and puts one hand on the lid. As he lifts it up, I unconsciously lean in to see the swirl of red and yellow sludge filling the barrel, then stumble back a second later when the stench hits me.

“You should’ve seen Prince Charles’ face when I showed him that!” Dennis chuckles and gives the barrel an affectionate kick. I build up my courage and take a closer look at the sludge.

The barrel is full of fermented fish guts, which Dennis tells me are being consumed and transformed by billions of tiny organisms, and the brightly colored sludge I see on top is just a few inches of floating scum. Beneath it lies 50 gallons of fish emulsion, full of nitrogen, phosphorus, and potassium at a ratio of 4:1:1, comparable to most chemical fertilizers. Dennis’s son, a local fisherman, generates a lot of inedible “waste” products that are full of nutrients, but aren’t immediately available for plant uptake. Dennis puts them in big barrels with some water, pours in a gallon of molasses to feed the fermenters and increase the osmotic pull on nutrients in the fish, and lets it sit for a week or two. Microbes immediately start breaking the organic structures down, the molasses speeds it up, and the fish is broken down into highly concentrated fertilizer, produced at no cost besides labor.

Dennis uses this simple procedure to extract nutrients and minerals from dozens of other sources—whatever he thinks might benefit his vegetables and soil. One example is silica, a mineral which research has proven to increase plant growth and pest resistance. The mineral is abundant in horsetail grass, a common plant in North ern California, so Dennis chops it up and ferments it with some water, mo lasses, and microbes to give his vegetables an extra boost of silica. “Once you have this knowledge of how to extract the nutrients, you can look at any plant that you think might help. Once you start to look at your en vironment and can pick and choose what you need, it makes the food chain im mediate and available.”

He might have four or five barrels fermenting at the same time, full of horsetail grass, fish guts, kelp, stinging nettle, or any other plant he thinks will do well in his fields. By extracting nutrients from the surrounding land, Dennis can acquire all the fertilizer he needs in a year from within a few miles of his house. But the key to his success lies not in the fertilizer he feeds the crops, but in the microbial networks thus fostered in their roots.

As Dennis explains, healthy soil is alive with billions of diverse microbes: the soil food web. In most modern industrial farms, the soil food web is absent, but Dennis actively promotes it. He believes a healthy web can, among other things, make nutrients available to plants and provide protection from harmful pests, making chemical fertilizers and pesticides unnecessary.

One example of nutrient-cycling microbes is nitro- gen-fixing bacteria, which can draw atmospheric nitrogen into the soil and convert it to its plant-available form, ammonia. Other microorganisms, like lactobacilli, colonize plant cells, stimulate plant growth, and guard against harmful bacteria, and fungal microbes like mycorrhizae bond with roots to build support structures in the rhizosphere. Almost all land plants are partnered with at least one type of soil microorganism, and we’re still discovering the true variety and complexity of these extraordinary and diverse relationships. Dennis studies these interactions, determines the most beneficial microorganisms for his crops, and introduces them to his soil.

“It’s a beautiful way of looking at the forest. It becomes more than just a spectacle and something pretty, and you’re also studying the systems and replicating them.”

Dennis’s farm lies in a broad, flat valley surrounded by thickly forested slopes. If I dug up some forest soil on the slopes, I would see delicate threads of white hyphae winding through the soil particles: mycorrhizae.

The mycorrhizae build dense complexes of thin hyphae strands that can extract hard-to-reach nutrients from the soil to the plant, receiving carbohydrates in return. These hyphal networks also stabilize the soil, improve water-holding capacity, out-compete pathogenic fungi, and sequester carbon in the process. These microbes are constantly at work in the forest around the farm, and Dennis has brought them into his own soil.

Oaks in California form particularly robust partnerships with mycorrhizae, so Dennis gathers those for his crops. A clump of soil gathered from under an oak is put into a wooden box filled with cooked white rice, which is mostly carbohydrates, to serve as “bait.” The oak mycorrhizae feed on the rice and multiply, but Dennis is not done yet. The fungi that bond with bamboo are fantastic for water-holding capacity and filtration, and he wants these as well. He buries the box a few feet deep in a bamboo grove by his house, covers it with soil, and leaves it. The white rice draws in mycorrhizae from the soil and when he re- moves the box after a week it “looks like a rainbow from all the fungi covering it.” The bright clump is then mixed with water and molasses for food and put in a pail until Dennis is ready to apply it to his fields.

Another type of beneficial microbe is lactobacillus, a genus of yeasts whose uses to humans are numerous, from making yogurt to sourdough bread and in Dennis’ case, growing vegetables. Lactobacilli can be found in many wild plants, even colonizing the very cells of plants, and increases plant growth while out-competing pathogens.

The gathering process is, again, surprisingly simple. Dennis washes rice and pours the water, now milky white from rice millings, into a pail. The pure carbohydrates from the rice millings draw yeast out of the atmosphere, which begin feeding and multiplying.

After a few days the pail is bustling with microbes, but Dennis wants to isolate the lactobacilli. He pours milk into the pail, giving the dairy-loving lactobacilli a chance to outcompete the others, and a week later a thick cap forms on top, which “looks like a living skin.” This is just the fat separated from the milk, but right under it is a clear layer of pure lactobacillus, which Dennis siphons out and puts in another pail with some molasses for food.

At this point in the season, he has a pail of lactobacillus, another of mycorrhizae, a few 55-gallon barrels of various fermented fertilizers, and a greenhouse full of young plants. He has all the ingredients and is ready to begin combining and applying them. As he says, he always remained a painter. “I just changed my palette from paints to soils.”

Dennis mixes his ingredients in something called an Aerated Compost Tea Brewer, which extracts, multiplies, and combines the microorganisms living in whatever you put in it. First, you take some finished compost (which is full of decomposing microbes), stuff a large “teabag” with it, and hang the bag in a 55-gallon tank. Fill this tank with water, molasses, and desirable microbes, then put in a pump at the bottom of the tank to push air bubbles up through the solution and keep the microbes aerated. “All these pieces just sort of kept coming together over time. And the field tells you exactly what you’re doing, if it’s right or wrong.”

Dennis fills the Aerated Tea Brewer with some of everything he has gathered so far: lactobacillus, mycorrhizae, fish emulsion, and the plants he’s fermented that year. All these nutrients and microbes blend into a densely populated microbial tea full of plant-available nutrients.

The little greenhouse plants are soaked in this solution for a few hours, and the microbes so carefully gathered and fostered over the prior months finally seep into their roots, where they will live until harvest. At the same time, the fertilizers fermented from fish, kelp, and horsetail grass provide much-needed nutrients to tide the plant over. The kelp extract provides vitamin D, which is known to help plants deal with stresses like transplanting, and the horsetail offers silica, helping the plants form strong structures as they are planted in the fields.

The rest of the compost tea, along with other ingredients including the unmixed mycorrhizae, lactobacillus, and fermented plants, are diluted with water, poured into a tank hooked to the back of a tractor, and sprayed over the field. The solutions are sprayed over the field three or four times before harvest, and provide Dennis’s plants with all the nutrients and pest-protection they need. Dennis the artist-farmer has mixed and applied his microbial paints, and the finished product is beautiful.

In contrast with his vegetables, or similarly grown produce, Dennis says, “most commercial stuff is mostly just water. There’re no nutrients in it, and it just doesn’t have any life!”

Much of American agriculture is highly industrialized, and has replaced the soil food web with chemical fertilizers and pesticides. But, these practices are degrading our soils at unsustainable rates. While Dennis’ soil is home to a living complex of microbes, the dirt under most industrial farmland is dead, with no hyphae holding it together, and erodes easily once plants are harvested. It also has a lower water-holding capacity, making flooding events worse. The crops lack a supportive rhizosphere and have a difficult time accessing nutrients applied by chemical fertilizers, so a lot of it runs off into nearby waterbodies. Not only is this wasteful, it can also produce algal blooms like those plaguing Lake Champlain or the Gulf of Mexico.

Developing countries are better poised to take advantage of the microbial world than any other, because most of their farmland is still held by small farmers that have not fully industrialized. These farmers can use methods like Dennis’, adapted for their own environment, and achieve self-reliance while also producing high quality food.

The prospect of a shift towards microbes and soils as the key to agriculture is an exciting one, and gaining traction worldwide. On top of the practical benefits farmers can gain from this shift, Dennis has found enormous joy in his farming. He says, “a lot of it is just sitting on the ground, using my senses. Once you start to understand these systems a bit, how they work and how you can use them, you just get totally absorbed by them.”

I asked him if he had any tips for the next generation of farmers, who might follow the path he did:

“Have fun!” H

Art by Sadie Holmes