Vermicomposting:

Worms in Compost by Karen Kerney

Worms in Compost by Karen Kerney

Every year millions of tons of organic refuse finds its way to landfills, incinerators, municipal sewer systems and septic systems via trash pickup or garbage disposals. The environmental Protection Agency estimates that on average, each American generates 4.3 pounds of trash each day. On a yearly basis, this is equivalent to burying 82,000 football fields 6 feet deep in compacted garbage. Approximately 47% of this amount is organic in nature. The environmental and financial implications of this are huge. The best way to mitigate the resultant environmental problems might well lie in dealing with it before it enters the waste stream.

Most people are familiar with the process of composting whereby the natural breakdown (decomposition) of organic materials results in a dark soil-like material which has great value as a soil amendment. Composting is a natural occurrence in nature that humans over years have recognized as a process that can be utilized in a managed way to dispose of refuse. One step beyond this and a complement to it is the utilization of worms to compost organic matter. This is known as vermicomposting, vermi being the Latin term for things relating to worms.

The advantages of vermicomposting are several. Regular composting is a thermophilic process, relying on heat generated by the decomposition process to work effectively. This requires a deep pile and varied composition of material. The optimum pile temperature for composting to occur ranges from 90° F to 150° F. Pile temperature below this range will result in little or no composting taking place.

Vermicomposting, on the other hand, is a mesophilic process, taking place at ambient temperatures. The optimum temperature for the vermicomposting pro-cess is from 55° F to 80° F. The composting process involves the worms eating and excreting the organic matter. There is no need to turn or layer a pile in order to achieve the proper temperature as may be the case with regular composting.

Regular composting must take place in an outdoor location and the recommended pile size is a minimum of 1 cubic yard. Vermicomposting can be carried on in a bin which may be as small as 1 square foot of surface area by 6” deep. These temperature and space factors allow for the indoor use of worms. Ver-micomposting can easily be done in cold climates and urban settings. Many urban dwellers are happily feeding their kitchen scraps to their composting worms. Not all worms, however, are suitable for use in a compost bin.

Several thousand species of earthworms have been identified by researchers. These many species have been grouped into three categories. The categories are anecic, endogeic, and epigeic worms.

Anecic worms are large worms, that live deep in the soil. They may tunnel down as deep as ten feet, establishing permanent burrows. They come to the surface of the soil in order to pull organic matter into their tunnels, storing it inside tunnels until they are ready to consume it as food. The most familiar worm in this category is the nightcrawler. When the anecic worm is taken from this environment, it will not grow or reproduce.

Endogeic worms rarely come to the soil surface. They build horizontal burrows and feed on mineral particles and decayed organic matter. These worms are often found around the roots of plants where they feed on soil rich with decaying matter and bacteria and fungi.

Our Worm Bins in the Hoophouse

Our Worm Bins in the Hoophouse

Epigeic worms live in decaying organic matter on the surface of the soil, not in soil. This is the category of worm that can be utilized in vermicomposting. Because it is a surface dwelling worm, it is possible to replicate its environment in a bin. The earthworm most commonly used in bin systems is the red worm, whose Latin name is eisenia fetida. This worm is found throughout the world. It is the preferred worm for composting systems because of its toler-ance for handling and changes in environment. These worms are raised on earthworm farms located throughout the country and can readily be obtained via internet sales or a visit to a local farm. A vermicomposting system utilizing red worms is feasible on an individual level or on a large scale municipal or insti-tutional scale. This article will deal mainly with how an individual or family can get started in vermicomposting.

Several factors should be taken into consideration when undertaking a vermicomposting venture. The temperature range for the red worm is roughly 35° F to 88° F. The worms are most productive between 65° F to 80° F. Temperatures at the extremes will stress the worms. Below 50°, the worms will slow down and become less productive. Above 90° F, the worms may well be too hot to survive in a closed bin. The preferred location, therefore, would be an area in the middle of the temperature range.

The worms also have a need to live in an aerobic environment; in other words, they need to live in a bin that has a good flow of oxygen. It is also important that moisture drains readily out of the system to prevent it from becoming anaerobic, or deprived of oxygen. The ideal moisture level in the system would be in the 60 to 70% range. This is roughly equivalent to a damp sponge which gives off a few drops of water when squeezed. Once you have decided on the proper location for your system, it is time to either make or buy a bin.

A worm bin can be made from many materials. Scrap lumber or an old plastic tote can be used. There are many bins available commercially that are designed in a specific fashion for worm composting, some of which facilitate the worms separating from the finished compost as the process evolves. In general, a homemade worm bin should be longer and wider that it is deep. Holes should be drilled on the sides and cover of the bin to insure adequate oxygen supply. Holes must be drilled in the bottom of the bin to allow for drainage; ¼” holes at 15 holes per square foot. The bin should be elevated so that moisture that percolates through the system can be collected. This can also be used as a liquid fertilizer for house plants or gardens. An advantage of some commercial bins is that features designed to optimize aeration and drainage are built into the system. Once you have your bin constructed and a location picked out, it is time to obtain your red worms and prepare the bin.
There are some basic steps to take to insure that your vermicomposting venture is a successful one. When building a bin out of wood, make sure not to use pressure treated lumber. The materials used in the process of pressure treating are harmful to worms. Plastic totes being used to build bins should be washed and exposed to sunlight before worms are placed in the bin. The optimum temperature for the worms is between 65° F and 80° F. A location that provides this would be ideal. Avoid feeding the worms anything that is greasy, fatty or overly salty. Make sure that the bin has adequate aeration and drainage. Realize that you are dealing with an ecosystem not a machine.

As mentioned earlier, there are many worm farms with a presence in the internet or you may be able to locate a worm farm in your area. Many nurseries and garden centers may have a connection with a worm farm.. County extension agents are another resource and may know of a worm farm. Worms are custom-arily sold by the pound. When starting out, it is probably a good idea to begin with 1 or 2 pounds of worms, keeping in mind that given proper conditions, the worm population will grow over time. The general rule of thumb is red worms will eat half their weight in decomposing material everyday. It is a matter of personal choice as to how many worms you want to start your system.

The bin will need to be prepared for the arrival of the worms. Initially, the bin is lined with a layer of bedding. This is where the worms will live. The food waste is buried in the bedding. Shredded newspaper is a convenient and widely used bedding material. Avoid glossy, colored paper, as it has a metallic content which produces toxins harmful to the worms. The shredded newspaper should be fluffed up to a depth of six inches and moistened to the consistency of a damp sponge. Some commercially made bins come with a block of cocoanut fiber which can be soaked in a pail of water. This will absorb eight times its weight in moisture and can be spread out in the bin as bedding. Once the worms are at home in the bedding, it is time to start feeding them.

Worms like a vegetarian spread. Fruit and vegetable scraps and peels are good food for them. Any number of organic items that would usually be discarded can be fed to them: coffee grounds and filter papers, tea bags, crushed egg shells, pasta and rice, bread and cereal, house plant clippings and dead flowers, shredded paper, paper towels and napkins. The worms do not start to eat until the waste starts to decompose. Some people chop up the waste or even puree it to speed up the decomposition process so that the worms can get at the food more quickly. The worms are actually eating both the waste and the aerobic microorganisms that cause the decomposition. They have no teeth and thus cannot eat until the food is broken down.

As the worms settle in to their new environment in the bin and become acclimated the population will begin to grow. The rate at which the worm population increases is the variable that determines how much waste can be composted. Given the proper temperature, aeration, food and space the worms will multiply rapidly. A mature red worm can produce two to three cocoons per week. Each cocoon will average three hatchlings, which will become mature worms in two to three months. When mature, they will begin to produce cocoons. When the population of the bin exceeds 1.5 pounds of worms per square foot of surface area, the worms will slow their reproduction because of space constraints. It is not unusual to start a bin with 1 pound of worms and a year later to have 3 to 5 pounds of worms in the bin.

Mature worms are characterized by a swollen ring about 1/2 of the way down their body. This is called the clitellum. The clitellum produces mucus needed for cocoon production. Worms are hermaphrodites having both male and female sexual organs. The worms need a partner, however, to reproduce. Two worms of approximately the same size will come together at the clitellum and exchange sperm. Mucus then hardens and each worm will slough off a cocoon after being joined together for up to three hours. The cocoons look like grape seeds and turn from light to dark as the time to hatch approaches. Red worms can produce many such cocoons during the course of a year.

Once the bin has been established and the worm population has begun to grow, it will be observed that the consumption of organic waste by the worms has increased. After 3 to 4 months, it will be observed that there is a layer of fine dark material building up on the bottom of the bin. This is the vermicompost or as some call it, the worm castings. This material constitutes the second benefit of feeding your garbage to worms. The first benefit is achieved by taking the organic material out of the waste stream. The second benefit is the production of a wonderful soil amendment for gardens and house plants. This mate-rial is highly valued by those who wish to garden organically and reduce reliance on chemical fertilizers. Some people may not participate in gardening or growing plants. There is a good chance they may know someone who does. A gift of vermicompost is sure to be well received.

Harvesting the vermicompost can be done in different ways, depending upon the size and type of bin being used. A commercially made bin with a system of stacking trays makes it quite a simple process. The worms start eating on the bottom level. When the tray is full of vermicompost , another tray is stacked on top of it. These trays have hundreds of holes in them that the worms can crawl through. As food is added to the new tray, the worms begin to crawl up-ward through the holes following the food and leaving behind the finished vermicompost. This process is repeated with a third tray. By the time this tray is full, the worms will have left the bottom tray following their food upward. The vermicompost can now be emptied out of this tray. The empty tray is then placed on top and the process continues.

Harvesting the vermicompost from a single layer bin can be somewhat more labor intensive.

One method for separating the worms and compost in a single layer system is to put the food on one side of the bin. Over time, as the worms exhaust the nu-trients on the unfed side, they will migrate to the side being supplied with food. It is then possible to take the compost and remaining worms and make a py-ramidal pile on a flat service. Over this pile place a strong light. Because the worms do not like light, they will move to the middle and bottom of the pile. The worms that have congregated at the bottom can be scooped up and put back in the bin.

A more mechanical means of harvesting would involve building two 2×4 frames. Build one frame 2’wide by 3’ long. Build another frame 2’ wide and 2’ long. Attach ¼” hardware cloth to the bottom of the 2’ x 2’ frame. Place the 2’ x 3’ frame on top of a tarp laid on a flat surface. Place the 2’ x 2’ frame with the hardware cloth on the bottom side on top of the larger frame. Fill the smaller frame with the compost and worms. Slide it back and forth over the bottom frame. The vermicompost will fall through the hardware cloth and the worms will remain on top. Place the worms back in the bin and collect the vermicompost from the trap.

The vermicompost is a most valuable commodity for anyone who is an indoor or outdoor gardener. Used as a soil amendment in place of chemical fertilizer quite amazing results can be achieved in terms of plant growth. The vermicompost is a superior product when compared to regular compost. Testing has shown it to be significantly higher in phosphorus, calcium, magnesium, potassium and nitrogen. It also has superior moisture retention properties. Passing through the worm’s digestive system, the organic matter acquires enzymes not found in regular thermophilic compost.

Vermicompost is a wonderful medium for starting seedlings in the spring. A mixture of 20% vermicompost to 80% potting soil will produce strong and healthy seedlings at a very high germination rate. Seeds planted in rows in a vegetable garden will benefit greatly from vermicompost sprinkled in the bottom of the seed row. Vermicompost placed in the bottom of the hole when transplanting plants will help the plant achieve strong root growth.

Once your worm bin is in operation and you have begun to harvest vermicompost, you have completed the circle of sustainability. The worms have turned your garbage into a product that can be used to grow plants and enrich the soil.

Awareness of the implications our behavior has for the quality of our environment is growing all the time. While it is important for government and business to strive to improve the environment, it is equally important for individuals to take positive action in this area. The decision to handle your garbage in a sus-tainable way can only be made by you. Once you have made this decision, there is an army of red worms waiting to be your partner.