How to crush, grind, pulverise charcoal

[erich]

The 16'x16' tarps (heavy gauge) did not even puncture.
2 opposite edges I rolled up with 2 - 2x4s, with 2 more 2x4s screwed across on top, then purse strung the other two edges.

Didn't spill a drop

Erich

[lemit]

Are we going to use a granular fertilizer spreader, a manure spreader, or some other way of applying the char? I am concerned about dust, both for nuisance and health reasons and for the efficacy of the application.

Thanks.

--lemit

[Freerangefarmer]

Personally, I was thinking about mixing the biochar with fresh horse manure and the wood shavings used for bedding (the shavings are typically saturated with urine) and composting for maybe 60 days, and then spreading with an old manure spreader. Then incorporating with either a disk or plow and/or a subsoiler.

I would expect that this mixture would be moist enough that dust would not be a problem.

FRF

[maikeru]

Originally Posted by Flapjack

Please remember your plastic still gets warm replacing items

Haha, true.

I'm thinking of shredding and processing feedstock beforehand--this is probably more the way to go.

[maikeru]

Originally Posted by Freerangefarmer

Excuse me if this has been mentioned, but what about spreading it on a concrete slab and driving back and forth over it with a car tire, then just sweeping it up?

I think some people actually did this...some of the older threads might have info or firsthand experience. When I made my first batch, I jumped on it and used a wet burlap sack to contain the dust. (Not recommended, unless you like a sore back!)

Does anyone know, by chance, how well biochar seems to fragment on its own through natural processes, like worms, plant roots, etc.?

[mathuranatha]

I left about a cubic meter of homemade biochar in a pile for about 3 years .Grass,roots and weeds etc grew through it .When I shoveled it up it was definitely finer than when i made it .Another 2 thousand years and it should be fine as the terrapretta and I can sell it to the local landscape supply

[maikeru]

Interesting. If one deposits the biochar as chips, can we expect enough fragmentation to make it into something like sand within a few to several years? Looking at my first batch, it seems like it's gotten finer over the last 3 years, but I'm not sure exactly. The resulting mix was of char of all sizes, from about thumb-sized pieces to fine dust.

[Essay]

Originally Posted by maikeru

Interesting. If one deposits the biochar as chips, can we expect enough fragmentation to make it into something like sand within a few to several years? Looking at my first batch, it seems like it's gotten finer over the last 3 years, but I'm not sure exactly. The resulting mix was of char of all sizes, from about thumb-sized pieces to fine dust.

That is what the book suggests:
Under "Particle fragmentation" they have listed:
Freeze-Thaw cycles, Rain and wind, Penetration by plant roots and fungal hyphae, and Bioturbation.
"Earthworms ingested these particles (>2mm) (but did not digest them) and redistributed them in the [soil] profile (concentrated at 0.8m depth) by excretion...." -Lehmann, 2009

By exposing new (functionally active) surfaces when they break apart, larger chunks contribute to an ongoing small "priming" effect that some fresh biochars can overexpress. It'd probably be better to say that fresh surfaces, on occasionally fragmenting char, contributes to biochar's enhancement of the pedosphere's resilience and microbial diversity.

p.s. ...but there's a whole 'nother chapter on "Biochar Application to Soil."