It all started with a visit to a local meat cutter to pick up lamb. They had my lamb meat wrapped and ready to go. They also had a big barrel full of bones left over from the carcasses they had been butchering. They were dumping them somewhere and I had a feeling that a big opportunity was being missed. Last year I bought bags of fish bonemeal to compensate for what a soil test had determined was a lack of phosphorus in my vineyard. You could really see the plants perk up in places where I spread it. If you look on almost any bag of fertilizer, you will see an NPK rating. My bags of fish bonemeal said 5-16-0. This equates to 5 parts nitrogen, 16 parts phosphorous and no potassium. It was a good source of phosphorus because the phosphorus was already an organic molecule having been part of a fish. Plants take up minerals that are a product of biology more easily than they do straight chemical elements.
Bells went off in my head – (or maybe it was just tinnitus ringing in my ears). Here was something valuable for the soil, sourced locally, and free. There had to be a way to convert it to bone meal. So, I immediately contacted an expert, Google. Sure enough, there were lots of videos showing machines that could grind big bones to bits in minutes if not seconds. They were expensive. There were also ads for bonemeal. It was not too expensive at around $2 per pound. I blew right past those. I didn’t want to support some confined animal feeding operation and slaughter house.
There were also several youtube videos on how to make your own bonemeal. It didn’t look too hard. First, they suggested boiling the bones to loosen up the meat and fat so it could be removed from the bones. Then you needed to clean the meat off the bones, next dry the bones and finally grind them into bonemeal. But what about the expensive machines? They might be worth it if you could make enough bonemeal in a kind of light industrial operation to sell to your neighbors and use for yourself.
Still, I was not up for an expensive experiment. Then it struck me. I have a shredder. If that 10 horse Tecumseh motor on the Troy Bilt shredder could crunch canes pruned from the vineyard. Maybe it could break bones to bits. I dug into the bottom of the freezer and found several bags of bones that had been there for years. Getting them out was a good thing no matter what happened next. After they were mostly defrosted, I took one out to the shredder, started it up and threw in the bone. Voila! Bone bits. Well actually, bone bits and the grate inside the shredder had definitely been slimmed. Yuck! Boiling off the fat etc. was very necessary.
So back to boiling. I got out a 10 gallon stainless steel pot and set it up on a propane burner that could have been used to heat enough oil to fry a whole turkey. In went the bones and a bunch of water. Soon they were boiling away. This is where things got out of hand. After a few hours of boiling, checking once in a while, I went inside to listen to Wait, Wait, Don’t Tell Me on NPR. When I went outside again, there was a new smell in the air. Yikes! I ran to put more water in the pot. The damage was pretty-much done. What had been a merrily boiling batch of bones was now a gooey brown mess. The water was too hot to clean bones. I shut it down.
The next day I came back to do burnt bone triage: a box for bones, another for fat and gristle, and some old milk jugs to hold the left-over liquid. The fat and meat did come off the bones but not as easily as I had hoped. The 5 hour cooking time in the video was only for a pressure cooker. 12 hours was recommended for open pot boiling. Burning the batch was not recommended anywhere. Still, I had the boiled bones and a lot of other left overs. Maybe in the back of my mind I was thinking bokashi. Bokashi is a Japanese term for “fermented organic matter”. What sets it apart from normal composting is that it can make fertilizer out of meat scraps. Also, it is done in a sealed container so there is no smell. The final step after 4 to 6 weeks of fermenting is to add the liquid back to a regular compost pile. Later for that. One disaster at a time.
While cleaning the bones I realized that there was not much bone to the batch. Many bones packaged from the butcher still have a lot of good meat and possibly useable fat on them. The bones that I had seen in the barrel were big bare bones. The ones from the freezer were small pieces with plenty of meat, fat and gristle still on them. Thinking about it that night, I realized that my thinking was wrong and backwards.
I should have valued the process more than the dry bonemeal goal. I could have boiled the bones in good water for a full 12 hours. It might have been possible to then pour off the water and seal it in jars for bone broth. We use bone broth all the time for soups, sauces and even just to cook rice in. After the batch was cool, there would be fat on top. That could be handy too. The bones were probably the least valuable part.
The shredder did break them into tiny bits. But bits are not bonemeal. They needed to be dried in a dehydrator for 24 hours. After that you might be able to make bonemeal out of them in a food processor or even grind them up in a steel plate four mill. I’m sure stone wheels would clog up quickly. At that point they might best be blended with other compost. There are too many stories out there of gardens fertilized with bonemeal only to be dug up by dogs, skunks or rats.
On the broader scale of dust to dust, putting the remains of animals back into the ground might be best accomplished by other animals. Chickens and pigs will eat almost anything. There is also a lot more to recycle than bones. The skin, guts and hooves of butchered animals have uses too, even if they do end up underground eventually. So, my boneheaded bonemeal test was mostly a bust. $2/pound is starting to sound pretty reasonable.