Introduction: Animal Bones As Fuel and Fertilizer

The main goal for me in this project was to produce a fertilizer from animal bones I collecting from the food waste. But bacause in order to do so I had to burn the bones I decided to cover the usage of the bones as a fuel here as well. The method I'm showing here is not the only one available for producing fertilizer from animal bones at home, without any complex procedures or operations. I'll mention some of the alternatives a bit later, but there's one particular method I want to try by myself, so I'll cover it then in details in different instructable.


While ash, gipsum and other substances were used by people to enrich the soil for ages without even knowing the chemistry behind it, animal bones were overlooked in this role for a long time. Nevertheless they contain a lot of phosphorus, nitrogen and other mineral substances (up to 60%) that are essential for the plants, and are not present in soil in big quantities naturally.

Nowadays you can buy industrially produced bome meal (or bone flour as we call it) which is used as fertilizer or food additive for animals. But what to do with bones that we produce at our homes dayly as food waste. It is nearly imposible to mill bones into fine flour acessible for plant consumption without special heavy duty mills*. And you can't just thow it into regular compost bin because it'll take years for the bones to decompose, especially for the larger ones. So what can you do? Here's some options:

- You can dispose small bird or fishbones by digging them under the bushes or trees in your garden. They can be crushed into smaller pieces with a hammer if needed. A. Bekarevich (А. Бекаревич), the reader of journal "Make It Youself" (or "Do It Yourself") in his letter to the editorial staff (Сделай Сам (Огонек) 1998-03, страница 19) says that in order to do so he bores 5-6cm in diametre and 15-20cm deep shafts in the ground near at the plant. Then he partially fills them with crushed bones and fills the rest wit manure or compost. The bones disposed in this way decompose in one month (as he claims)

- Larger bones in big quantities can be turned into fertilizing mass in a couple of ways described in the book of P. N. Shtainberg (П.Н.Штейнберга «Обиходная рецептура садовода»(М.—Л.: Госиздат РСФСР, 1926 г.)).

a) Dig a hole in the ground. Fill it with 12-15cm layers of wood ashes, crushed bones and a mixture of wood shavings, manure and kitchen waste. Keep layering up to the top and cover then with soil. Make holes in the coverage, pour in diluted manure and plug openings with straw. After 10-15 days uncover the pit, mix everithing with a shovel, add more diluted manure and cover with soil. Repeet the procedure after 2-3 months without adding the manure. It's needed to produce the oxigen to the mixture for better decomposition of bones. It takes a half of a year to transform the mixture into fertilizer mass. Other components that are used here along with bones are adding its own organig matter to the substance.

b) You'll need some neutral (wooden or plastic) vessel. Fill it with 10cm layers of wood ashes and boiled and crushed bones. (I'm not sure about adding water, there's nothing said about it). The bottom and the upper layers are should be ashes. Leave it for a half of year, and crush then bones into powder, which is much easier to do now.

There is also a similar way to process bones using ashes and lime, developed by prof. I.V. Engelgardt (И.В. Энгельгардт) in 19'th century, but I'll cover it in other instructable.

- The other way to turn bones into ferilizer is to burn them and then crush into powder. And this is what I'm going to show you here. I'll talk about the qualities of the fertilizer produced this way at the end.

* Although there was an industrial method of boiling bones under high pressure (later with special additives) in order to apply transformations that make them easily crushable. I know almost nothing abou how it was done and how it can be replicated at home conditions.


It may seem a bit weird at first glance. We all know, bones consist mostly from calcium, and calcium doesn't burn. But ~10% of the bone matter is fat and this is what acts as a fuel. There's a lot of archeological evidences that animal bones were used in ancient times as a fuel by humans, especially at tundra regions, where not much of trees are growing. Here's an example.

In order to make bones burn, some twigs, dry grass or other materials were used to make initial fire, that than heats bones to the point when melted fat starts to drip out and act as a fuel.

Obviously nobody talks here about using animal bones solely for heating your home or something like this. But it may be usefull to know in survival situation that you can have some alternative or additional source of fuel. And also it won't harm to know that you can thow bones into the stove or your camping fire to dispose the waste in convenient way.

Step 1:

As everything've been said to introduce you to the concept, now let's get to work. First of all we need to collect bones and preserve them till the point where we'll have enough to process. On the photo you can see the amount of bones (I forget to weight them) the family of 3 people produce during the Winter season (and a little bit of Autumn). The best way to keep them during warm seasons is a freezer. At Winter you can keep them otside. Some people recomend to clean and wash the bones throughly to prevent rotting, and store them without freezing. It's may be an option too (although I havent try it), but I think it requires removing cartilages as well, which is definitly an additional work, and a loss in richness of produced fertilizer because cartilages contain most of nitrogen.

The first and only preparation we need to make with our bones before burning them is to let them unfreeze in some warm place.

Step 2:

Now make a fire and let it burn for a while. What I'm aiming here for is to create nice layer of glowing coals while some pieces are still burning.

Step 3:

Place suitable grates ontop of coal bedding and start putting the bones. Eventually they'll heat up enough and melted fat start to drip onto coals feeding the fire. For this reason you don't really need a lot of wood or other fuel to burn the bones. At some point the fat will be able to provide fire just by itself, and as you can see on the photos it can burn quiet vigorously. Bones are even getting red-hot in the core of the pile.

The smoke can be a little bit of a problem, although, I believe the part of it is actually a steam from the frost on some bones that haven't defrost. And it smells not that bad as one can imagine, but I recomend not to were your everyday clothing because it'll stink atleast for a cople of days.

At some point it may look a bit gruesome, but try to think of it as of partial cremation and say a couple of nice words if you want to.

Step 4:

When the bones are all burned leave them to cool for a few hours. At this point you can crush them even with your fingers.

Step 5:

Collect bones and mill them into powder in any preferable way. I putted them into bag and hammered then with a hammer. After that I sieved them and repeated the procedure with remaining large pieces.

Step 6:

And this is our fertilizer now. As I said, it consists for the most part of phosphorus (I'm bad at both: Chemistry and English, so I'm not attempting to translate more detailed composition). And as far as I aware the general rule says that phosphorous fertilizers are have to be applyed at Spring time. The same say recomendations for bone fertilizers like this. I don't know precise quantities to be used, so I can't recomend anything. I just spreading everything I have evenly all over the place, and I think it's hard to overdo with quantities the food waste bones provide. But if you have some information on this, let me know. Also burned bone meal loses all the organic substances, so other methods are superior in this.

The bone meal produced this way acts slowly in the soil releasing elements for the plants to be consumed in a period of 3-4 years. This is why it's recomended to use it for trees (Fruit trees particulary).

So this is it for this project, thank you for your attention and have a nice bones.