VERMICOMPOSTING. Red worms are a specialized species used for vermicomposting.

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1 VERMICOMPOSTING Vermicomposting is a method of composting that involves feeding kitchen scraps to worms kept in an aerated container. It is called vermicomposting because vermi is the latin word for worm. It is also referred to as vermiculture, or worm composting. There are two possible end-products: castings are materials that have been digested by the worms (worm feces) and vermicompost is a mixture of castings and decomposed or partially decomposed organic matter that has not been digested by the worm. Both castings and vermicompost are extremely nutrient-rich and beneficial for soil and plant health. Red worms are a specialized species used for vermicomposting. WHY VERMICOMPOST? Vermicomposting is an easy and fun option for those who want to recycle food scraps, paper goods, and other organics generated at home; but have little to no yard waste, or access to a yard. Vermicomposting also works well in conjunction with traditional backyard compostingespecially if you have a higher ratio of food scraps to yard waste. Castings are perhaps the best soil amendment available for improving growing conditions in soil. Vermicomposting typically produces faster results than traditional backyard composting, and the end-product is more nutrient-rich. Vermicomposting is particularly fun for families with children. The worms can be viewed as a family pet, and children are fascinated by the changes that occur in the bin. Many schools are using worm composting with great success to divert waste as well as teach their students about organics recycling, chemical-free gardening, resource conservation, and biology. THE WORMS There are about 3,000 species of earthworms, but most are not suitable for vermicomposting. The standard garden earthworm is more of an earth-mover versus an earth-processor. They do not digest large amounts of organic material, do not reproduce well in confinement, and do not tolerate habitat disruption. They are extremely beneficial organisms to have in your garden, given the benefits to overall soil health and porosity. One of the most common garden earthworms is Lumbricus terrestris, commonly called the nightcrawler. Consider yourself lucky to have earthworms in your garden soil; just don t try to confine them in your worm bin. The two most common species used for vermicomposting are Eisenia fetida (red wiggler), and Eisenia andrei (red tiger). These two worm species are very closely related and commercial sellers often offer a mixture of the two. These species have the same performance characteristics and are only distinguished by biochemical analysis of their digestive fluids. Both species are well suited for vermicomposting given that they are extremely prolific breeders and efficient decomposers, can tolerate a wide range of temperatures and moisture conditions, and are tolerant of handling and confined spaces. They are not likely to survive if released in your garden, as they rely on decaying surface matter and are not capable of traveling far for food 17

2 sources. Eisenia fetida is the most commonly sold species at commercial facilities here in San Diego County, and therefore is the most prevalent amongst local home vermicomposters. The number of worms you need depends on the size of your worm bin, the amount of food scraps your household produces, and how quickly you want to produce finished castings. An average population necessary to start a vermicompost bin is 1 pound of worms. THE BIN Before decisions are made about what size or type of bin is needed, a waste audit should be conducted. Your container size will depend on the amount of organics generated on a weekly basis. A waste audit simply entails setting aside your compostable materials for a week and weighing them. As a general rule, 1 square foot of bin space is needed for each pound of food scraps generated per week. If your household creates 6 pounds of kitchen scraps in a week, then a 2ft by 3 ft bin should suffice. Worm bins are available commercially, or you can make your own. If you decide to build your own, there are many versions and styles to choose from. One version can be found on Solana Center s website. Some prefer to construct bins out of wood, others prefer to use plastic. It is important to remember that red worms prefer a shallower environment. Typically, vermicomposting bins are 6-18 inches in depth. The vermicomposting unit needs to meet the worms needs, as well as the needs of the user. It should have a lid to keep moisture and worms in and pests out. It should have small holes drilled for ventilation along the top and/or sides. Holes should also be drilled in the bottom to allow for drainage of excess moisture. The liquid that drains from your worm bin is called leachate and contains nutrients that can be applied to your plants as a soil drench. Many vermicomposters set up a catch system under their bin in order to collect this liquid. Worm bins must also be opaque to keep light from entering the bin as worms do not like direct sunlight. Although worms do not have eyes, they have light sensitive cells and will work to move away from introduced light. Worms must have the proper diet, temperature, moisture, oxygen, acidity, bedding, and volume to thrive. BEDDING As the primary source of carbon in the bin, worm bedding is an important aspect of vermicomposting. Proper bedding should hold moisture and contain air space for the worms. The bedding should also be edible, so use care when choosing materials. Common bedding choices include: moistened shredded paper, newspaper, corrugated cardboard, napkins, paper towels, or paper egg cartons. Coconut coir, a bedding material made from the fibers inside a coconut shell, is not only edible, but helps retain moisture in the bin. It can be purchased online or at select locations. Coir is a more sustainable replacement for peat moss for several 18 Making your own worm bin out of stacking plastic tubs is easy! Remember to drill holes for air and drainage.

3 composting and gardening functions. Coffee grounds, along with coffee filters, also help create a moist medium that allows the worms to travel easily throughout the bin. Once you ve selected a bin and acquired your bedding materials they will need to be presoaked and wrung out. Drain off any excess water, and put it in the bin without packing it down. Leaving it looser provides more air space for the worms. Ideally the bedding should fill about ¾ of the container. You ll be amazed at how fast it will shrink as they begin to eat. Worms also require small grit substances in order to aid in digestion. When you are setting up your bedding, make sure to add a small handful of sandy soil, egg shells broken into small pieces, or bird grit into the bin. All bedding material will eventually be digested by the worms. You can set up a bin that will yield lots of castings by filling it with lots of bedding. MOISTURE Worms require moisture in order to perform necessary bodily functions. A moist body allows them to breathe, or absorb oxygen through their skin. Moisture is also necessary for movement through the bedding and for excretion of waste to take place. The general rule for bin moisture is the same as with traditional composting. The bedding should feel about as moist as a wrung out sponge. If you want to be exact, you can create a bin with a wet-to-dry bedding ratio of 3:1. This creates a 75% moisture level. You can obtain this by weighing the dry bedding, and then adding water until the bedding is equal to 3 times its weight. If your bedding feels too dry, you can simply add water. It is possible to have too much moisture present. Standing water in the bin can reduce available oxygen and drown worms. Also, if too much water is added, it can leach out nutrients. If your bin is too wet, you can simply mix in some dry bedding material such as shredded paper, or cardboard. As a worm population becomes more established the moisture level will remain more consistent due to the additional moist food being added and the worm fluids produced. TEMPERATURE Red Wigglers and Red Tigers thrive at temperatures between 55 F and 79 F. They can survive in temperatures as low as 32 F, and as high as 85 F. Temperatures below 32 F, or above 85 F can be lethal. The location of your bin should take this into account. Worm bins should never be placed in direct sun. Direct sun exposure can lead to high internal bin temperatures even if the ambient temperature is still within the acceptable range, so providing shade for the bin is highly recommended. Outdoor bins may be insulated with blankets or soil, or brought inside during cold snaps. You may also choose to keep your worm bin permanently inside under the kitchen sink, in the basement, or in the garage. Choose a location that's convenient for regularly adding 19

4 kitchen scraps and one that is good for the worms. When temperatures are extreme, moisture also should be considered. If it is extremely warm then moisture will evaporate more quickly. If the temperature is approaching freezing, it might create ice. ph Red worms do best at a ph close to neutral or slightly alkaline. Their optimum range falls between on the 14 point scale. If conditions become too acidic or alkaline you will see worms attempting to escape the bin. Although not necessary, you can occasionally measure the ph of your bin using ph paper placed in damp bedding. If conditions are too acidic, some crushed egg shells or powdered lime (CaCO 3 ) can be added. DIET AND DIGESTION Worms are detritivores, meaning they feed primarily on dead or decaying organic material. Red Wiggler and Red Tiger worms are extremely efficient recyclers, consuming about half their body weight in food scraps per day. So if you have a pound of worms, they should have access to about a ½ lb of food scraps each day. Food scraps should be cut, torn, or broken into smaller pieces in order to promote faster ingestion and processing. Picture source: Worms have a fairly simple digestive system. They do not have teeth and rely on their pharynx to act as a suction pump to draw food in. As the food passes through the pharynx and esophagus, mucus is secreted. Once the food reaches the gizzard, strong muscles contract in order to take advantage of the ingested grit that will help grind up the food. Food continues into the intestines where the presence of symbiotic microbes further assists in the breakdown. The mucus located in the worm s intestines provides substrate for these microorganisms. In turn, the microorganisms help in the decomposition of complex compounds into simpler 20

5 substances that are then digestible by the worm. In the process of digestion, the nutrients are altered into forms that are accessible to plants. The quality and quantity of nutrients available are dependent on the food provided for the worms. A greater diversity of ingredients will produce a greater diversity of nutrients. Worms will eat a number of different organic materials, but there are some items that are not recommended for backyard vermicomposting systems. For example, meat and fish provide an excellent form of nitrogen for both worms and microbes, but we suggest keeping these out of the bin because they may attract rodents, cause odors, and may be associated with less desirable types of bacteria. The same is true for dairy products. Once you become more experienced with vermicomposting, you may decide to add small amounts of these items. If you choose to add meat, fish or dairy, be sure your unit has a tight lid on it, bury the scraps a few inches under the surface, and chop the material finely before placing it in the bin. Some of the worms preferred items include soft vegetables and fruits. Melons, bananas, and avocados are bin favorites. Citrus pieces can be added in small amounts, but can be harmful in large doses due to d limonene, oil present in citrus rinds. Yard waste should only be added in small amounts, and grass is discouraged given its ability to heat up a bin. Woody yard waste should never be added since it contains lignin which is indigestible by worms. The following table outlines the basic diet for a smaller backyard bin. Commercial-scale vermicompost systems may be better equipped to include items that would not be suitable for a small, backyard system, such as herbivore manure. Worms LOVE to eat: Worms will eat SMALL amounts of : Worms DON T like to eat: Fruit Pieces & Peels (Esp. Bananas, Melons, Avocados) Citrus Pieces & Peels Meat, Fish & Bones Vegetable Pieces & Peels Spicy Foods (i.e. Jalapeños, Onions, Garlic) Carnivore Manure Coffee Grounds & Filters Plain Bread, Pasta, Cereal Dairy Products Tea Bags (without staple) Egg Shells Leaves & Yard Waste (grass is not suitable) Herbivore Manure (not recommended w/ children) Oily & Salty Foods Sticks & Woody Plant Material (contains lignin) Shredded Newspaper & Paper Glossy/ Shiny Paper 21

6 When feeding, it is best to bury the food among the bedding. This is ideal for the worms and also discourages pests. The amount of food needed is dependent on the size of the bin and the number of worms you have. Remember that worms can eat up to half their body weight in a day and if they do not have food, they will re-ingest castings which will deplete the nutrients of your finished product and can be harmful to your worms. As you care for your worms you will see how much food they require. At first you will want to check on your new population every few days to monitor how much food they ve eaten, their moisture level, and if they need more food. As the bin becomes established, you won t need to tend to it as often. You ll learn which foods your worms do and do not like. If you notice certain foods are not disappearing and are breaking down via fungus/mold, then you know that they are not a favorite item for your worms. Avoid overfeeding, and simply freeze excess food scraps or put them in your traditional compost bin. REPRODUCTION AND POPULATION CONTROL If worms have all their needs met and ample food available to them, they will flourish. You will begin to see more worms in your bin and the food will disappear more quickly. Small golden capsules, about the size of a sesame seed, will appear. These are cocoons that may contain up to 10 baby worms. If these are present, you know you re providing a healthy environment for your worm population. Worm reproduction is a fascinating subject. As you might have noticed in the previous diagram on page 20, worms have both male and female sexual characteristics, making them hermaphroditic. When worms reach reproductive age at about 10 weeks, their clitellum will develop. This raised band is located about 1/3 rd of the way back on their body. It is also known as the girdle or saddle. During copulation, worms will join together and secrete a slime tube. Both worms release sperm cells which are received in the opposite worms seminal receptacles and stored there. Once the animals separate, the clitellum secretes a mucus ring. This ring Detailed shot of worm cocoon. The average incubation period of a red worm cocoon is 23 days. Although worms have both male and female reproductive organs, asexual reproduction is very rare. slides over the anterior portion of the body and picks up eggs from the animal s oviducts and sperm from the seminal receptacles. The ring, which is the forming cocoon, continues sliding down the body and is eventually released. Fertilization occurs in the cocoon. Once breeding has transpired, a worm can deposit 2 to 3 cocoons per week for 24 weeks. This means that one breeding worm can produce 96 babies in just six months (with an assumed average of 2 babies per cocoon). 22

7 As the cocoon develops it changes color from pearly white, to a reddish yellow when the worms are about to emerge. It typically takes about 3 weeks for the babies to hatch, but is dependent upon environmental conditions. Most cocoons contain 2 to 3 worms, but can hold as many as 10. When worms emerge they are whitish and transparent, but have a pink tinge as a result of their blood vessel. Babies are ½ inch to almost an inch long. Picture source: Some vermicomposters are concerned that their population will get too large for the bin to support. Luckily, worm populations are self-regulating to meet available space and resources. If they do not have ample food, then they will not reproduce rapidly. If environmental conditions are not ideal, cocoons can delay hatching for up to 2 years. If you do feel that you have too many worms for the space available you have several options. You can create another bin, or another tray depending on your system. You also might be able to donate the extra worms to a neighbor or local school that has a vermicomposting program. WORM ASSOCIATES The red worms do not work alone. There are other organisms that are working diligently in your vermicompost system. Some are visible to the naked eye, like sow bugs, while others can only be seen under a microscope. In general, most of these organisms are not only harmless to your worms, but actually aid in the decomposition process. There are a number of helpful organisms that are typically found in the standard backyard worm bin. For example, fungus or mold can be a welcome sight in small amounts. Fungi are able to break down tough debris including cellulose. They also can handle organic matter that is otherwise too dry, acidic or low in nitrogen for certain bacteria. Other common allies include pot worms, also called white worms or enchytraeids. These are very small segmented worms only reaching about mm long. They not only eat decomposing food scraps, but also feed on mycelia, which are the thread-like strands produced by Springtails (Collembola) Sow Bugs (Isopoda) 23

8 fungi. Many vermicomposters confuse them for baby red worms, but they can be differentiated by their fully white coloration. Baby red worms have a pink tinge because of the hemoglobin they possess. If you notice an excessive amount of pot worms in your bin, it might indicate that conditions have become too acidic. This might also be the case if your bin is swarming with mites. If this occurs, assess the food sources you are providing. You might even need to start a new bin and transfer your worms over. Centipedes vs. Millipedes: identification is important for keeping your worms safe! Other critters you might see include springtails, sow bugs, millipedes, snails, and ants. Ants are an indicator that your bin may be too dry. If your worm bin has legs or a stand, you can discourage an overpopulation of ants by placing the legs in a standing bowl of water. The ants will not be able to cross the water barrier. One organism you ll want to discourage is centipedes, due to their predatory nature. A few here and there are not a big concern, but if you start to notice a decline in your worm population, you might want to start removing centipedes. You can tell a centipede from a harmless millipede, by the number of legs attached to their bodies. Centipedes have only one pair of legs per segment, while millipedes have two pairs of legs per segment. TROUBLESHOOTING Occasionally problems arise that will require your attention. The table below addresses some common concerns and the possible solutions. PROBLEM BIN IS TOO WET BIN IS TOO DRY WORMS ARE TRYING TO ESCAPE WORMS ARE DYING WORMS ARE BEING PREYED UPON SOLUTION Add more dry bedding, and avoid foods high in water content Add water with watering can or spray bottle, assess temperature and location The conditions are not ideal, assess the temperature, moisture level, ph, sunlight, amount of food, and what food is being added Often the bin is either too wet, too dry, the worms do not have enough food, or the food added has created an environment that is too acidic. Sometimes too much food can be added, and have a smothering affect. Make sure the lid is secure and no holes larger than a quarter inch are present throughout the bin that rodents might be able to slip through. If that doesn t help, search for centipedes and remove them. 24

9 EXCESSIVE FRUIT FLY POPULATION THE BIN SMELLS BAD Often there is too much food, or not enough bedding covering the food. You can try stopping feeding for a week, and adding more bedding. Also, make sure your kitchen collection container has a sealed lid or empty it more often. If fruit flies are present there, then they are laying eggs that will transfer to your worm bin. One other solution would be to place a fruit fly trap near the bin. The bin may be overfed, too wet, and not ventilated well enough. Make sure drainage and ventilation holes are not blocked, and stop feeding for a few days. You might consider adding more substrate as well. Assess the items you have been adding and remove any meat, dairy, or fish that might have been added. MEETING YOUR NEEDS The level of maintenance required for vermicomposting is up to the composter. You may choose to set-up a low-maintenance one level system, or one that has multiple stacked trays at various stages of decomposition. Multiple stacked trays involve setting up a new tray either directly above or below your processing tray. You then only add food scraps to this new active tray and allow the worms to migrate through holes in the bin to reach the fresher food source. Some systems have as many as 4 stacked trays being processed at one time. The method you choose should be based on ease of use, desired results and expectations, and time available. THE FINISHED PRODUCT After about three months, the material in your worm unit will begin looking black, homogenous, and crumbly (assuming additional bedding/carbon materials have not been added recently). It will also retain water well at this stage and should be very moist. Since worm systems differ, it s up to you to decide when to harvest. Bear in mind that harvest time coincides with providing your worms with fresh bedding. Even if you re not quite ready to harvest and use the vermicompost yourself, it may be time to remove some castings and add new bedding to the bin to keep your worm population thriving. Remember, worms Remember to remove your worms from the harvested castings so they can get back to work in your bin! need sufficient oxygen, nutrients, and moisture. Detailed harvesting methods and uses of vermicompost will be discussed in chapter Setting up a multi-tray system allows for more frequent harvesting of castings.