I sometimes wonder how many of us actually think about the importance of soil when we go about our way daily. And yet soil, along with the sun’s energy, water and oxygen, is the reason our planet can be home to humans and all other living species. After reading this story, if I have done my job well, the next time you are walking outside, maybe you will pause for a moment to think about the teaming, vital life under your feet, and give a heartfelt thank you for all the gifts it bestows on us. Soil is composed of two components, the living and the non-living. The non-living part consists of mineral particles, clay, sand and silt that range in varying amounts depending on which environment they are in. One would expect to find more sand near the sea shore and more silt or clay near wetlands. Our soil in New England is especially acidic. That is because all soil is influenced by the rock base under it. In our case granite is the base under our thin 4-6 inches of top soil. The minerals that granite gives off, as it slowly decomposes and wears down, gives the acidic level to our New England soil. Because our soil has a high acidity level, all our native plants, which have evolved under its influence, are acid loving plants. To explain further, acidic loving plants are really iron loving plants. Acidity releases the iron in the soil for easy consumption by plants. Iron is a micronutrient and is necessary in all plants for their production of chlorophyll. TOPSOIL: Why do we have such thin top soil in New England? The Laurentide Ice Sheet withdrew from New England about 18,000 years ago. Remnants of this ice sheet can still be found in Greenland today. We can thank this glacier for the formation of our irregular sea coast, Cape Ann, Cape Cod, lakes and ponds, eskers*, moraines*, drumlins*, glacial erratics* and for the richness of rocks in our soils today. It also removed all our topsoil. It is often said that New England’s number one crop is rocks! It takes at least one hundred to five hundred years under the right conditions, depending on climate, latitude, vegetation and other factors, to make one inch of top soil! And because of poor farming techniques, over grazing of farm animals and the cutting down of forests, much of our valuable topsoil annually gets washed down stream or out into the oceans when it rains. MICROORGANISMS: Good soil that is capable of supporting a living element has a structure that is composed of about 25% water, 25% air and 50% solid matter, of which least 5-10% should be organic material. In addition to the sun’s energy, all living species on this planet, including plants, need water and air. However, for any plant to grow it must have a living component in the soil. These living components, sometimes referred to as the Soil Food Web, are microorganisms. Most microorganisms in the soil cannot be seen by the human eye. They include bacteria, fungi, protozoa and nematodes. In addition, small arthropods (insects) and finally earthworms round out this important list of essential participants. All microorganisms also need water and air. Thus, you will find them living only in soil that has not been compacted and has a good structure. Compaction squeezes out the air and water from soil. Have you ever noticed that nothing grows on a path that has had constant use? Without the presence of these organisms, the soil is dead, lifeless and just dirt. It is incapable of supporting any growth of vegetation. These microscopic organisms have many roles to play on this planet. In this blog I am going to talk about only two important functions. First, they are responsible for the decomposition of all dead species on this planet from a leaf to a bird to a giraffe. If it weren’t for microorganisms, we would be forever walking on our dead! As they facilitate the decomposition process, all the microorganisms also absorb and lock valuable nutrients in their bodies. Mother Nature does not waste anything, and if it were not for these organisms, valuable nutrients from the bodies of all dead species would be washed away by rain water, or be wasted by leaching through the soil. Instead, the microorganisms consume these nutrients and use them as food. PHOTOSYNTHESIS: Green plants are the only species on our planet that have the pigment chlorophyll. They alone are capable of making their own food directly from the sun’s energy in the process called photosynthesis. Chlorophyll’s unique job is to absorb sunlight and change it from light energy to chemical energy that can be utilized right away or stored for future use. This energy gets converted to sugars, carbohydrates and starches and is then stored in the roots of plants. Chlorophyll is found in leaves which are the food factory of all plants. It is the reason why all plants are green. Plants also are the only species where part of their bodies live above the ground and the other in the ground! An interesting note is that plants cannot move to go find food because they literally are rooted where they are. Yet Mother Nature has figured out a unique way, through the process of photosynthesis, for them to be fed. One of the plants major roles on this planet is to pass all this food energy onto all other species, both above the ground as well as in the soil. RHIZOSPHERE: The second key role microorganisms play is in their vital interaction with all green plants and it happens at the root zone. This is the key to why we have such diversity of life on this planet. Where the plant’s roots are located and the area directly around them is called the rhizosphere. The rhizosphere is teaming with microorganisms! One third of the plant’s food supply is used for immediate growth needs, 1/3 is stored for next year’s growth and 1/3 is given to microorganism in exchange for the nutrients that the microorganisms have harvested from decaying dead bodies. Green plants want the nutrients that microorganisms have and microorganisms gladly share some of their hard won nutrients with the plant roots in exchange for sugar and starches that otherwise they would not be able to acquire. This is a great example of a symbiotic relationship where two different biological organisms come together in a long term biological interaction that is beneficial and necessary to both. To create a thriving ecosystem above the ground, you need to create an equally thriving system in the ground! There is a saying among organic gardeners, farmers and environmentalists, “Feed the soil, not the plant”. Mother Nature has always relied on the exchange of nutrients for sugar at the root level that occurs between microorganisms and plants. This vital service, that evolved around two billion years ago, happens all over the planet in all green plants from the smallest blade of grass, flowers and vegetables in your gardens to the largest tree. Simply put, the actions of microorganisms are essential to the health and success of all green plants on our planet! We, as gardeners, can follow Mother Nature’s example and feed the microorganisms in our gardens by top dressing our garden soils with organic materials such as leaves and compost. After the microorganisms have broken down the organic materials into nutrients, they in turn will share these nutrients with the roots of all your plants in return for sugar and starches that your green plants make. So the next time you are out for a walk, you just might want to look at the ground you are walking on and think of the billions of vital interactions between microorganisms and the roots of plants all over our planet that is taking place. In future blogs I will address the subjects of composting, using leaves as mulch in your garden and how plants pass on the sun’s food to all other above ground species on our planet. *Eskers: A long ridge of gravel and other sediment, typically having a winding course, deposited by meltwater from a retreating glacier or ice sheet. *Moraines: Material usually rock or soil that is left behind in a mound by a moving glacier. *Drumlins: A low oval mound or small hill, typically one of a group, consisting of compacted bolder clay moulded by past glacial action. *Erratics: Deposited rocks differing from the size and type of rock native to the area in which it rests that were carried and deposited by retreating glacial ice. Note: Humans all over the planet consume roots of plants directly getting not only the suns energy but the nutrients the roots received from micro-organisms. We call this food, root vegetables, and it includes, to name a few regional favorites, carrots, parsnips, radish, beets, potatoes, yams and turnips. The nutrients we receive from plants we call vitamins. A note of caution: Chemical fertilizers such as Miracle Grow are synthetic fertilizers that have been engineered to directly feed plants to make them grow. However in doing so, they kill all the microorganisms in the soil thus leaving a dead, sterilized soil. Your plants are now chemically dependent on artificial fertilizers and can no longer receive food otherwise from the soil. Scientist who manufacture these chemical fertilizers do not know how long they will remain in the soil. Scott’s lawn fertilizer is also a synthetic chemical fertilizer. Using it will kill all the healthy microorganisms in the soil, sterilizing it and making your lawn chemically dependent on a yearly use of more chemical fertilizers. Both Miracle Grow and Scott’s companies are now offering organic fertilizers.
2 Comments
Paula Jones
2/12/2021 02:23:16 pm
Terrific article... Would love a recipe for compost tea too. Thanks Catherine.
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Paula Jones
3/3/2021 06:04:55 am
Catherine, I have been very impressed with Neptune's Harvest... your thoughts?
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AuthorConsultant, designer and educator transforming commercial and residential landscapes sustainably Archives
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