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I've heard claims that it is a bad idea to place meat in your compost pile.

What is the reason for this? I'd like to be able to compost all my table scraps to reduce my waste stream, however, if meat is not a good idea to compost, I'd like to know. Or alternatively, if there is a way to compost meat effectively so as to not waste stream it, that would be good to know.

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    In Germany, the paper bags for organic waste have signs that bones and fish rests doesn't belong there. I don't know if they have reason for it and if I should ignore it, but with this rule, bones actually belongs nowhere... maybe I should eat them? ;) – Danubian Sailor Jul 25 '13 at 19:11

10 Answers 10

64

I include all organic materials in my compost, including meat, bones, dairy, grains, oils, and citrus - all of which are often listed as inappropriate for compost.

Meat attracts pests such as dogs, mice, and flies. After adding new material to my compost pile, I put a thick layer of straw on top, and then a scrap of metal mesh fencing on top of that. This contains the smell and discourages digging. I get no flies.

I use plenty of sawdust in my compost mix, providing carbon to balance the high nitrogen of the materials I want to compost. The sawdust also acts as a sponge to hold and moderate moisture in the pile. A compost pile should be damp (bacteria needs water to travel) but not wet (aerobic bacteria needs access to oxygen).

I include manure in my compost. It would otherwise be a waste product, but in my here it makes a richer compost and provides the ideal bacteria for a hot, active compost pile.

I build my compost piles pretty big, so they can get hot and contain their heat. The heat helps everything break down nicely.

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    Right, it can. That is why it is important to turn/mix your compost as much as possible. Sometimes as much as once a day. – Gabriel Fair Jan 31 '13 at 6:04
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    @user1205935: It's impossible for a compost pile to sterilize itself. If it gets too hot, the heat-producing bacteria population would shrink, to find equilibrium. Also, remember that the perimeter of the pile will never be as hot as the center, providing a refuge for other non-thermophillic bacteria until the center cools down. – Jay Bazuzi Jan 31 '13 at 6:44
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    @GabrielFair: The need to turn compost is not absolute, especially if you're not in a hurry to produce finished compost. See humanurehandbook.com/downloads/Chapter_3.pdf on page 48. – Jay Bazuzi Jan 31 '13 at 6:55
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    While adding meat to an intensively managed compost pile may work it isn't a good idea for many of the reasons listed, especially if your pile isn't intensively managed. If you can't feed the meat scraps to a pet or finish them yourself maybe you should start a worm bin... as an aside consuming meat especially factory farmed meat is not very sustainable. – hortstu Jan 12 '14 at 4:51
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    FWIW I composted by literally throwing vegetable waste in an 18" plant pot. Never turned it. Once it was full after ~6mos, 6" of excellent compost at the bottom. Turning's not a requirement. – Chris Moschini Dec 15 '14 at 22:26
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Anything that has been living can be composted. Local compost manufacturers in Finland suggest strongly that meat can be composted.

As I understand the problem with meat has something to do with attracting anaerobic processes and overheating the compostor slowing the process down. Make sure your compostor gets enough air and the contents are not too tightly compressed to only sustain anaerobic processes.

Here are couple of articles from National Geographic’s Green Living: “Can I compost meat?” and “How to Compost Meat Waste”.

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    Actually one thing that you don't want to add to your compost. And that's tomatoes. It really halts the process, and it's most easily measures if you capture and measure the output of biogas (a direct and prime bipoduct output of composting) – Escoce Nov 5 '15 at 17:13
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    Luckily chickens and worms will both eat tomatoes. – Móż Jun 8 '16 at 3:54
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The main/most convincing reason I have heard not to compost meat (as well as dog or cat manure) is due to the possibility that it may harbor pathogens harmful to humans or other animals.

There are steps that can be taken to reduce this risk--mainly high-temperature composting. Although it can be difficult or impossible to achieve the necessary temperatures to kill such pathogens in a small-scale/backyard compost pile. See here:

These are organic materials and therefore can be composted, BUT they tend to smell and to attract more rodents and other critters. Decomposing meat may contain bacteria that's pathogenic to humans, so it has to be composted at a very high temperature to kill off the pathogens. Depending on the conditions of your pile, it might not get hot enough for that. So we discourage the composting of meat and dairy in backyard piles. (emphasis added)

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You can compost meat, but the problem is that it will start to smell and attract flies and maggots (as well as neighbourhoods cats and dogs possibly). It also slows down the composting process.

You can use a bokashi bin to preprocess all left-overs including meat, fish and dairy. It doesn't smell and after about 2 weeks the bin contents can be mixed with the compost heap. Tips on how to do this can be found here. The downside is that you'll need the buy EM microorganisms regularly.

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Some concerns I would have about putting meat in the composter:

  • Attracting rodents, dogs, and cats
  • Things like bones aren't going to compost well (whether very heavily boiled chicken bones might compost is another matter entirely)
  • Meat is going to be very high in nitrogen and consequently may pose problems unless you mix in low-nitrogen/high-carbon mixtures as well
  • There is the theoretical concern over pathogens. However unlike the fecal-oral transmission cycle, I think the risk of this getting spread back via food is pretty low. Also I treat this as theoretical because all kinds of other stuff we compost (read: anything that you'd want to refridgerate if saving to eat again!) could also grow bacteria that are pathogenic to humans...

These are just concerns. Like all concerns they mean that you can plan for them and overcome them with a little bit of effort. Keep it enclosed to ensure critters can't access. Add low-nitrogen material to compensate (straw might be good), and accept that the bones are going to still be in large pieces when youa are done. Adding meat to the compost pile adds maintenance. It is not a hard rule to avoid.

This being said, trimming what you serve, and recycling the meat products in the kitchen as much as you can first, is where I would start. Reduce and re-use first, then recycle (compost) what is left.

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    I have been putting meat in my compost for years. I have seen a small rat, once. But the heap is near a big forest, so I feel that I am helping the struggling raptor community. – Gabriel Fair Jan 31 '13 at 6:05
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    it may depend on where you are. here in Jakarta, both rats and cats could be a significant nuissance. – Chris Travers Jan 31 '13 at 6:12
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Although I think the other answers do provide good information, I would argue that, as posed on sustainability.stackexchange.com, all of them are still wrong (albeit maybe Chris Travers' answer is only partially so).

You should not put meat in your compost pile.

Sustainability of Eating Meat in the First Place

If you're even remotely concerned with sustainability (underlying assumption I'm making, based on where this question is), then you shouldn't be eating meat at all. Meat is hands-down the most inefficient, unsustainable way to feed a human being, as it stands today.

To really go back to first principles, consider the laws of thermodynamics. You can't create energy from nothing, and no process is perfectly energy efficient. In order to build an animal from food, first you have to grow, process, and transport the food. The animal has to eat it and process the food into energy, which it does not do with perfect efficiency. Then, the animal has to live for a while (weeks, months, or years, depending on the meat), during which time it has to move around, eat, poop, heat itself and make noise. All these things take energy.

Instead of performing this cycle, skip the animal altogether and just grow (non-animal) food that can be directly consumed by humans.

How inefficient it is to eat meat depends on the animal, what you feed it, and the processes used. There is no one answer here. But, a reasonable range, for example, might be that in order to produce a given unit of beef energy (e.g. a calorie), you have to put in 6 to 50 times that much energy in the process. That puts the effective energy efficiency of the process at between 2% and 16%. That's terrible.

Unfortunately, it gets worse. The previous figures only discussed energy efficiency. If you believe that climate change is a problem, you need understand that not all greenhouse gases are equally potent. Methane is 22x more effective at trapping heat in the atmosphere than is CO2, and the animals we get our meat from produce a lot of methane, meaning that their contribution to global warming is even worse than suggested by looking at their energy efficiency alone.

So, don't eat meat (cow, pig, sheep, deer, etc.) in the first place. Poultry (chicken, turkey) is a bit better. Seafood is better still. A vegetarian or vegan diet is most sustainable.

If You Do Eat Meat, Don't Compost It

As has been said many times on this site, including in Chris's answer, sustainability choices need to be prioritized to reduce use first, then reuse second, then recycle last.

Why do you have extra meat at all? If you have leftover meat, then buy a smaller cut. Virtually everywhere I see meat sold allows you to buy pieces in an almost continuous array of sizes.

In the developing world, currently about 1/3 of food is lost, mostly to disease or spoilage (lack of preservatives, but also refrigeration). However, in the developed world, the loss is almost exactly the same (1/3), for different reasons. One reason is people buying and preparing more food than they need and just throwing the rest out (or composting it). If you need to eat 2000 calories per day, then prepare 2000 calories. Don't prepare 2500, and then compost the unused portion.

If you find yourself in a scenario where you can't find a way to stop eating meat, try to buy the correct portion, but you still have leftovers, then save the edible meat for tomorrow. Chop it up to make a lunch sandwich. If you still have fat and gristle left, those things probably won't break down quickly in your compost bin, and can create health/rodent concerns outlined in other answers. Just bury the fat in a hole you dig.

Aside: in response to the plethora of responses everywhere online about people saying "I compost meat and rarely see rats", I respond: "Rats tend to come out when you're not there. Trust me, they find the meat, unless your bin is under tight lock-down."

Conclusion

Asking a sustainability question about putting meat in a compost pile really is like asking one about the proper tire inflation pressure for a Humvee. True, you can save some gas by keeping tires inflated properly, but if you have a Humvee at all, you've already gone awry. I don't pose this comparison simply as a rhetorical tactic. The direct contribution of agriculture to global warming is roughly equivalent to that of transportation (about 10-15%). If you add in secondary effects from land-use change, it's even worse.

Making the decision to not to eat farmed meat at all is one of those currently uncomfortable sustainability solutions, along with having fewer babies, and not keeping pets. People don't want to consider it, but the impact of the choice is large, and completely within your control, right now.

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    @Nate Your advice on fat and gristle is good, but it is buried inside a pile of criticism for people who have meat that is going to waste--that's why I don't like your answer. You did not directly answer the question, but instead chose to devote most of your response to criticism of meat consumption and food waste, which both deserve separate questions. Your answer about meat in backyard compost piles is good, but I had to wade through 34 lines of your diatribe to get to them. Cut to the chase, then link to other info about meat at the end if you feel it's important. – Evan Johnson May 3 '13 at 14:52
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    @EvanJohnson, there's a reason for that. The issue of (a) whether eating meat at all is sustainable is roughly an order of magnitude more important than (b) making sure you consume all the meat you prepare, which is an order of magnitude more important than (c) what you do with the scraps that you really can't eat. As a result, it's entirely appropriate for me to dedicate more words to the more important factors, and a 34:1 ratio sounds just about right. I did "cut to the chase". The second sentence I wrote (in bold) was my answer, and everything after that was support for that. – Nate May 3 '13 at 20:58
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    @EvanJohnson, especially in the context of the highest-voted answer to this question offering zero support from any references/sources, and completely ignoring the number 1 and 2 sustainability issues with meat composting (1: meat eating is unsustainable, and 2: not consuming all your meat is, too), I find your latest critique of my answer rather poorly applied. – Nate May 3 '13 at 21:05
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    I would have liked to have read those comments. Such a flaw in the SE model. – Randy Aug 19 '13 at 5:09
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    There are plenty of reasons to ask about composting meat while still not supporting factory farmed meat. 1. You have a deceased animal to get rid of. I've put dead birds, etc. in my compost heap for example. 2. You eat sustainable meat - ie, you shoot rabbits and eat that. People have different understandings of what sustainable meat production is, so this really is a separate question. 3. You raise your own chickens for eggs, which means you will have some roosters to consume at the very least (as well as the hens when they reach the end of their life). – daamsie Jan 8 '15 at 3:50
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I've been told to not put meat in compost heaps because it would attract rats.

I've only seen one rat in the 15 years I've been living here, and that rat was nowhere near the compost heap. So it must be working ;)

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    ... or the rats know not to come out when you're around ;) – Nate Apr 21 '13 at 22:11
  • Hehe, could be :D I haven't seen any dropping either. Perhaps we have the cleanliest rodents here in Denmark ;) – Nis May 2 '13 at 19:42
  • Rats, foxes, badgers - all kinds of animals you maybe do not want near your children or your bare feet. If you want to see the creatures in your garden, check it out quietly at 2 am, or get one of those wild-life cameras. – RedSonja Jun 9 '16 at 10:58
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    A joke would seem more appropriate in a comment than in an answer which otherwise provides no (or barely any) useful information. – PJTraill Oct 19 '17 at 9:50
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The above answers are correct for 'traditional' composting but by using bokashi composting you can compost all of your food scraps, including meat, bones, cooked food, dairy etc.

The bokashi process works by first pickling or fermenting your food scraps using healthy bacteria. Once the fermentation process is complete (after about 2 weeks) the pre-compost (the pickled food scraps) can be buried directly in your garden where the soil biota will finish off the work. The pickled food waste is not attractive to pests.

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    Hi Nicki and welcome. You don't need to put a sig or sign off at the end of each post here: as you can see, your name and a link to your profile appear under each of your posts anyway. So although other websites allow or even encourage it, here they're firmly discouraged. If you want to post a general comment (such as "happy to answer any questions on bokashi"), then your profile is the place for that. This is all because we're not a forum - we don't do back-and-forth discussion; just questions & answers. – EnergyNumbers Nov 2 '15 at 17:52
  • Bokashi is not composting. It's pickling. It still needs to be composted separately. – Graham Chiu Mar 10 '18 at 20:42
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there is the possibility for hot composting. I read if you use the Johanna Green bin that you can put everything in this bin. Temperature get so high that it decomposes everything.

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    Can you add more information into your answer? It's a good direction. – Peter Ivan Jan 7 '14 at 8:05
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I heard too much meat can bring up nitrogen too high. Also heard should add decomposers such as lacto-bacteria and yeast.

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    This answer would be improved if it had references to support the claims made. – Fred Sep 21 '15 at 9:07

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