Get to Know Your Soil
From Chapter 3 of "Healthy Garden Healthy You" by Milo Shammas
If you pause to contemplate your garden or the plant life around you, you may wonder:
• What makes plants so large?
• What makes them healthy?
• What causes plants of a species to develop differently from each other?
• What keeps causing plants to wilt right away?
• How do you get a green thumb?
• How do you give plants the best chance at healthy development?
• What determines the health of plants?
While the science to answer these questions can be quite complex, it is easy to understand in general terms. In their natural environment, plants rely on environmental conditions, their genetics and a healthy soil foundation to spread their roots. Location (mountains, valleys, river banks) weather and air quality shape environmental conditions. Each plant needs a proper balance of sunlight, hydration and nutrients such as carbon dioxide and nitrogen from the air or soil. Exposure to wind, rain and other living organisms also help determine a plant's life course. Any factor out of proper balance in "the equation of life" (too much, too little or at the wrong time) can lead to a plant's demise. Genetics also help determine whether a plant can survive, especially those that mature in extreme environments with high competition for nutrients.
Home gardeners who want maximum plant growth potential cannot control environmental factors nor plant genetics. Especially for organic growers, controlling the genetics of each seed is not an option. By using greenhouse growing to shelter plants from unsuitable environments, we have created pseudo environments. Because so many factors affect plant development, we cannot completely control our results. For these and other reasons, our strongest power to influence the health of plants is to control the health of the soil. If you want your plants to grow tall and be nutrient rich and resistant to pests, you must have healthy, balanced soil.
The interaction between plants and soils, sometimes over an entire life course, has received a lot of research attention during the past century. Among the important findings: When we control the health of the soil, we influence plant health in many ways. Scientists also agree that the best, most fertile soils have great consistency and structure for root extension, water retention and an abundance of organisms living in symbiosis with plants.
Consider your soil as a given that you learn to deal with. Since you cannot completely dig it out and replace it, you must get to know its nature and characteristics, and modify it as best you can to cultivate it successfully. Among the important soil qualities are:
• Composition (heavy clay or light sand, for example)
• pH (the acid-alkaline spectrum)
With this information, you can intelligently choose the most suitable plant material for your environment. These factors also determine the best ways to modify your soil (adding amendments and nutrients) to gain the full potential for a healthy garden.
Living organisms are the bridge that connects nutrients stored in the soil to plant growth. Organisms ranging from bacteria, fungi to earthworms and insects perform a wide variety of tasks that create a regulated balance of nutrients. Soil organisms vary in size from microscopic up to small mammals like moles, groundhogs and mice. On the microscopic level, healthy topsoil contains billions of living organisms growing, reproducing and dying in each gram of soil. These species are crucially important to all life on earth, for they recycle nearly 100 percent of organic waste. They are able to provide nutrients in a form usable by plants through their digestive enzymes, changing complex molecules into a simpler form and making them bioavailable for plant root absorption. These invisible helpers serve as vehicles to transport stores of nutrients in the soil to plants, then to animals and ultimately to us.
Soil organisms play many different roles in the soil ecosystem. All living things must die and eventually decompose. Because animals and humans eat plant materials grown in the soil, organic waste must be broken down and recycled back into the soil to nourish future generations of plants. This waste may consist of animal or plant materials or both. Decomposers break down this organic matter to feed our plants, which feed our animals, both the ones we call our pets and the ones we eat for our health. They complete the cycle of living and prevent the build up of wastes. (Imagine not having the decomposers. Nothing would break down. Animals and plants that died millions of years ago would rest under mountains of waste. If dinosaurs were still on the side of the road, nutrients would never make their way back into the soil. We would run out of plant nutrients and all life would stop.)
This is why "living soil" is so crucial. The decomposers, (under attack by commercial farming practices) create a healthy balance of nutrients available in the soil to perpetuate life as we know it. Briefly, here are some major contributors to the soil and its life.
Bacteria make up an enormous portion of living matter in the soil, weighing more than a ton per acre. In each gram of fertile soil, we can find about one million different species of bacteria just on the surface. Bacteria also exist far below the surface, more than a mile down. But they are most active around the root depth of plants, known as the rhizosphere. These hard workers are decomposers and recyclers. Some are responsible for decomposing naturally occurring organic matter such as dead cells released by roots or other organic plant and animal remains. They release carbon dioxide and other crucial nutrients supporting plant and animal life.
Other types of bacteria provide plants the essential nutrients they need to survive by transforming inorganic matter into forms plants can use. These organisms need carbon dioxide to function. Bacteria also provide plants essential nitrogen through a process called "nitrogen fixation." The Rhizobia bacteria, for example, are symbiotic with the legume family of plants, which includes more than 18,000 different species. They convert atmospheric nitrogen (which makes up 79 percent of our air) from its gaseous form to a water-soluble form that plants can take up through their roots. Nitrogen then becomes available to plants. Through both types of functions, bacteria are essential to plant nutrition.
Actinomycetes are decomposers and recyclers. They break down organic matter and convert gaseous nitrogen from the atmosphere into soluble particles for plants to feed on. The nitrogen fixers have little filaments that invade or grow into root hairs and form small aggregates there. Actinomycetes are most popular as a source of antibiotics. Even at microscopic levels, we find a system of checks and balances. They help keep bacterial populations from growing out of control and throwing off the delicate balance of nutrient cycling to benefit plants. Around the time scientists observed the relationship between actinomycetes and plant health, they also discovered antibiotics like penicillin to fight bacterial diseases.
Fungi decompose fallen leaves on forest floors and in our back yards and digest dead plant and animal remains. Fungi come in many different species with a plethora of functions. Some fungi work to degrade organic matter in sequence, from tough fibrous matter down to soft simple matter that produces nutrients in the soil usable by existing plants and animals. Other species form mutual relationships with plants and protect them by consuming nematodes or other bugs before they eat plant roots.
The fungus that is perhaps the most directly beneficial to plant life is known as mycorrhizae, which forms a symbiotic relationship with roots. Two types exist, endomycorrhizae and ectomycorrhizae. The endo- version embeds some of its arms within plant roots. The ecto- version attaches to the outside of the roots. In both cases, the fungi extend their arms (hyphae/filaments) out into the soil to increase the reach of the roots wider and deeper. These mycorrhizae webs allow entire populations of plants to share nutrients.
Algae contribute much organic matter to the soil. In some species, such as blue green algae, they fix nitrogen from air, helping prevent the depletion of the critical nutrient for plant growth. The organic matter composed of algae helps improve soil structure by assisting soil particles stick loosely together, which in turn enhances water retention and decreases erosion. They are also food for other bugs living in the soil. In some cases, they form alliances with fungi, giving them sustenance that strengthens their ability to absorb even trace nutrients from the soil for plants to consume. Common lichen are an example of this alliance.
Nematodes, pot worms and earthworms decompose organic matter into humus and secrete a sticky substance that helps the soil form nice cake-like aggregates. These creatures exist in the highest numbers on or near grassland, prairies and pastures. They feed on plant debris as well as some bacteria or actinomycetes that share the same topsoil. Some nematodes will feast on insects within the soil. As a result, some gardeners use nematodes as a natural form of pest control. In turn, some bigger bugs and even mycorrhizal fungi feast on nematodes.
Earthworms are larger than the other two types. They travel through the soil by burrowing, eating minerals and organic matter as they go. As they do, they minutely perforate and loosen the soil, producing a similar effect as machine tillers. Throughout digestion, the matter consumed is mixed and many unusable minerals are transformed for plants to consume later. In addition, the remains of an earthworm, commonly referred to as "castings," are much higher in nitrogen, phosphorus, potassium, calcium, trace minerals and beneficial bacteria than the surrounding soil. By these processes, earthworms create more nutrient-rich, fertile soils with a pH close to neutral. Having many earthworms in your yard is a good sign that you have good soil.
Mites and spring tails decompose many types of organic substances in the soil. They are known as arthropods, which have characteristic exoskeletons and jointed legs. They are the most abundant soil dwellers. Of the arthropods, mites and springtails are the most vital source in the creation of humus, breaking down everything from nematodes and pot worms to fungus and leaf litter. Their main job is to break down leaf litter and other relatively large remains into smaller pieces so microbes can continue the nutrient cycling.
These are only a few of the billions of organisms in or around our gardens that have been evolving for millions of years. Growing methods that clear the soil of these organisms undermine the goal of producing healthy food through healthy soil. Agricultural practices that disrupt the bio-diversity of organisms responsible for sustaining growth of all types of plants throughout the world seem like a recipe for disaster.
The soil is a living, breathing, unique and dynamic force. Soil management practices of giant agribusiness are inefficient and inferior. Their focus is directed to large-scale, single-crop growth and "miracle" results by applying broad-spectrum chemical fertilizers. Many modern practices ignore the need for complex and highly diversified soil enrichment. Instead, they use the continuous applications of three water-soluble fertilizers: nitrogen, phosphorous and potassium N-P-K). This practice compromises the biological health of soils, leading to poor plant health and ultimately poor human health.
The amount of nitrogen fixed for plants by rhizobia bacteria, actinomycetes and green algae is double the amount of applied nitrogen in commercial fertilizers. Starting in our backyard, we can begin to change this trend by supporting the organisms that provide our plants with the sustenance they need to give us the nutrients and vitamins we need for our health.
Milo Lou Shammas
Founder and Formulator