Subject: Re: [SANET-MG] Charcoal's dubious merits

From: Frank Teuton <[email-masked]>
Date: Wed, 4 May 2005 08:14:14 -0400

John, and others following this thread:

The potential importance of charcoal, or certain types of coal extracts, as
soil amendments, is highlighted by research into the Terra Preta phenomenon:

http://www.css.cornell.edu/faculty/lehmann/terra_preta/TerraPretahome.htm

" Amazonian dark earths have high carbon contents of up to 150 g C/kg soil
in comparison to the surrounding soils with 20-30 g C/kg soil (Sombroek,
1966; Smith, 1980; Kern and Kämpf, 1989; Sombroek et al., 1993; Woods and
McCann, 1999; Glaser et al., 2000). Additionally, the horizons which are
enriched in organic matter, are not only 10-20cm deep as in surrounding
soils, but may be as deep as 1-2m (average values probably around 40-50cm)!
Therefore, the total carbon stored in these soils can be one order of
magnitude higher than in adjacent soils.

" Furthermore, the organic matter in the dark earths is persistent since we
find these elevated carbon contents even hundreds of years after they were
abandoned. The reason for the high stability of the soil carbon is currently
under discussion. So-called black carbon was identified as a probable reason
for the high stability (Glaser et al., 2000). Further research is necessary
to quantify the recalcitrance of the soil carbon over long periods of time
and determining techniques for creating such soils. The structural
similarity to charcoal led the authors to assume that accumulation or
purposeful application of organic carbon from incomplete combustion may have
been the primary reason for the high carbon contents and fertility of these
soils (Glaser et al., 2001), a theory that had been proposed by Smith
(1980). If they were actually created by charcoal applications has still to
be demonstrated."

See also:

http://www.energybulletin.net/1337.html 

http://www.discussanything.com/forums/archive/index.php/t-68405.html 

http://www.bidstrup.com/carbon.htm 

Any intelligent discussion of the use of charcoal in creating sustainably
fertile soils needs to reference and discuss the whole Terra preta concept
and research, it seems to me.

Frank Teuton--still awaiting Joel Gruver's promised review of the literature
on composting versus fresh application of organic residues; charcoal would
be somewhere well before compost on an ascending scale of least to most
labile carbon, methinks...

-----Original Message-----
From: Sustainable Agriculture Network Discussion Group
[mailto:[email-masked]] On Behalf Of John D'hondt
Sent: 3 mai 2005 19:41
To: [email-masked]
Subject: Re: [SANET-MG] Charcoal's dubious merits

From: "Lion Kuntz"

> The "theory" of plant growth is against charcoal having much
> value as a soil fertility amendment. The "illusion" of value
> comes from wildfires, which support a burst of growth after a
> fire.
>
Two remarks that I did not think of making before may be useful still :

1) the earliest means of prehistoric wood preservation was to partly burn
that wood. Quite a few poles and house timbers buried in a half burned state
have survived for thousands of years in the ground. This means that
charcoal/burned carbon makes an extremely sterile substrate. Sterility and
fertility are natural oposites. It makes me think that at best the burned
carbon will do nothing for a growing medium. This comes true in my
experimental experiences described before.
Carbon can be very usefull for fertility but then rather under the form of
cellulose or lignine. Soil organisms can easily convert this material into
their own body constituents and this means that more phosphorus, nitrogen
and all kinds of trace elements can remain bound and recycled.

2)The value of burning carbon, whether called "gassing" or not, is of
dubious value for the planet.
 Here in SW Ireland burning is one of the oldest agricultural methods still
surviving from the debts of time. The effect of this has been two-fold. A
vegetation has developed that needs regular burning to survive and
outcompete richer plant associations. Dominating species are Molinia grass
and the prickly Ulex europeus (Gorse) that themselves burn extremely well
and produce so much heat that few other plants can survive.
Irish settlers took gorse to distant countries like New Zealand where gorse
fires have reduced native flora and the general environment in many areas.
In many cases even the soil is reduced by burning to the thinnest of
coverings of bare rock but that is no problem for gorse seedlings.
There is a rapid show of fast growing green (mainly from Molinia and Ulex)
after a fire but the general effect is loss of nutrients and a more
oligotrophe environment.
And I am certain that the same can be said for major scale "gassing"of
lesser (than trees) carbon sources. It decouples all other elements from the
life giving carbon chains and moves them into a basically anorganic type of
chemistry. You gain a little energy but you loose biomass in a big way. It
turns live material into dead chemicals and I do not think that is what this
planet needs.
john

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