When describing an earthworm to someone who has never seen one, it sounds like you are describing a creature that is too good to be true and can’t possibly exist. They don’t have any ears, eyes, or a nose, but they do have senses. They have a mouth, but they don’t have jaws or teeth.
Each earthworm is both male and female (they’re hermaphrodites) but it still takes two earthworms to make little earthworms. Earthworms are truly specialized creatures, perfectly adapted to subterranean life, and they excel at turning the stuff we would consider waste into a useful product.
When earthworms feed, they take in bits of rock and organic matter (humus), digest what they can, and deposit the rest as excrement (castings).
Earthworm castings improve the soil in several ways:
Castings are close to neutral in pH (around 7 on the pH scale) no matter what kind of soil the worm ate.
For example, even if a worm fed in a very acidic soil, its castings would be neutral, not acidic. Earthworm castings also contribute to neutralizing soil pH by adding calcium carbonate to the soil.
Castings are rich in minerals and nutrients needed by plants. A study at Cornell University showed that the nutrient level of castings is usually much higher than that of the surrounding soil. Castings were found to be high in nitrogen, potassium, phosphorus, magnesium, and trace minerals. Castings were also shown to supply needed micronutrients to plants.
Another study estimated that castings contain five times the available nitrogen, seven times the available potash, and one and a half times the calcium found in good topsoil. So castings are excellent plant fertilizers and provide nutrients in a form immediately available for plant use.
Castings are food for other beneficial microorganisms. They contain thousands of bacteria, enzymes, and the remnants of plant and animal material that were not digested by the earthworm. The composting process then continues long after the casting is excreted, adding beneficial microorganisms back to the soil and providing a source of food for the ones already there. Some of these soil organisms release potassium, phosphorus, calcium, magnesium, iron, and sulfur into the soil ready for plant use.
Castings increase the humus content of the soil. An excreted casting is 65 to 70 percent organic matter, or humus. Soil rich in humus soaks up and holds water better. The soil is loose and is less likely to become hard and compacted.
Humus can also buffer soil by binding with and holding the heavy metals from materials such as manure, sewage sludge, and vegetable waste matter (stems and roots) left over from crops.
Castings hold their nutrients in mucus membranes that are secreted by the earthworm. This allows the nutrients to be slowly released so they are available to the plants over a period of time as needed.
Earthworms are excellent composters. They can compost organic material faster than any composting system. Some earthworm species will eat half their body weight in food per day. The nightcrawler will come out at night and search for plant matter it can pull back into its burrow. Once the food is pulled in and eaten, the nightcrawler will deposit its castings back on the surface of the soil. The castings in turn become fertilizer for plants.
So, for example, if you mow your lawn with a mulching mower — one that returns the clippings to the lawn — earthworms can find and eat the clippings and spread their castings through the top of the soil. This is a simple example of recycling the clippings’ nutrients back to the lawn. But the benefits of recycling with earthworms don’t stop there.
Earthworms can be maintained in a controlled situation to compost household and garden and waste. The homeowner can easily maintain a household worm bin to take care of kitchen wastes. A gardener can use earthworms directly in his garden soil or in an outdoor worm bin to help compost plant material. Finally, animal wastes can also be composted into rich vermicompost that can be used on garden plants. Approximately 70 percent of the material we send to landfills, including kitchen wastes, farmyard manures, and garden wastes, can be used to feed worms.
If we did feed this material to the worms, the worms could give us 60 percent of the volume back as vermicompost fertilizer. This fertilizer would be a safe, natural soil enhancer and plant food that would be a benefit to the environment.
Worm farming is fun for everyone. It is interactive, fascinating and an excellent way for children to become environmentally aware as worm farms replicate nature’s recycling system. Properly maintained worm farms are odourless, can be kept inside or out, take up little space, and only need a small amount of time and effort to recycle food waste.
Worm farms produce three main products:
• Worm casts or faeces, which are high in nutrients. These can be mixed with potting mix, garden soil or used as a mulch.
• Vermi-liquid (“worm wee”), which is the liquid that drains through into the collection bin. This is very high in nutrients and can be used as a liquid fertiliser once it has been diluted with 10 equal parts of water. Diluted vermi-liquid can be used on houseplants and in the garden.
• More worms. Over time your worms will breed and outgrow the space available.
Getting started with worms
In order to keep worms, you will need a suitable home for them, located in a place with a moderate temperature, such as a garage or laundry room, or even in a kitchen cupboard. Because the vermicomposting process is practically odourless, there is no reason why you cannot keep your worm farm in your house or flat if you have no suitable outdoor area for it.
Never keep your worm bin where it receives direct sunlight, as it will almost certainly get too hot and your worms will die, unless you’re making your wormery with old tyres which will provide enough insulation from the sun’s heat.
If you’re not keen to spend money on a worm bin, there is no reason at all why you can’t make one yourself. Worms can be grown almost anywhere, from small Styrofoam cooler boxes to old refrigerators, from plastic storage containers to wooden boxes.
How can you make your own worm bin?
Start with a plastic container which fits the space you have for it. A single-level worm bin could be a simple as a plastic container with a lid and holes drilled in the sides and the bottom. You should also have a tray (perhaps an extra lid?) to catch any drippings from the worm box.
Multiple-layer worm bins can be stacked: place bricks or empty cans in the first container, and once it has filled with vermicompost, place the next container on top of the bricks or cans, with its bottom (in which you will have made holes) touching the surface of the vermicompost.
Place fresh bedding and food in the second container, and the worms will gradually (over the course of a few weeks) migrate upwards until the bottom container is empty of worms, and filled with lovely, rich vermicompost! You can then remove the bottom conatiner and repeat the process over and over.
The larger you make the container, the more worms it can sustain. Estimate half a kilogram of worms (roughly 1,200 worms) for every 1000 cm2 of surface area. The maximum productive depth for your bin is around 60cm deep because composting worms will not go further down than that.
The bin should have a cover to prevent light from getting in and to prevent the compost from drying out. Choose or make a lid that can be removed if your compost is too wet. Use a canvas tarp, doubled over and bungee-corded on, or kept in place with wood. Burlap sacks also work well, and can be watered directly.
Or you can use four old car tyres
To make a four-tyre wormery, create a base from old bricks or flagstones (must be flat and with as few cracks as possible). Place a layer of heavy newspaper on top of the bricks. Stuff the insides (where the tube would fit) of four old tyres with newspapers. Pile the tires on top of each other, with the first tire on the layer of heavy newspaper. Use a piece of board weighed down with bricks as a lid. The lid must be big enough to stop rain getting in.
Prepare the bin for worms
Among all the ingredients and materials necessary for a vermicomposting worm bin, bedding is one of the most important. Bedding refers to the loose, moisture-retaining organic material used to fill the worm bin and which provides carbon for bacteria, which constitute the bulk of the nutrients in the worms’ diet and also break down the organic material fed to worms so it can be ingested by worms and other organisms.
The importance of good bedding material is one of the least understood aspects of vermicomposting, and improper maintenance of the bedding is one of the main reasons for the failures encountered by those who are new to the process. Fill your bin with thin strips of unbleached corrugated cardboard or shredded newspaper, straw, dry grass, or some similar material. Sprinkle a handful of dirt on top (sandy soil is best, as it provides grit to aid the worms’ digestion), and thoroughly moisten. Allow the water to soak in for at least a day before adding worms.
There are several varieties of worms that that are bred and sold commercially for vermicomposting; just digging up earthworms from your backyard is not recommended. The worms most often used, Eisenia foetida (Red Wigglers), are about 10cm long, mainly red along the body with a yellow tail; see the sidebar on page 11 for suppliers of worms.
Maintain your bin
Keeping your bin elevated off the ground, using bricks, cinder blocks, or whatever is convenient will help speed composting and keep your worms happy. Worms are capable of escaping almost anything, but if you keep your worms fed and properly damp, they should not try to escape.
Sprinkle the surface with water every other day. Feed your worms at least once a week. Feeding lightly and more often will produce more worms, which is especially good when starting a new bin. Add more cardboard, shredded newspaper, hay, or other fibrous material once a month, or as needed.
Your worms will reduce everything in your bin quickly. You will start with a full bin of compost or paper/cardboard, and soon it will be half full. This is the time to add fibrous material.
What to feed your worms
Select foods that are suitable for worms including most fruits, vegetables, cereals and grains, and other organic items like cardboard and tea bags. It is best to cut food scraps into small pieces before placing them in the bin. The smaller the pieces the more surface area there is for bacteria to start breaking down the food, making it easier for the worms to consume. Some people put their food scraps, including eggshells, into a blender and make a slurry. The worms seem to love this, but it is not necessary.
Keep shredded black and white newspaper over the food at all times. Newspaper or bedding helps keep the bin dark and moist and discourages fruit flies. Other organic material such as burlap or shredded cardboard or paperboard can also be used. The worms live in these materials and they also eat them. To feed the worms, place the food under the newspaper in a different part of the bin each time. Do not bury the food in the castings.
How Much Food?
Worms need to adjust to their new home and new foods so do not overfeed them the first few weeks. In addition to the food you are giving them, they’re eating their new bedding. Once they are settled, comfortable and happy they will quickly munch through their food. The bin will require more food as its population grows.
You want to feed the worms just ahead of their rate of consumption. Before adding new food, consider:
- Have they had enough time to consume old food?
- Is there food remaining because theydo not like it?
- Has the food not been broken down enough by bacteria for the worms to consume it?
If there is a little food left and the worms are eating, additional food can be added. But if food is left due to one of the other reasons, cover it with newspaper and don’t feed again for a week or remove the food from the bin.
Unlike other animals, worms don’t demand to be fed on a schedule. They can be fed once a day, every two or three days, or once a week. You can go on holiday for a month without worrying about them. Just give them a regular amount of food before you leave and place plenty of shredded newspaper, cardboard or paperboard on top of the food. Make sure you leave the bin in an area where the temperature will not get too hot (not over 32ºC) and the cover material is wet enough that it will not dry out. Happy redworms will eat half their weight in food every day. That doesn’t sound like a very large quantity of food because they’re so small, but when you get a few thousand worms living in a bin, food disappears rather quickly.
Examples of Worm Food
- Fruit: apples, pears, banana peels, strawberries, peaches and all melons
- Vegetables: beans, cabbage, celery, carrots, cucumbers, tomatoes, all greens, corn, corncobs and squash
- Cereals and grains: oatmeal, pasta, rice, non–sugared breakfast cereals, cornmeal, pancakes
- Miscellaneous: coffee filter paper, tea-bags, eggshells, dead flowers
- Other food/bedding: newspaper (no shiny or coated paper), cardboard, paperboard,paper egg cartons, brown leaves
Use Caution When Adding These
- bread — can attract red mites
- potato skins, onions, garlic, ginger — get consumed slowly and can cause odors
- coffee grounds — too many will make the bin acidic
Because worms have no teeth, they need to take in grit with their food. Rock dust or crushed seashells offer grit for their diet and can also help correct problems if you’ve added too much food to the bin. These can be purchased at many garden centres. To add these powders to the bin, sprinkle a small amount on the food scraps once or twice a month.
Eggshells, pulverised with a pestle and mortar, are an excellent source of grit. If you are adding eggshells to your bin you probably won’t need to use other types of grit.
Never feed these to your worms:
- dog and cat faeces or cat litter
- roots, flowers and seeds of persistent weeds
- leaves with diseases or residues of chemical sprays
- fish and cheese
- cooked food, especially meat
- glossy paper brochures
- treated wood / sawdust
- coal ash
Harvest the compost
Pull back the top layers of bedding to harvest the compost or check progress.Put on rubber gloves, and move any large un-composted vegetable matter to one side. Then, with your gloved hands, gently scoop a section of worms and compost mixture onto a brightly lit piece of newspaper or plastic wrap. Scrape off the compost in layers. Wait a while, giving the worms time to burrow into the center of the mound. Eventually you will end up with a pile of compost next to a pile of worms. Return the worms to the bin, do whatever you want with the compost, and repeat.
If you prefer a hands-off technique, simply push the contents of the bin all to one side and add fresh food, water, and bedding to the empty space. The worms will slowly migrate over on their own. This requires more patience, of course.
Problems and solutions
The most common problem is unpleasant, strong odours which are caused by lack of oxygen in the compost due to overloading with food waste so that the food sits around too long, and the bin contents become too wet. The solution is to stop adding food waste until the worms and micro-organisms have broken down what food is in there, and to gently stir up the entire contents to allow more air in.
Check the drainage holes to make sure they are not blocked. Drill more holes if necessary. Worms will drown if their surroundings become too wet.
Worms have been known to crawl out of the bedding and onto the sides and lid if conditions are wrong for them. If the moisture level seems alright, the bedding may be too acidic. This can happen if you add a lot of citrus peels and other acidic foods. Adjust by adding a little garden lime and cutting down on acidic wastes.
Fruit flies can be an occasional nuisance. Discourage them by always burying the food waste and not overloading. Keep a plastic sheet or piece of old carpet or sacking on the surface of the compost in the bin. If flies are still persistent, move the bin to a location where flies will not be bothersome. A few friendly spiders nearby will help control fly problems!
A final word of advice
Taking worms out of their natural environment and placing them in containers creates a human responsibility. They are living creatures with their own unique needs, so it is important to create and maintain a healthy habitat for them to do their work. If you supply the right ingredients and care, your worms will thrive and make compost for you.