Another method of natural composting is through the use of earthworms. The process of using worms to convert organic waste into black, earthy-smelling, nutrient-rich humus is called vermicomposting. Vermicomposting is a simple process which can be achieved inside one’s home by setting up a “worm bin.” It is a convenient method used to convert organic wastes into usable end products. Vermicompost contains worm castings as well as partially decomposed bedding and organic waste. Casting is the material deposited after it has moved through the digestive tract of a worm.
Worms need proper temperature, moisture and ventilation conditions to thrive. The first step in setting up a worm bin is to set up a proper container. The container needs to be shallow and of a proper size. Wooden boxes tend to work best and last longest. Once you have a container it is necessary to set up proper bedding for the worms. Beddings which are most desirable are light and fluffy. These conditions are essential for air exchange which helps control odors. Shredded corrugated cardboard makes one of the best beddings for worms. Shredded newspapers or computer paper are also good choices as are animal manure, leaf mold or peat moss. Soil is recommended for the initial bedding because it provides some grit to aid in breaking down food particles within the worm’s gizzard.
Redworms are the best worms to use in worm bins. They process large amounts of organic material in their natural habitats of manure, compost piles or decaying leaves. They reproduce quickly and in confinement. The scientific name for redworms is
Nightcrawlers are another type of worm that usually do well in gardens but aren’t as productive in worm boxes.
A redworm has both sexes which allows each worm to produce both eggs and sperm. There is a swollen region between the head and tail of a worm called the clitellum. The clitellum is an indication that the worm is sexually mature. The worms extend themselves from their burrows to seek other worms to mate with. Through glandular secretions, they find each other and lie with their heads in opposite directions, and their bodies closely joined. Their clitella secrete large quantities of mucus that forms a tube around each worm. Sperm from each move down a groove into receiving pouches of the other worm. The sperm, in a seminal fluid, enters the opening of sperm storage sacs where they are held for some time. After the worms separate, the clitellum secretes another substance containing albumin. This material hardens on the outside to form a cocoon. Here the eggs are fertilized and the baby worms hatch. When the adult worm backs out of the hardened band it deposits eggs from its own body and the stored sperm from its mate. The sperm fertilize the eggs and set up a home for developing worms known as cocoons.
Cocoons are lemon shaped objects about the size of a grain of rice. As baby worms develop, they change color from pearly white to yellow to brown. When ready to hatch the cocoons are a reddish color. The baby worms develop in the cocoons for about three weeks before they are ready to hatch. Each cocoon can contain up to about twenty fertilized eggs but only two to three worms actually emerge from each egg. For a redworm to become sexually mature, proper temperature, moisture and food availability is necessary. Once they are sexually active redworms can breed and lay about two or three cocoons per week for up to a year. Worm survival depends on the availability of food and space in the bin.
Vermicomposting is easy and requires very little upkeep. After the proper environment is provided, burial of garbage is done maybe once or twice a week. Because bedding and garbage is converted to earthworm casting and bedding should be kept fresh. This means changing it and adding to it about every two to three months.
The number of worms needed in the bind depends on the amount of food waste buried daily and the size of the bin. The worm: garbage ratio should be 2:1—one pound of worms to 1/2 pound of garbage. Good food choices for the worms include potato peels, citrus rinds, outer leaves of lettuce or cabbage, celery ends, plate scrapings from carbohydrates, coffee grounds, tea bags, eggshells, and meat waste. You should not use non-biodegradable materials in the bin—plastic bags, bottle caps, rubber bands, aluminum foil and glass would cause problems in the bin. The garbage should be added about twice a week and then covered with bedding. The garbage creates a perfect natural environment for other organisms to feed and reproduce. Worms keep the conditions aerobic and odor free. They reduce the mass of material to be processed and produce castings.
Once decomposition begins to occur in the worm bin you will begin to see some other creatures present. They play important roles in breaking down organic materials to simpler forms that can be reassembled into other kinds of living things.
The food web in a compost pile is varied. (Figure 1).
Organic residue is eaten by first level consumers, such as molds and bacteria. Earthworms, beetle mites, sowbugs, enchytralids and flies are also responsible for consuming waste directly. The first level consumers are eaten by second level consumers, such as springtails, mold mites, feather-winged beetles, protozoa and rotifers. Third level consumers are flesh eaters or predators. These include centipedes, rove beetles, ants and predatory mites.
Many of the organisms are microscopic. Enchytracids are usually known as white worms. They are not harmful in the worm bin. Springtails are primitive insects that jump all over the place. They live in almost all types of soil. Isopods or sowbugs look like tiny armadillos. They are vegetation and eat leaf litter so they present no harm to the worms. Centipedes are predators and do kill worms so if they are present get rid of them. Mites are very small with eight legs and a round body. They are not desirable organisms to have in your bin. Although there are a few organisms which can pose a threat to the worm bin, most of the organisms serve as food for each other, clean up each other’s debris, convert materials to forms that others can utilize and control each other’s population.
When a worm bin is set up in a classroom, students will have the opportunity to participate in various activities. Besides helping to prepare the bin and care for the worms, students will be able to observe and study many aspects of a worm’s behavior and biology. Food preferences, mating habits, identifying castings, charting the distribution of cocoons and the rate of growth development are all areas to be studied. These studies also integrate important math skills such as graphing and estimation as students keep records and journals of their observations and findings.
Once the worms have done their job effectively you can begin to use the vermicompost on your house plants and in your garden and almost immediately you will begin to notice healthier plants. Vermicompost is a mixture of worm castings, organic materials and bedding in various stages of decomposition, plus the living earthworms, cocoons and other organisms present and composting continues after a worm casting has been deposited.
Humus is an important component achieved in the mixture formed during the breakdown of organic matter. It contains humic acid which is released as plants require it. Humus has been known to stimulate growth and organic gardening encourages carrying out procedures that increase humus content in soil. The vermicompost developed in the worm bin also holds in moisture in soil so its uses are diverse. It can be used in seed beds, in transplanting garden vegetables and as a top—dressing for plant growth in both outdoor gardens and potted plants.