[Terrapreta] On the practical side

[MFH]

See images: http://terrapreta.bioenergylists.org/henderson041908

 

Dear All,

 

For those on the list who haven't had the opportunity to experiment, here
are some photos of my first trials. Apologies to those who are well ahead of
this stage.

 

Photo 1 shows the very basic kiln, constructed of un-bonded second-hand
bricks and sized to take a 200 litre drum (55 gallon in he US). This
particular drum has a removable lid held in place with an over-centre clamp.

 

Photo 2 shows the drum in place and loaded with seasoned offcuts of local
hardwoods such as Ironbark (Euc piniculata), which is hard and dense. The
drum is raised off the brick floor the height of 2 bricks to allow firewood
to be placed under.  The base of the drum (on its side) is drilled with 8 x
8mm holes in a line evenly spaced. These permit the generated gases to exit
and burn.

 

3 shows the flames after the load has started to gassify. Depending in the
intensity of the external fire and the sizes, moisture content and density
of the timber load, the beginning of the gasification phase can take from 30
minutes upwards.

 

4 and 5 show the char output.

 

Photo 6 gives an idea of the vast amount of energy released. At this trial
the front of the kiln was also bricked up once the fire had started, to
further concentrate the heat. For pure spectacle this is best done at night,
preferably lubricated with copious cold beers. This is indeed hot and
thirsty work. What you can't hear is the whistling of the gas as it exits
the holes in the drum, and the roar of the fire. Obviously there is huge
opportunity to capture surplus gas and compress to store.

 

7 shows the first experimental vegetable bed prior to planting, approx 4m x
1.2m. The char was broken up before adding but this could have been done
much better. Around 10cm thickness was added to the bed. Also added was 5 cm
of compost and 1 kg of NPK fertiliser (13:13:15 + 2Mg). The bed was then
forked a number of times to a 20cm depth. For comparison purposes an
adjacent bed was prepared in the same manner including the compost and the
NPK, but no added char.

 

Corn, broad beans and basil were planted in both. Definitely germination was
better in the char bed and definitely initial growth was also more vigorous.
Unfortunately the wallabies broke the fence ending that trial, but the fence
has been reinforced and the beds planted again. This time I've added a third
bed the same as the first with the char, compost and NPK, but added 5 cm of
worm castings from my composting worm experimental pile. (I believe
composting worms have equivalent miracle capacity as does char).

 

The test site is just above the creek flats on land that was a dairy farm
for maybe 100 years before being abandoned some 20 years ago and allowed to
return to natural forest, mainly eucalypts. Around 5 acres have been
cleared. Soil texture is loamy, with recent tests indicating deficiencies
across the full range of nutrients. Annual rainfall is in the 1500mm range.
Being a fairly civilised part of the world we don't have any of that snow
stuff but winter daytime temps can plunge horrifically to 10 deg C (50F),
with occasional night time frosts. Terrifying. Right now we're at the
beginning of Autumn.

 

I'll update in a couple of weeks.

 

Max H

 

 

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