Last Updated: Jun 11, 2020
Almost every child has been told at one time or another that he or she cannot leave the table until they have finished eating what is on their plate. However, this common parental reproach points to a deeper problem that affects both children and adults alike. A University of Arizona study estimates that each American throws away an average of 1.3 pounds of food per day or close to 500 pounds per year per person.
On a global scale, anywhere between one-third and one-half of all the food produced is never eaten, but rather ends up as food waste worth a whopping 1 trillion dollars. While this wastefulness is problematic, especially in a world where one out of every nine people is chronically malnourished, food waste also contributes to several other environmental problems.
Not all food waste is avoidable. Coffee grounds, banana peels, onion and potato skins, eggshells, and the plate of spaghetti your toddler dropped onto the ground all contribute to the kitchen waste a family produces. Millions of households in the United States, however, simply throw those kitchen scraps into the same garbage bin where plastics, glass, and other household trash end up.
By not separating organic waste, like your kitchen scraps, from other sources of household waste, all trash ends up in the same landfill. Because of the sheer amount of incoming waste sent to landfills around the country, organic waste products decompose anaerobically (without access to oxygen), and this leads to the production of methane, which is one of the most dangerous and potent greenhouse gasses.
The EPA estimates that methane makes up 50% of the gas emissions from landfills and that municipal solid waste is responsible for over 15% of all methane emissions in the country. Because methane is 28 to 36 times more effective at trapping heat in our atmosphere, those banana peels that end up in your kitchen garbage bin are directly contributing to global warming.
Often with household scraps, we consider composting. What if there was another option, one in the comfort of your own home? Vermicomposting could be a great option to add to your household all year round - and here's why.
Vermicomposting is the breakdown of organic materials through worm digestion. As the worms move through your compost pile, they consume the waste and store it in their crop before moving it past into the gizzard (like in birds).
Here the material is broken down by small rocks that the worm has swallowed and passes through the simple intestine. The remaining worm excrement, or worm castings, are full of non-digested nutrients and coated in beneficial microorganisms that line the worm's digestive tract. When castings are left to sit, through the aid of soil microorganisms, they begin to breakdown further into a humus-like substance.
Vermicomposting is comparable to standard composting with a few differences. First, vermicompost is a cold composting technique. The high temperatures regular compost reaches are not achieved here, which could result in the potential germination of seeds in your compost. Second, the process requires less work because the worms turn the material for you, so you don't need to get your hands dirty. Finally, this can be done inside and odor-free with the right balance of compost materials and design.
You can find various vermicomposting strategies online from a small apartment to a large property system. I discovered that Soni Cochran listed it best with five simple requirements: a container, some bedding, water, worms, and food scraps.
The most common containers for vermicompost are going to be either plastic or wood. First, I would state that a 2019 study showed that worms living in conditions with HDPE microplastics saw an average weight decrease of 3.1% over 30 days. Worms living in control conditions with no microplastics saw a weight increase of 5.1% over the same period. While these tests were not explicitly looking at red wiggler worms or vermicomposting in plastic, it's still something I found essential to consider going forward.
If you're planning on using plastic, be sure to drill plenty of holes along the top of the bin and sides to ensure your worms don't suffocate. Drill holes into the bottom of the worm bin and place wooden blocks into another undrilled container. You can then place the worm bin into the catchment bin, where the excess liquid will drain. This "worm tea" can be used in the garden as a liquid nutrient for plants.
If choosing to make a container out of wood, Cochran recommends the "1-2-3 Portable Worm Bin" design by Mary Appelhof. It is a wooden container, one foot deep, two feet wide, and three feet long. What makes this bin successful is that worms only feed at the upper layers of the soil, especially red wigglers. If your vermicompost heap is too big, the worms won't consume all the waste, resulting in the materials beginning to rot and smell.
Some bins of eight inches deep, two feet wide and two feet long will also work when space is limited, but you still want to compost indoors.
The bedding is comprised of shredded materials like cardboard or newspaper and will make up roughly two-thirds of your container. The size of your bin will ultimately determine the amount of shredded material you will need. Ame Vanorio recommends approximately two to four pounds of bedding per 2-foot square container.
There are a few things to consider if you're choosing to add manure to your vermicompost bin. First, be sure to use manure from herbivorous animals. Popular choices for a home would be guinea pigs and rabbits, but you can also consider manure from horses, goats, and even chickens. Next, ensure to add dry manure. Wet manures are too "hot," meaning that they will cook the worms. Do not include dog or cat feces as these can contain pathogens in them.
You're going to want to ensure that the materials are thoroughly shredded, to give the worms the ability to move freely through it. The bedding acts as a substitute for a natural litter of leaves, manures, and well-decomposed woody debris. Aim to try and mimic natural soil conditions as best you can, meaning airy and moist.
When dampening your bedding, there is a line between too wet and too dry. Aim to have your bedding the consistency of a well-wrung sponge or washcloth. If you firmly squeeze the material, if adequately saturated, moisture will begin to appear at the edges but not drip off.
You can leave two inches of water in the base of your bin and allow it to be soaked up by the bedding. Or you can dampen the materials as needed when it begins to dry. Be sure to pour out excess moisture, as too much can also negatively affect the worms.
When it comes to dampening your vermicompost bedding, don't be afraid of trial and error. Making sure you've got the right moisture level is ideal in successful vermicompost.
Now for the linchpin of vermicomposting: the worms. The worms you want to use in your system are Eisenia fetida (red wiggler). This shallow soil species lives in the top few inches of the soil and prefers temperatures between 55-77°F (12-25°C). When exposed to temperatures below freezing or above 84°F (29°C), the worms will die, so be sure to bring them in during the cold winter months and away from direct sunlight.
These little worms have a respectable processing rate of 2:1, meaning that one pound of worms can process half a pound of food daily. And with ample food, this species will reproduce well in captivity.
Other worm species do not do as well in vermicomposting, with some preferring the ability to burrow deep into the earth. But you don't have to dig up the garden to find red wigglers. There are plenty of places that you can purchase the worms online or from your local garden supply store.
So, what can go into vermicompost? There are plenty of kitchen scraps that can be consumed by your worms.
You can add almost any fruit or vegetable to your bin. Be sure to chop the scraps up before putting them in to make it easier for the worms to break down. But don't stop at the scraps! You can consider things like coffee grounds, tea bags, crushed eggshells, and even most grains. Just sprinkle the scraps over the bedding and then cover with an inch of bedding or some already processed castings.
Some vegetables to stay away from are onion, garlic, or hot peppers as the worms have trouble processing them. Also, exclude citrus as it has properties that make it difficult to digest. Like with regular composting, meat takes a long time to breakdown, and it will eventually begin to rot before it is processed. This rot will give your bin a foul smell and potentially attract rats. Also, do your best to make sure no non-biodegradable items end up in your container.
At any stage of this design, you can always purchase products explicitly designed for vermicomposting. If you're nervous to begin the process and want the ease of adding food scraps and worms to a completed bin, this would be an excellent option for you.
Once your worm compost bin begins to fill up with dark, fertile soil, you can "harvest" the worm castings. This is easiest done by only placing food waste on one side of the container for several days. The worms will naturally move towards the food waste, thus leaving the other side of the container for you to harvest the fertile to the soil. You can share the harvest with your houseplants or the tomatoes growing in your front flowerbed.
Because of the increasing popularity of kitchen vermicomposting, several online companies offer "starter kits." These kits often contain red wrigglers, other types of composting worms, and other vermicomposting supplies. This company sells red worms, by the pound. Others sell starter indoor composting bins and additional accessories.
Having a bin of worms underneath your sink might not, at first, appeal to the everyday homeowner. However, when properly managed, this bin will emit absolutely no smell. The worms will quickly and efficiently turn your kitchen waste into fertile topsoil that you can then "harvest" for the benefit of your household plants or small vegetable garden.
Tanner Sagouspe has a Masters in Environmental Management and is a Permaculture Designer who promotes tackling the climate crisis at home.