[Terrapreta] more on logistics of corn biochar

[Robert Klein]

Thank you for the elucidation on activated charcoal
itself.  I was a little hesitant to mention the term
but also felt that the cooking environment was going
to produce a range of end products that could include
some truly activated charcoal.

Certainly the process would be underway for a long
time and there would be internal moisture available. 
The hard question is to estimate the maximum achieved
temperature.  My sense, is that it would rarely get
much over 400 degrees ever.  But that would be
sustained.   We are going to have to build a stack and
find out.

I do expect that we will achieve an end product that
will have a broad distribution of combustion products
that may still contain not just a lot of charcoal but
perhaps some of the more energetic activated charcoal.

What we do know is that even low temperature biochar
is chemically active and is fairly stable in the face
of microbial attack.

Has anyone ever seen a paper describing the
characteristics and behavior of plant material cooked
to a range of finely tuned preset temperatures?  We
really need that data for understanding and predicting
the behavior of terra preta.


--- rukurt at westnet.com.au wrote:

> Robert Klein wrote:
> > This is a  very good question and needs a lot of
> > experimentation to establish our actual limits.
> >
> > Having said that, I was exposed to the extensive
> > effort that has been put into the application of
> > zeolites in agriculture and in the process became
> very
> > aware that activated carbon is similar in
> performance.
> >
> >   
> We are not talking about activated charcoal when we
> talk about 
> terrapreta. Activated charcoal is made from ordinary
> charcoal by holding 
> it at high temperature while treating it with steam,
> for quite some 
> time, depending on just what properties the
> activated material is 
> supposed to have. There is no similarity between the
> char in terrapreta 
> and either zeolite or activated charcoal. The
> technology required was 
> highly unlikely in the Amazon 6,500 years ago, nor
> generally, today.
> The porous nature of terrapreta charcoal is due to
> the structure of the 
> wood (hardwood according to my memory of what has
> been written). The 
> voids are quite a lot bigger than those generally
> found in activated 
> charcoal.
> > Both are now described properly as solid
> crystalline
> > acids.  Some are 10,000 times as powerful as
> sulphuric
> > acid which eliminates any question as to potential
> > chemical activity.
> >
> > The point that I would like to make is that this
> > apparently benign substance, in the form of
> biochar is
> > a great reactor in the face of more mobile ions.
> >   
> I think you're grabbing properties from unrelated
> substances and trying 
> to claim them for terrapreta charcoal.
> > My core thought here, is that I suspect the carbon
> > dominates and quickly supports the growing
> environment
> > regardless of the general soil condition and Ph.
> >   
> Perhaps it does, and perhaps it only provides an
> environment for 
> microbes and fungi, as well as extra water retention
> capacity and 
> somewhere for excess nutrients to be stored for
> later release. If the 
> carbon was so re-active, then would it not be used
> up over the years? Up 
> to 6,500 of them, we are told.
> >
> > The really interesting experiment will be in
> trying to
> > remediate saline soils.  I must admit that I do
> not
> > think it will work very well at all, but I would
> love
> > to be proved wrong.
> >
> >
> >   
> Any results from the experimental use of charcoal in
> terrapreta 
> analogues would be interesting. Remediating saline
> soils is mainly a 
> matter of rebuilding water tables and leaching out
> the salt anyhow. It 
> is highly unlikely that a "magic bullet" soil
> additive could possibly 
> have any useful effect.
> 
> 
> Kurt
> 



       
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