Good, current article on Biochar

I found this article on biochar to be pretty fascinating.  It explains why including charcoal with composting material from the beginning of the compost process works better, interesting facts about making raised beds from biochar/compost, and some really cool comparison photos between crops grown in compost and crops grown in compost with biochar.  I hope people find it as interesting as I did.

A perspective on terra preta and biochar

That was interesting, thanks for posting it!  I'm glad I'm making char right now and it'll go in my chicken greenhouse compost bin before I add more leaves.

Is there an optimal size for the chunks?  I've been stomping on the bag to break them down a bit.

The most current stuff I have read said one quarter inch or smaller. I don't worry about it much. Some of mine ends up an inch or more. I just figure the freeze cycles will take care of it. In my potting soil, I shift out the bigger chunks, but in my gardens I don't worry about it.

Was wondering the same thing Mike. Read through most of this post:  Advice-Crushing-Biochar Seems like the consensus (as a lot of things in life) is personal preference. A mixed blend of various sizes seems to also make sense - everything will find its own niche - some bacteria may like a hotel while others like a modest small home. However, I do like the grinding it up with a stick blender part - a good piece of advice because I'm getting tired of all that dust too!

Thanks for posting that article, Trace.  It's useful to me to see newer and more established scientific perspectives on biochar.
John S
PDX OR

I am a huge fan of biochar!

For way to much information on Bio Char, click this link.  biochar

I was particularly interested in the claim that adding biochar to the beginning of the compost cycle decreased the off-gassing of some of the compounds that we don't want in the atmosphere due to its "greenhouse" effects. Currently, my access to biochar doesn't coincide with my compost building, so I'm tending to add it when I've got it, rather than being more organized. I may have to re-think that approach and make more of an effort to stock-pile it.

If people are working with and crushing charcoal, do be careful with protecting your lungs. Of course, that's true of any dusty situation. As my husband likes to quote, "the dose makes the poison".

Good point Jay.  I have always tried to keep enough moisture in the biochar so that it doesn't become the air that I breathe.  Since I am inoculating it with a mixture of worm castings, compost, urine, and rotten fruit, that's usually pretty easy.
John S
PDX OR

I love that page Harry Soloman!  I'm going to read it more in depth but I'm going to go play baseball now.
John S
PDX OR

I've managed to get myself confused. I think I understand that when first made out of wood heated with limited oxygen, you get charcoal and that it only becomes "biochar" after it's had a healthy population of micro-organisms move in. Is this right?

If it is, when people talk of adding "biochar" to a beginning compost heap, what they're really doing is adding a whole pile of workers with housing. Is this right?

Thus if I don't have "biochar" but only the chunks of charcoal left from incomplete combustion, will this still help my compost heap? Will it turn into biochar as the horse-shit/fall leaves/goose bedding/dead chicken etc all gradually decompose in my barely managed compost heap? I genuinely believe that even though I don't make "professional compost" by any stretch of the imagination, my heaps don't generally get stinky, which to me is a sign that they're doing what plant matter, animal matter and shit has done for millenniums.

Jay, I think you have it right.  It's just fully cooked charcoal until it is populated with microbes.  I am pretty sure that article intended to say that adding the charcoal to the compost feedstock when you build the compost pile is the best way to turn it into biochar.

Jay, there are two camps in the nomenclature conversation. One group says that biomass which is pyrolised at sufficient temperatures to drive off volatile fractions and form aromatic C structures, for any series of cascading uses but with the ultimate destination being the soil (and to a lesser extent water or building materials), is biochar by definition. The other team says that it is just charcoal until you charge or potentiate it with microbial life by some method such as co-composting, infusion with effluent, etc.

I'm in the first camp but I try not to get too zealous about it. My main motivation is public perception and marketing, along with the fact that I am getting it out into settings where the raw, uncharged material will be filtering out excess nutrient contamination from water, or used in litter for calf rearing and poultry sheds, but its final destination will normally be arable and pastoral soils.

Yes, Jay.
Charcoal that you buy in a store is burned with low oxygen but intentionally leaves wood in there so that you can burn it easily, say, in a barbeque.

Biochar has a different purpose, as Phil explained.  It is optimally made so that all of the burnable wood is transformed. You don't make it to create a new fire later.  You want all of the burnable stuff completed, and you want the volatile oils and other products out so that it is just crunchy carbon.  Then it will make amazing numbers of surfaces when crunched.  If there's still wood, it won't crunch properly.  Then it is inoculated with nutritious stuff, so that it doesn't suck all the nutrients out of the soil that you put it into at first. Then it will make great hotels for microbes to move into and out of.  
John S
PDX OR

John Suavecito wrote:

You want all of the burnable stuff completed, and you want the volatile oils and other products out so that it is just crunchy carbon.

OK, that is part of my issue. At this time I have no way to make dedicated "pre-biochar". I'm stuck harvesting out of our wood stove any bones or charcoal that hasn't turned into ashes. Some of it is probably the crunchy carbon I'm looking for, but some of it is probably still has some wood +/- some volatile oils.

That said, I tend to have heavy clay soil and it tends to rain all winter and be a drought in the summer. Even if some of what I'm adding to my compost and eventually my soil is "charcoal" rather than "biochar," it's still sequestering some carbon and lightening my soil, so unless some of you feel it is doing harm, I will carry on.

Thanks for all the input from all of you!

Yes, I live in PNW too with lots of acidic drizzle and poor draining clay.  Biochar is great for us.  When to stop burning it is key.  

This is a really important point.  I made a biochar stove based on this video:



However, they didn't explain when to douse the fire so that only pre=biochar would remain, and it wouldn't keep going until it made ashes. You will always have a little bit of ash and that's good for our acidic soils to make them a bit more alkaline.  But you want max crunchy pre=biochar and minimum ash.   I think the best rule of thumb is when the flames have died down to when they are barely above the burned wood, douse it. In a 55 gallon drum, it's usually about an hour/ 1 1/2 hours.  When I do this, I keep getting light, metallic sounding crunchy pre=biochar 99% free of wood. The tiny bits of wood I just save for the next session of biochar.  Tiny bits of ash.

The main other thing to improve on that video is just to draw a circle on the top of the barrel for the chimney, and use that as the basis for angle grinding the hole up into the chimney.

John S
PDX OR

Thank you John for that excellent video. They do briefly suggest that when drops of water are thrown at the lower part of the barrel, if they turn instantly to steam then it's ready for dousing, but how accurately that will happen, I'd have to try it to see.

A question for you all on raw materials. A friend has a huge number of veggie-oil contaminated cardboard boxes that he can't recycle by the normal means. We are trying to compost some of them. I'm wondering about biocharing them? Would that work? Are there reasons not to? I know some people are worried about some of the chemicals that may be in cardboard. It's been shown that microorganisms are really good at sequestering nasty chemicals (and some good ones in a positive way like carbon and nitrogen), so I'm wondering if the benefits would outweigh the potential negatives.

Yes, they said to throw a few drops of water.  Not helpful.  It will dry up whether it's time to stop or not.  I tried that many ways and then gave up, because it didn't give me any useful information.

I wouldn't worry about the cardboard.  I'd use it.

John S
PDX OR