Shrimp shells in compost

Air Date: Week of June 9, 2000

Jeff Holden, owner of Portland Shellfish, has found a creative way of getting rid of more than five tons of shells his company produces every day. Matthew Algeo of Maine Public Radio has the story.


CURWOOD: If one person’s trash is another person’s treasure, then Jeff Holden has struck gold. Or as he calls it, gardener’s gold. For years, Jeff Holden has been processing shellfish in Portland, Maine. These days he’s also making fancy-grade compost from some of the state’s most common byproducts: seashells and sawdust. As Maine Public Radio’s Matthew Algeo reports, this new business began as a surprise.

(Crunching shells)

ALGEO: Jeff Holden owns Portland Shellfish, a company that processes more than ten tons of crab, lobster, and shrimp daily. That’s a lot of shellfish and a lot of shells.

(Crunching continues)

ALGEO: Holden says Portland Shellfish generates five tons of shells every day. The shells are ground up and stored in giant tubs outside the plant.

HOLDEN: Got some claw shell here, some ground claw shell. And then some ground body shell here. And then, in that big tub there, we have some…

ALGEO: Shellfish processors have long considered shells the bane of their business. Some sell them to pet food companies. Others simply dump them, lawfully, at sea. For years Holden gave his shells to a potato farmer, who spread them on his crops. But Maine’s Department of Environmental Protection put a stop to that last year. It turned out the farmer was storing the shells improperly. Instead of keeping them on an impervious surface, like concrete or asphalt, he was simply piling them in a field. Environmental officials feared nitrates from the decomposing shells might contaminate groundwater. So Jeff Holden had to find a new way to get rid of his shells, which were quickly piling up outside his plant.

HOLDEN: They attract vectors, seagulls, flies. Plus they smell. So it’s something you have to get rid of quickly every day.

ALGEO: Holden did a little research. He found out shells, especially crab shells, can be used as an ingredient in compost, which farmers and gardeners use as an organic fertilizer. Crab shells contain a carbohydrate called chitin, which is a natural bug repellent. Soon Holden began thinking of his shells as an opportunity, not a problem. He contacted the same environmental officials who’d made him stop sending his shells to the potato farm, and asked them to help him set up a composting business.

WRIGHT: Composting can be great. It takes, you know, a smelly waste product and turns it into a highly-valuable soil amendment.

ALGEO: David Wright is with the State Department of Environmental Protection’s Residuals Utilization Unit, which oversees commercial composting operations in Maine. He says it takes more than shells to make a good compost.

WRIGHT: You’re looking for high-nitrogen material like a fish waste, and a high-carbon material like a sawdust. And you blend those together in a recipe.

ALGEO: Jeff Holden had no problem finding sawdust for his compost recipe.


ALGEO: He called the Saunders Mill in Westbrook, Maine. The mill takes raw logs and turns them into dowels and other wood products. Plant manager Bob Gregoir says the company turns out about 50 tons of sawdust and wood shavings every day.

GREGOIR: You know, we used to call our sawdust waste product and now we call it fuel. We call it a marketable shaving. It’s got some use somewhere.

ALGEO: Gregoir says Saunders sells its sawdust to several companies besides Portland Shellfish. He says it’s used as everything from animal bedding to an absorbent to clean up spills. Using some sawdust from the Saunders Mill, his own shells, and a pinch of leaves and grass clippings from nearby towns, Jeff Holden has created a compost that is, in his estimation anyway, the top of the line. He calls it Gardener’s Gold, and he’s so proud of it he keeps a pile of it under a giant tarp outside his office.

HOLDEN: So you can see little bits of crab in it. Little bits of shell.

ALGEO: Holden has just started selling the compost in local Maine stores. He’s building a full-scale composting operation, and he hopes to distribute the product all along the East Coast. It’s a business he never expected to get into.

HOLDEN: Initially, we got into it just for a way to get rid of our shells. And the more I learned about composting and the more I learned about the properties of the shells, then the rest of the business came along after that.

ALGEO: Given its abundance of sea shells and sawdust, Maine is poised to become the country’s biggest compost-producing state. A company called Coast of Maine has been distributing a premium compost in New England for four years. Their recipe includes mussel shells and fermented salmon. Tom Esterbrook runs a nursery in Yarmouth, Maine. He says most of his customers prefer to use a home-grown compost.

ESTERBROOK: “Because it is made from a product that’s here in Maine, that is basically a waste product of the fishing industry, which means a lot to us. If we have customers that are, you know, resistant to it, we say, well, try a bag with the plant. And when the plant does better then the others that they planted, you know, they come back and they buy more.

ALGEO: And environmental official David Wright says Maine’s compost is already highly-regarded among farmers and gardeners outside the state as well.

WRIGHT: It’s really become a product that people seek out. People like the fact that Maine has a clean environment, and that these materials are being recycled, and are anxious to buy compost products from the state of Maine.

ALGEO: Wright hopes Maine compost will soon be available from coast to coast. For Living on Earth, I’m Matthew Algeo in Portland, Maine.


“From the Bay to the Garden,” is the mantra and the background story of “The World’s Biggest Crab Feast.”

By Elvia Thompson // Photography by Tony Lewis, Jr.

The Annapolis Rotary Club has turned the operation of its annual Crab Feast—now in its 72nd year—completely on its head several years ago by directing food and service ware waste to the compost farm rather than the landfill.

It took a great deal of cooperation among the Rotarians, the Annapolis Green nonprofit, and the Veteran Compost company over the course of three years to make “zero-waste” a reality at this high visibility and iconic event.

Here’s how it started. Annapolis Green approached the Rotary in 2013 and proposed composting the huge amount of food waste produced by the 2,500 feasters to keep it out of the landfill. Rotary agreed to try out the project in the Preferred Dining area that accommodates almost 300 people. Annapolis Green got busy explaining the composting process to the Rotarians and working with the Crab Feast committee to consider changing the service ware purchasing (plates, knives, forks, spoons, soup bowls) to the compostable type. Rotarians got on board immediately, understanding the importance of reducing their impact on the landfill. The 2013 effort was so successful that the Rotary agreed to take composting to the entire Crab Feast the following year.

The first couple of years were challenging because there were products that had to be separated out: not only single-use plastic water bottles and cans, but also the cutlery and tiny seasoning cups. But now, since there are compostable versions of everything—including beer cups—the cleanup is much faster and easier.


Between 2014 and 2016, the process was refined and in 2016 a full 13 tons of compostable product was taken to the Veteran Compost farm in Aberdeen and turned into sweet-smelling soil amendment, or fertilizer. The crab shells, watermelon rinds, soup bits, hot dog leftovers, and even beer leftovers are returned to the Earth in the form of garden compost. Veteran Compost, the area’s only licensed composting company, has been Annapolis Green’s partner in composting for more than seven years.

Justen Garrity, owner of Veteran Compost, says he especially enjoys working the Crab Feast. “It’s the biggest special event we do and the most involved in terms of logistics, staff support, and sheer volume.” In the past two years, he has ought two staff people to help at the feast. When volunteers wheel his 96-gallon totes full of food waste to the specially-lined dumpsters, he and his staffers are ready to empty them and screen out any non-compostables; not that this is an issue at this event.

“Really, it’s amazing how clean it is and that’s thanks to all the volunteers who help people separate out the compostables from the recyclables right at the table,” Garrity says. “And thanks to the signs that Annapolis Green puts out everywhere.”

Then there’s the question of cost. Moving to compostables has actually allowed Rotary to save a bit of money on the service ware and on waste disposal. Annapolis Green helped the Rotary change what it buys for the event from plastic knives, plates, and cups to compostable versions. That not only resulted in nothing going to the landfill, but also a 70 percent reduction in recycling because so much plastic was eliminated. In fact, at the 2016 Crab Feast, there were only 25 to 35 bags of recycling to be picked up since most of the waste was composted.

Veteran turned the Crab Feast waste into sweet smelling, healthy compost in just two months.

How does that work exactly? Backyard composters know that it takes a long time for yard waste and kitchen scraps to eak down enough to become a usable soil amendment. It’s the sheer amount of material Veteran Compost deals with that makes it possible for tough materials like crab shells and bones to decompose relatively quickly. Big piles get very hot, speeding up the natural rotting process. Garrity also has developed a proprietary formula that includes adding wood chips, water, and aeration to the big piles. In the winter, the piles emit steam and you can feel the heat coming off of them…more so when Garrity’s staff turns them over with tractors and backhoes. “We have enough thermal mass to eak the materials down quickly without smelling bad and attracting raccoons and other animals,” he says.

“I wouldn’t advise trying to compost crabs in the backyard,” he adds. “It gets pretty smelly if it’s not oken down quickly. In fact, by the time the compost actually gets to the farm, it’s already started to eak down in the dumpster. Within 48 hours, our piles are already at 140 to 150 degrees.”

The natural process of rot and decomposition creates Mother Nature’s best fertilizer. Compost is much better than manufactured fertilizers since those add no life to the soil; that is, none of the microorganisms that plants need to thrive and to create food that is nutritious and good for us.

Composting is a growing business. There is a U.S. Composting Council and jurisdictions around the country such as San Francisco and Seattle have made composting mandatory. The reasons for this are not only based on environmental issues, but also on the fact that more than half of municipal solid waste in the United States is made up of organic material that can be composted.


Garrity has already expanded his business, mostly with big industrial clients like hospitals and schools, to Northern Virginia and the District of Columbia. “Yes, I hope that someday in the future, the crabs won’t have to travel so far to turn into compost,” he says, adding that he is on the hunt for a farm in Anne Arundel County.

Working with Veteran Compost ings another sense of satisfaction, too, in that it was set up by an Army veteran, Garrity, to employ other vets.

The Annapolis Rotary is to be commended for all the hard work that goes on behind the scenes for months. It’s the organization’s largest fundraiser and the proceeds go back into the community in the form of grants for various worthy causes.

For many local families, the Crab Feast is their annual family reunion. For other people, it’s a fun afternoon with friends. For a lot of “newbies,” it’s a chance to learn how to pick crabs and enjoy the bounty of the Bay, from corn on the cob and watermelon from the Eastern Shore to locally-prepared BBQ and of course, our beloved crustacean, Callinectes sapidus, the beautiful swimmer, or Atlantic Blue Crab.

For Annapolis Green, it’s a great example of how the community, working together, can have fun and be good to the environment at the same time, just by changing the way we work and play. Working along with the Rotarians is a cadre of non-Rotarian volunteers who tote compost and recycling to the dumpsters, who buss tables, and who explain the process to the feasters.

Annapolis Green is working to fund the purchase of a product that will replace the single-use plastic water bottles with an eco-friendly solution. When that happens, the only non-compostable products at the Crab Feast will be metal soda cans!

This August 4th, when the 2017 Crab Feast winds down, feasters will remember the volunteers working hard to make everything run smoothly. What they won’t see are little microorganisms already hard at work starting to eak down the crab shells right in the dumpster, right at the Navy Marine Corps Memorial Stadium. Mother Nature does it right. Composting is just following her lead…and doing the right thing.

4 million pounds of shells get thrown out every year in just one coastal county, you can see little bits of crab shell in the soil

By Gregory Jackson

Merwin’s Wharf zero organic waste week gave us a treat: 25 pounds of crab shells, which we composted at Forward Church’s Willow Community Garden. This week also brought challenges in residential leaf donations, leaves were buried under a half a foot of snow, but we managed to pickup leaf donations and mix it with crab shells.

The average coastal county will waste about 4 million pounds per year of crab shell waste, when Patrick Condon of Chesapeake Bay discovered crab waste is a great natural fertilizer and saves space in landfills, and founded New Earth Services 21 years ago. At Wal-Mart Stores (WMT) they sell crab shell as a natural fertilizer for $16.06 for a 4-pound bag.

What is the benefit of composting shells?

Groundz has been composting egg shells for the past year, allowing them to crunch and pulverize as other food waste material is added. Crab shells contain chitin, a natural bug repellant and great source for nitrogen, phosphorous, calcium, and magnesium. Jeff Holden, owner of Portland Shellfish (in Maine), created a composting business about 14 years ago, using his company’s own shell waste. He used to donate the shells to a potato farmer, but the farmer was not storing the shells properly, according to Maine’s Department of Environmental Protection.

Composting shells like crab strengthen plant’s defenses against insect (thus a natural “insecticide”) when added to the soil, by mimicking the presence of chitin creatures like insects. The plant produces small quantities of chitosan, an enzyme that breaks down chitin; it’s like a natural “immunization” for the plants natural defenses in the event an insect or exoskeleton of fungus, or nematode eggs are made of chitin. As chitin, in the form of crab shells or added to the soil through compost, the plant with build up defenses. However, not all fungus or nematode are bad for plants, in fact fungal, bacterial, and nematode diversity are good for soil ecology, as Groundz learned in our most recent compost sample tested at earthfort lab.

The other component of adding shells (which contain minerals like calcium) is soil integrity. Try to get past the idea of “perfect looking compost”. We tried for months to sift our compost of material not looking like soil, for instance shells, sticks, leaves. If there is no smell and you cannot tell where your food waste went, in a complete assortment of composting materials, then we would say just go ahead and add compost to your beds, as is. The reason is because material like shells will naturally take longer to break down because of minerals, which are meant to take longer in soil ecology. This brings two benefits. First, imagine a piece of shell or leaf mixed into your soil; soils compact over time and the shell can serve as a “roof” underground, which improve drainage, a place for future roots to grow, and aeration. Secondly, mineral richness in soil contributes to clay (which despite popular belief of getting rid of clay soils is good), actually serves as a type of “backbone” for humus to adhere to. Without clay in your beds, humus you create with compost will only last a couple years in the soil from rain and rinsing, but when it binds to clay, humus will last decades in a much needed bio-accumulation of nutrients and minerals.

Why you should prepare a seafood dinner for your soil

The longer I live, the more I appreciate food that is simple and knowable. It might seem easier to make soup from an envelope of dehydrated mix. But filling the pot with real potatoes, leeks and thyme is easy, too, and results in a tastier soup.

I want the same clarity when feeding the soil in my garden or, more precisely, the microorganisms that live in it. Their consumption of organic matter makes the soil fertile, by making nutrients available to my plants’ roots. So I feed them what I know: manure, kitchen scraps, plant parts — either broken down in the compost pile or incorporated directly into the soil.

The same impulse led my husband to a crab processing plant many years ago. The owners were happy to give him crab shells they’d otherwise have hauled away for incineration. The shells enriched his soil and helped him grow healthy, productive plants. Since then, he’s sought any crustacean shells he could find, tilling them into our gardens and fields.

Here’s how they work their magic. The exoskeletons of crabs, lobsters, shrimp, crayfish and countless insects contain a substance called chitin (pronounced KYE-tin), a slow-release source of the nitrogen that plants need. Because it doesn’t leach out of the soil, it doesn’t pollute waterways the way soluble nitrogen fertilizers do.

But that’s not all. When crustacean shells are added to the soil, they stimulate and increase populations of chitin-devouring bacteria and fungi. Once these have decomposed the shells, they go on to devour certain chitinous pests, most notably root-knot nematodes, which can lead to poor yields in a number of crops.

The shells also contain calcium carbonate, the key ingredient in garden lime. Calcium is another essential element for plant health, and it raises the pH of the soil in areas that are too acidic. The shells of mollusks such as oysters, mussels and clams are also rich in calcium. Those don’t break down as rapidly as crustaceans do, but that’s not a defect. We see the white clamshell fragments in our dark earth as time-release calcium pills at work.

Gardeners who don’t live near a coast where shellfish waste is plentiful might make a deal with seafood restaurants, offering to take it away as an even exchange. But they can also buy dried, ground crab or shrimp shells in bags. This is also a good option if neighbors object to fresh seafood waste. (Look for pure meal without additives, such as urea.) If local stores don’t carry them, check online sources such as Peaceful Valley Farm Supply (

Shellfish meal can be added, raked in or tilled just before planting, but whole crustacean shells are best chopped up, turned under and allowed to mellow in the soil for a month or more. Leaving them on the soil surface, as we once did with some crab shells when the ground was frozen, is a bad idea. They attracted flocks of sea gulls, whose habit it is to pick up shells and break them by dropping them on shoreline rocks — or in this case our neighbors’ cars.

A better idea: Invite the neighbors to a big lobster or crab feast, and after dinner put all of the shells on the compost pile. Burying them with a garden fork will not only hide them from birds but also set the heap to “bake,” cooking up the best compost you’ve ever made.

Damrosch is the author of “The Four Season Farm Gardener’s Cookbook.”

Clam shells for the garden

What a great idea! It is hard to teach children not to trammel plants and beds, but my parents’ garden (and houseplants on the winter windowsill) is where my siblings and I learned much. We started with the names of colors, and over time where our food came from, about seasonality and, as we grew older, the difference between annuals, biennials, perennials, cuttings for propagation, planting seeds, the difference between bulbs and corms and tubers, digging and storing these. Perhaps most of all, we learned about patience. We pressed colored autumn leaves and grasses between wax paper (waxy sides inward) and taped them in the kitchen windows. When older, we kids figured how to dry flowers. My mother bought one of those Four Season’s salad dressing bottles (or was it Seven Seas?) and threw away the flavoring packet. We’d fill it to the lines marked for vinegar and oil, and she’d let us choose what herbs we liked from the herb garden. I imagine we had some odd combinations! When my father brought in lettuce from the garden, and it had been washed, we kids loved swinging it in one of the those french wire baskets to get the water out. That was before salad spinners. You’ve hit on a rich vein! But you didn’t want sentimental recollections; you wanted ideas. Raised beds, pots and flower boxes will help the trampling issue. A calendar and schedule and a quart kitchen pitcher for watering will teach useful skills including measuring volumes and some beginning math. For fun, consider a winding tunnel of hoops with vines trained over it. Crawking height will be high enough, but have an exit at the half-way point for kids who loose their nerve. Consider a teepee of poles with vines on them. Scarlet runner beans and purple hyacinth beans provide showy flowers as well as beans. Be aware that any enclosure like these needs to have a clear view into them for you to keep track of the kids, and for kids to see you for a sense of security. Maybe a friend can cast concrete disks for a garden path, with numbers inscribed on them. Or the alphabet letters in them along with images of leaves, flowers, fruits, birds, insects, animals with names that start with that letter. Then you can develop counting and word games around them. Gift shops can probably find for you those stones with engraved words on them that you can tuck around the garden for kids who may be ready to sound out their first written words, or you can invent your own versions of with paint. You can look up online every plant you use to find out ahead of time whether it is toxic. It will be useful to search by the binomial Latin name. Water can be an insurance and liability issue, and a maintenance task. But if you think it through carefully, there are safe ways to use it. For example water that flows down a verticle surface and through a surface grate into an inaccessible trough for recirculation. Anything where water gets no deeper than 1/4 inch. Kids will love to stick their finger against the sheet of water it to watch the pattern in the flow change. Pretty tiles from the local kitchen store can give it visual appeal. Don’t forget the idea of an indoor fish tank on a sturdy surface up at kid’s eye-level, and with nothing to climb on that would give them access to the top. There are plenty of interesting insects to learn about. If you have one of those do-it-yourself ceramic shops near you, and you have some artistic talent, you might make tiles with familiar insects on them to place around the garden. There are some children’s rhymes that go with these: Itsy bitsy spider; lady bug lady bug… there are websites full of such rhymes and folk sayings. Pressing leaves with a hot iron is definitely not for little kids. But it is something you may want to have kids watch you do (put the waxy sides toward one another). It is a great chance to ask them to compare and notice the different kinds of profiles and veins. They can be posted in your windows, or cut up and sent home with the kids (in which case it might help to tape the edges shut). For rainy days, you can have kids cut out and tape (or staple together) three dimensional flowers of their own invention, if their motor skills are far enough along. That might be for older kids, but I’ll never forget the teacher who had us put all of them together on a the bulletin board in a big bouquet that cheered us through March! Or the kids can shape them from PlayDo while you read aloud to them. If you have a fenced yard — you probably will — there are some thornless roses with a sprawling habit that can be trained horizontally across the top of the fence (which encourages bloom). Rose hips (fruits) are non-toxic, rich in Vitamin C, and so sour the kids won’t eat more than one! But they can be used in little bouquets in autumn and winter. As for fairy gardens, what great miniature project, if the kids’ handskills are up to it. Bark, twigs, lichen, dried grass, moss can make a pretty effect. Maybe an indoor rainy-day tabletop project. And there must be reading aloud opportunities to go with that, or a chance for the kids to make up stories to go with it. If you plant trees, do your research to locate ones with pretty flowers and pretty fall color. If deciduous, you can add twinkle lights to cheer the scene when days grow short. If you live in a snowy climate — or even if you don’t — don’t forget that childhood favorite of making paper snowflakes with ordinary printing paper and scissors. But around the holidays you can get shiny foil papers, which kids like working with. The first thing kids learn to write is their name, even before they know their alphabet. Signing art projects gives them a use for writing their name, and if you decorate with their work, it helps you sort things out when it is time to take them home. A lot of these ideas may be too old for the age level you’ll be caring for, but you are the expert and can sort that ideas. I hope this gets the creative juices flowing. Have a great time with it!

Mulch Your Garden Using Crushed Shells

Mulch your garden frequently to keep it weed free, improve soil health, and give it a well-groomed and professional look. Adding mulch also retains moisture in the soil and prevents evaporation. Instead of purchasing expensive mulch from nurseries or stores, you can use items from your home and garden such as pebbles, compost, wood chips, bark, grass clipping, or decaying leaves. Organic mulches that break down in the soil include crushed shells, bark chips, straw, and compost. Follow these steps to mulch your garden using something as simple and ordinary as crushed shells.

Step 1 – Get Shells

You can purchase shells from a landscape material supplier, but depending on the size of your lawn, these could get costly. An alternative is to contact your local seafood restaurant and ask them for shells. They are frequently more than willing to get rid of them, at a nominal price.

Step 2 – Clean Shells

Be sure to thoroughly wash and boil the shells because the salt that may be encrusted on these shells will be added to the soil which can burn nearby plants. Boiling will also rid the shells of the smell that may be transferred to the garden.

While there is no need to break small sized shells like mussels into tiny pieces, the big ones will need treatment. Cover large full shells such as oyster and crab shells in a cloth and use a hammer to break them into several smaller pieces.

Step 3 – Apply a Layer to Your Garden

Collect all the crushed shells in a thick cloth or tarp and move outdoors to your garden. Apply a layer of crushed shells mulch over the garden surface. To do this, simply throw the crushed shells over the site you want to mulch, whether it is a flower bed, a vegetable patch, a portion of your lawn, or the area around a tree.

The best time to add this organic mulch is later spring or early summer when the soil is warm. These shells will provide the soil the minerals and calcium they need as they decay, allowing you to save money in the long run on soil additives and amendments.

Step 4 – Spread the Mulch

Add at least 2 inches of crushed shells over the area you want to mulch. Seashells decay slowly, preventing the need to replenish the mulch for at least two years.

Seashell mulch is good for all types of plants such as perennials, annuals, trees, vines, ground covers, and many vegetables. You can also add it to flowerpots to enhance their appearance.

Step 5 – Water the Mulch

Water the mulch thoroughly after you spread it to allow all the pieces to interlock and prevent them from blowing away with strong winds or heavy rain. The seashells will resemble a light colored carpet of mulch that reflects the suns heat to keep the soil and roots cool.

If, however, the need to compost any particular area of your garden arises, simply rake the crushed seashells mulch aside, lay the desired composted material and replace the shells over the site.

Treasure Trove of Fertility: Composting Mussels

By Maria Dimengo

For about the last two years, I have been experimenting with composting mussels. Head to southern West Virginia and you’ll meet farmers who are learning to amend the brown, yellowish sandy soil deep within the Appalachian Plateau. The Berks-Pineville and Gilpin-Lily soil created by weathered shale, siltstone and sandstone can be unpredictable. Though it appears to be well drained in some areas and easily cultivated in others, the black gold they need to amend their crops is all but gone.

Here in the southern coalfields that surround Mullens, Itmann and Pineville, mountaintop soil and dirt can be tightly packed and tough to work.

Compost can take a long time to break down, especially when there are long stretches of dry hot weather.

I knew little about the soil in Mullens when I first started experimenting with my zebra mussel shell compost mix. I first made a visit there last summer and stumbled upon a row of gardens at the Mullens Opportunity Center while I was in town for a meeting.

There, I met the executive director of the Rural Appalachian Improvement League and a farm-to-school AmeriCorps worker who was caring for their summer crops and high-tunnel complex. I asked if I could return to Mullens with just the right remedy for their soil.

The author has experimented with a compost mix of zebra and quagga mussels.

Experimenting in Cleveland

I have been working with a compost mix of zebra and quagga mussels, invasive bivalves that are plentiful in and around the Great Lakes. Whenever I shared buckets of it with other farmers, we were excited to see the results. Few people care to understand the value of the mussels and instead, fear them, because of the way they wreak havoc on lakes, streams and inland waterways.

They are a nuisance because they can alter the entire ecosystem of a body of water if a tiny, single veliger travels on the hull of a boat and creates their own colonies. Luckily, the mussels I use in my compost are already dead, and far from the Guyandotte River that snakes alongside Mullens and other southern coal communities.

Plus, I only use the composted shells — not the actual mollusks — which grow like crazy in water temperatures of around 50-55 degrees and warmer.

The author’s compost is being used at school and community gardens.

I consider myself a casual scientist because I don’t hold a degree in botany, biology or earth science, but I do like to study conservation and focus on environmental issues that are beyond manageable for the governments and researchers who study them.

After I discovered mounds and mounds of the shells on Lake Erie, I found an online recipe for zebra mussel shell compost on the Cornell University website.

I took Cornell’s recipe, removed the peat and tinkered with the recipe so I could teach children to apply the compost in urban gardens. The goal was to teach them about turning lemons into lemonade, so they in turn could teach senior groups and refugees in the city who were looking for opportunities to amend their own backyard gardens.

The principal from Near West Intergenerational School, a charter school on the west side of Cleveland, found the idea in perfect alignment with their mission to think outside the box. She allowed me to work with a group of sixth and seventh graders, and after two years, they saw the benefits of using this compost firsthand. I asked them to write a letter to farmers about the compost as one of their assignments. One student wrote: “I would recommend that a farmer use zebra mussels, shells, chicken poo and sawdust because it works well for vegetables. In science class, we had a taste test for peppers. They were super good.”

Aliza, another student at the school, echoed what others in the class had to say. “Keep using the zebra compost for your crops,” she wrote. “The outcomes we saw in the peppers that were grown in the zebra compost was that the peppers grew very big.”

Real Results

When you first mix the recipe, your compost will look like the color of oatmeal cookie dough. But in two years, that same compost will create a moist black soil that makes a wonderful amendment.

In Cleveland, educators around town were asking me where they could harvest the shells to create their own mix, and some urban gardeners were feeding the shells to their chickens as a low-cost grit alternative.

Others were adding the uncomposted shells straight to hay, grass and other compostables and finding the end product great for container gardens.

We conducted a lot of informal trials at Kentucky Garden, which is a community farm across from the school. A fellow gardener suggested a great way to determine if my first batch was usable. “Maybe you could take four or five plants and put regular soil around them, like this,” he said. “Then, get an equal number of plants, add the zebra mussel compost and do the same thing … measure the height of each plant, then see how they grow.”

I knew it wouldn’t be an exact science, since my peppers would be taking up space in a community plot.

I simply couldn’t watch their progress every day, so I cordoned off a small section and placed each pepper in the ground. A handful of peppers received two cups of vegetable compost while the others received the zebra mussel shell mix. Each time I watered them, I was careful to give each plant the same amount. Twice, I amended the soil, giving each plant equal parts of compost.

Tomatoes growing in soil treated with mussel compost mix.

I couldn’t control what others did while I wasn’t around, but over time, I observed some interesting outcomes.

Each time I stopped by to water, the plants with the shells yielded peppers that were longer, stronger and wider.

In addition, plants with the shells had multiple yields, so I was constantly picking fresh peppers from my zebra plants.

It seemed whenever I would visit the plot to check on them, the plants with the shells were just bursting to be picked. The other plants lagged behind and took forever to grow. I gave my mix to other gardeners and they recorded similar results. One gardener said the flowers in his garden yielded brighter colors after using the zebra mussel shell compost.

What’s in the Shells?

Using shells to boost soil fertility is nothing new — eggshells are a given, and many farmers use oyster shells and fish waste to give their crops an extra boost. When I was doing research, I ran across a company called Coast of Maine Organic Products in Portland. The company’s Quoddy Blend contains lobster shells, which are said to be rich in nitrogen and chitin.

Cornell University’s Waste Management Institute Department of Crop and Soil Sciences experimented with the compost after receiving an EPA grant to compost zebra mussel shells at a New York waste facility.

They were one of the few resources I found online when I went looking for ways to re-purpose the shells into something useful. I wondered if anyone else had seen the value of using them for clean fill or other things, so I traveled to Ithaca to meet the researchers for myself.

At first they seemed surprised that I was reviving a recipe that was written so long ago, but they suggested that I cook my compost at least nine months to break down the pathogens.

They also suggested I build a two-can bioreactor to aerate the compost if I wanted to produce small-scale batches indoors.

They told me that the calcium carbonate in the shells is what gives plants a boost. When mixed with chicken poop and sawdust, zebra mussel shell compost can support an optimal pH level, especially when you compost the shells for two years or more.

Since I knew I would be working with young kids, I wanted to find out if zebra mussel compost is harmful.

I reached out to Remegio Confesor, a research scientist at Heidelberg University in Tiffin, Ohio. Confesor suggested I first test the shells for contamination and then test the compost to see if any toxins were being transferred to my soil. He said that anyone who performs compost analysis could help, since they look for heavy metals, lead, PCBs and other toxins.

Confesor and other researchers have been studying the nitrogen and phosphorus movement across Lake Erie waters because of recent algal blooms. With zebra and quagga mussels, there is a connection. Around 2002, a researcher by the name of Hank Vanderploeg looked at how zebra mussels selectively filter the phytoplankton that provide food to aquatic creatures. Apparently, zebra mussels will eat whatever they can filter, except for Microcystis, a species of freshwater cyanobacteria that create harmful algal blooms or HABs.

Once they’ve had their fill, zebra mussels excrete all the phosphate and ammonia nutrients so their excrement works like fertilizer, allowing the toxic algae to proliferate.

Researchers with the Great Lakes Environmental Research Laboratory (GLERL) also experimented with zebra mussels. Using special video equipment, they found that the mussels eat algae and filter the water, but spit Microcystis back into the water. During their selective feeding process, the mussels excrete nutrients like phosphate and ammonia, which serve to fertilize further growth of the harmful cyanobacteria.

So if we know that zebra mussels play a role in nutrient loading when they are alive, who’s to say they aren’t a valuable source when they’re dead? Whatever the outcome, we have moved our experiments to an Appalachian coal town, and now we have a whole new round of baselines and healthy crops to grow. I also hope to look at Japanese Knotweed and kudzu — two other invasives in Appalachia that have impacted the mountain valleys and riversides.

Recipe for Composting Mussels

Cornell researchers wanted to see if they could make a recipe for folks who might want to compost anywhere from 100 to 1,000 pounds of zebra mussels. Since a zebra mussel is mostly shell and hardly any organic matter, you probably need to mix mussels with some other organic material to provide the right nutrients for compost microorganisms.

After a number of small tests, the researchers found that a co-composting mixture of 1:14:17:18 parts by weight of peat, sawdust, poultry litter and water could be made and then mixed 1:1 with zebra mussels for composting.

An equal volume of wood chips for bulking was then added. Two compost piles were built, each containing one cubic yard of zebra mussels supplied by Rochester Gas and Electric on a bed of wood chips and perforated PVC drainage pipes. In monitoring the compost, it was observed that the shells probably help maintain good pore structure for airflow.

After three months of composting and maturing, the wood chips were screened out, the compost was mixed with various ratios of topsoil, and tomatoes and radishes were grown in the mixtures. All seedlings did as well or better than the topsoil alone.

Recipe Source: Erin McDonnell.

By Maria Dimengo. This article appeared in the December 2015 issue of Acres U.S.A.

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The usage of ‘comprise’ and ‘compose’ is currently a much-debated issue amongst grammarians. However, some scientific publishers, as well as many reviewers, are very picky about the technical usage of these terms, so it is important that you are aware of how to properly use them.

The vast majority of the time, comprise can be substituted for “is made up of,” but 1% of the time, comprise may mean “include.” The difference between these two usages is as follows:

  • Primary usage: “The whole comprises (i.e., “is made up of”) all of the parts”
  • Less-popular usage: “The whole comprises (i.e., “includes”) most of the parts” or “the whole comprises all of the parts that we know of right now.”
  • Note: Please avoid using ‘is comprised of,’ which does not fit the definition of the word.

The complicating factor in this situation is the phrase is composed of. This phrase is frequently substituted for ‘comprised,’ but some publishers dislike it. Compose should be used when you list or state the parts first. The following examples help demonstrate the differences between ‘compose’ and ‘comprise’:

  • “Graduate students compose the seminar.”
  • “Seven steps compose our purification scheme.”


  • “The seminar comprises graduate students.”
  • “Our purification scheme comprises seven steps.”

Why does this usage matter? Scientific writing aims to be clear and concise in relating precise information to a knowledgeable audience, and the phrase ‘is composed of’ is wordier, less precise, and a more passive way of saying ‘comprised.’ We hope that this tip will help you set your reviewers’ and publishers’ minds at ease by demonstrating a technical awareness of the proper usage of these terms. Please email us with any questions about this topic.

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