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I have read that composting things like bones and fat should be avoided as it can get smelly and attract pests. However, I expect that there are a lot of nutrients that I am wasting if I threw these things in the garbage (or the city compost).

So, I am planning on building up a new compost pile this fall and letting it run till next fall. I have a ~2' diameter, ~3' tall compost bin. I am planning on lining it with composted manure and bone meal to deter pests. I will supplement the heavy kitchen waste with plenty of branches and leaves. Will this work? What else should I be doing (esp. about the pest deterence)?

  • interesting question. i have always read that cooked food cannot be composted but, yes, it seems that there ought to be some goodness there if only it can be safely extracted. – Tea Drinker Nov 5 '11 at 8:02
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    it can be, but the fats and oils slow down "bug" growth, and meat and bone take a long time to break down and attract unwanted pests. bones won't break down within a reasonable amount of time unless you're going to try to chip and crush them first (thus making your own bone meal). – baka Nov 5 '11 at 16:47
  • @baka's answer is my understanding: I suggest you put it as the answer. Essentially breakdown is slower, and you are more likely to attract unwelcome pests such as rodents and carnivores. Also you always want "a good balance" (your leaves will help here) - eg. it might be okay to put a few potato chips in, but lots will end up salting your compost (obviously a BAD idea!) – winwaed Nov 6 '11 at 21:24
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It will "work" -- after all, the city compost takes meat. It's just that they're willing to put up with pests and stink. And they monitor and manage the compost so it "cooks" properly.

I will tell you from experience that, unless you are putting it in a bin that is pest-proof, a foot or two of manure and leaves will not keep them out. I've buried kitchen compost (no meat/fat, just veg) 2-3 feet deep in horse manure only to find the next morning that a skunk dug it out. If you are composting meat and fat, I would bet that the smell of rotting meat will get through a few feet of manure and leaves.

As JoeHobbit says, an alternative is to pass the waste through another animal. In my case, we sometimes give the chickens meat scraps.

I've been tempted, like you, to put some of the "prohibited" items into my longer-term compost piles. I haven't yet because I don't want to encourage chicken-killers (e.g. skunks) to come around. Also, I'd have a constant feedstock of small amounts of meat/bones/fat to add to my compost, but I might not always have enough other material to balance the mix the way I'd want it.

Getting around to the answer, with the caveat that I'm not a meat-composter, so this is only the procedure that I would follow if I was going to try it:

  • Build it bigger: 4' high, 3' diameter at a minimum.
  • Don't bother with the bone meal. (I'm not sure what your purpose for it is.)
  • Know that you will attract rats and/or other pests.
  • If you add bones, the marrow and bits of meat attached may compost, but the bone itself will not break down in your lifetime. You'll need to sift them out of the finished compost.
  • If you want to try to deter pests, bury it under 4-5' of manure. This might help, but I wouldn't bet much on it.
  • The leaves will give a good carbon source; don't add too much at once or they'll mat down.
  • I wouldn't add branches, they'll just slow things down. (Unless they're chipped, and then small quantities would be ok.)
  • Don't add large quantities of cooking fat. (E.g. don't put the oil from your turkey fryer into the compost! Even the city doesn't want this.)

I'm not sure how you're going to manage the feedstock: putting small amounts of meat into the compost feedstock in a way that it breaks down reasonably and doesn't make a horrible smell.

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Fat and rotting meat are better suited to creating manure. Bones don't compost easily either. The fastest way to break down fat and rotten food is to have an animal digest it first. I take my leftover bacon lard and dribble 1-2 tbsp per day on my dog's food... he loves it! Depending how rotten the meat is, I may or may not give it to my dog as well (he doesn't like chicken). However cooked bones should merely be discarded since they take a long time to break down. Only raw bones are good for dogs--small bones like chicken bones are not good for dogs either.

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

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I've been composting bones, meat, fat for years. It breaks down great and I don't attract pests. I built a bin 3' high and 3' in diameter. I fill the bottom with newspaper, cardboard, then leaves- about 1/4 of the way up. THen I start putting in my food scraps, which include meat, dairy, eggs, bones, etc. I only put the food (that I have premixed with dry material like leaves and straw) in the center. And build up then the top quarter I top off with lots of leaves and compost from a previous batch. The whole thing looks like a pile of leaves and doesn't smell. The trick is the there is a super thick insulative later on the bottom and all sides. Additionally, I monitor the temperature and it reaches between 140 and 160 degrees Fahrenheit for 2+ weeks. After a couple months, I may turn it. After some more time passes, I sift it and there are a few bones and I just stick those in the next compost in the center.

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Apparently bones and other products derived from animals can be safely composted in a "hot" composter which generally means a bin that's approximately a cubic yard (3' on a side). I've rarely seen common commercially sold composters like what the @OP described (2'x3') successfully generate sufficient heat and typically take at least 3mths to compost generally by attracting insects rather than by heat... the size is required to insulate the chemical activity in the center, a smaller size just lets too much heat escape. Once a successful "hot" compost bin is running successfully, it's actually too hot to touch the center of the bin with your bare hand so is easily over 170 degrees F, required to kill salmonella and other bugs instantly. A successful "hot" composter will compost the entire cubic yard within 6 weeks (with turning). Of course, this would never be considered in a "cold" composter like a worm bin, despite worm's ability to consume bacteria, both good and bad.... There's no sense risking germs that might not have been consumed by your worms.

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