“I have come to understand, like Darwin had, that earthworms are not destroyers, but redeemers. They move through waste and decay in their contemplative way, sifting, turning it into something else, something that is better.”
― Amy Stewart, The Earth Moved: On the Remarkable Achievements of Earthworms
Vermicomposting is a collaboration between gardeners, worms, and microorganisms in a beautiful system of regeneration.
Gardeners supply the organic material for the worms to eat, and their gut bacteria and other soil microbiota and fungi help to break the material down into a rich garden amendment: worm castings.
Worm castings are essentially worm manure, high in nutrients and other beneficial properties that your plants can use for improved growth and pest resistance.
Vermicompost is so beneficial that it has even been shown to be able to replace fertilizers, and reduces need for pesticides and herbicides (source).
Earthworms condition the organic material into something suitable for the microorganisms to break down into usable compost (source).
Soil fungi are a major component of what earthworms eat, and can help break up woody material in the vermicomposting system. Amazingly, once the vermicomposting process is complete, the resulting material is higher in fungi than in the original substrate (source).
Vermicomposting as a solution to green waste
Currently, green waste (such as food) is biggest waste category, making up 44% of global waste (source).
When green waste ends up in the landfill, it doesn’t go through the same process as when it’s composted. Instead, as the material breaks down, it emits potent greenhouse gases such as nitrous oxide and methane, which are x and x times more potent than CO2, respectively (source).
In total, 9.2 bn tonnes of CO2e emissions each year can be attributed to global food waste. To put that into perspective, that’s equivalent to the overall emissions from the US and the EU put together (source).
Vermicomposting as a solution to fertilizer emissions and pollution
Synthetic fertilizers have a high carbon footprint because they are typically made from petrochemicals. The manufacturing process utilizes fossil fuels, and then there’s transportation of the end product. Finally, in agricultural situations, diesel is needed for the tractors that spread the fertilizer. In fact, two thirds of fertilizer ghg emissions are actually from application and usage (source).
Synthetic nitrogen fertilizers alone account for 2% of global GHG emissions. To put this into perspective, that’s the same amount released from commercial aircraft.
Moreover, synthetic nitrogen fertilizers emit nitrous oxide, which is 265 more potent than carbon dioxide (source).
While synthetic fertilizers, pesticides, and herbicides decrease the beneficial soil microbial population, vermicompost increases it, which further promotes soil and planetary health (source).
Vermicompost to the rescue - it can be applied to crops instead of environmentally-damaging synthetic fertilizers.
In fact, numerous studies have shown that vermicompost produces end yield and plant health results similar to chemical fertilizers, and sometimes even surpasses them. As an added bonus, vermicompost is cost-effective to make and the resulting plant health reduces overall farm input and expenses (source).
A study in 2020 found that vermicompost and vermicompost tea can effectively substitute synthetic fertilizers while also decreasing pest and disease, leading to an additional benefit of a reduced need for herbicides and pesticides (source).
This is fantastic news for anyone looking to reduce their carbon footprint.
Vermicompost as a solution to herbicide and pesticide emissions, habitat damage, and pollution
The production of insecticide and herbicide contributes to ghg emissions, and similar to fertilizers, they frequently contain petrochemicals.
On the whole, pesticides release 19.9 million metric tones CO2e.
Producing 1 kg of pesticide is 10 times more energy intensive when compared to making 1 kg of nitrogen fertilizer (source). Around 1 billion pounds of pesticides are applied to large farmland in the United States each year (source, and around 90 million pounds of pesticides and herbicides are applied yearly to residential lawns and gardens (source).
While the amount applied residentially is just 9% of that applied in agriculture, it is still a significant amount: a survey done by the EPA found that 1/4 of national pesticide + herbicide spending was for homes and gardens (source).
As an alternative, vermicompost has been shown to decrease diseases. Studies have shown that vermicompost is a valid solution to issues such as powdery mildew, late blight, damping off, root rot, and fusarium wilt. Pests that have been effectively controlled with vermicompost or vermicompost tea include corn earworm, aphid, tomato hornworms, cabbage white, cucumber beetles, spider mites, and mealy bugs (source).
Many gardeners and farmers practice traditional composting - so why should they bother with vermicompsting?
While compost is amazing and incredible material, and benefits the environment and your garden, there are differences between compost and vermicompost.
Both compost and vermicompost are amendments that increase soil health and fertility, and benefit plants. They both add biodiversity to the soil through microbiota. Studies show that they both can increase plant growth and decrease pest and disease pressure (source).
But vermicompost pulls ahead in a lot of categories. First, it offers a higher nutritional value for plants. Compost NPK make up is 8.6, 4.8, and 5.3, while vermicompost is 10.8, 7, and 5.6, which demonstrates significant increases in nitrogen and phosphorus (source). Vermicompost also contains twice the amount of calcium and zinc as regular compost, and also has more manganese, copper, and boron (source).
Vermicompost has been shown to have lower phytotoxicity levels, so you don’t need to worry about burning your plants upon application. It also provides higher microbial numbers, growth hormones, and enzymes for plants and the soil, and is better at preventing pest and disease when compared to traditional compost (source).
Vermicompost is quicker to produce and can be made year round in a variety of situations.
Traditional compost does have some advantages when compared with vermicompost, however. Typically compost has less residual viable seeds, which can turn into unwanted plants otherwise. This is due to the high temperature that properly made compost reaches. These high temperatures can also kill off harmful bacteria (source).
Compost also contains higher sources of magnesium and iron (source).
What you’ll need:
1. Vermicomposting location
Typically, vermicompost is made in a bin that has a few layers or “levels” to the structure for the worms to move through.
One benefit of vermicomposting is that these bins can be kept indoors or outside, as long as temperatures are above freezing and below 95 degrees F. This means that you can make vermicompost if you live in an apartment, or you can store it in a basement, garage, or outside in the shade (source).
Vermicompost can also be made in beds or windrows for larger production.
Vermicomposting beds are dug into the soil, which has the added benefit of keeping the ambient temperature stable, but involves the added labor of digging.
A windrow is made by piling long heaps of organic material above the soil. This means that the soil in the ground is not disturbed, and while a shovel will still need to be involved, the work necessary to access the finished product is a lot easier to get to. This is a great option for farms with a lot of organic material who want to try vermicomposting on a large scale. Windrows require very little store-bought materials - typically just tarps are necessary to keep temperature and moisture levels stable (source).
2. Vermicomposting organic materials:
For vermicomposting, you’ll need to have a balance of nitrogen and carbon. Before you add in green kitchen waste, you’ll need to add in layers of bedding materials like organic straw, coir, or leaves so that the ratio of carbon is slightly higher than the “green” material (source).
It’s essential to wet the bedding material, as the worms need water to survive. The moisture level should be similar to a damp sponge - not too wet but not dry. When you begin, bedding material should take up 1/2 to 3/4 of the bin (source). Add in the worms to just this carbonaceous bedding material and let them hang out in their new home for a week before adding in greens (source).
Then, begin to add in green material. Observe your worms and notice the rate at which they finish processing your food and plant scraps (source). They will need a consistent source of green material, so be sure to add some every other day or so (source).
It’s important not to add in too many greens at once. When nitrogen levels are too high, there’s increased microbial activity which causes the material to reach high temperatures (source).
Mix the food and green material in with the bedding so that it is covered by the brown material. If you notice that the bin starts to stink, add in more bedding and wait a while before adding in more greens (source).
3. The best worms for vermicomposing:
Red Wiggler, or Eisenia fetida is the worm that is most frequently recommended for vermicomposting. is able to reproduce quite quickly, and is prized for its ability to create vermicompost from food, garden, and agricultural waste (source).
These worms will process the green waste in a way that is preferable for vermicomposting, where as worms found in your garden prefer the soil and will not thrive in a vermicompost system (source).
4. Time
In a standard small bin, vermicompost can be removed at around 3 to 4 months. A good indicator that your vermicompost is ready is when the bedding is gone (source).
How you harvest your finished vermicompost will depend on what type of system you have been running.
For bins, you can harvest 2/3 of the finished material, worms included, to add to your garden. From there, add new bedding and start the process over again. The remaining worms will quickly reproduce (source). This is probably the easiest method and can be applied to any system - bins, windrows, or trenches.
If you purchase a vermicomposting bin, the manufacturer may have tips on how to harvest the finished product in a way that works with their system.
For example, multi-tray systems allow you to entice worms to a different tray by putting materials into the tray above where they are currently living. Worms will move up to the next tray over the course of a month (source).
DIY vermicomposting bin option:
Sometimes issues can arise when maintaining your vermicomposting bin. Here are some common problems and solutions to help you troubleshoot your vermicomposting bin.
If your vermicomposting bin starts to smell funky, it’s probably because there are too many greens for the worms to work thought at a reasonable pace. Worms should be able to finish their food within a couple of days.
Solution:
Hold back on adding new materials until the worms have gone through what is in the bin presently. Only add enough food that your worms can consume in a few days.
Alternatively, it might be due to excess moisture. You can add in more bedding to balance this out (source).
If your vermicomposting bin is not producing enough castings, it may be due to a lack of worms.
Solution:
If your worm bin doesn’t have proper aeration, things might not be working properly. Move the material around, and add some more bedding to encourage air flow.
Also, avoid over feeding them - worms should make their way through new material in 2-3 days. If you have an excess of material throughout the year, you may want to get a bigger vermicomposting system (source).
If you notice that your worms are dying, it may be due to improper feeding, temperature, or moisture levels.
Solution:
Make sure that you are feeding your worms a balanced diet of food scraps and bedding materials. Avoid feeding them foods that are high in fat, salt, or sugar.
Check the temperature of your bin. Worms prefer temperatures between 55-77°F. If it is too hot or too cold, your worms may not survive.
Finally, make sure that your bin is not too wet or too dry. Worms need a moist environment to survive, but too much moisture can lead to anaerobic conditions and too little moisture can lead to dehydration (source).
Fruit flies are a common problem in vermicomposting bins. They are attracted to the food waste in the bin and can quickly multiply.
Solution:
To prevent fruit flies, make sure that you bury your food scraps in the bedding material. You can also add a layer of dry bedding material on top of your food scraps.
If you already have fruit flies in your bin, try removing any food scraps that are exposed and adding a layer of dry bedding material on top. You can also try setting up a fruit fly trap near your bin (source).
Vermicomposting is not only a sustainable and eco-friendly way to dispose of food waste, but it is also a method of producing nutrient-rich soil amendments that can benefit your plants and garden.
It is a simple process that can be done on a small scale, such as in an apartment, or on a larger scale, such as in a farm or garden.
Vermicompost is so beneficial that it can replace fertilizers and reduce the need for pesticides and herbicides. It increases soil porosity and aids in water retention, making it a great solution for sustainable gardening.
With the many benefits of vermicomposting, it is worth considering this environmentally-friendly practice for your garden.
