Can You Compost Dog Poop?

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Robert Pavlis

The number of dogs and cats in North America has skyrocketed and pet waste is becoming a huge problem. Can you compost dog poop?

In an urban area, leaving it where the animal dropped it is not a good idea. Collecting it and putting it in the trash bin has its own problems as you will see below. That only leaves composting, but there are also warnings about composting pet waste. Is composting really a problem? Is there a safe way to compost it? As a gardener it seems like a real waste not to use dog poop in the garden.

Dog standing on its hind feet, with a shovel and rake, picking up dog poop
Should You Compost Dog Poop?, photo source: Shmula.com

A Mountain of Dog Shit

There are 78 million dogs in the US, producing 10 million tons of waste each year. That is enough to fill 270,00 tractor trailers and lined up end to end, they would stretch from Boston to Seattle. The EPA now considers dog waste to be a major environmental source of pollution, along with pesticides, oils and mining wastes. There are also about the same number of cats, but the volume of waste is smaller.

The average dog produces 400 pounds of waste per year (180 Kg ) and it has an NPK of 2-10-0.3. That is as much nitrogen as you get from an 18 lb bag of urea but the dog waste also adds organic matter, making it better than urea.

Microbe Science for Gardeners Book, by Robert Pavlis

It is estimated that pet waste represents about 2 billion dollars worth of fertilizer.

Can You Compost Dog Poop?

A lot of information online says dog poop should not be composted but that’s a myth – it can be composted. Others say that there are no useful nutrients in dog waste but that is not true. Dog waste composts as easily as any other manure and with an NPK of 2-10-0.3 it definitely adds nutrients.

It has a low C:N ratio, about 8:1, meaning that it is a “green” material and needs to be added to browns for faster composting.

As far as composting goes it can be treated just like any other manure, however there are two specific concerns; plastic and disease.

Plastic in Dog Poop

A lot of dog poop is collected in plastic bags. Some of this plastic is neither compostable or biodegradable so it remains after composting in both commercial operations and in home composting bins. Just sitting in plastic will add microplastic particles to the waste. At home, it should be removed before adding the waste to the compost pile.

You might think that compostable or biodegradable plastic solves this problem, but it doesn’t. I’ve discussed this in detail in Is Compostable Plastic Really Compostable?

According to a press release put out by the Federal Trade Commission (FTC) in 2015, manufacturers and marketers of dog waste bags were told that “their ‘biodegradable,’ ‘compostable,’ and other environmental claims may be deceptive.

Parasites and Diseases in Dog Waste

The main concern about dog poop are the parasites and diseases which are collectively called zoonotic organisms. Humans can pick up the organisms by having direct contact with the waste.

Your own pet is much less of a concern since you come in close direct contact with it anyway. You can easily catch zoonotic diseases from their fur, from foot prints on the carpet and even from walking your dog down the sidewalk, since dogs tend to spread small amounts of their poop on the ground as they walk.

How prevalent are zoonotic infections? A Canada-wide study found that 34% of dogs were infected by at least one organism. It is not clear how that translates into human infection, because of a low number of infection events and poor tracking of infections.

The University of Florida suggests you wash your hands after each contact with your pet and that children should be kept away from them. That does not really happen and yet these same pet owners are afraid to touch some composted dog poop. If you have a dog, you are exposed, no matter what you do with the poop.

The danger of zoonotic diseases is also why most pet owners get their dogs treated, so they aren’t carriers. In that case composted poop is even less of a concern.

The Benefits of Composting Dog Waste

The EPA has identified several benefits for composting dog poop.

  • Composting removes raw dog waste from the environment where it can pollute groundwater and streams.
  • Good composting destroys pathogens and produces a safe soil amendment.
  • On-site composting eliminates transporting dog waste to a disposal facility. This saves time, money, energy, and landfill space.
  • Composting produces a quality soil additive that improves both the physical condition and fertility of the soil.

Does Composting Dog Poop Smell?

It smells more before you start composting it. Composting quickly removes the smell and the finished compost smells like moist soil in the woods. Gardeners enjoy its smell.

How to Dispose of Dog Poop

Other than home composting, there are a couple of disposal options; trash bin, green bin, toilet, vermicomposting, Bokashi and dog poop composters.

Trash Bin

This will end up in landfill and may be the worst option from an environmental point of view. Material in landfill decomposes anaerobically (devoid of oxygen) and produces methane which leaches into the air. Methane is 28 times worse than CO2 for causing global warming.

Green Bin

This is only an option in some municipalities. Where it is collected, a proper high temperature composting process will convert the waste into useable compost. This compost is disease and pest free. If you have such a service, this is a good option, except that you lose the value of the compost.

Flushing Down the Toilet

This is considered an environmentally sound option, except that it does add extra pressure on municipal sewage systems, which means we need to build bigger systems. It also increases the use of fresh water.

Vermicomposting

The worms will do a good job digesting dog poop, but there is no guarantee that parasites are killed in the process.

Bokashi Composting

Bokashi composting is a special technique that doesn’t actually “compost” (decompose) the ingredients. Instead, it removes oxygen inside the bin, fermenting the materials and killing parasites and pathogens in the process. The finished “ferment” can then put into a composting bin or directly into garden soil for composting.

Dog Poop Composter

There are several commercial products that can also be used. One such device, a pet septic tank, is the Doggie Dooley 3000 (affiliate link), and you can find similar DIY solutions on the internet. You certainly don’t have to buy it.

It’s a dog poop composter system; essentially a hole in the ground where you mix the poo with some poo digester to speed up the decomposition process. Over time the nutrients and organic matter seep into the soil. It does not give you compost for the garden, but at least you’re not sending it to the city for processing. The pathogens are not an issue since you don’t stick your hand into the hole. This system stops working in cold weather, similar to any composting system.

Cover it With a Rock

You can use a fake rock and cover the issue. (affiliate link)

 

Can You Put Dog Poop in a Composter?

Several different composters can be used for dog poop.

Hot Composting Pile

Dog poop that is composted at a high temperature is safe to use. The high temperature will kill the worms, worm eggs, and diseases. How hot is hot enough? The United States Department of Agriculture recommends 145 F (60 C) while industry standards say 130 F (55 C) for a minimum of three days for safe compost.

A home compost pile can reach these temperatures if the pile is big enough, has the right ratio of carbon to nitrogen and is being done in a warm environment (summer time). But home compost piles rarely meet all of these requirements. Unless you are measuring the temperature of your pile, assume yours does not get hot enough which means your compost might contain pathogens.

In that case you have two options. Either use the compost anyway or don’t put dog waste into the compost pile.

If you use the compost, keep it away from the vegetable garden. Use it on the lawn or better still, ornamental beds. That will reduce the risk of any pathogens even more. Consider spreading it around shrubs – an area where you rarely dig, so you are very unlikely to come into contact with the compost.

One thing to understand about pathogens is that they only live for a period of time outside of the animal. Over time the risk of getting sick from compost drops. The longer it sits in the garden, the safer it becomes.

Tumblers and Rotating Drums

These come in a variety of designs that can be either purchased or made at home as described in Composting Science for Gardeners.

These systems compost slower and at a lower temperature, so they won’t kill parasites and pathogens as easily.

Plastic Garden Composter

These are simple devices that sit on the ground. You place compostable material in the top and wait for it to compost. As with tumblers, these systems compost slower and at a lower temperature, so they won’t kill parasites and pathogens as easily.

plastic dome in a garden setting, with a lid to allow you to add compost
Plastic bin composter, source: Snowmanradio

What About Cat Poop?

Cat poop is discussed in a separate post.

Should You Compost Your Pet Waste?

If you are not concerned about handling your pets and having them roam around the house, I see no reason why you should be concerned about using their composted waste. You are much more likely to catch something directly from your pet.

The large number of dogs in North America is starting to make dog poop a big environmental problem. It really is best if you keep your pet waste in your yard and out of landfill. Although health authorities warn that there is a chance of catching a disease from pet waste, the chances are small if you are keep the pet healthy. Given the fact that simply touching your pet can also give you the same diseases, I see little reason not to compost the waste.

FAQ

Q1. Why can’t dog poop be composted?

It can be composted easily. The reason some sources say it should not be composted is due to parasites and pathogens, but they really are not a problem in your pets poop.

Q2. Does dog poop decompose into soil?

It does not become soil, but it does turn into organic matter that is then incorporated into soil.

Q3. How long does dog poop take to compost?

That depends on the method used. Hot composting takes about a month. Slower methods can take several months.

Q4. Is dog poop good for the garden?

It’s excellent for the garden providing it with nutrients and organic matter that feeds soil microbes.

Q5. Does dog poop attract rats?

Yes. Rats will eat dog poop. Once it is composted they will leave it alone.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

9 thoughts on “Can You Compost Dog Poop?”

  1. Thank you for this article. I doubt composting dog or cat poop will ever catch on. But if their poop is contributing towards global warming, then we just need less people.

    Reply
  2. Interesting that the conventional wisdom on composting poop might be wrong. I had never thought about the megatons of dog doo in the environment!

    I’m not a composting authority, but one thing I think my experience has shown is that eliminating pathogens in home compost probably isn’t possible. Reducing them, yes, but getting the entire volume of a pile to get very hot is difficult. After the first big temperature spike, successive ones after turning the pile are unlikely to happen without adding more green matter. Even then, I wouldn’t be confident that all the contents have been heated to 140 or so in the center of the pile. That’s why many people don’t compost tomato plants at all–the pathogens might persist even if the compost had a finished look to it.

    I suppose that confining all this “green” dog poop to the center of the pile would be safer, since it would all be cooked. But spreading it throughout the pile could be a problem.

    Reply
        • Surely the heat generated by the microwave oven would kill off any pathogens, if one was that concerned about pathogens before putting it in the compost

          Reply
          • heat kills pathogens – microwaves don’t. If you take pathogens and place them in microwaves they are not harmed because of their size. A large solid object containing water absorbs the waves which heat the water and when it gets hot enough it kills pathogens.

  3. Good post. You mentioned cat poop composting was in a different post. I couldn’t find it in your site index. Please provide the link. Thanks

    Reply

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