[Terrapreta] some thoughts about Terra Preta

[John Cowan]

After monitoring this group for a month, I am both encouraged and 
disheartened by the messages submitted by others.

First off, Terra Preta is about adding charcoal and other 
organic-derived nutrients to the soil. The spinoffs of somehow saving 
the earth from runaway carbon dioxide by dreaming of massive charcoal 
production and soil incorporation are just a bit unrealistic when you 
consider the scope of the problem, the complexity and who controls the 
infrastructure resources of the planet to make such a program possible.

After years of doing my own organic growing research, I would say that 
from my experiments done last year that the use of charcoal in specific 
ways can be a very powerful tool for improving the physical, chemical, 
colloidal properties of the soil.and microbiological ecology.

One of the big reasons that charcoal is so beneficial to worn out 
tropical soils is that the colloidal nature of the soil is changed so 
that it can hold on to cations in a way similar to most temperate soils. 
Check out mellitic acid and its variants. Google for "Soil: Our 
Interface with the Environment" by Bruce Johnson. This explains the CEC 
transformation.

The most important issue about improving the soil for plant growth is 
the microbiology. Charcoal provides all sorts of factors favorable to 
beneficial microbes. Everyone needs to know about mycorrhizia and the 
exudates they produce. Also about the nitrogen fixers like rhizobia, 
azosprillium and azotobacter who need excellent soil structure to 
perform. Think about the living process of granule formation and crumb 
structure. These are the true marks of progress to a healthy soil.

This leads me to the crazy notions about adjusting soil pH like we are 
adjusting the air/fuel mixture on a carburetor. Applying large amounts 
of sulfur, chemical nitrogen or various limes to move the pH down or up 
has many problems - nutrient imbalances, microbe die out, toxicity to 
name a few. Yes, it is espoused by ag and hort experts as important and 
pragmatic. Consider the source and what other sterling advise they give out.

The biggest problem with charcoal is how to make it efficiently on a 
small scale with local materials. I don't have any good answers yet. 
Some of the work in India looks good but requires lots of time to manage 
the process. Like Sean said high tech retorts aren't cheap. Plus you 
have to be in an area where such a process is legal to do.

So far I have used Cowboy lump charcoal ground to a powder, more or 
less, with an old meat grinder and/or an electric coffee mill. Don't 
laugh. It works for a few pounds. I have cultured the charcoal with my 
own high quality worm castings, about 50/50, plus a small amount [3-5% 
vol.] of soluble fish powder [or krill meal] plus a little rock 
phosphate. I've use a very small amount [ maybe a couple of heaping 
TBS.] of this on problem plants in pots or as a test on a few plants in 
the veggie garden with positive results that were very obvious. And, 
yes, I've used these materials separately without these results. It is 
not a raw nutrient effect. This was all surface applied and watered in.

I've also played around with potting soil tests and found the charcoal 
to be too much at 5-10% compared to controls. A coarser charcoal might 
be different but seems a waste [expensive] unless you have lots of 
charcoal at hand. For potting soil there are lots of other granular 
materials to increase porosity.

Here is another idea worth pondering - "magic coal" made by pressure 
cooking biomass. It avoids certain problems with making charcoal but has 
some new issues to overcome.
http://www.dw-world.de/dw/article/0,2144,2071791,00.html

If anything I have said is worth discussing publicly or privately, 
please have at it.

John Cowan