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.
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.
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”.
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)
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.
Some concerns I would have about putting meat in the composter:
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.
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.
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.
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."
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.
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 ;)
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.
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.
I heard too much meat can bring up nitrogen too high. Also heard should add decomposers such as lacto-bacteria and yeast.
