[Terrapreta] Biochar Packing Strategies

[code suidae]

On 9/26/07, Robert Klein <arclein at yahoo.com> wrote:
> But I think that we can all agree that a stalk of
> biomass with a brick attached is a great start. As
> good as a box of Leggo.

Interesting idea. However, in all the harvested corn fields I've ever
seen the part of the stalk still attached to the roots is perhaps a
foot long and many are broken off near ground level. I suspect that in
order to get material suitable for this method you would have to
either harvest by hand or invent something gentler than a combine.

Thinking out loud:
After harvesting you'd have to collect the stalks and carry them to
the burn location. For a 1/5th acre plot that's on the order of 6000
plants to move. With a couple of pounds of dirt attached to each one a
worker would be limited to moving perhaps 2 or 3 dozen plants at a
time for around 200 trips. Assuming reasonably quick workers you're
looking at 1 day per acre for a 5 man crew (4 gathering, 1 stacking).

Presumably this would be one-time or very rare activity which could be
accomplished over many years. Each year you could set aside some
number of acres to be harvested by hand (or special machine) to allow
this sort of processing. It wouldn't even be necessary to wait until
after harvest, you could pull them, allow them to dry, then char the
whole plant.

> I see two strategies. One in which a windrow is build
> with one side forming an earthen wall. [...] A second
> windrow can then be build against the first
> windrow on the non walled side.
> The second strategy is to lay out a 12X12 square [...]

I wonder if it would be practical to do a dome? It seems like the sort
of thing you'd really have to be out in the field working on to see
how the stalks behave.

Rather than packing dirt over the top of anything it seems like it
would be much more efficient, in terms of labor cost, to have large
reusable covers. You'd stack up the stalks then drop a lightweight
nonflammable plate on top. You could perhaps adjust vents in the cover
to control the burn rate.

I'm picturing companies that hire seasonal labor to do the work and
that move from area to area contracting with land owners as they go. A
crew could be kept busy for most of the growing season.

> Observe that we have minimized the labor input
> throughout.

Well, I don't know about that, compared to any mechanized harvesting
it is a huge amount of labor, but amortized over the period when the
char is effective it is small.

> From the perspective of sequestering carbon, we want
> this done twenty to fifty times. From the perspective
> of building a viable soil base, several times should
> be more than ample.

I haven't the slightest idea how much char you could expect to get
from an acre of corn in a year. I'd suppose that you could do the same
acre at least twice and maybe three times a year (no need to wait for
mature ears, just give it 6 weeks or so to get big enough to provide
the most char per season).

But 50 times? Surely at some point there is a concentration of char at
which agricultural performance begins to drop off or some other
undesirable effect comes into play? Beyond that point you'd have to
leave the char in a pit or disturb the topsoil to incorporate it
deeply.

Dave K
-- 
"Our ignorance is not so vast as our failure to use what we know." -
M. King Hubbert