Bone Char in Alkaline soils— and the best way to make it.

I have a soil with a pH of 7. It is very deficient in phosphorus. I can't lower the pH effectively in this soil, except by adding organic matter.

Will bone char phosphorus be available in this sort of soil?

Will the char raise the pH? (And what about wood char? I want to use it for darkening my soil and retaining water, but what about the pH issues?)

What is the best way to make small quantities of bone char? Out door burning is not very practical here, due to fire danger and possibly annoyed neighbors. (I am assuming that bone char smells bad.)

I have heard of putting stuff in a metal container in a wood-fired cookstove to create charcoal. What kind of container would be best? I'm sure it needs some holes in it, but how many? Would it work in any kind of wood stove? And might the metal off-gas or flake undesirable compounds into the charcoal?

I am sorry that I am asking an awful lot of questions, but it is so hard to get climate and soil specific advice from a permacultural standpoint.

Phosphorus is a finicky element to work with; if the pH is below 6, it gets fixed by iron and aluminum, if it gets above 7.3, it gets fixed by calcium. However, plants and their beneficial fungi can be persistent and un-fix the phosphorus, perhaps with some acidic or basic root exudates and enzymes, depending on what is needed. It's unlikely that phosphorus is completely absent from soil, all sorts of critters dropping dead and decomposing provide a fairly constant source from above. The big question is the availability, and that's where things like bone char can help tremendously. A piece of burnt bone, once colonized by mycorrhizal fungi, can be an oasis of phosphorous in an otherwise phosphorus-fixed landscape.

Can you barbecue? Get yourself a tin like the one Christmas cookies come in and poke some holes in it. This is for the flammable gases that the organic material will give off when it is heated to BBQ temperature. Pack it with your chicken bones, rib bones, ham bones, T-bones along with some twigs and other pieces of wood. Make sure the lid is on snug, put it in with the wood and charcoal and get the BBQ going. Open a beer. As you watch the fire, and wait for it to get to the point where you can throw some meat on the grill, you will notice flames shooting out of the holes in the cookie tin. This is good. You are getting pyrolysis of the organic material inside the tin and the wood is turning to biochar and the bones are turning into bone char.

Don't just throw a couple of hot dogs on the grill, this biochar burn is going to take some time. Put some chicken on the BBQ, that will take a good half hour to cook. Better yet, how about a tri-tip? That can take an hour or more to get just right. Yum, can't beat a Santa Maria Barbecue!



OK, so after dinner is over and the barbecue has gone out and cooled down, you can retrieve your cookie tin from the ashes in the BBQ grill and get your bone/bio char. You should have about 1/4 of the volume of the original starting solids.

Gilbert, did you make the bone char? was it problematic for neighbors? Thanks

Hello Joshua,

No, I did not. I had done a cheap hardware store test, which indicated low phosphorus. However, when I did an expensive university test, I found that there was too much phosphorus!

However, if I was going to do it John's way sound pretty good. John always has wonderful ideas!

Since the gases coming from the bones are being burned up, I would guess this would only effect neighbors as much as a standard BBQ.

Dry, clean bones will not give off any offensive odors when being turned into bone char. The act of making char out of fresh bones won't really stink but would smell some because they would most likely have some flesh still attached. The fire you put the tin on will take care of all of those odors before they are detected or deemed offensive. Bone meal is simply clean, dried bones that have been pulverized in a hammer mill. Fish meal is composed of the "nasty" parts of cleaned fish, all bones (including the head), fins and guts. These are thoroughly dried, then ground in a hammer mill until they are a fine powder, to go by a plant that makes fish meal will make anyone not want to take that road again. The big plants do use gas fired dryers but they still stink like fifty collected star fish taken home but forgotten in the trunk.

seems like you could soak your bones in vinegar (boil them in vinegar?) instead of charring to get the phosphorous out of them, according to other thread on this.

Gilbert Fritz wrote:Hello Joshua,

No, I did not. I had done a cheap hardware store test, which indicated low phosphorus. However, when I did an expensive university test, I found that there was too much phosphorus!

However, if I was going to do it John's way sound pretty good. John always has wonderful ideas!

Since the gases coming from the bones are being burned up, I would guess this would only effect neighbors as much as a standard BBQ.

Posting this again from other lead-sequestration thread:

THE RESULTS ARE IN--and here are the nominations for lowest lead levels....

I got plant tissue results back for sunchokes (leaves) and collards (leaves)

I chose these because

collards: I want to eat them, and they are a worst-case scenario as they are brassicas; maybe not the most accumulating brassicas, but the ones I like best to eat.
results: lead 0.00 ppm. (at most that could possibly be 4.9 parts per billion, within the range I think FDA has for lead of 1,000 parts per billion in foods).
!!! woohoo!

sunchokes (Jerusalem artichoke): for biomass, and to get a read on the soil's current lead-supplying propensity
results: 2.20 ppm.
Now, that's not good for eating, 2,209 pp billion ostensibly. BUT people are always saying "just add biomass" and this quantifies that. Imagine I had soil that had 2ppm of lead, then I wouldn't even be blabbing on this thread here. I'd be completely carefree about lead. So, if I put my sunchoke leaves back in as compost I'm golden. the biomass is good enough for soil by far. And so whatever other lead is in there is either a) not bioavailable b) not interesting to plants because they have enough of other better material to work with or c) some other how not an issue, even to a lead accumulator like a sunchoke.
I don't know how their roots are doing for lead, but a) I figure I'd eat them only in an emergency, for a short time-period, if I need to and b) the lab doesn't accept root samples, only leaf, so Idk what i'd do. But I can use the home lead-test kit I suppose to find out if there are egregious concentrations of lead in it.

What was also fascinating:
sunchokes were really lacking in molybdenum, almost got none!
and low in nitrogen, despite having compost put down and a couple of nitrogen fixers (legumes) planted in there
while the collards (this is all in the same tiny tiny front yard area, about 6' x 25' between the house and the sidewalk) had sufficient molybdenum--in healthy range--and decent nitrogen.

Both had elevated zinc and calcium.

Joshua Myrvaagnes wrote:Great questions, Dan!

Raises more questions, if you're willing. If you write an ebook on this, I'd buy it, it's definitely important info and something that's held LOTS of people back, I am pretty sure, from gardening or getting started in permaculture, even if they weren't fully conscious of it, just that thought in the back of the mind "but what about lead paint?" Any barriers that can be removed, it's good.

So, here's my situation. I have what Umass lab tells me is 454 ppm "_soluble_" lead, and they say that that indicates over 2,000 ppm of total lead. I am in an urban, urban, suburban area (Somerville has the highest population density of any city, I've heard(?)). The City of Cambridge next door puts out a flier that says "if you have a house older than 1985, get your lead levels tested or garden in raised beds, don't grow in soil above I think it was 400 ppm" --something I was definitely way over the limit for. The lead ironically is HIGHER farther away from the house in the back yard than in the front bed. Someone MAY have had an apple tree there years ago and MAY have had hte bright idea, "let's spray lead-arsenic pesticide on this sucker. What could possibly go wrong?" even though they KNEW back then that lead was poisonous, this didn't just get discovered in the 80s when kids had been eating paint chips and pencils for decades. Mmmmm, that sweet sweet taste of lead. I don't have any proof of this, but I am not near a major highway or even that big a road, there's a whole mini-park between my back yard and the small road. The road in front is a dead end and narrow narrow, so hardly anyone ever drives on it. I know, I'm spoiled silly, right? I have the quietest place to live in Somerville.

SO:

--do I pay attention to what the lab says is "soluble"? does "soluble" mean anything? does it have any correlation to bioavailability? does their estimate of total lead mean anything?
--what chelating agent would you say to apply in my case? is calcium phosphate chelating or just "binding"? is compost an acceptable one? can "apply" mean just put it on top (of my mulch) and let it gradually work in over the course of a year? how much compost per "ppm" or per mole of lead--ballpark high figure?
--will the lead test tell me how much is now bioavailable? do I need to just do a plant tissue sample? if I use a home lead-test kit with a leaf will that give me an accurate enough test that you'd trust it?
--if I test a leaf of, say a sunflower and of a raspberry plant and a comfrey, will that give me a sense of the range of what's getting into a leaf?
--what's a genuinely safe level of lead in a plant tissue for human consumption, in your opinion?


One more clue--there was a weird bumpy area of land my landlord (who's blind, but probably correct) says was pushed over from the neighbors and dumped on her yard when there wa sconstrustion years ago. That part tested separately (I spent a good deal of money on lead tests) had LOWER lead than the back yard--450 instead of 700.

And yes, I followed the instructions for the lead test, 12" deep samples, mixed around, dried them out, kept them separate and not in a lead or kryptonite container.


Thanks so much!!! really, I'm blown away by the freakin USEFULNESS of this website! I am pinching myself in wonder.

John Elliott wrote:

dan long wrote:

Hi Gilbert,
Making bone char has been part of our family routine during the winter heating season. Our household will start a wood fire in the Jotul wood stove in the evening that is nice and hot, and if we have bones (cooked and dried after making bone stock, for example) we will add these in the last stages of the fire or to the hot coals. This is more than sufficient to burn the remaining fat and protein matrix out of the bone and result in an easily crumbled product the next day. The bone still keeps its normal shape in the stove so that it is easily separated from the ash or biochar. There is not much need for a separate container in the stove. The bone will literally crumble to powder with minimal force. We prefer to add this bone char to the compost piles to further the process.

The theory behind this approach is that the bone char provides a rich source of phosphorous as some form of hydroxyapatite that still requires mycorrhizal support to make it available to plants and will not result in the inhibition of the plant-fungal association that occurs in high levels of free phosphate. Theory aside, there has been remarkable improvement in production from our base soil that is a sand and silt mix that is poor source of minable phosphate. We can easily process much of rib bones from a moose or caribou over the course of the winter.
The picture shows a pile of the accumulated bone char before it is crushed to powder.
Christine

Editing to add:

first year, soil test: 600+ppm; planted sunflowers (Russian Mammoth) every 2 feet, some died so replaced with sunchokes. sunflowers (sunchokes are close relative) are used for lead or arsenic or other heavy metal remediation--they accumulate lead from the soil. We cut the sunchokes down and uprooted the sunflowers and put them in the landfill (sadly).

second year--practice garden, planted some collards and a few other veggies and fruits. Sunchokes grew back (and were fruitful and multiplied).

was going to do another soil test BUT with the discussion of binding lead in an inert form--lead apatite, lead+calcium phosphate--and "just add compost, it'll be fine"--I thought well the lead number in the soil means nothing. What's the lead level in the plant tissue itself, the part that we actually care about because we're going to eat? So I tested the brassica (they're lead accumulators) that we want to eat, and the sunchokes (we'd like to eat the root but the lab would only test leaf, and this was useful since it lets me know if they should be thrown in the landfill or can be useful biomass--compost. Biomass by a long shot!)

the test results are attached at the bottom of the post here.

Joshua Myrvaagnes wrote:Posting this again from other lead-sequestration thread:

THE RESULTS ARE IN--and here are the nominations for lowest lead levels....

I got plant tissue results back for sunchokes (leaves) and collards (leaves)

I chose these because

collards: I want to eat them, and they are a worst-case scenario as they are brassicas; maybe not the most accumulating brassicas, but the ones I like best to eat.
results: lead 0.00 ppm. (at most that could possibly be 4.9 parts per billion, within the range I think FDA has for lead of 1,000 parts per billion in foods).
!!! woohoo!

sunchokes (Jerusalem artichoke): for biomass, and to get a read on the soil's current lead-supplying propensity
results: 2.20 ppm.
Now, that's not good for eating, 2,209 pp billion ostensibly. BUT people are always saying "just add biomass" and this quantifies that. Imagine I had soil that had 2ppm of lead, then I wouldn't even be blabbing on this thread here. I'd be completely carefree about lead. So, if I put my sunchoke leaves back in as compost I'm golden. the biomass is good enough for soil by far. And so whatever other lead is in there is either a) not bioavailable b) not interesting to plants because they have enough of other better material to work with or c) some other how not an issue, even to a lead accumulator like a sunchoke.
I don't know how their roots are doing for lead, but a) I figure I'd eat them only in an emergency, for a short time-period, if I need to and b) the lab doesn't accept root samples, only leaf, so Idk what i'd do. But I can use the home lead-test kit I suppose to find out if there are egregious concentrations of lead in it.

What was also fascinating:
sunchokes were really lacking in molybdenum, almost got none!
and low in nitrogen, despite having compost put down and a couple of nitrogen fixers (legumes) planted in there
while the collards (this is all in the same tiny tiny front yard area, about 6' x 25' between the house and the sidewalk) had sufficient molybdenum--in healthy range--and decent nitrogen.

Both had elevated zinc and calcium.

Joshua Myrvaagnes wrote:Great questions, Dan!

Raises more questions, if you're willing. If you write an ebook on this, I'd buy it, it's definitely important info and something that's held LOTS of people back, I am pretty sure, from gardening or getting started in permaculture, even if they weren't fully conscious of it, just that thought in the back of the mind "but what about lead paint?" Any barriers that can be removed, it's good.

So, here's my situation. I have what Umass lab tells me is 454 ppm "_soluble_" lead, and they say that that indicates over 2,000 ppm of total lead. I am in an urban, urban, suburban area (Somerville has the highest population density of any city, I've heard(?)). The City of Cambridge next door puts out a flier that says "if you have a house older than 1985, get your lead levels tested or garden in raised beds, don't grow in soil above I think it was 400 ppm" --something I was definitely way over the limit for. The lead ironically is HIGHER farther away from the house in the back yard than in the front bed. Someone MAY have had an apple tree there years ago and MAY have had hte bright idea, "let's spray lead-arsenic pesticide on this sucker. What could possibly go wrong?" even though they KNEW back then that lead was poisonous, this didn't just get discovered in the 80s when kids had been eating paint chips and pencils for decades. Mmmmm, that sweet sweet taste of lead. I don't have any proof of this, but I am not near a major highway or even that big a road, there's a whole mini-park between my back yard and the small road. The road in front is a dead end and narrow narrow, so hardly anyone ever drives on it. I know, I'm spoiled silly, right? I have the quietest place to live in Somerville.

SO:

--do I pay attention to what the lab says is "soluble"? does "soluble" mean anything? does it have any correlation to bioavailability? does their estimate of total lead mean anything?
--what chelating agent would you say to apply in my case? is calcium phosphate chelating or just "binding"? is compost an acceptable one? can "apply" mean just put it on top (of my mulch) and let it gradually work in over the course of a year? how much compost per "ppm" or per mole of lead--ballpark high figure?
--will the lead test tell me how much is now bioavailable? do I need to just do a plant tissue sample? if I use a home lead-test kit with a leaf will that give me an accurate enough test that you'd trust it?
--if I test a leaf of, say a sunflower and of a raspberry plant and a comfrey, will that give me a sense of the range of what's getting into a leaf?
--what's a genuinely safe level of lead in a plant tissue for human consumption, in your opinion?


One more clue--there was a weird bumpy area of land my landlord (who's blind, but probably correct) says was pushed over from the neighbors and dumped on her yard when there wa sconstrustion years ago. That part tested separately (I spent a good deal of money on lead tests) had LOWER lead than the back yard--450 instead of 700.

And yes, I followed the instructions for the lead test, 12" deep samples, mixed around, dried them out, kept them separate and not in a lead or kryptonite container.


Thanks so much!!! really, I'm blown away by the freakin USEFULNESS of this website! I am pinching myself in wonder.

John Elliott wrote:

dan long wrote:

I've never had any odor issues at anytime and I've made over 200 lbs. of bone char.
Bone char is not biochar, it is bones roasted enough to crumble, not crack when ground.

** added to clarify: Bones need to be clean, that means removal of all things not bone, this is done by soaking in a bleaching solution which will break the disulfide bonds (sulfur is the stink atom in bones) this can be as simple as using a commercial bleach soak.
Once the bones are cleaned in this manner, there may be a small amount of disulfide bonds that remain, but the act of slowly raising the temperature of the bone structure will break these remaining bonds so any odor would be almost insignificant.

Even when you are going to make "biochar" you have to first make the char then you have to introduce it to a microbiome, biochar is biologically active char.
I mostly use marrow bones and hog bones too, which if cleaned properly so there isn't any thing but bone, have never given off any odor, even in the Laboratory.

If the bones haven't been cleaned properly, then yes there will be odor from the non bone parts that were left on and the breaking of the disulfide bonds contained in the bone matrix.
*** comment removed

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