Office paper?

I was just reading a random blog (about my current obsession, walipinis) and they mentioned just in passing that they used waste office paper and cardboard to make biochar, "partially burned paper and cardboard waste" is actually what they said.  That caught my attention because I'm a teacher at a public institution and have three school-aged children---used paper is something we have. At my job, the pandemic hastened our move away from paper, but I still have plenty of it, especially exams, which are treated as sensitive material that need to be properly disposed of after the time period students have to contest the results has passed.  As for my children's notebooks, in 2020 we did some recycled paper making, but they produce more than we can use for that.
CAN WE MAKE SOIL AMENDMENTS FROM THIS WASTE?
We need soil amendments!
Sounds like a win-win if it's true.
Thanks in advance for any advice you wise ones can contribute.

A chunk of dead tree has structure - and that structure is full of tiny tubes that when alive, carry water etc, so fire has paths it can enter without loosing access to oxygen. Yes, the concept of biochar is to burn in a low oxygen environment, but low doesn't mean "no". Paper doesn't have that structure. What I just don't know is whether it's that shape of the wood - intact cells and structures - that's what make biochar so valuable for microorganisms in the garden?

"Professional biochar" is made at certain temperatures and the results are crushed to certain sizes to get the "best results". Many people make it at home and totally accept results that are "good enough". I certainly do! But the paper won't start with natural structure.

Hubby occasionally burns business paper in our wood stove. Using it as the only material, or too thick a "pad" results in incomplete combustion. An acquaintance years ago had a cottage that burned down (lightening strike). The only thing that didn't burn was their stash of newspapers that had been stuffed into a box for years - the outside was charred, but the center was still sheets and legible. The theory (being physicists) was that oxygen couldn't penetrate so the fire couldn't follow.

Hopefully some of our biochar experts will chime in. This may well represent a need for some experimentation. My land is heavy clay. I'm using biochar to lighten the soil as well as providing homes for microorganisms and as a way to sequester carbon to offset the little driving that I do. If there's a way to use waste paper to accomplish the soil lightening and the carbon sequestration, that alone is worth the time to find ways to make it work. My brain's thinking, roll 3 or more sheets into straw-shaped tubes and see what happens then? Unfortunately, that sounds time consuming - less for you if you download the task onto the students!

I think Jay is onto something here.  We hear about wood waste, of course, but also any agricultural waste.  Any organic waste.  You never hear about processed pulp waste.  You can see the pictures under microscope of the structure that Jay was talking about.  It's on a microscopic level, so crushing wood or other organic waste results in superior biochar, because it has so much more surface area.  I have read research where they explained that the total value of burned and crushed wood biochar is more than other organic waste, because it has more mass (and more structure?) in it.  You often hear about how the wood, etc.  needs to be put in there with spaces in it so it will burn well.  It makes sense that stacks of paper wouldn't burn.  I am also a teacher, so I would love it if it would work, but my guess is that it wouldn't.  Like Jay, I am a "home biochar maker" and I am not making it on a commercial level.  As she said, hopefully more credentialled people will chime in.

John S
PDX OR

I like Jay's explanation, and John helped me understand it better.

Here is an older thread that will help to explain it further:

https://permies.com/t/61925/Biochar-cardboard-paper

My take on this if I am understanding this is that paper and cardboard will not hurt the biochar.  To get the microorganisms we want to add to the soil, it is better to have wood waste be the main component.

The one other question to add to this discussion is "Does the paper contain things that will be harmful to the bio char long term?"  I know from other discussions that people are saying at least some paper contains things harmful to garden space such as chlorine residues from beaching, heavy metals and toxic chemicals from the inks, buffer and binder materials added to the paper etc to slow aging or produce smoother or more reflective paper.  I also know that other people question whether those exist and if they are a problem.  Cardboard adds questions about the glues used too.  So to add to that if they exist in a threatening form, are they a threat after being burnt to biochar?

Paper smells different when it burns, and the charred remains feel very different from wood biochar.

I wouldn't hesitate to burn paper, as long as it's not the chemically coated thermal stuff (like till receipts).

But I think I would spread the result on shelterbelt trees, not on my food growing areas.

Some newspapers only use soy based inks, intentionally, so as to not contribute to heavy metal pollution. My home paper (The Oregonian) does that.  I almost always use a bit of newspaper and brown cardboard to get it going, but it is not a very high percentage of the mass, either before burning or after.

JOhn S
PDX OR

Echoing prior comments, I am doubting that paper has the structure needed to make beneficial biochar. I would be tempted to either shred/compost clean paper or burn it in a hot fire for ash.