Biochar in wood stove

Hello permies.  I'm sure everyone's seen this before but me.  I watched this Edible Acres video a couple weeks ago and just tried this in the last couple days.  It works great and you get to keep the heat inside the house.  We used a stainless steel pot with a decent lid.  This time of year we only need dinky fires so having the char pot on one side of the stove and some small wood on the other side to keep everything burning works great.  We're getting about three batches a day and I've almost filled a 5 gallon bucket with char.  Now I just need to get better at crushing it up and I need to figure out how to turn it from char into biochar.  Time to research...

Hi Mike, Biochar is charcoal made in such a way as to make it most suitable for the soil.  That means making it at a proper temperature more than anything, which is between 400-500 degrees Celsius (the temperature where the char is just starting to glow during the pyrolysis process).  This gives the best balance of properties to the char you'll want for the soil.  At that point it is Biochar, but it's just not ready for soil incorporation....i.e. not charged up with nutrients and "redecorated" by soil microorganisms.  To do that send your Biochar through your compost pile.  I put 2" in the bottom of my compost bucket every time I empty it to help keep the bucket from getting stinky.  Then every time I empty the bucket I'm incorporating Biochar into the pile.  The compost pile will get hotter and compost better, and the Biochar will absorb nutrients that would otherwise leach out or vaporize off.  Also use Biochar as part of a sheet mulch or in the bedding for animals.  Good going on making your own Biochar!!!

Thanks Greg, that's a good way to incorporate it evenly over time.  I'm pounding it with a 2x4 in a 5 gallon bucket.  It ends up anywhere from dust size to 1" cube.  Should I be mashing it until the big pieces are smaller than that?  

The main thing you need to do, besides crushing it as you mentioned Mike, is inoculating.  You can do that, as Greg suggested, but there are other ways.  

A bucket full of char can be inoculated by urinating in it, or by mixing up some compost tea or manure tea or nettle tea, or comfrey tea, and putting it in the bucket.  You can inoculate it in any number of ways... but that is the essential step that you need to do after crushing and before applying it to the soil.  

Get some nutrients and get it into the crazy honeycomb matrix of the char.  The biology will get caught up in all the small corners of the crevices of the char structure, and as a result will be teaming with microbial life.  Once it is added to the soil, the multifaceted colonies have a habitat/refuge, from which to grow and expand into the rest of the soil.  The char serves as a matrix for small water catchments, which also boost microbial life, and when these overflow, it spills microbes out!  The char also serves as an aggregate like sand, but with all the above mentioned benefits.      

Yup, I knew I needed to charge it to turn the "char" into "biochar".  I was assuming that I'd use direct contact between the char and the compost pile or some kind of compost tea to inoculate it.  I hadn't thought of pee.  I know that would give it plenty of Nitrogen but would it give the char any biology?

Char is a great way to neutralize the smell of urine, and the urine's nitrogen combines well with the carbon dust in the microscopic corners of the char to create pretty much instant compost... so there's that. That compost will attract microbes like crazy.    Probably not much biology directly in the urine (though I don't know this for certain), but the high nitrogen in that urine batch will be very useful as an additive to the soil, and plants will go for it with their feeder hair roots.  

You could, for instance have a manure batch, a urine batch, a nettle tea batch, a comfrey batch, a horsetail batch, a yarrow batch, and an actively aerated compost tea batch, and you might mix them so that you get this huge variety of biochar aggregates when you put out your biochar, instead of just one type, like say just manure tea.  

The char is a matrix for water, nutrients, and microbes, and air.  Eventually you will likely see (under a scanning electron microscope), much of the chambers within the structure of the char, filled with mostly microbial colonies and fungal networks, regardless of what was originally used to inoculate it.  

I think some are making it far more complicated than it is. Anything charred that you throw into your compost pile is Bio-Char. The inoculation happens inside the compost pile. And that is all there is to it.

Straw or wood or any organic matter can be burned/charred and composted and it qualifies as bio-char. Straw or grasses that are sealed in a container and heated to charring are some of the absolute best bio-chars you can get. They easily powder, and disperse wider than anything else. Wood doesn't have to be charred in a kiln, there is no voodoo or mystery magic. Dowse a brush pile after it burns and settles to coals and you have the best wood char you can get. Once the wood burns to coals, all the gasses are out of the wood and it is just charcoal, if you took a lump and smothered it by removing oxygen, then you would have a piece of charcoal just as good as any other wood based char, ready to be composted.

It doesn't matter if you pull it from your wood stove, BBQ/Smoker, outdoor fire pit, burnt brush pile, or nearby recent forest fire. If it is charcoal, it has tiny nooks and crannies for all the good microbes to live in and flourish. Grind or pound it somewhat small, compost it, and apply compost anywhere you normally compost. There is nothing more to it. It has the ability to make your compost better.

And just to dispel a myth I see from time to time, it doesn't last a hundred years. Anyone that thinks it does needs to go walk in a forest a few years after a fire, they would be hard pressed to find any char in the soil because it all decomposed.

Copy off nature, she is always the smartest kid in the class. And she has been making bio-char for a lot longer than anyone else.

Paul Busey wrote: It has the ability to make your compost better.

I hope this is true.  I really want this to be true.  I have spent many hours making retorts and charcoal in case it is true.  But I haven't seen evidence yet that it is true.

Paul Busey wrote: And just to dispel a myth I see from time to time, it doesn't last a hundred years. Anyone that thinks it does needs to go walk in a forest a few years after a fire, they would be hard pressed to find any char in the soil because it all decomposed.

It may be a myth that it lasts a hundred years in soil.  Rather than decomposing though, it seems it actually moves to the ocean.  Where does the charcoal go?

Mike Jay wrote:Now I just need to get better at crushing it up and I need to figure out how to turn it from char into biochar.  Time to research...

I put it in empty chicken food bags and run over it with the truck in the driveway.  Works great.

Now that's an idea.  I ended up making a hand crank grinder but driving over it sounds easier.  As long as the bag doesn't blow open

It may be a myth that it lasts a hundred years in soil.  Rather than decomposing though, it seems it actually moves to the ocean.  Where does the charcoal go?

 i read that link and meditated upon it.  Thoughts that came forth were in relation to Terra Preta, which has demonstrated the longevity potential of biochar.  Which made me think that all charcoal does not become bio-char, as it is not necessarily infused with biology, and thus can not form the intimate bonds with the soil community which creates the longevity.  The next thoughts related to how the char ended up being in the water cycle.  Certainly if it is ground small enough that it can be dissolved into a water solution then anything can be lost to the oceans.  The only way for the char to end up in the water cycle is through erosion, be it wind blowing it, or landscape not containing it from being washed away, or soil microbes (bing attached to it) keeping it from being leached downwards into the water table.  I consider then permaculture, where we try to make systems which build permanent diverse biological soil structure and volume, while eliminating or vastly decreasing erosion via earthworks, windbreaks, and other plantings, and I do indeed see the potential to have biochar be a very long lasting part of the soil ecology.

Mike Jay wrote:Now that's an idea.  I ended up making a hand crank grinder but driving over it sounds easier.  As long as the bag doesn't blow open

I have done quite a few batches that way now.  I fill a chicken food bag about halfway or a little more.  Then I take another bag and put it opening down over the first bag, trapping the charcoal between the two bags.  Then I just lay it in the driveway and leave it there for a few trips over it.  It will kick some dust out the opening between the two bags but not very much and it crushes the charcoal really well.

Interesting, so you don't even tie the bags shut?  It makes sense that double opposite bagging it would do the trick but I was just assuming the last bag would need to be tied somehow.  That's cool and I can see how you can fit much more into the bag if you don't have to cinch together the end to secure it.  Thanks Todd!

Mike Jay wrote:Interesting, so you don't even tie the bags shut?  It makes sense that double opposite bagging it would do the trick but I was just assuming the last bag would need to be tied somehow.  That's cool and I can see how you can fit much more into the bag if you don't have to cinch together the end to secure it.  Thanks Todd!

Exactly Mike, I don't tie them.  Give it a try and see what you think.  Another thing that surprised me was that even in my gravel driveway, the bags last quite a while before showing any signs of wear or holes.

Paul Busey wrote: And just to dispel a myth I see from time to time, it doesn't last a hundred years. Anyone that thinks it does needs to go walk in a forest a few years after a fire, they would be hard pressed to find any char in the soil because it all decomposed.

No myth, it's estimated that 13.7% of global soil carbon is Biochar.  It builds up in the soil over centuries of fires and is actually as much as 60% of soil carbon in some of the globe's richest soils.  It does break down in size over the years, which is why it's hard to tell that it's there and is also why I don't bother with crushing mine up...it will break apart by itself and the chunky size is helpful for keeping a compost pile aerated.  Lines up pretty well with terra preta, which has been carbon dated from 500 to 1000's of years.

If you're interested please check this out:  "Pyrogenic Carbon in Soils: A Literature-Based Inventory and a Global Estimation of Its Content in Soil Organic Carbon and Stocks", Moritz Reisser, Ross S. Purves, Michael W. I. Schmidt and Samuel Abiven*, Department of Geography, University of Zurich, Zurich, Switzerland, Front. Earth Sci., 31 August 2016 | https://doi.org/10.3389/feart.2016.00080

I make a lot of my char the same way. But I use two #10 cans, which I get for free in unlimited supply from my local grocery. I crimp the rim on one of them so it fits inside the other, making a tight enough seal for oxygen not to get in, but enough gaps for gases to escape and undergo secondary combustion as in Mike's video.