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The Full Scoop on Composting Poop

Human and animal waste is considered to be a good garden fertilizer in much of the world. In more civilized countries we call it ‘icky’. Can you compost urine and poop? Are there disease issues? Does it need to be composted differently than other organic ingredients? Read on to get the full scoop on poop.

urine and straw equals compost

Urine and straw equals compost

Composting Urine

Urine is a good source of nitrogen and it is usually sterile as it is leaving the body. With certain illnesses it is not sterile, and even if it is sterile, it quickly picks up microbes as soon as it exits the body. These facts should not be a concern in the compost pile. It is a good additive.
Note: April 2016: After some further checking, I believe the above statement “is usually sterile as it is leaving the body” is not correct. Urine is sterile until it enters the urethra, at which point it gets contaminated. So it is not sterile when it leaves the body.

The picture above is a device, called the urinare, that might make it easier to get all of your friends to contribute urine at your next party. Just push the special spouts into a straw bail, and starting collecting.

Urine contains 0.9% urea, or about 0.4% nitrogen. It also contains 0.1% potassium, so it’s fertilizer numbers are 0.4 – 0 – 0.1. Unfortunately it also contains 0.2% sodium which can be toxic to plants.

Urine is good on the compost pile or applied directly to the garden as long as it is used in moderation.

Composting Pet Waste

In 2012, 62% of homeowners in the US had at least one pet. That is a lot of poop.

Animal waste is just like manure. As far as microbes are concerned, it is a good addition to the compost pile. There are some possible concerns. Does pet poop contain diseases that could be spread to humans after being composted? Does pet poop contain drugs that cause health issues if we eat vegetables grown using this compost.

Let’s look at the second point first. I am not very concerned about traces of drugs, given to animals, making it through the composting process and then traveling through the soil and into the vegetables we eat. Why? Because, we are talking about very small amounts of drugs leaving the body of the animal. All chemicals degrade over time, especially in a compost bin. Even if some of the drug survives the composting process, it needs to be absorbed by the plant which also decomposes foreign chemicals. Very little, if any, will make it to the part of the plant we eat.

As far as diseases go, I personally would not worry too much about them either. Let’s be honest—do you really pick up every last trace of your dog’s poop, when they go in the garden? What happens when your neighbor’s cat shits in your garden—does the cat tell you were it went so you can pick it up? There is pet poop in your garden even if you don’t have pets.

However, the official story is that we don’t really know how much of a risk animal poop is, so all of the government agencies recommend that compost made using some animal waste should not be used to grow food. It is fine for lawns and perennial boarders.

If you don’t want to contaminate your compost, keep a separate pile of the animal waste, and place some at the bottom of the hole each time you plant a perennial, or dig it in between your plants. It will compost in the soil .

Composting Human Waste

Human waste is just another type of manure, and should be a good addition to a compost pile. The concerns are similar to pet waste, namely diseases and drugs.

Drugs should not be a concern, in most cases, for the reasons given above. Some special treatments such as radioactive compounds may be an exception.

As far as diseases go, consider the fact that you now live with the people in your home. If you are not getting any diseases from them now, would you expect to get them by eating a tomato grown in soil containing compost, made from their human waste? The reality is that human feces can be found on many home surfaces. You are more likely to get a disease from that, than from compost in the garden.

I consider the risk of disease transfer from composting human waste, from your own home, to be small. The official government advice is to not use it in compost.

According to The Salt (ref #2), in 1908, a contractor paid the city of Shanghai $31,000 in gold for the privilege of collecting 78,000 tons of human waste and carting it off to spread on fields. There is money to be made in poop!

References:

1) Composting Dog Waste: http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CDcQFjAE&url=http%3A%2F%2Fwww.nrcs.usda.gov%2FInternet%2FFSE_DOCUMENTS%2Fnrcs142p2_035763.pdf&ei=KhAKVYrCIdXasATj0oGQBA&usg=AFQjCNHDOZ9XYPHBE-LXr05xXtt_6LhR_g&sig2=DQXendSm9kq_aaUeJCBX0Q

2) Is it Safe to Use Compost made From Treated Human Waste: http://www.npr.org/blogs/thesalt/2013/05/07/182010827/is-it-safe-to-use-compost-made-from-treated-human-waste

3) Photo Source: http://pogledaj.to/drugestvari/olaksati-se-u-plastu-sijena/

Robert Pavlis
Editor of GardenMyths.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. 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!

I hope you find Garden Myths an educational site that helps you understand your garden better.

8 Responses to 'The Full Scoop on Composting Poop'

  1. What the heck is ‘humane’ waste?

  2. Kim Smith says:

    Thanks for this additional information. There is so much to learn out there, and I guess we have to get over our preconceived notions.

  3. Tarjei T. Jensen says:

    Hi,

    I’m afraid you will have to do more research, because urine is NOT sterile, but contains mostly benign bacteria.

    Pee into a sterile container and it will start to smell after a while. Avoid smell by adding a bit of poop to the brew.

    • Can you provide some references to back up your statement?

      The information I found said that urine is sterile inside the body, but that it gets contaminated as it leaves the body.

      • Damien says:

        Tarjei T Jensen may be referring to a recent study called: “Sterile Urine” and the Presence of Bacteria European Urology, Volume 68, Issue 2, Pages 173-174
        Alan J. Wolfe, Linda Brubaker.

        Regardless, if urine is not completely sterile it is near enough and arguing semantics does not change the fact that it is reasonably safe. If I compost urine from my household it is unlikely to infect me with any disease that I have not already got from my family. Lets be honest here, people have been using human urine in compost for a long time and I have not heard of many ill effects being attributed to it.

  4. w. Hansen says:

    Thanks for the info on pine needles!

  5. The ‘urinare’ device is really cool! I would like to see though the variant to be used by the opposite sex 🙂 If all pets poop left unpicked would be collected and used, it would make it for a lot of compost!

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