Can You Compost Milk? (And Milk Cartons?)

They say water is life, but I beg to differ, slightly. Almost all mammals have to feed exclusively on milk once they are born for some time before feeding on other foods. Not a dig on water, but for the few weeks or months of life for newborn mammals, milk is life.

Milk can be used to make several other products like yogurt, cheese and ice cream. At the same time, milk goes bad incredibly fast. It, therefore, begs the question, can something else be done with spoiled milk, like composting? This article has more on composting milk and related products.

Can You Put Milk in the Compost?

Milk can be composted, but you should highly avoid doing it if you are unfamiliar with the process. Composting milk and dairy products bring up some challenges and you have to abide by certain rules to effectively do it.

Food waste is generally high in moisture but what makes dairy products different from other types of food is their very high moisture and fat content. This fat content attracts pests to the composting process, meaning they will damage your compost if additional steps are not taken.

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

Take milk, for instance, it literally is a liquid and can spill around inside or leak outside the composting bin. It is therefore recommended that you mix the dairy products with fibrous materials.

There are a couple of reasons why it is recommended to mix milk and dairy products with dry fibrous materials when adding them to the compost.

First, 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.

Secondly, there is the issue of the high-fat content in dairy products. Fats and oils tend to slow down the composting process, primarily 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.

Thirdly, dairy products are also highly prone to odor production when composted, usually because clumps of food, stick together and encourage anaerobic decomposition. Anaerobic decomposition results in a slower process and is undesirable in a composting pile.

To effectively compost milk, firstly use bigger compost bins for they will have the advantage of building up more heat at the center of the composting mass. Hot composting will kill any pathogens resulting from waste like dairy products.

Secondly, bury the dairy waste at the center of the compost pile. By putting the dairy products on top of a nest of dry brown materials and compost, will act as a filter to break down any leachate from the dairy products.

Thirdly, bury the dairy under a thick layer of already decomposing compost and dry materials, to also help filter the smells that could attract pests. You should also mix the milk with plenty of brown materials, which act as a bulking agent and help absorb anything that can leach out of the composting bin.

Also, ensure your bin is far away from a source of water like a well or stream to avoid leachate contamination. Next, turn the compost regularly to aerate it well and avoid an anaerobic composting process. Finally, use gloves to avoid carrying pathogens, parasites and bacteria that arise from meat and dairy wastes.

Is Spoiled Milk Good For Compost?

Of course, you can compost spoiled milk. In fact, spoiled milk has two added advantages over fresh milk when being used as fertilizer or compost. Understand this, once milk goes bad, it is worthless and its price goes to zero, yet the mineral content remains the same.

So, first, spoiled milk will be a fertilizer that costs amounts close to zero, as compared to costly fertilizers. Why go for an expensive and chemically-filled fertilizer when you can use cheap spoiled milk for a similar operation?

Secondly, there is a slight concentration that happens when milk spoils. The milk separates into solids, which carry a good portion of the nitrogen and phosphorous required in fertilizers.

The separating milk also carries “whey”, which contains a lot of the milk sugars, which are not necessarily useful as a fertilizer. If you spend any money separating the two, it is not really a “free” fertilizer anymore, so be sure to consider that. However, if you use spoiled milk as it is, it will serve the intended purpose.

Like composting fresh milk, composting spoiled milk requires a similar process. You should use bigger compost bins to encourage the generation of enough heat to kill present pathogens, as well as speed up the process.

You should also bury the spoiled milk at the center of the composting pile where the heat is highest, and can also conceal the odors that attract pests. Something slightly different with composting fresh liquid milk is that spoiled milk separates into solids that need to be broken up into smaller pieces whenever possible.

Smaller chunks will decompose quickly and will avoid creating an anaerobic environment.

Next, mix the content with plenty of brown materials that will act as a bulking agent and also help absorb anything that can leach out of the compost bin.

You also need to turn the compost regularly to aerate it well and avoid anaerobic bacteria. Make sure the bin is far away from a supply of water and use gloves to avoid carrying pathogens and bacteria present in such waste.

Can You Compost Milk Cartons?

Yes, milk cartons are compostable, although they will take longer to decompose than other cardboard boxes or cartons. Cartons are made primarily of paper but also have a thin layer of polyethylene, or plastic, with shelf-stable cartons containing a layer of aluminum.

Paper milk cartons are encased with a wax layer, which seals the milk in the paper cartons. The wax also seals out the moisture needed for decomposition to start, slowing the decomposition process. The coating also makes milk cartons effective for recycling, and not composting alone.

Luckily, milk and juice cartons are some of the few forms of packaging that have a high content of renewable raw material, cardboard. Cardboard is biodegradable, recyclable and is made from a renewable resource, making it sustainable.

When you look at an empty milk carton, it might not be immediately obvious that it is suitable for composting. This is because the waxing or coating, that preserves the carton when milk is added, could preserve it from trying to decompose.

So, if you see a milk carton in the compost and does not appear to want to decompose, it is probably because of the combination of polyethylene and aluminum protecting the paper element.

You, therefore, need to remove the carton from the compost and send it to the landfill with the rest of the trash or consider recycling it. Luckily, there is a new breed of cartons that have a layer known as ‘bio-plastics, made from corn starch, forming a ‘vegetable’ rather than ‘synthetic’ cartons.

These are completely biodegradable and do not require additional attention when sent into the composting bin.

For those made from synthetic polyethylene and aluminum, recycling is a better route than composting, which allows the cartons to be used over and over again. Allowing them to decompose could be a wasted opportunity for extended use.

Can You Water Plants with Milk?

Yes, milk can be used to water plants. Any type of milk, whether fresh, evaporated, powdered or expired can be used in a garden, although it has to be diluted properly. You should mix the milk with water in a 50-50 ratio and pour it into a spray bottle.

Watering down the milk is essential to ensure it actually benefits your garden, rather than destroying the plants. The ratio does not have to be exact and in fact, you can even just mix up the very last dregs of the gallon as you finish off the jug, using just a quarter-cup or so of milk.

After applying the milk mixture to the leaves of the plants, check back in about 30 minutes to ensure the watery milk was absorbed. If a liquid still sits on the leaves at that time, gently wipe it down with a wet cloth.

Some plants like tomatoes are prone to developing fungal diseases if such liquids sit on their leaves for too long. You can also pour the milk mixture directly into the soil at the base of the plant, allowing the roots to absorb it.

Milk as fertilizer is a good source of calcium, proteins, vitamin B and sugars that are good for plants, improving their overall health and crop yields. The microbes that feed on the fertilizer components of milk are also beneficial to the soil.

Feeding plants with milk has also been used with varying effectiveness in pesticide applications, especially with aphids. Perhaps the best use of milk has been in reducing the transmission of mosaic leaf viruses such as tobacco mosaic.

After applying the milk mixture, refrain from using chemical fertilizer or pesticide for it will kill the bacteria in the milk that helps the plants grow. However, a slightly unpleasant odor will follow after using the milk on the plants, but will eventually subside.

This is due to the spoiling of the bacteria in the milk and fats in the milk, which results in foul odors and poor growth. Also, dried skim milk has been reported to induce black rot, soft rot, and Alternaria leaf spot on treated cruciferous crops.

Can Milk Be Used as Fertilizer?

Yes, milk can be used as fertilizer in the garden. As mentioned above, you need to mix 50% milk with 50% water. When using milk fertilizer as a foliar spray, add the solution to a spray bottle and apply it to plant leaves, which will then absorb the solution.

However, some plants like tomatoes can develop fungal diseases if the fertilizer stays on the leaves for too long, meaning you have to wipe down the leaves with a wet cloth or spray them with water. If you have a large garden and a lot of plants to feed, use less milk in the solution.

Also, use a garden hose sprayer to feed the crops. Continue spraying until the entire garden is coated. You can use about 5 gallons of milk per acre, (which is about 19 liters per half a hectare), or about a quart of milk per 20 by 20-foot garden (which is about one litre per 6m x 6m) patch of garden.

Allow the milk mixture to soak into the ground and repeat the process every few months or spray once at the beginning of the growing season and again during the mid-season.

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About Rinkesh

A true environmentalist by heart ❤️. Founded Conserve Energy Future with the sole motto of providing helpful information related to our rapidly depleting environment. Unless you strongly believe in Elon Musk‘s idea of making Mars as another habitable planet, do remember that there really is no 'Planet B' in this whole universe.