making charcoal and testing the results in clay

   i think i had started to write this up,
but i don't find the draft.  so...

  first of all some background.  the soil
i normally use for one garden is mostly
clay that i've been reconditioning over
the years by growing cosmos and then
burying the leftover dried stems and any
other remaining organic materials i can
find in a long trench.  from year to year
i keep moving the trench back and forth
digging it up and chopping the stems as i
shovel.  the stems don't fully rot for
several years.

  this past year after reading about terra
preta and biochar i thought i would try to
make some charcoal and then use it in areas
to see what the effect would be on seed
sprouting (and later growth as the season
advances) for several species of plants.

  first of all i used the worst part (the
area with the most clay) of the trench from
last season to dig down further into the
clay (about 3ft down total).  making a
space about 10ft long and 3-4ft across.  i
put all the super dry cosmo stems and other
easily burning stuff in the bottom and
stomped it down good before taking some
dried up shrubs and trimmed off all the
small leaves and stems and put that down
next with the trunks on top then stomped
all this down too.

  then to start building a canopy i put
some long branches across and other longer
pieces of wood and old pallet pieces that
we would normally just bury and let the
fungi/mushrooms work on.  on top of these
i put some cardboard and damp earth to
seal things up on top.  i left both ends
open a little so i could get a fire going.

  with the wind shifting constantly it
was a real PITA.  i walked miles around
that trench and the smoke kept shifting to
follow me.  with my lungs it wasn't the
best, but the smoke actually was mostly
steam coming out.

  as the ends burned and dried the covering
soil it tended to cave in and self limit
the amount of oxygen, but i also wanted to
make sure it was getting hot enough to char
as much of the materials as possible.
using such a primitive thing as a trench,
cardboard and dirt i wasn't going to get
perfect results.  i was curious to see
how well it would do anyways.  a more
controlled setup like a double burner made
of metal would probably give better results
but that is beyond my current skills to
build/operate.

  after several hours of steaming and
burning i finally buried the largest
chunks remaining and called it a day.
heavy rains that night and the next day
put the trench under water and i was
busy for a few days letting it dry out
a bit before curiousity and time became
available to do a little digging.  after
a few minutes i could tell there was a
lot of change in how the clay and
charcoal with plenty of water added was
sticking to the shovel.  actually, it
wasn't.  that was an immediate nice thing
when it comes to clay.  i normally spend
a fair amount of time just knocking or
scraping the stuff off the shovel.  this
made digging it all up much easier and
faster.

  i ended up with about 3cu feet of
charcoal and as i was digging it out
it mixed somewhat with the baked clay
and clay around it.  there was standing
water at the bottom of the trench so
that gives you an idea of how wet it
was, but i didn't have much of a
sticking mess problem at all.  for
that reason alone i would consider this
a good thing...  what it will do longer
term we shall see, and if i keep making
more and adding it that will also be
interesting to see what happens.

  with the charcoal/clay mix i made two
test areas a few feet long and a little
over a foot across separated by normal
soil of about the same size and another
part on the other side with some extra
sand in it.  then i ran four lines of
different seeds through the whole area
crossing the test patches, regular soil
and added sand soil.  after about a week
it appears to not have negatively impacted
seed germination for birdsfoot trefoil,
alfalfa, green beans or buckwheat.  i
expected some change because it was so
newly burned and it wasn't mellowed at all
by adding any compost or aged or anything
other than watered.

  further through the season i will keep
an eye on all of them and see how they do.

  i'm unsure what i will do in the future
as the burning took a lot of effort.  a
better means of doing it (covering with
metal instead of cardboard) and then sealing
it up with dirt would let me fire it, get
it going and then leave it alone so i wouldn't
have to spend so much time monitoring and
fiddling.  of course an oven with temperature
and oxygen controls would be much better but
that's unlikely to happen any time soon here.

  the carbon in the charcoal should stick
around for many years longer than the stems
and sticks otherwise would have so this is
a sure soil building tactic.  adding compost
and green stuff to it and then getting some
worms planted into it would certainly make
it even better.  the charcoal itself will
lighten the clay, i've already seen the
direct evidence in that from digging it out
of the trench.

  grinding it up some would probably help too
as there are enough larger pieces in there,
but i'll let that go for now and let them
break down as i spade and turn under materials
as i normally would when done with a plot. the
stripes of birdsfoot trefoil and alfalfa along
the edge will be left alone for a multiyear
observation.  other than weeded i have no
plans to turn or add materials to those
plantings other than what grows there itself.  
unfortunately i didn't have enough material to
set aside larger areas to use as controls and
test plots or to have more variables to test.
some other time perhaps.

  i thought for sure that the charcoal and clay
mix would be too harsh for worms but as i was
smoothing out the areas to get them ready for
seeding i did notice several worms in there
that seemed ok.  it being so wet and the clay
probably well buffered or neutralized any harsh
chemicals.  if it was dryer and there was dry
ash i wouldn't have expected to see worms that
is for sure.

  so it is possible to make charcoal in a low
tech way and to sprout seeds in it within a
few days.  nothing really earth shattering
in any of this, but interesting that the
effect on clay was immediate.  i could see
why an ancient rain forest dweller with clay
subsoil (as is common in rain forests) would
notice it and want to use it for a garden/soil
ammendment.


  songbird

 

Keep up the good work. Your efforts are very interesting.

You may want to invest in a metal trash can. Once the fire is going,
throw in the small stuff, and put the lid on the trash can.

Tropical rain forests have laterite soils, not clay. Water absorbs CO2
from the atmosphere, and becomes carbonic acid (H2CO3). The carbonic
acid, in turn, disolves metals in the soil, leaving a soil rich in iron
and aluminum. The soil is usually very porous and will not hold
nutrients (being a rain forest, water retention is not a concern).
The classic example is from a book called "The Ugly America". IIRC it
concerned a tractor salesman in the 1960s, who was spreading the word
about the "Green Revolution" in farming. He plowed a rice paddy as a
demonstration, somewhere in South East Asia. When he finished, the rice
paddy disappeared, because he had destroyed the lining of the paddy
(organic or clay, I don't know), and the water went down the laterite
like water down a drain.

Keep us up dated.
--
- Billy

Mad dog Republicans to the right. Democratic spider webs to the left. True
conservatives, and liberals not to be found anywhere in the phantasmagoria
of the American political landscape.

America is not broke. The country is awash in wealth and cash.
It's just that it's not in your hands. It has been transferred, in the
greatest heist in history, from the workers and consumers to the banks
and the portfolios of the uber-rich.
<http://www.politifact.com/wisconsin/statements/2011/mar/10/michael-moore
/michael-moore-says-400-americans-have-more-wealth-/>

 Billy wrote:
...

  it sure beats tv.  :)



  i suspect there is too much oxygen
and opening the lid would introduce more.
from what i can tell there has to be heat
and lack of oxygen.  if i filled the trash
can with stuff and then was able to get
another fire going in a larger trash
barrel like a 55 gallon drum and then
set the smaller metal trash can on top
of the fire in the drum that might do
it, or not, that would be one of the more
simple designs.

  the question would be about how much fuel
i would have to put underneath to bake the
contents of the trash can to charcoal.  and
i probably would need some sort of one-way
valve to let off the steam and gasses.

  this being a low tech and low budget
operation i only have access at present to
some flat sheet metal pieces that i can
use to lay over the top of a trench.
piling dirt around the edges to seal it
up and some wet dirt on top to keep the
metal cool so that it doesn't warp is
about the level of technology here.  i
almost scored some heating duct tubes from
my brother but he forgot i wanted them and
took them to the metal recycler.  oops.

  one other interesting aspect is that
by firing the stuff in a trench in the
ground any liquids given off that aren't
driven off as vapor are absorbed by the
soil under and around the trench.  i'm not
sure if there are much in the way of
nutrients in that liquid (i suspect most
of it would be water or alcohols, but my
reading so far isn't very detailed on the
volatile byproducts) but a steel contraption
would lose that.  it remains an item i'll
continue to look into as i get time and
rainy days.

  i don't have enough new dry materials to
do any more test burns until either this
fall or next spring.  the metal instead of
cardboard over the trench will likely be
the change i'll make to see if that makes it
much easier.  i'm not looking to scrounge
new organic materials either at this point.  
too much other stuff going on that needs work
or weeding.  a few interesting angles are
possible with some local enterprises yet it
will be a bit before i'll get a chance to
explore them.  :)



  thanks for the correction/information, i knew it
was very poor soil (not what you would expect from
such a rich canopy overhead) and was surprised to
find out that most of the nutrients are quickly
recycled or leached away.



  never heard of this one before.  huh.

  similar to the design of terraces and
how much a simple change like introducing
a different species of worms can destroy
the ability of the edge to effectively
hold water requiring a change from rice to
different crops.



  sure thing.  :)


  songbird

 

1491: New Revelations of the Americas Before Columbus by Charles C. Mann
<(Amazon.com product link shortened)
32059/ref=sr_1_1?s=books&ie=UTF8&qid96839060&sr=1-1>

p.344
GIFT   FROM   THE   PAST
Terra preta exists in two forms: terra preta itself, a black soil thick
with pottery, and terra mulata, a lighter dark brown soil with much less
pottery. A number of researchers believe that although Indians made
both, they deliberately created only the terra mulata. Terra preta was
the soil created directly around homes by charcoal kitchen fires and
organic refuse of various types.
---

Charcoal isn't particularly high tech to make. Locally, they used to dig
a cave (short tunnel) in the side of a hill. Fill the cave with wood.
Set the wood on fire, and then bury the mouth of the cave. The charcoal
would be removed a week later.

More in the vein of your approach would be the "Chuckwagon Hoedown Bbq".

  You need a backhoe to dig a hole big enough to accommodate
  several cords of wood. Use hardwoods, apple is good and fenceposts
  are acceptable, but do not use treated or creosoted wood. Once the
  wood has burned down to a bed of coals several feet deep, about four
  hours, prepare the beef: cut into large chunks of 15 pounds each,
  wrap in butcher paper and then in wet burlap bags; tie securely. Toss
  the packages directly onto the coals, quickly cover with a large
  sheet of tin, and cover the tin with dirt. The secret is to keep out
  oxygen so the coals do not burn quickly and burn the meat. The beef
  is left to cook- allow 12 hours for this.

  After the 12 hours are up uncover the bundles; they will not be
  charred. Unwrap, slice and serve with baked beans, fresh bread,
  salads, pickles and for dessert 60 assorted pies and 30 cakes.

Yield: 480 Servings

Not only do you get charcoal,  you also won't have to cook again for at
least 4 month ;O)


The Ugly American by Eugene Burdick and William J. Lederer (Jan 1, 1999)
<(Amazon.com product link shortened)
1_1?s=books&ie=UTF8&qid07818900&sr=1-1>
(Avalable at a library near you, until they are closed)


I didn't remember correctly, the book was published in 1958.


- Billy

Mad dog Republicans to the right. Democratic spider webs to the left. True
conservatives, and liberals not to be found anywhere in the phantasmagoria
of the American political landscape.

America is not broke. The country is awash in wealth and cash.
It's just that it's not in your hands. It has been transferred, in the
greatest heist in history, from the workers and consumers to the banks
and the portfolios of the uber-rich.
<http://www.politifact.com/wisconsin/statements/2011/mar/10/michael-moore
/michael-moore-says-400-americans-have-more-wealth-/>

   ok, some results appear already.

  all of the legumes are growing fine.
all rows of them are of the same height.

  the buckwheat shows a decline in height
of a few inches in the zones where there
is charcoal mixed in the soil.

  since i am not a chemist and cannot
test the soil itself directly i can only
guess that the difference is that the
charcoal is binding some of the nutrients
in the clay.

  as a testable hypothesis, eventually i
expect the height to even out for the
buckwheat and the rest would remain the
same (the legumes).

  too busy ATM to trim and post the
picture...  not even sure it turned out
until i import it from the camera to
the computer.  some day.


  songbird