Can You Compost Dairy Products?

Can you compost dairy products? Many people wonder if you can add milk, yogurt, sour cream, and cheese to a backyard compost. While technically dairy products will decompose under the right conditions, adding them to the average backyard compost will attract pests and create foul odors. The high fat content in most dairy products is what makes them difficult to break down. Dairy is also not recommended for worm bins either as the foods will become rancid.

Composting your food scraps at home is a great way to reduce waste, while producing nutrient-rich soil for your garden. But when you start adding dairy products like yogurt or cheese into the mix, things get complicated fast.

We’ll explain why dairy can be problematic for the average home composter, and how to safely add dairy in very small amounts (because we know that if you’re here reading this, you’ll probably want to try it out!).

Why dairy is problematic for home composting

Many compost guides, including one from the U.S. Environmental Protection Agency (EPA) will tell you not to add dairy products such as butter, milk, sour cream, and yogurt to your compost pile. This is because they’ll create bad odors (think rotting cheese and rancid milk), and attract backyard pests from flies, to rodents and raccoons.¹

This is definitely true, especially when done incorrectly, or added in large amounts.

However, the University of Georgia Extension says, “Fruits, vegetables, dairy products, grains, bread, unbleached paper napkins, coffee filters, eggshells, meats and newspaper can be composted. If it can be eaten or grown in a field or garden, it can be composted.”²

So we know that yes, dairy products will decompose over time, but they may create more problems for the average home composter.

What makes dairy hard to decompose? The answer: it all comes down to the fat content. Dairy products are high in fat which means that they can’t be easily broken down by microbes like most other organic materials can.

A 2004 study examined the breakdown of fats during thermophilic composting, or hot composting. They created lard mixtures of varying ratios and combined it with dog food. The results showed that the decomposition of organic material was impeded when the fat content was higher than 33.3 percent. This was especially true during the beginning stages of composting.³

So, foods with high fat content (which is most dairy products), decompose slowly.

While dairy products are slowly decomposing in your backyard, they’ll quickly create rancid odors and attract all sorts of pests.

YayImages_CanYouCompostDairy_home-made-dairy-products — Credit: Yay Images

Tips for composting small amounts of dairy

So, even though we’ve warned you about the possible problems with composting dairy, there’s always a few people who would still like to try it anyway. If this is you, read on for a few tips.

Keep it small: The key to composting dairy is moderation. So avoid dumping in a whole jug of milk, or an entire block of cheese. Not only will this create a smelly mess, it’ll take a very long time to decompose. Cut up any large pieces of cheese into smaller chunks.
Keep it hot (your compost pile, that is): Hot composting is a method of composting in which heat-loving bacteria called thermophiles thrive. As the name suggests, this method of composting gets hot: the sweet spot is at temperatures between 105 and 140 degrees Fahrenheit (41–60 degrees Celsius), according to the University of Florida Extension.⁴ At these higher temperatures, food breaks down quickly which results in less chance to attract rodents and pests. It’s difficult for most home composting systems to get this hot though (most simply aren’t big enough), which is why the following tips are important.
Mix it with a bulking agent: Dairy products like sour cream, yogurt, and of course milk are high in moisture. To reduce some of this moisture content, the University of Georgia recommends mixing food scraps with an absorbent bulking agent such as sawdust, dry leaves, or other yard scraps.² These “brown” composting agents are high in carbon which helps to balance out the nitrogen-rich content of food scraps.
Place it in the center: The middle of your compost is where all the action is and where the microbes are most active. Make a little well in the center of your compost pile, place the dairy in it, and cover it well with some dry brown materials such as leaves to mask any odors.
Put a lid on it: To keep out potential pests such as rodents or raccoons, place a lid or cover on your backyard compost pile.
Turn it frequently: Regular turning of your compost keeps it properly aerated. Aerobic conditions are vital to a healthy compost as it creates a favorable environment for microorganisms to thrive.

Besides adding to your backyard compost, there are other ways to compost dairy products.

Bokashi composting

Unlike regular backyard composts, it’s completely safe to include meat scraps and dairy products in a bokashi bin. Bokashi is a method of composting which uses a closed bin (creating anaerobic conditions) along with inoculated bran or oat feed to kick-start a cycle of fermentation composting.

Municipal composting programs

Many local composting or recycling programs accept dairy products. Under larger industrial composting systems, dairy products break down easily.

Dairy products are a no-no for worm bins

If you have a vermicompost at home, unfortunately dairy products are not something you should feed to your red wigglers. As dairy decomposes, it’ll produce rancid odors, especially within an enclosed worm bin. This may attract pests to your bin.⁵

Tips for preventing dairy waste

As composting dairy can be tricky, it’s much easier to prevent food wastage in the first place by buying only the amount of food you can reasonably eat. Proper food storage also plays a role in the shelf life of dairy products.

Refrigerate right away: While sometimes you can get busy after making a run to the grocery store, it’s important to put perishables like dairy products in the fridge as soon as possible. For food safety, there’s a two-hour window in which food can be kept out at room temperature, according to U.S. Food & Drug Administration (FDA).⁶ If room temperature is above 90 degrees Fahrenheit (32 degrees Celsius), this time frame reduces to one hour. Not only may food become unsafe to eat, it’ll shorten the shelf life of your food.
Avoid plastic wrap for cheese: Cheese lasts longer if it’s able to “breath”—something it can’t really do when smothered in plastic wrap. Instead, use either wax paper, parchment paper, or aluminum foil to wrap cheese in.

Conclusion: can you compost dairy products?

While dairy products such as milk, cheese, yogurt, and sour cream are decomposable, they may create problems for the average backyard compost pile. They may create strong odors and attract pests and backyard rodents.

The high fat content of most dairy items will make them more difficult to break down than regular organic waste.

If you are looking to compost dairy products, it’s best to only try a small amount and mix it with a bulking agent such as sawdust or dry leaves to absorb the moisture and reduce the odor. Dairy also isn’t recommended for a vermicompost because the foods can become rancid over time.

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References

United States Environmental Protection Agency (EPA), Composting At Home, https://www.epa.gov/recycle/composting-home. Accessed June 2021.
University of Georgia Extension, Food Waste Composting: Institutional and Industrial Application, https://secure.caes.uga.edu/extension/publications/files/pdf/B%201189_4.PDF. Accessed June 2021.
Nakasaki K, Nagasaki K, Ariga O. Degradation of fats during thermophilic composting of organic waste. Waste Manag Res. 2004 Aug;22(4):276-82. doi: 10.1177/0734242X04045430. PMID: 15462335.
University of Florida, Institute of Food and Agricultural Sciences, Managing a Compost System, https://sfyl.ifas.ufl.edu/sarasota/natural-resources/waste-reduction/composting/what-is-composting/manage-a-compost-system/. Accessed June 2021.
Uncle Jim’s Worm Farm, Composting Worm Feeding Guide: Best and Worst Foods, https://unclejimswormfarm.com/worm-feeding-best-foods-composting-worms/. Accessed June 2021.
U.S. Food & Drug Administration (FDA), Are You Storing Food Safely?, https://www.fda.gov/consumers/consumer-updates/are-you-storing-food-safely. Accessed June 2021.

Author: Josh Tesolin

Josh is co-founder of RusticWise. When he’s not tinkering in the garden, or fixing something around the house, you can find him working on a vast array of random side projects.

Can You Compost Dairy Products?

Why dairy is problematic for home composting