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Organic Gardening

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Working With Nature to Build Organic Soil

“Organic farming” is often defined in negative terms such as no insecticides, no herbicides, no fungicides. Thinking of “organic” in this way doesn’t contribute to growing nutritious food, and it may result in the uneconomical practice of buying many amendments for soil and plants. In this article, I’ll discuss a more positive definition of “organic” that can actually result in less work, greater profits and more flavorful and nutritious food.

Organic Means Carbon

A positive definition of organic farming features carbon as its star player. When we come to see that the relationship between plants and the micro-organisms in the soil is based on the element of carbon, we can grow crops in ways that enhance this relationship. Let’s take a glance at the chemistry of carbon to better understand what we’re working with.

The entire branch of chemistry that is based on carbon is called “organic chemistry.” Therefore, we shouldn’t be surprised that organic farming is also based on carbon. Carbon has three characteristics that make it so special and thus essential to the structure of all living things:

1. Carbon is plentiful. After hydrogen, helium and oxygen, it is the most plentiful element in our solar system.

2. Carbon is able to make extremely strong bonds with other elements because it can form four bonds —the maximum number. Each of these bonds is held closely to the magnetic pull of its nucleus. Practically speaking, that’s why an oak tree can grow tall and has the strength to stay standing.

3. The carbon atom is capable of forming complex molecules which include long chains, branching chains and looped structures. This is essential for complexity in living things.

Soil from Air

Organic Soil is Made of Air!

The ability of plants to build soil out of air is essential to having healthy soil. For us to appreciate and facilitate this process, we’ll now look at the biology of what it means to farm organically.

Plants have openings on the under-side of their leaves, called stomata, in which they take in carbon dioxide. With energy from the sun and enzymes from the minerals in the soil, plants link these carbon atoms together in longer chains. The simplest chain is a six-carbon sugar called glucose. Plants also make longer and more complex chains of carbon, forming starch for their food and cellulose for their structure.

The simple, sugar molecules are used by plants in exchange for the nutrients plants need from the soil. The billion of soil microbes get the sugars they need to survive through the plants’ root exudates. In return, plants get the nutrients that they and we need from the soil via these microbes.

There are 118 elements on our planet, and scientists now know that living creatures require almost all of these for good health. (Read "SOS: Save Our Soils" about the life-giving link between carbon and healthy topsoil.)

See what’s happened to carbon? It journeys from air to the plant to the soil. We can also say that carbon has gone from a gas to a liquid to a solid. In the soil, microbes create humus by linking carbon into long, vertical chains. Humus holds water in time of drought, absorbs water in time of excess rain, gives healthful food and sequesters carbon. Nature’s way of forming soil results in healthy plants, creatures and a healthy planet.

We’ve heard that it takes 100 years to “grow” one-inch of soil. That’s true when soil is created from the erosion of rocks by rain and wind. But when soil is created “from the air,” plants can grow four to six inches of soil a year. That is truly organic farming!

The Soil-Food Web

Humus, the top-soil, is not built without the soil’s microbes receiving carbon-based sugars from plants. An ongoing balance among the billions of microbes is also required to create humus from these sugars. Without an undisturbed exchange between microbes and plants, there is no nutritious food.

To be successful in farming organically, we must familiarize ourselves with the complexity of the soil-food-web so we can work in harmony with the microbes. For an in-depth look at all the players in the soil, see Jeff Lowenfels and Wayne Lewis’s, Teaming with Microbes,The Organic Gardener’s Guide to the Soil Food Web.

soil microbes necessary

As we get acquainted with the microbes in the soil, we come to realize how interdependent they are. We don’t kill a slug or nematode without destroying the shredders of organic material and the aerators of the soil. We don’t plow without damaging the mycorrhizal fungi whose essential functions include extending the plants’ roots, making available important elements like phosphate, and secreting glomulin which prevents soil compaction. And we don’t mono-crop or leave soil bare without starving these essential microbes. To farm organically means to foster life that is too small for our eyes to see.

Healthy Plants Resist Disease

Most of us remain wary about the “bad bugs” that damage our crops, but nature has a built-in solution for this. When plants are truly healthy, they have a high sugar-content. The “brix refractometer” measures the sugar content in plants to determine their nutritional content. Nature doesn’t want to damage successful plants and their progeny. If the brix measurement in a plant is above 12, it is largely resistant to harmful insects. The message is clear; if we support nature, we get healthful produce.

Understanding how nature incorporates carbon in plants and soil allows us to work in harmony with this organic system. In the following blog, I will discuss specific methods, such as compost and cover crops, which allow us to do this.

Click here to read Part 2 about using cover crops to build healthy soil.

Image for Soil Food Web.

Mary Lou Shaw is formerly a family practitioner who emphasized preventive medicine, and is no homesteading with her husband in Ohio. Besides growing their own food, the pair preserve genetics and knowledge needed by others to grow their own food. They have a large garden and orchard, Dorking chickens, Red Wattle hogs, Narragansett turkeys, Dutch Belted cows, bees and three funny Ancona ducks. Read Mary Lou’s book Growing Local Food, and find all of her MOTHER EARTH NEWS posts here.


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