composting dairy products

Composting Dairy Products (The Truth about Dairy in Compost)

If, like myself, you compost a lot of your kitchen waste, you inevitably ask yourself whether you can compost dairy products like cheese, cream, or even milk. After all… All food is organic and ends up rotting… Right? 

So can you compost dairy products? Dairy seems to be one of the food types that traditional composters tell you to avoid. The main reason is because animal food waste is considered to attract pests. But if you want to compost dairy produce the answer is yes, it’s possible, provided that you stick to certain rules...

The big question is how to compost dairy products safely and without having to worry about pests. 

How to Compost Dairy Produce

Food waste in general is high in moisture. What makes dairy products different from other types of food is their very high moisture and fat content

Also, dairy products are not very substantial and have a low material structure. They tend to be soft and don’t have much roughage or texture.

These are a couple of the reasons why it’s recommended to mix dairy with dry fibrous materials when you add them to compost. Adding dry leaves, straw, or even shredded paper, helps compensate for the wetness and lack of texture of dairy products. This improves the structure and encourages air pockets to help keep the compost aerated.

In case you don’t know, these dry fibrous materials are generally high in carbon, and in composting terms are called “browns”. For efficient composting you need a proper balance of browns and greens. Greens are materials which are high in nitrogen and include things like food waste.

Another issue with dairy is its high fat content. Fats and oils tend to slow down the composting process. This is because fat can create a watertight coating over other materials. The microorganisms responsible for decomposition need air to function correctly so this waterproof barrier causes problems.  

On the other hand, fats are high in energy and will be broken down quickly by the composting microbes. Later I'll give you some tips on how to compost dairy more effectively.

Food waste also tends to yield higher amounts of leachate. This is the liquid which is produced during the decomposition process. There are ways to deal with this as you’ll find out below.

Dairy products are also highly prone to odor production when composted. This is usually because clumps of food stick together and encourage anaerobic decomposition.

Anaerobic decomposition (without air) is undesirable in a compost pile. This process is much slower than aerobic decomposition (which uses air). If your compost smells of ammonia, then you have anaerobic conditions.

In my opinion, you should only include small amounts of dairy waste in your compost and only if you carefully control your composting methods.

Dairy Composting Tips:

If you want to add dairy products to your compost bin try to follow these recommendations:

  • Bigger compost bins are better at composting animal food waste. Your compost bin needs to be at least 1 yard square (or 1 square meter).  Larger compost piles have the advantage that they build up more heat at the center of the composting mass. Hot composting is said to kill any pathogens resulting from waste like dairy products.
  • Bury your dairy waste in the center of the compost pile. By putting dairy products on top of a nest of dry brown materials and compost, this will act as a filter to break down any leachate from the dairy products.
  • Bury the dairy products under a thick layer of already decomposing compost and dry materials (about 18 inches should do). This will also help filter smells.
  • Mix with plenty of brown materials.  They will act as a bulking agent and help to absorb anything that can leach out of your compost bin.
  • Make sure your bin is far from a water supply such as a stream or a well. This is to avoid leachate contamination.
  • Break up dairy produce into small pieces whenever possible. Smaller chunks will decompose quicker and maybe avoid anaerobic conditions.
  • Turn regularly to aerate the compost pile. Again, this will help avoid anaerobic bacteria and generally speeds up the process.
  • Use gloves if you intend to compost animal food scraps. All organic waste carries parasites and bacteria, and dairy and meat products have a higher risk of pathogens. For the same reason you should always wash your garden vegetables well before eating them.

Remember, the center of the compost is the hottest and most active. By dumping your dairy waste in the middle of your pile you help avoid problems with leachate and odors. And at the same time you make it less easy for pests to get those tasty snacks !

Tip: If you buy in straw for your composting check to make sure that is hasn’t been treated with any chemicals. Chemical fertilisers could linger in your compost and have a negative effect on your plants when you apply it.

The Advantages of Hot Composting Dairy Waste

If you regularly throw away dairy products, you might want to consider a hot composting bin. 

Hot composting, as its name implies, takes advantage of the microbial activity during decomposition to produce very high temperatures. As a result, hot composting produces finished compost quicker than other methods (some people report as little as between 1 to 3 months). And it can handle a wider range of materials, including dairy and meat. This is because the hot temperatures kill most harmful bacteria and pathogens, and it’s even said to kill off seeds from weeds.

As an added advantage, the hot temperatures help to discourage vermin!

The hot composting method needs a little more care and attention to keep the balance of greens and browns in the right ratio. But if you’re interested in producing good quality compost quickly using a wide variety of organic materials, then hot composting could be worth the effort.

If you’re interested in trying hot composting, you can buy specially designed “hot” compost bins. These are usually a closed design, and have improved insulation compared to standard bins. An interesting example of this kind of design is the “Green Cone” food digester which has a dual wall for added insulation.

Can you add Dairy waste to a Wormery?

Vermicomposting has become very popular with composting enthusiasts. In this kind of system you need to keep your wriggly friends happy by maintaining the best conditions. So what happens if you add dairy waste products to a wormery?

Worms can’t digest lactose based products very well.  

Worms require a pH level which is alkaline to survive. Since adding dairy to a wormery can lower the pH of the bin (make it more acidic), it’s best to avoid dairy if you’re making vermicompost. Otherwise those wriggly critters will 

If your worm bin smells of vinegar then the acidity level is probably too high.

The bottom line.

If you’re just starting out with composting then I would recommend you avoid things like dairy until you become more comfortable with the composting process. For the reasons I listed above, I prefer to limit the amount of dairy waste I add to my compost pile.