Crab legs dripping with melted butter—what’s not to love? As seafood lovers, we all enjoy indulging in a pile of delicious crab, but the empty shells left behind can be a pain to deal with. Rather than feeling guilty about adding to the waste crisis by tossing them in the trash, you’ll be happy to know that crab shells are actually 100% compostable!
Composting crab shells is an easy, environmentally friendly way to repurpose food scraps while creating a nutrient-rich fertilizer for your garden. In this article, we’ll cover everything you need to know about composting crab shells the right way.
Why Are Crab Shells Compostable?
Crab shells are primarily made up of calcium carbonate along with organic matter like chitin. This natural composition allows the shells to break down through the decomposition process just like other compostable materials such as fruit and vegetable peels, grass clippings, and dead leaves.
When added to a properly balanced compost pile or bin, the crab shells get broken down over time by fungi, bacteria, invertebrates, and other decomposers. Given the right conditions, the shells will eventually decompose into usable compost full of nutrients that your garden will love.
Composting also prevents the crab shells from ending up in landfills where they won’t be able to decompose properly Diverting food waste from landfills is an important step in reducing the growing waste crisis
The Benefits of Composting Crab Shells
Some of the top benefits of composting crab shells include:
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Reduces food waste by giving shells a sustainable second life
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Provides key nutrients like calcium, phosphorus, magnesium and chitin that enrich the compost.
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Improves soil health by boosting nutrients, drainage, aeration and moisture retention.
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Deters common garden pests like fungi and insects due to the chitin.
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Saves money on buying commercial fertilizers by making your own compost.
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Reduces your carbon footprint by diverting waste from landfills.
How to Compost Crab Shells Successfully
Composting crab shells is relatively simple if you follow these steps:
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Clean the shells thoroughly to remove any remaining meat, butter or sauce residue. This prevents odor and pests.
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Crush the shells into smaller pieces using a hammer or rolling pin. The smaller the pieces, the faster they’ll decompose.
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Distribute and mix the crushed shells throughout your compost pile. Don’t let them sit in clumps.
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Balance high-nitrogen “green” materials like fruit and veggie scraps with high-carbon “brown” materials like dried leaves or wood chips.
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Maintain proper aeration and moisture in the compost, turning periodically and keeping it as moist as a wrung-out sponge.
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Be patient! Crab shells can take 6 months to 2 years to fully break down. But it’s worth the wait.
Composting Other Seafood Shells
The composting method for crab shells also works great for other types of seafood shells including lobster, shrimp, mussels, oysters and more. Simply rinse off any residue, crush the shells, distribute in the compost pile, and keep things balanced. The shells will all gradually break down, adding fantastic nutrients and pest-deterring chitin to your finished compost.
Using Crab Shell Compost in Your Garden
Once your crab shell compost is finished, it makes a wonderful organic fertilizer and soil amendment for your vegetable garden, flower beds, trees and shrubs. Here are some of the best uses for it:
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Mix compost into garden beds and container soil before planting each season.
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Make compost “tea” to use as a nutrient-boosting foliar feed for plants.
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Sprinkle compost around transplants to give their roots an extra nutrient kick.
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Use compost as a nutritious top-dressing for plants during the growing season.
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Add compost when potting up houseplants and container plants.
As the compost gradually releases nutrients into the soil, it will fuel healthy plant growth and help suppress diseases. It’s an organic, sustainable fertilizer solution from recycled food scraps!
Frequently Asked Questions
How small should I crush the crab shells?
Break them into dime-sized pieces or smaller if possible. More surface area speeds decomposition.
Can I add crab shells to a worm compost bin?
Avoid vermicomposting as the salt content can harm worms. Stick to traditional compost piles/bins.
How do I know when my crab shell compost is finished?
It will look dark, crumbly, and earthy-smelling without any recognizable shell pieces.
What plants benefit most from crab shell compost?
Tomatoes, peppers, leafy greens, carrots and fruit trees appreciate the calcium and nutrients.
Crab Shells Are Compost Gold
As seafood lovers, there’s no need for us to feel guilty about all those leftover crab shells anymore. By composting the shells, we can reduce waste while creating an amazing fertilizer for healthier, more productive gardens.
With just a little effort to prep and compost the shells properly, you’ll turn trash into treasure for your plants. So next time you crack open a pile of crabs, don’t throw those shells away – put them to work boosting your garden instead!
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 persons trash is another persons treasure, then Jeff Holden has struck gold. Or as he calls it, gardeners gold. For years, Jeff Holden has been processing shellfish in Portland, Maine. These days hes also making fancy-grade compost from some of the states most common byproducts: seashells and sawdust. As Maine Public Radios Matthew Algeo reports, this new business began as a surprise.
ALGEO: Jeff Holden owns Portland Shellfish, a company that processes more than ten tons of crab, lobster, and shrimp daily. Thats a lot of shellfish and a lot of shells.
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 Maines 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 its 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 whod 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 Protections Residuals Utilization Unit, which oversees commercial composting operations in Maine. He says it takes more than shells to make a good compost.
WRIGHT: Youre 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. Its got some use somewhere.
ALGEO: Gregoir says Saunders sells its sawdust to several companies besides Portland Shellfish. He says its 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 Gardeners Gold, and hes 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. Hes building a full-scale composting operation, and he hopes to distribute the product all along the East Coast. Its 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 countrys 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 thats 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 Maines compost is already highly-regarded among farmers and gardeners outside the state as well.
WRIGHT: Its 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, Im Matthew Algeo in Portland, Maine. Please enable JavaScript to view