[Terrapreta] FW: Charcoal in soil

[Nikolaus Foidl]

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From: Nikolaus Foidl <nfoidl at desa.com.bo>
Date: Wed, 09 Jan 2008 16:28:52 -0400
To: "terrapreta-request at bioenergylists.org"
<terrapreta-request at bioenergylists.org>
Conversation: Charcoal in soil
Subject: Charcoal in soil

Dear All!

Looking on the trials done so far with Charcoal in soil and terra preta, the
most common plant used was corn so far.

I do trials with charcoal since one year and I have as well soils at hand
where huge amounts of forests after clearing where piled up in long rows and
burned down, leaving behind ashes, charcoal and torrefied wood and all the
condensates from the burning.( as well a good amount of soil burned together
with the wood because the soil was on the roots and part of the logs and
branches where covered by soil when they pushed the chained down trees to a
row with caterpillars.

In the first 2 years only certain grasses ( brachiaria) would grow on those
stripes. After some 3 years the planted corn and soy and sunflower show
pronounced growth in the beginning but after about 60 to 70 days all plants
in the field reach the same height and have the same state of development.

Looking at the harvest data there is no significant difference between
charcoal and non charcoal in fertile well fertilized land not suffering
drought. 
If there is drought during the development of the plants then the charcoal
plot is more sensible and shows earlier drought damage in the plants.

If you make a mass balance over the amount of forest cut down and dragged
with a caterpillar from a stripe of 50 meter each side to a small long heap
of about 15meter width then you accumulate some 5 times the volume of the
intact forest in the stripe of 15 meter or you concentrate the amount of 5
ha forest in one ha area and burn it . If we suppose a average dry mass
yield of total biomass per ha ( including roots) of some 200 to 250 tons
this would be some 1000 to 1250 tons of dry biomass burning in this ha.

>From sampling I can estimate that there are some 150 to 180 tons of
partially or fully charred material per ha in the burning zone. So this
leaves us with a huge amount of ashes in the same area. As most of the
material are trees with an average diameter of 15 to 20 cm ( some are more
then 60 cm, but most are smaller brush like trees) we have a good amount of
barks with quite a high ash content. Wood without bark is in the range of
0.3 to 0.8 % ash and barks are in average around 7 to 8 % ash, some more.

We urgently need to make mineral mass balances about the ashes and we need
to know as well in which chemical form those ashes are in the soil and to
what chemical form they convert. From the first look it seems to me that
potassium and calcium and then magnesium and phosphor would be the mayor
constituents.( someone has figured out the plant availability of those ashes
?)

Now imagine that the indios additional used these burn and char areas as
waste disposal and most of there waste where ashes from cooking fire and
rests from there meals like fish heads and spines or bones or non edible
parts of the animals beefing there diet ( as well needed a mass balance over
at least a period of several tens of years to get a grip on quantities and
content of minerals) then you easy can imagine that the terra preta sites
are an enormous accumulation of minerals in different chemical forms. The
adding of biologic material enhances whatever biology is working there and
for sure will enhance growth of whatever plant you grow there.

Now the charcoal does not play an important active role in the beginning but
degradation over the centuries transforms the charcoal into more stable
chemics like humic acid and fulvic acid etc. which have high interchange
capacity and high chelating capacity.

Maize reacts very strongly to high amounts of potassium ( the mayor
ingredient of ashes)as well does soy and sunflower. Brachiaria as well is
addict to high potassium. Other grasses do have problems with high potassium
and do not grow in the first years in those burned areas.( dont think that
this is a coincidence)

Conclusion is that we may be get distracted by fast visible effects on corn
and other potassium and only relate those effects with charcoal but not with
ashes and other micro minerals accumulated in waste disposal sites.

I believe in several enhancing effects of charcoal like vigor enhancing from
the liquids produced during charring but I think there is very low direct
short time effect from charcoal itself on growth of plants ( first 10 to 50
years). There is without doubt a indirect sink and source effect by its
capacity to adsorb micro and macro nutrients.

Best regards Nikolaus




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