Friday, July 15, 2011
These are generally called microbes, because they are so small. However, they play a very big part in the soil, because they are concerned with the decomposition of organic material, both vegetable and animal. It is tremendously important work, for decomposition leads to re-composition by supplying food for new plant life.
It will be convenient to divide the microbes into five main groups:
Group I: The Yeasts, Moulds and Fungi:
It is possible to have about one million fungi in a gram of soil. Fungi can be said to be plants, but plants which have no chlorophyll, and therefore, do not make food. Most fungi are parasitic, that is to say they live on other plants and animals. Certain fungi live on the remains of recently dead plants and animals. These fungi are called saprophytic; they aid in the production of humus in the soil.
The mycorrhizas form a group of fungi that are in a close symbiotic relationship with green plants. The name mycorrhiza comes from the Greek, myco, meaning fungal and rhea, meaning root. Modern research shows that certain plants benefit from a relationship with the mycorrhiza in the soil. The green plants roots are invaded by the mycelia root like hairs, of the mycorrhiza. The mycorrhiza gets its carbohydrates from the roots of the green plant and in return it gives the plant nitrogen, certain other nutrients and moisture. About eighty percent of green plants benefit from a relationship with mycorrhizas in the soil. In this complex relationship it must be remembered that the mycorrhiza are living on the humus in the soil. The mycorrhiza appear to be the means by which growth promoting substances, found in the humus of the soil, are transmitted directly to the active areas of the roots of green plants. This is probably nature’s way of providing protective substances that aid green plants in growth and the resisting of disease.
Group II: The Bacteria
Bacteria are microscopical. Most are round; however, some are rod-shaped. Some bacteria have phlagella, that is to say little tails, by means of which they can swim about in moisture. Bacteria increase quickly by cell division. It is possible from one bacterium to produce sixteen million more in twenty-four hours.
Some bacteria live and multiply in nodules formed on the roots of leguminous plants. They receive carbohydrates from the plants and supply nitrogen, taken from the atmosphere, to the plant in return.
One group of bacteria, known as an azotobacteria, lives in the decaying organic matter, or humus of the soil. They work on the gases and other compounds that might easily be lost in the soil, making them available to plants. About twenty-five tons of nitrogen may be fixed in this manner in the top six inch layer of an acre of soil each year.
All bacteria play a great part in building up the fertility of land. There should be fifty thousand pounds of bacteria and fungi in the fertile top six inches of an acre of good soil.
Group III: The Protozoa
A protozoon is many times the size of bacteria. They come in many shapes. Many protozoa appear to be green in color, because they are often associated with the microscopic green plants known as algae. The algae probably provide the sugars which the protozoa’s need to live. Some experts consider them to be animals by night and plants by day.
Group IV: The Algae
Algae are green plants without true roots, leaves or stems. Some are very large, such as seaweeds, and others are microscopic, such as the algae that live within the protozoa. They trap the energy of sunlight, as other green plants do. Algae are bathed in moisture, whether as seaweed, or in ponds, or as microscopic algae in the water films of the soil. They are certainly adding nutrients to the soil.
Group V: The Actinomyces
Actinomyces are an anaerobic form of bacteria that form fungus-like, branched networks in the soil. They produce a number of enzymes that help degrade organic plant material, lignin and chitin. As such, their presence is important in the formation of humus in the soil. It is the actinomyces which gives the earthy smell to soil.
Some may wonder why we must concern ourselves with the countless trillions of microscopic organisms that live and die beneath our feet. The answer to that question is actually very easy. We are intimately connected with this enormous quantity of life in the soil. Our very health rests on this profound connection to the soil.
The good news is that there is nothing really to worry about. These microscopic beings unknowingly carry out their functions day by day, without any instructions from us. The
Lawn maker or gardener need not worry about the addition of microbes to the soil. The desirable thing is to add sufficient organic matter to the soil each year so the microbes have plenty of material to work on.Back