Vermicomposting worms its way into the College community

There are thousands of worms squirming their way through the Environmental Center.

Don’t worry, though; they’re hard at work. Like a tiny colony of worker bees, they chew through scraps of food waste and shredded copies of the Record to produce a nutrient-rich substance called “castings.” They’re sophisticated, all-natural composting machines, multiplying the fertilizing value of food by passing it through their digestive systems.

The worms belong to Henry Art, professor of biology, and Mike Evans, assistant director of the Zilkha Center. They live in a black worm composter, no bigger than a mini-fridge, in the corner of their shared office space. Yet their coworkers are not bothered. “No, it doesn’t smell,” Evans said. “Or if it does, it just smells a little earthy.” 

Inspired by their own experience with “vermicomposting,” Art and Evans led a workshop at the end of Winter Study where participants could make their own worm composting systems. First, though, they had to learn. Don Kjelleren, director of the career center and a dedicated gardener, was among the workshop’s eight participants. 

“We learned about the inputs needed to create a favorable ecosystem for worms to reproduce and make castings,” Kjelleren said. “We talked about pH, temperature, moisture levels and nitrate percentages.” 

The environment in which worms survive best is simple to recreate. For those of you following along at home, all you need is a plastic container, wood shavings or shredded newspaper for bedding (we recommend the Record!), some food waste and a handful of soil. The last step is the redworms themselves, which are available on Amazon for $25-35 a pound, which is about 1000 worms.

Participants drilled holes in the covers of their bins and watered the bedding so that it was wet “like a wrung-out towel,” according to Evans. Once they had set up, they grabbed a handful of worms and soil from Art and Evans’ system. All that was left was the food.

“They like apple cores, banana peels, coffee grounds, teabags,” Evans said. “You can’t put in oil, meat or much citrus.” Complex foods like meats, oils and dairy products take longer to break down than fruits and vegetables, and they can attract fruit flies. Citrus fruits, like orange rinds, are too acidic for the worms’ tastes.

Participants were allowed to take their bins home, but they will not see results for a while. In small numbers, it takes time for the worms to go through food and produce castings. Most of the populations cannot actually go through very much food at all. Kjelleren said he stores food waste in a stainless-steel container and only gives some to the worms every two weeks or so to avoid food rotting in the bin. Evans added, however, that even mold is not a huge problem — it’s all natural, after all. Just turn over the soil, and give the worm population time to grow.

When the worms finally get through the food and produce castings, the process of extracting that rich fertilizer from the system is also slow-moving. The simplest method is to add food to one side of the box. Over the course of a few weeks, the worms will migrate to that side. Then you can pull out the soil from the worm-free side, and replace it with new soil and food. In a more complex setup, like the one Art and Evans have in their office, you put another layer of bedding and food on top, with a mesh underneath, so the worms can crawl up through the holes. Then you remove the bottom container. The fertilizing substance can be used in gardens and potted plants to encourage plants to thrive, grow and produce fruit. 

Kelly Chen ’17 also took part in the workshop. She did not have room in her dorm to take home the worms, but she plans to build one for her dad when she gets home, since he likes to garden. And she’s a senior: When she moves out, into her own apartment, she is seriously considering setting one up for herself.

Worm composting is not a new idea. Worms have been breaking down organic material and excreting nutrients throughout history. Vermicomposting just takes that natural process and simulates it in a controlled environment, where the byproduct can be harvested. Art and Evans’ inspiration was Will Allen, founder and CEO of Growing Power, where vermicomposting takes place on a much larger scale in greenhouses. 

The reality is, vermicomposting is no miracle for large-scale agriculture. For reasons of cost and space, it is an inefficient way to generate fertilizer from waste. Yet on a small scale, for an avid gardener or a recent graduate in an apartment, it is an easy, no-stress way to reduce waste and create healthier soil. 

For Evans, the best part of worm composting is just that — minimizing his food waste. Now, when he is snacking in the office, he can toss an apple core straight into the worm bin. For Kjelleren, who plans to use his worm castings on his houseplants, the joy is in the concept.

“It’s just something about the brilliance of that circle, connecting worms to compost to gardening,” he said.

The best part of worm composting? The creatures do good for any soil you put them in. So if you get tired, you can throw the baby out with the bathwater: just toss it into the garden, worms and all.

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