   Vermicomposting - August 25, 1999 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Vermicomposting is the use of worms to convert organic matter into high quality compost. Red worms are used usually in an upright bin with adequate aeration and screen covering the holes to keep the workers on the job. It is being used on a small scale by many backyard gardeners and on a large scale to reduce waste in institutional settings. It's not as simple as piling up compostable material and waiting for the end product. Worm composting requires that you pay close attention to the needs of your workforce: the worms. Redworms are the best choice for vermicomposting. Garden worms and night crawlers are adapted to living in the soil and will not thrive in a worm bin. In nature, redworms live in manure and are well suited for breaking down organic materials. Redworms are also known as red wigglers, manure worms, red hybrids, striped worms, fish worms and many others. Two species are commonly used. Their scientific names are Eisenia foetida or Lumbricus rubellis. They prefer temperatures between 55 and 77oF and a moist, but not soaking wet environment. Redworms can be purchased from dealers or bait shops or mail ordered. One or two pounds of worms are adequate for the methods described in this article. They can cost between $12 and $18 per pound. Most home vermicomposters use a wooden or plastic bin as a worm container. The container should be shallow (no greater than 18") because the worms feed near the surface. The amount of material your household generates will vary from family to family. This determines the size of the vermicompost bin. In general, a family of three to six people should have a bin about two feet by three feet (L x W). Excess materials can be put on a traditional compost pile if desired. The bin can be made of plywood, metal, or plastic. Just make sure that it is clean and has no chemical residues. A common worm bin is a 10-gallon plastic tub. These are readily available and fairly inexpensive. Bin aeration is provided by drilling 1/16" drainage holes in the bottom (about 20 or so) and a few in the sides near the top so air can circulate. The bin should be elevated on wood blocks or bricks to provide air circulation on the bottom and a plastic or metal tray can catch the drippings (use it as liquid fertilizer). During winter, it can be kept in a garage, breeze way, or other protected area. To start your vermicompost operation, create the bedding using a few handfuls of sterilized soil or sand mixed with shredded newsprint or computer paper, moistened peat moss, crushed leaves, dried yard waste (not green grass clippings), cardboard, or other bulky organic matter. Do not use glossy paper or materials printed in color. Moisten the materials with water so that it feels as moist as a wrung-out sponge. Add the worms and feed them. Worms thrive on potato, carrot, or other vegetable peelings, onion skins, lettuce, cabbage, grape stems, melon rinds, or other kitchen waste. They may not eat citrus peels and banana peels really attract fruit flies. Coffee grounds (filter included), tea bags (minus the tag), plate scrapings (minus meat, fat and bones), rotten food from the refrigerator, stale crackers, and a host of other materials are suitable worm food. Bury smelly materials in the bin to avoid attracting insects. DO NOT feed worms pet feces, kitty litter, non-biodegradables, or foods high in fats and oils. Add crushed egg shells or small quantities of lime to balance the pH. You will eventually get a feel for their preferences by watching what they eat most readily and using your nose. Under optimal conditions, worms will double their population in about 60 days. Worms seem to know their carrying capacity (maybe better than we do) and in time the population will stabilize. Now for the rewards! To harvest the castings (composted material), simply construct a sieve using 3/16" hardware cloth, remove the bulky material at the top of the bin and set it aside in a plastic bucket, and sift the castings separating the worms and placing them in the bucket as you go. You will end with a rich organic soil amendment and bucket filled with worms and bulky debris. When done, reconstruct the vermicompost bin as outline above, add the worms and reserved bulky material and you are back in business. As a side note, this process is being used to solve commercial solid waste problems around the world. Large scale organic growers are using vermicompost for fertilizer. In fact, worm castings are really quite a valuable commodity and it's a sustainable agricultural practice. They'll get us now or they'll get us later, but we can be sure that our future is in worms. The University of Arizona Cooperative Extension has publications and information on conventional composting and cover crops. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. |