By Jeff Poppen
When we look at the great soils of the world, we can see these principles of permanent agriculture in action. The prairies have the grasses and clovers that together structure the soil and incorporate nitrogen. The grass roots finely divide the soil particles and then decay after the tops are grazed. The mobs of bison on small acreages of the Great Plains, for short periods of time ate a small percentage of the growth and trampled the majority of the carbon back into the soil. The heavy animal impact included manure, urine and tillage from their split hooves. It is fascinating to watch a bovine’s hoof split apart and literally plow the soil sideways, as the weight of the animal comes down on it.
Afterward, the land rested with no animals, and grew back up better than ever. This cycle produced phenomenal soil humus.
This same thing happened in Northern Europe with wolves chasing reindeer and in the African savanna, with lions chasing water buffalo. Everywhere you find great soils in nature, you’ll find mobs of grazing herbivores moved by predators. This is how humans will reverse climate change — by sequestering carbon with the use of grass, legumes and large herds of herbivores on small acreages for short periods of time.
Glaciers are another great contributor to building soils, because they grind up rocks. It took me a long time to learn how to grow stuff because I grew up in the beautiful black soils of Illinois, where a glacier had been just 15,000 years ago. It has been a million years since a glacier went through my land, and Tennessee’s soils need minerals. I learned that wood ashes, ground granite, rock phosphate and lime really help on our farm. By burning bones or limestone rocks and spreading the ash, we can add these minerals in a more available form.
The abundance of the earth is made possible by just a few elements, and the primary ones are free. Carbon, hydrogen, oxygen and nitrogen are everywhere, in air and rain. I have really good news. We know how to grow food without hurting the land, air or water, in a way that is good for us, too. It’s simple and easy, but we need four things: minerals, a grass/legume pasture, ruminants and some way to loosen the soil. Also, we can’t be too greedy.
At Long Hungry Creek Farm we have been exporting 100,000 pounds of produce annually for 25 years with no irrigation, fertilizers or other agricultural inputs. This produce has been mostly these four elements in the form of carbohydrates and proteins. Most of what I sell is simply transformed air and water. It only works because at least 95 percent of the farm’s annual growth stays on the farm (only the surplus leaves). We do this by incorporating forests and wetlands, grass and clover, cover crops, composting, intensive grazing, crop rotation and remineralizing, which are all tried-and-true pillars of sustainable agriculture.
The principles of agriculture are summed up in this quote from the USDA’s experimental station at the University of Illinois, 1910: “To maintain adequate amounts of phosphorus [and calcium] in the soil makes possible the growth of clover and other legumes and the consequent addition of nitrogen from the inexhaustible supply in the air; and, with the addition of decaying organic matter in the residues of these crops along with the wastes from livestock fed on these pastures and hay fields, comes the possibility of liberating from the immense supplies in the soil sufficient potassium, magnesium and other essential elements for the production of large crops at least for thousands of years.”
Before World War I, the USDA did not recommend separating animal husbandry from crop production, and did not advocate for fertilizer sales. Instead, they echoed principles we have known for 2,000 years. Columella, in the 1st century A.D. says, “some of the leguminous plants manure the soil, and make it fruitful while other crops exhaust it and make it barren.” One hundred years before that, Cato comments, “where-in does a good system of agriculture consist? In the first place, in thorough plowing; in the second place, in thorough plowing, and in the third place, in manuring.”
According to Pliny the Elder, “The use of ash is viewed so favorably by farmers, that they actually prefer it to the manure furnished by their cattle.” Sustainable agriculture is not new.
I have really good news. We know how to grow food without hurting the land, air or water, in a way that is good for us, too. It’s simple and easy, but we need four things: minerals, a grass/legume pasture, ruminants and some way to loosen the soil. Also, we can’t be too greedy.
Permanent Agriculture: Minerals
Using ash on the farm is important because it contains the other mineral elements necessary for plant growth; calcium, silica, potassium, magnesium, phosphorus and the trace elements. Slash and burn agriculture worked because of the release of these minerals through combustion. We also get minerals from limestone or phosphate mines.
Many pounds of minerals are in the soil and subsoil, but are locked up and unavailable for plants. In permaculture systems the minerals of the earth supply nutrients to legumes and other plants, which feed cattle and other animals whose wastes are tilled in by humans for crop production.
One of the reasons we grow legumes is to bring nitrogen into the soil. This happens through a symbiotic relationship with specific bacteria. With 70 million pounds of nitrogen in the air above every acre of land, farmers traditionally plant legumes to provide nitrogen for the next crop. The amount of nitrogen in the soil can be the major limiting factor in crop production, but not if the crop rotation includes legumes.
The biology in the soil is enhanced by composting manures with crop residues and soil.
As a plant grows into a humus soil, bacteria and fungi colonize the roots and live off of root exudates. This is the stuff that sloughs off of the root as it penetrates the soil. There are more than 100,000 species of these microbes, and many of them work with specific plant species. There can be a million bacteria in a spoonful of soil, or 1,000 times that many, which is what we want and why we make compost. We have seen huge microbial activity happen in our soils literally overnight. It is simply amazing.
There’s no hard and fast line between where the root ends and the soil begins, because the colonizing fungal hyphae (fungus roots) stretch out through the soil. These microbes are experts at getting minerals loosened from the unavailable state. Since they have a vested interest in healthy plant growth, their food source, they pick up on signals the plant gives for nutrient requirements. A hydrogen ion is swapped for a cation nutrient, and off it goes, up into the plant.
Farming with nature’s intelligence is easy. The microbes do all of the work; we just have to let them. A stable clay-humus complex forms a microbial connection underground that boggles the imagination. There exists a single fungi as big as the state of Rhode Island. Dye put in a tree shows up on the opposite end of a forest by the end of the day. Everything in nature is interconnected.
A larger transport system moves these liberated nutrients around. Protozoa, nematodes, earthworms, bugs, reptiles, birds and mammals all contribute to the distribution of necessary plant foods. It is arrogant for humans to think that it is we who “feed” plants. Nature does a great job, but we have to somehow loosen the soil through mindful tillage.
All farms need cattle, sheep, goats or another species of four-stomached cud chewers. You’ll notice that the rise of civilizations is connected to the domestication of livestock. They go hand in hand. We either wander nomadically, following large herds of herbivores, or we tame them and settle down.
Something magical happens in a cow’s belly — the grass that goes in does not come out until 18 days later, totally transformed. The manure is not only the perfect plant food, it has the ability to fertilize more soil than is needed to grow what the cow lives on. A full-grown cow needs 2 acres of pasture, but can potentially make 4 acres fertile. The flora and fauna engendered in a ruminant’s digestive system, when incorporated into the soil, helps to make unavailable minerals available for plant use.
The value of soil microbes is truly the real wealth of the world, and it is through ruminants’ digestive systems and legumes that they proliferate. Compost, compost, compost. We have to continually re-enliven the soil that we disturb when we crop it. The farm is full of new organic matter every year, with plenty to go around, as long as we feed most of it to our animals and microbes and don’t export more than sustainable agriculture allows. Liberal use of composted manure annually has made our gardening easy. High sugar in the plants means no leaf-eating bugs and plenty of microbes in the soil, keeping the plants fed and creating loose and fluffy soil.
Tillage & Water
I find the term “natural farming” a bit misleading. Agriculture is anything but natural.
Nature grows stuff really well, and we do our best to mimic her systems, but to produce large amounts of food, we need plowing and cultivation, a distinctly human activity that can be either beneficial or detrimental.
If you take a book and fold it, the pages all slip a bit from each other. When we plow, this same action involving layers of soil slipping incorporates air. Microbes propagate when air is added, and they can make the unavailable minerals available to the plants.
At Long Hungry Creek Farm, we rarely use the moldboard plow and only on sod in the fall. The winter freezing and thawing of the exposed soil thoroughly pulverizes it in a better way than any tool can. The chisel plow is our primary tillage implement, as it tills but does not invert the soil. A spike-tooth harrow levels the fields and is used to conserve soil moisture.
Tilling has a bad reputation these days because it destroys soil microbes and can cause erosion. But guess what? Microbes that die become plant food and then more microbes grow. The trick is to be gentle and wise in the use of tillage and to always work along the contours.
We use the keyline plowing system because it saves water and builds soil. With a transit, we find the contours along our hillsides. Every other shoe is removed from the chisel plow so that only four remain, 2 feet apart. It is put in 4 inches deep and pulled along the contours. I go deeper the next year, as the topsoil increases. After a rain, the furrows stay muddy for days. Water that would have left the farm stays and soaks in, and the farm will use that extra moisture next summer.
Much of Tennessee’s farmland is hard and packed and doesn’t easily absorb water. The impervious clay stays too wet and dries out rock hard. It needs plowing, settling and stirring. Tennessee gets plenty of rain; the trick is to conserve it for later. This is why we plow along contours and cultivate to create a “dirt mulch” on the surface, which checks evaporation. In backyard gardening, we often add mulch. We never irrigate as it is simply not necessary when you get 40-50 inches of rain each year.
Deep plowing in the fall allows the winter’s rain to soak into the subsoil. This moisture becomes available through capillary action next summer. As the roots of the crop use up water, the damp subsoil yields its moisture to the drier soil around the plants. Surface tillage prevents it from evaporating into the air.
Despite my altruistic rhetoric, I grow food for one main reason. We get hungry. Not only should the livestock be fed from within the farm, so should the farmers. After all, the most important aspect of farming is people — that’s why we do it, and that’s who gets it done. Not only are the farmer’s footsteps the best fertilizer, where they step offers the farmers the best nourishment.
Locally owned and operated sustainable farms stimulate the economy and conserve and protect the rural landscape. Farms build communities and offer places to take walks and enjoy nature. Farms teach moral ethics and practical skills. Healthy farms sequester carbon and positively affect our climate. And, farms are the best place to find the best food.
Owner and operator of one of the oldest and largest biodynamic farms in Tennessee, Jeff Poppen inherited his love for growing high-quality produce using organic methods from his parents. With a 100-member vegetable CSA in Nashville, it is hard for Jeff to find time to leave the farm, but when he does, he enjoys lecturing and consulting on other farms and gardens. You can see him on the Nashville Public Television program, Volunteer Gardener. This article appeared in the May 2016 issue of Acres U.S.A. magazine.