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Differentiating between biochar and charcoal...

 
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Biochar is light, has lots of holes, is beneficial for the soil, etc.  Charcoal is more solid, heavier, still contains resins and stuff, etc.

I've seen text and videos where the authors or speakers seem to use the two words interchangeably, jumping back and forth in the same discussion.  Why?

So, does charcoal have any benefit for the soil?  Or only when it moves on to become biochar?

 
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Kola Redhawk has a very clearcut definition. He says that biochar is biomass that has been pyrolysed and then inoculated (charged, potentiated, etc.) with microbial life. This is a good working definition. However, as I have been out promoting this stuff over the past couple of years and sometime want to apply it in contexts where inoculation is not appropriate, I tend to make a broader characterisation: Biomass that has been pyrolysed and whose intended end use will be in soil, water, or some durable application, and with any number of cascading uses along the way.

The following quote is useful from the research point of view. From A. Schmalenberger, A. Fox, "Bacterial Mobilization of Nutrients From Biochar-Amended Soils" in Advances in Applied Microbiology, 2016:

The term biochar is relatively new and found its entry in peer-reviewed research papers in 2000 (Karaosmanoğlu, Işigigür-Ergüdenler, & Sever, 2000) and subsequently replaced terms like charcoal when the product was aimed to be added to soils for benefits that include carbon sequestration and plant growth. This resulted in a more widely accepted description of biochar by the International Biochar Initiative (Joseph, Peacocke, Lehmann, & Munroe, 2009).

 
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Further adding to the confusion is also coal. Coal is comprised of 90% carbon so it is basically biochar that has not been inoculated yet.

A guy on another site wanted to experiment with ground up coal as a medium for growing hydroponic food, and used coal as his "soil". He immediately ran into trouble, his tomato plants grew so fast, and so tall, that it started to push up the small greenhouse he had built around them!! He showed pictures, and it was incredible.

I know coal has a poor reputation, but it is 90% carbon, and could be converted to biochar very easily. In that case it is just nature using pressure and time to make the conversion. A person could buy a ton of rice coal, and then charge it with manure tea, and have biochar very quickly and easily.
 
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Sue Monroe wrote:Biochar is light, has lots of holes, is beneficial for the soil, etc.  Charcoal is more solid, heavier, still contains resins and stuff, etc.

I've seen text and videos where the authors or speakers seem to use the two words interchangeably, jumping back and forth in the same discussion.  Why?

So, does charcoal have any benefit for the soil?  Or only when it moves on to become biochar?



There's two kinds of charcoal you can buy for cooking. One is called lump charcoal and is the same thing as freshly made biochar. The other is charcoal briquettes and has chemicals in it, all the same size and shape because they're pressed.
 
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If we look at the likely origin of biochar in the Amazon basin, there was lots of cooking going on, with wood as the fuel. Sometimes a small fire and sometimes communal things where food would be wrapped and have coals from the fire raked over it.

Then there was pottery making, which was not like our modern kilns today. Piles of wood burning around items to be fired. The simplest way to put something like that out, is to rake the soil over it. It's going to result in some leftover charred wood.

But it probably all started with repeated slash and burn agriculture. Land is usually only farmed a few years and then let grow up in pioneer species, before it is slashed and burned again. Each time, the amount of char in the soil would increase.

Some biochar may have been intentionally made, but I'm sure that plenty of haphazard dumping of the waste from fires, were a major contributor. So there would be no quality control.
 
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I agree with Dr Redhawk. After charcoal is inoculated, it becomes biochar.
 
Sue Monroe
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"After charcoal is inoculated, it becomes biochar."

But biochar is more airy, and charcoal is more dense.  Biochar I can break with my fingers, but charcoal is harder and more dense, without that brittle 'ring' to it.

Is biochar just any burned wood?
 
Phil Stevens
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The biochar I make has nut shells, corn cobs, sunflower stalks, floor sweepings (lots of cat hair), pine cones, and all manner of other things thrown in with the wood. It's all biomass to start with and to me it's all biochar when it comes out.

A lot of commercial charcoal is made at much lower temperatures in order to leave some of the volatile hydrocarbons in the mix so that it lights more easily. This makes for a denser product and is pretty poor quality for most of the uses we care about.
 
Trace Oswald
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Sue Monroe wrote:"After charcoal is inoculated, it becomes biochar."

But biochar is more airy, and charcoal is more dense.  Biochar I can break with my fingers, but charcoal is harder and more dense, without that brittle 'ring' to it.

Is biochar just any burned wood?



I'm not sure where you got the idea that charcoal is dense? Maybe your referring to charcoal briquettes that you buy at the store?  Because those aren't really charcoal, they are charcoal mixed with a lot of crap that makes them start burning easily and whatever else.  The charcoal I make that will be biochar is exactly as you describe. Its very light, and sounds like glass breaking when you stir it.
 
Sue Monroe
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Trace, No, I'm talking about the consistency of my results.  I am burning fairly small amounts of wood, I'm going through it piece by piece afterward, and breaking up the actual biochar with my fingers, and setting the hard, solid black stuff aside. I call the hard stuff charcoal.  I think it needs reburning to advance it to actual biochar, IMO.  So, is it ALL really biochar, just because it's black all the way through?

People keep jumping from the word 'biochar' to the word 'charcoal' like both are the same.  Is it really?  It seems that if you're talking about biochar, stick to the word 'biochar'.

I am under the impression that biochar is the light, holey, black stuff that all the residue has burned off, that crushes easily.  I thought the charcoal is the harder, more solid black stuff that takes more effort to crush, and it still contains the volatile residue.

Am I misunderstanding that ALL of it is really biochar as long as it's black???
 
Trace Oswald
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Sue Monroe wrote:Trace, No, I'm talking about the consistency of my results.  I am burning fairly small amounts of wood, I'm going through it piece by piece afterward, and breaking up the actual biochar with my fingers, and setting the hard, solid black stuff aside. I call the hard stuff charcoal.  I think it needs reburning to advance it to actual biochar, IMO.  So, is it ALL really biochar, just because it's black all the way through?

People keep jumping from the word 'biochar' to the word 'charcoal' like both are the same.  Is it really?  It seems that if you're talking about biochar, stick to the word 'biochar'.

I am under the impression that biochar is the light, holey, black stuff that all the residue has burned off, that crushes easily.  I thought the charcoal is the harder, more solid black stuff that takes more effort to crush, and it still contains the volatile residue.

Am I misunderstanding that ALL of it is really biochar as long as it's black???



No, it isn't all biochar.  None of it is  The stuff that is light, makes that glass-breaking noise, is charcoal.  That other stuff is just wood that is only partially charred.  It isn't "done yet".  And you're right that it needs to be run through again to be done, but then it will be charcoal.  That isn't to say it wouldn't still be good for soil.  I'm sure terra preta has plenty of partially burned wood in it.

For more information about charcoal, and the definition, you may want to look at sites about blacksmithing.  Blacksmiths use charcoal, and that is where I initially learned about making charcoal, long before I ever heard of permaculture, biochar, or the like.  Or you can ask Webster:  charcoal noun
char·​coal | \ ˈchär-ˌkōl  \
Definition of charcoal (Entry 1 of 2)
1: a dark or black porous carbon prepared from vegetable or animal substances (as from wood by charring in a kiln from which air is excluded)

I have heard people use Phil's definition, that biochar is any biological material that has been run through a retort, or burned in a low oxygen environment, but that doesn't make sense to me.  Charcoal has to be made from a carbon based biological material.  It isn't like you can make charcoal out of plastic, polyester, rubber, styrofoam,...  

 
Phil Stevens
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Charcoal has to be made from a carbon based biological material.  It isn't like you can make charcoal out of plastic, polyester, rubber, styrofoam...



Trace, I don't want to be pedantic, but where did the carbon in the manufactured items come from? If you trace back the "supply chain" far enough, just about every carbon atom you survey will have been part of a living organism at some stage.

FWIW, I occasionally throw small amounts of polypropylene (old baling twine and similar) onto hot burns in the kontiki. The result is small blobs of char with lots of holes. I took advice from an expert: The biochar researchers at Massey University did a study on pyrolysis of tomato "waste" from greenhouses as a growing medium and since it was just not feasible to separate the twine from the stems they heaved it all into a retort. As long as we stay away from chlorinated plastics and have a good process, small amounts of plastic are not a deal breaker. I'd far rather have the known quantity of stable carbon than the microplastics in my soil to contend with.
 
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Sue Monroe wrote:"After charcoal is inoculated, it becomes biochar."

But biochar is more airy, and charcoal is more dense.  Biochar I can break with my fingers, but charcoal is harder and more dense, without that brittle 'ring' to it.

Is biochar just any burned wood?



Pyrolized wood has no impurities left, they have all burned away so only the carbon matrix is left. That means cooking charcoal is not the right stuff, it's almost there but not quite.

The char we want for this purpose will sound like fine china breaking when it is fractured.
 
Trace Oswald
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Phil Stevens wrote:

Charcoal has to be made from a carbon based biological material.  It isn't like you can make charcoal out of plastic, polyester, rubber, styrofoam...



Trace, I don't want to be pedantic, but where did the carbon in the manufactured items come from? If you trace back the "supply chain" far enough, just about every carbon atom you survey will have been part of a living organism at some stage.

FWIW, I occasionally throw small amounts of polypropylene (old baling twine and similar) onto hot burns in the kontiki. The result is small blobs of char with lots of holes. I took advice from an expert: The biochar researchers at Massey University did a study on pyrolysis of tomato "waste" from greenhouses as a growing medium and since it was just not feasible to separate the twine from the stems they heaved it all into a retort. As long as we stay away from chlorinated plastics and have a good process, small amounts of plastic are not a deal breaker. I'd far rather have the known quantity of stable carbon than the microplastics in my soil to contend with.



Phil, I guess I don't really understand your point. Because the Massey Uni. was willing to accept some amount of contaminant to save time separating the twine, doesn't make it charcoal in my mind.  By your definition, I could fill my retort with Styrofoam and burn it, and I would end up with charcoal. By my definition, I would not.
 
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Here’s how I’ve come to think of the terms:

Charcoal: umbrella term that covers everything from a Kingsford briquette to the black stuff in the terra preta.

Char: pyrolized biomass that is both intended and appropriate for use as a soil amendment but has not yet been inoculated.

Biochar: char that has been inoculated and is either ready to go into the soi or already in use.
 
Phil Stevens
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Trace, all I'm saying is that at the end of the process I've got something which is chemically indistinguishable and physically in the ballpark (I'm aware that it doesn't have the internal microstructure of biochar made from plant residues...but people also make biochar from manure, rubber and sewage sludge). If all the volatiles are driven off and what is left is the carbon matrix, I'm not too concerned about what you call it. Quacks like a duck, basically.

The bigger picture goal for me is being able to reduce the amount of plastic that is trying to get into my soil. I'm gradually replacing all the old bale twine around the place with jute and in doing so I want to take responsibility for the waste. Putting into biochar that I'm producing at ultra-small fractions of a percent by volume ticks that box for me, and I still call it biochar.

Article about the hydroponic tomato biochar study

Marta's take on it was not letting the perfect be the enemy of the good. I apply that a lot these days.
 
John Pollard
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From Wikipedia, the free encyclopedia

Biochar is charcoal used as a soil amendment. Biochar is a stable solid, rich in carbon, and can endure in soil for thousands of years.[1] Like most charcoal, biochar is made from biomass via pyrolysis.

~~~~~~~~]

Regarding the definition from the production part, biochar is defined by the International Biochar Initiative as "The solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment".[7]

~~~~~~~~]

Application rates of 2.5–20 tonnes per hectare (1.0–8.1 t/acre) appear to be required to produce significant improvements in plant yields.




1-8 tons of feather light stuff per acre?

Approx a pickup truck full for 1/10 of an acre.

Doesn't seem worth making it purposely unless it can be done as a by product of some other process where it's not using any extra energy.

I saw a youtube video where a guy was using an ammo box, gasket removed and lid closed but NOT latched. The fumes that escaped were being burned and you could see that through the glass door of the stove. He was already running the wood stove for heat and was probably getting a few more BTUs from the ammo box gasses and he ended up with nice light charcoal(soon to be biochar). Any gasses from the pyrolizing of the wood were being burned and heating the house. Win win

If making it in a retort, you're usually making a bunch of heat for no other purpose but making the charcoal and you have to burn a bunch of wood to convert the other wood into char. Seems wasteful.
 
Trace Oswald
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John Pollard wrote:

From Wikipedia, the free encyclopedia

Biochar is charcoal used as a soil amendment. Biochar is a stable solid, rich in carbon, and can endure in soil for thousands of years.[1] Like most charcoal, biochar is made from biomass via pyrolysis.

~~~~~~~~]

Regarding the definition from the production part, biochar is defined by the International Biochar Initiative as "The solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment".[7]

~~~~~~~~]

Application rates of 2.5–20 tonnes per hectare (1.0–8.1 t/acre) appear to be required to produce significant improvements in plant yields.




1-8 tons of feather light stuff per acre?

Approx a pickup truck full for 1/10 of an acre.

Doesn't seem worth making it purposely unless it can be done as a by product of some other process where it's not using any extra energy.

If making it in a retort, you're usually making a bunch of heat for no other purpose but making the charcoal and you have to burn a bunch of wood to convert the other wood into char. Seems wasteful.




"Regarding the definition from the production part, biochar is defined by the International Biochar Initiative as "The solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment".[7]"

They can define it any way they like, but Webster and people like blacksmiths that were using it long before anyone every used the term biochar, use that definition for charcoal.  I don't see any reason to rewrite the historical definition because people want to use a new catch-term.

As far as it being wasteful, I see it differently.  I'm using dead wood that is lying around my property, or scrap wood from building projects, to create something that will benefit soil life and the planet for thousands of years, as opposed to letting it lie there and rot.  Nothing wrong with rotting wood, it benefits the earth as well, but not for nearly the same period of time.  I have plenty of wood for both purposes.  It also uses very little of my time to do.  I fill the retort and the burn area, light it, and go do something else.  The next day, I remove charcoal, crush it, and mix it into my compost pile.  So far, I'm very happy with the results of using biochar, so I'm going to continue to do so.

 
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 where does tbis video fall in the scope of biochar? Does anyone here know? Have any thoughts, or feedback? It would be appreciated.
 
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My concern with plastics in with the biomass is the temperature of pyrolysis. I get that chlorinated plastics are being avoided, at least theoretically, but generally speaking, the pyrolysis temperature needs to exceed 450 C in order to avoid dioxin formation. I think that I would need very specific infrastructure to be comfortable with pyrolysing plastics at all, let alone into something I am putting in my soil. If the temperature is excessively high, no problem for me, but I think that might be a dedicated process, separate from my pyrolysis of wood into charcoal for biochar production.

Incidentally, that is how I use the terms. Briquettes don't count, and until it's pyrolysed into charcoal, partially pyrolysed wood is just that. Charcoal is what tinks nicely when broken or tapped, and what is inoculated with soil bacteria to become biochar.

-CK
 
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