Homesteading, Gardening, and Off-Grid Living

Can You Put Shrimp Shells in the Compost Bin? 

By: Zac Friedman

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Can you compost shrimp shells? Yes. Shrimp shells can be composted in a regular backyard compost bin or pile. They are great for compost. In composting, they are considered a ‘green’ material. They are rich in nitrogen and other valuable nutrients. Shrimp shells also contain materials that are beneficial for the microorganisms that decompose your compost. There are some drawbacks to composting shrimp shells. They can cause odors and attract pests. 

Shrimp shells are easy to compost. If you have an active compost bin, you can bury them in the middle of the pile. You don’t need to wash them or anything. Just place them in the hottest part of the compost. They will break down quickly. I have been composting shrimp shells this way for many years and have never had any issues. 

In this guide, I’ll go more in-depth into composting shrimp shells. I’ll explain why you should consider composting shrimp shells. I’ll also outline all of the benefits and drawbacks of composting shrimp shells. In addition, I’ll explain exactly how to compost shrimp shells properly. 

How to Compost Shrimp Shells pin

Can You Compost Shrimp Shells?

Yes. You can compost shrimp shells. It is safe to compost both raw shrimp shells and cooked shrimp shells. They are completely organic materials. They also break down surprisingly quickly. In addition, they contain compounds that are beneficial to your garden soil such as nitrogen, chitin, and calcium carbonate.

Generally, it is not advised to compost animal products such as meat, grease, fat, fish bones, etc. According to the U.S. Environmental Protection Agency, these materials shouldn’t be composted because they can create odors and attract pests. 

Shrimp shells fall into the category of animal products. And they can stink and attract pests if they’re not composted properly. That said, they can add valuable nutrients to your compost. It can be worth the hassle to compost them. They also break down quickly so they don’t cause as many problems as other animal products. It is easy and beneficial to compost shrimp shells.

What are Shrimp Shells Made Of? Protein, Chitin, and Calcium Carbonate

Shrimp

Chitin

Chitin is a complex carbohydrate. It makes up around 15-40% of the exoskeleton of shrimp.

Chitin is also found in crab and lobster shells, butterfly wings, the cell walls of fungi, and insect exoskeletons. It is one of the most common organic compounds on the planet. 

Chitin contains carbon, nitrogen, hydrogen, and oxygen. The chemical formula for chitin is C8H13O5N·H2O.

There are several benefits of chitin. It is high in nitrogen, a vital nutrient that acts as a catalyst in the composting process. Nitrogen is instrumental in fostering the growth and multiplication of soil microorganisms responsible for breaking down organic materials into organic compost. A compost rich in nitrogen consequently enhances soil fertility, providing plants with the necessary nutrients for growth, health, and productivity.

Additionally, chitin naturally carries antifungal properties, making it a significant asset in managing and controlling fungal diseases in the compost pile and the garden. Its presence helps in creating a hostile environment for harmful fungi.

Chitin also proves to be a remarkable compost material in combating nematodes. Nematodes are microscopic worms that often pose harmful effects on plant roots. Over time, they can kill plants. Chitin prevents this.

When chitin is incorporated into the compost, it encourages the growth of certain bacteria that are detrimental to nematodes. These bacteria, in feeding on chitin, produce enzymes that adversely affect the nematodes, disrupting their lifecycle and reducing their population in the soil.

Chitin creates an ideal environment for the proliferation of beneficial microorganisms. It also enhances the fertility of the soil. For these reasons, it is commonly used as a fertilizer. 

The chitin compound is commonly added to fertilizers. It is usually derived from seafood shells that are ground into a fine powder. 

A compost bin

Calcium Carbonate

A considerable portion of shrimp shells is composed of calcium carbonate. This material is made from calcium, carbon, and oxygen. Its chemical formula is CaCO₃. 

Calcium carbonate acts as a natural liming agent. It is alkaline. This helps with neutralizing acidic soils, promoting a balanced soil pH. In other words, it can lower the pH of your soil. 

In addition, calcium carbonate helps with new cell development. It helps to fortify the cells of plants. Shrimp shells are a rich source of calcium. 

Proteins

Proteins found in shrimp shells help fuel microbial activity. This accelerates the process of decomposition and enriches the compost with essential amino acids and nitrogen. This makes shrimp shells a good fertilizer. 

A compost bin
Shrimp shells can go in a regular compost bin with food scraps

Benefits of Composting Shrimp Shells

Shrimp shells contribute to the composting process and the ultimate health of plants and soil. 

Firstly, shrimp shells are a rich source of nitrogen, a key component that facilitates the growth of microorganisms in the compost. The nitrogen in shrimp shells helps in forming protein and other essential cellular components in these microorganisms, enhancing their ability to decompose organic matter effectively. This makes the composting process more efficient.

Another significant benefit of composting shrimp shells is their content of chitin. Chitin has been found to have antifungal properties, which can be crucial in preventing diseases in plants. Including shrimp shells in compost offers plants a level of protection against certain fungal pathogens. 

Additionally, chitin is beneficial in managing nematode populations in the soil. Nematodes are microscopic worms, some of which can be harmful to plants. Chitin helps reduce the population of these harmful pests.

Shrimp shells are also rich in calcium carbonate, an essential compound that can help in regulating soil pH levels. Maintaining an optimal pH level is necessary for the availability of essential nutrients to plants, ensuring that plants can absorb these nutrients effectively. This contribution of shrimp shells can be particularly beneficial in soils that are too acidic, as it helps neutralize the acidity.

Drawbacks of Composting Shrimp Shells

The most notable downside is the potential odor problem. Shrimp shells, when decomposing, can emit a strong, unpleasant smell. Humans have evolved to react adversely to the smell of rotting meat. Your neighbors won’t appreciate this.

This odor can attract pests such as rodents and flies to the compost pile. This makes the composting process more difficult and less hygienic. You have to manage the compost properly to keep pests away. 

Composting shrimp shells takes more labor and attention compared to composting other types of organic waste. For example, you have to properly prepare the shells before placing them in the compost to reduce odors and keep pests away. 

The presence of shrimp shells in compost may make it more susceptible to pathogens if not properly managed. Shrimp shells, being animal waste, can carry diseases.

Ensuring that the compost pile reaches a high enough temperature to kill off these pathogens is crucial to avoid contaminating the plants and soil where the compost will be applied. 

A handful of compost

How to Compost Shrimp Shells

Step 1: Clean the Shrimp Shells

Thoroughly rinse the shrimp shells to remove any residual meat, butter, seasonings, spices, oils, or marinades. Alternatively, you can boil the shrimp shells for 20 minutes. 

Cleaning the shrimp shells helps to reduce odors that can attract pests. It also removes seasonings and spices that slow down the decomposition process. Worms and other decomposers don’t like spicy or citrusy food. 

Boiling helps to clean the shrimp shells and kill any bad bacteria. It also removes any residual fat that can slow down decomposition. 

Step 2: Dry the Shells

Place the shells on a baking sheet and put them in the oven on low heat until they are dry. This will make the shells brittle.

This step is optional but it can help speed up the decomposition process by making it easier to break the shells up. 

Step 3: Crush the Shells

For best results, crush or break the shrimp shells into smaller pieces. If you dry the shells, you can easily crush them with a rolling pin. If you don’t dry them, you can break them apart with your hands or even use a food processor.

Breaking them down increases the surface area. This makes it easier for the microorganisms in the compost to break down the shells more efficiently.

Step 4: Balance the Shrimp Shells with Brown Materials

Prepare brown materials to mix with the shrimp shells. Brown materials are rich in carbon and include items like dried leaves, paper, or wood chips. These materials help balance the nitrogen-rich shrimp shells and promote a healthy composting process.

Step 5: Mix the Shrimp Shells into the Compost

Add the crushed shrimp shells to the compost bin or pile. Dig a hole into the center of the compost and place the shrimp shells inside. Cover the hole with other compost.

It’s best to add the shrimp shells in moderation. Adding too many at once may attract pests. 

Ideally, the shrimp shells should be completely covered and placed near the center of the compost. Covering them with other compost will help to reduce odors. Placing them near the center where the compost is the warmest will speed up the decomposition process. 

If possible, it’s best to compost shrimp shells in an enclosed compost bin that has a lid. It’s also best to use a compost bin that is elevated. This can prevent rodents from entering. 

Step 5: Maintain Moisture and Aeration

Ensure that the compost is kept moist but not too wet. Regularly turn the compost to maintain aeration. This promotes a more efficient breakdown of the materials and prevents foul odors.

Step 6: Monitoring the Compost

Monitor the compost’s progress, ensuring that it doesn’t give off a foul odor. Also, check for the presence of pests. Regular turning and proper maintenance will help in creating a well-composted end product.

If you find that the shrimp shells are taking a long time to decompose or if they attract pests, you probably won’t want to add them again. Not all compost piles are suitable for shrimp shells. 

Step 7: Harvest the Compost

Once the composting process is complete, and the materials are well-decomposed, the compost is ready to be harvested and used in your vegetable garden or around fruit trees.

Ensure that the shrimp shells are fully broken down before using the shrimp compost. Shrimp shells will decompose in around a month in most compost piles. 

The Easy Way

If you don’t have a pest problem in your yard and you have a hot pile of compost, you can simply add the shrimp shell to the inside of the pile and mix. You don’t have to wash, dry, and crush them. They will decompose quickly. 

If your compost isn’t very active or if you have a pest problem, you should go through the process outlined above. It will really speed up decomposition and reduce odors. 

How to Compost Shrimp Shells with Soil Incorporation

In some cities, having compost piles is not allowed for health and safety reasons. Maybe you simply don’t want to have a compost heap in your backyard.

In this case, you might consider the soil incorporation method. This simply means burying food scraps deep in the ground so they don’t create odors or attract pests. 

  • Step 1: Collect and Prepare the Shrimp Shells- Cut or break the shrimp shells into small pieces. This speeds up decomposition. 
  • Step 2: Choose the Site- Select a site in your garden where you want to enrich the soil using shrimp shells. Ensure that the site is suitable for the plants you plan to grow. Also, make sure there aren’t any large roots or rocks in the way so you can dig. 
  • Step 3: Dig a Hole- Dig a deep hole in the chosen site, ensuring that it is deep enough to cover the shells adequately. The depth can be around 12–15 inches or 30–38 centimeters.
  • Step 4: Add the Shrimp Shells- Place the crushed shrimp shells and other kitchen scraps into the hole. You can create a layer 3-4 inches or 8-10 centimeters thick. Spread them evenly and mix in some soil to promote uniform decomposition. It can help to add a bit of water as well. 
  • Step 5: Cover the Shells- Cover the shrimp shells with the soil that was removed when digging the hole. Ideally, there should be at least 8 inches or 20 centimeters of soil covering the shrimp shells. This discourages pests and contains any potential odors.
  • Step 6: Wait- The shrimp shells will decompose over the course of 2-3 months. In some cases, they may take up to a year to decompose. 
  • Step 7: Planting- Once the shrimp shells have decomposed sufficiently, the site is ready for planting. The incorporated shells will enhance the soil’s nutrient content, benefiting the plants that are grown in that area.
raised beds
The finished compost is great for adding to flower beds

Are Shrimp Shells Considered Brown or Green?

Shrimp shells are categorized as “green” material in the composting world. In composting terminology, “green” refers to nitrogen-rich materials, while “brown” denotes carbon-rich materials.

Some examples of green materials in composting include fruit and vegetable scraps, coffee grounds, and grass clippings. Some examples of brown items include dry leaves, newspaper, straw, hay, pine needles, and dead plants.

Shrimp shells have a carbon-to-nitrogen ratio of 8. In composting, anything with a carbon-to-nitrogen ratio of less than 30 is considered green.

Nitrogen is a key element that aids in the proliferation of microbes, which in turn speeds up the decomposition of organic materials in the compost.

Having shrimp shells as a green component in your compost is beneficial as it helps maintain the balance between the green and brown materials in the compost pile. This balance is crucial for the effectiveness and efficiency of the composting process.

How Long Do Shrimp Shells Take to Decompose? 

The decomposition of shrimp shells in a composting environment varies based on several factors, primarily temperature. 

On average, shrimp shells take about one month to decompose in a compost heap under normal conditions. In a hot composting environment, where temperatures reach 120 degrees Fahrenheit or higher, shrimp shells can decompose within 7 to 14 days. The higher temperatures in hot composting increase microbial activity, allowing for a quicker breakdown of organic materials.

In cooler composting settings, the decomposition process of shrimp shells is slower. It may take several months for them to break down completely. Cooler temperatures impede the activity of the microorganisms responsible for decomposition, thereby lengthening the composting process. 

Shrimp shells decompose quickly compared to other materials. This is one of the reasons they’re a great addition to your compost.

Can You Add Shrimp Shells to Vermicompost

Yes, you can add shrimp shells to vermicompost. You will want to be cautious because vermicomposting systems tend to be more fragile compared to traditional compost heaps. 

Vermicomposting involves the use of worms to help decompose organic materials. Shrimp shells must be carefully managed to maintain a healthy worm habitat.

When introducing shrimp shells to your vermicompost, it’s best to start with a small amount. This allows you to observe how the worms react to the shrimp shells and whether it affects the overall health and balance of the composting system.

Breaking the shrimp shells into smaller pieces before adding them is also recommended. Smaller pieces will be easier for the worms to manage and help speed up the decomposition process.

It’s important to note the potential odor that shrimp shells might introduce to your worm bin. Shrimp shells can generate an unpleasant smell as they decompose. Adding only small amounts can minimize any odors. If the odor is too strong, you can attract pests. 

Another good thing to add to your worm bin is crushed egg shells. These are maybe even better than shrimp shells. 

Can You Compost Whole Shrimp? 

Yes, you can compost whole shrimp but it’s not recommended for several reasons.

One of the main concerns is the attraction of pests and scavengers. Whole shrimp are likely to attract a variety of unwanted visitors like rodents and flies to your compost bin or pile. This could lead to a pest problem.

Additionally, whole shrimp have a high fat content. Fats are known to slow down the composting process. They can coat other materials, preventing them from being readily broken down by microbes.

Composting Other Types of Crustaceans, Mollusks, and Seafood Shells

You can compost other types of crustacean shells such as crab and lobster shells. You can also compost mollusk shells such as clam, muscle, and oyster shells. 

Before adding these shells to your compost pile, you should always crush or break them up. Don’t add whole shells. This is important because these shells are far thicker than shrimp shells. They take much longer to decompose. Crushing them up increases the surface area so they can decompose faster. If you throw the shells in whole, they could take years to break down.

Can you compost shrimp tails?

Yes. You can compost all parts of the shrimp shell including the tail and head. The only part you shouldn’t compost is the meat because it can smell and draw pests. 

What else can shrimp shells be used for?

You can use shrimp shells to make a nice briny stock. Simply boil the shells, tails, and shrimp heads to extract the flavor. Use the stock to make seafood soups, stews, and sauces.

After you make the stock, you can wash the shrimp shells, dry them, crush them, and add them to your compost pile.

A homestead

Another Option: Community Composting or Commercial Composting

Participating in community or commercial composting programs can be a great way to ensure that shrimp shells and other seafood waste are composted properly. Many of these programs accept shrimp shells as part of their organic food waste intake. In addition, they often accept other seafood waste such as shells from clams, lobsters, crayfish, oysters, muscles, prawns, crabs, and more. 

These facilities are equipped with the necessary equipment and expertise to handle a wide variety of organic materials, including seafood waste, ensuring that they are processed in an environmentally friendly manner.

Community and commercial composting programs can manage the challenges that shrimp shells present in a more controlled environment. These facilities often operate on a larger scale and maintain optimal conditions for speedy and efficient composting. 

For those who are unsure about composting shrimp shells at home or do not have the necessary space or resources to do so, these composting options can be a good alternative. Some of these programs even offer curbside pickup. 

Using these programs ensures that shrimp shells and other seafood wastes are diverted from landfills, helping to reduce waste and contribute to sustainable practices. It also fosters community participation in environmental conservation efforts.

Of course, you can also put the shrimp shells in your garbage bin if you don’t want to compost them or if you can’t find a commercial composter to take them. 

My Experience Composting Shrimp Shells

I don’t eat shrimp all that often due to the high cost but when I do, I compost the tails. I have a pretty active compost pile so I don’t usually bother with drying and crushing the shells. Instead, I simply rinse them off and add them to the hottest part of my compost pile along with my yard waste. 

They usually decompose in about two weeks. Sometimes they take a little bit longer. I use the shrimp shell compost in my garden beds. I often put the compost around my tomato plants. 

Adding shrimp shells to your compost bin is beneficial. They make a great natural fertilizer. When properly managed, shrimp shells enrich your compost with essential nutrients like nitrogen and calcium, promoting a healthier and more fertile soil conducive to plant growth. They also add chitin, which has its own set of benefits. 

It is important to be aware of potential challenges such as odors and pests. With careful preparation and maintenance, shrimp shells can be a valuable addition to your compost. 

Do you compost shrimp shells? Share your experience in the comments below!

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