[Terrapreta] Charcoal costs

[Sean K. Barry]

Hi Jim,

I have a book compiled by Dr. Johannes Lehmann, with contributed writings by researchers for many years in the field of Terra Preta,
"Amazonian Dark Earths: Origin, Properties, Management".  It was a very expensive book, like $229!  I have read some, but not all of it.  I have also read many of the research papers that Dr. Lehmann and his associates (Dr. Christov Steiner, et al.) from Cornell University.  Many of the papers are available on the Cornell University site.

>From my reading of what their combined research has found, charcoal in soil alone does not attribute the characteristics that make it a more fertile soil (increased CEC, better water holding capacity, increased nutrient holding capacity).  Rather, it is the interaction between charcoal in soil, the soil microorganisms, and other organic matter, where the Terra Preta effect is grown from.  Charcoal does provide structure to the soil and because it is porous is has some ability to hold water in micro-reservoirs in those pores.

As you suggest, charcoal is nearly chemically inert in the soil.  It can oxidize when exposed to air, but only very slowly. The porous nature of the charcoal (it's structure), however, once in the soil provides a haven (with water) and a place to grow for soil microbes.  They have shown scanning electron micrographs of "hyphae" grown by vesicular arbuscular mycorrhizal (VAM) fungi permeating and growing through the pores of charcoal in soil.

The VAM fungi grows hyphae to serve plants in a symbiotic fashion.  These are hollow tubes that the fungi attaches to the hairs of roots, which extend penetration into the soil and deliver water soluble nutrients to the plants.  The fungi grows the hyphae in exchange for (the symbiosis relationship) and using the energy from sugars provided by the roots of the above ground plants.  The hyphae are covered with a sticky sheath, called "glomulin".  When the hyphae die, the glomulin is left in the soil.  The glomulin binds up water soluble nutrients and forms "aggregates" in the soil.  This is the mechanism that is believed to be responsible for the nutrient holding capacity of TP soil.

In general, charcoal in the soil makes for a more hospitable environment for soil microbes.  They bloom in greater numbers and are more active in soil containing charcoal.  Some researchers are trying to discover if the residual volatile matter (tars, bio-oils, etc.) left on charcoal in some way provide a decomposable organic energy source, food, for some microorganisms (for anaerobic bacteria for instance).  When there is available soil organic matter and a healthy soil microorganism population, that is when the chemical activity rises in the soil and when the CEC rises as well.

When charcoal is made from biomass, most , if not all of the inorganic plant nutrients that were in the original plants are retained in the ash portion of the charcoal (calcium, phosphorus, iron, magnesium, etc).  They do not burn off or exit the pyrolysis reaction as gases. So, in fact, charcoal from biomass, has nearly all of the same fertility enhancing nutrient content as composted biomass (save for nitrogen).  But, the carbon in charcoal will not gas off like the carbon in carbohydrates in compost.  Charcoal in soil does not emit CO2 like compost does.

The tools and the research work is being done out there and in real soils, Jim.  There are lots of researchers and lots of experiments in progress.  Not much of it seems to see the light of day on this list though.  That may be to do with the existence of "putzi" in this group, who don't get it and/or who want to discuss politics, economics, and fuzzy warm feelings about TP.  I don't know why.  I'm not an expert by profession about any of this, but my interests do lie more along the lines of applied science.  I have found external reading far more beneficial than most anything I ever read off of this list.

Regards,

SKB

  ----- Original Message ----- 
  From: Jim Joyner<mailto:jimstoy at dtccom.net> 
  To: Kevin Chisholm<mailto:kchisholm at ca.inter.net> 
  Cc: terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org> ; 'Nikolaus Foidl'<mailto:nfoidl at desa.com.bo> 
  Sent: Sunday, December 09, 2007 9:42 AM
  Subject: Re: [Terrapreta] Charcoal costs


  There is something missing here. I suspect it is tools.

  In Richard's tests the CEC does not increase with the application charcoal. It does increase the OM but that is probably not a true reading but a deficiency in our soil analysis.i.e., the test is reading the carbon in charcoal as organic when it is not.

  The CEC increases with compost and charcoal (in Brazil)  . . . well, of course it does. The compost yields a type of carbon that is acted upon through biological processes . . . but not the charcoal. The benefit of charcoal is that it pesists, but that is because it is not a part of the chemical (electrical, ionic). 

  There is no reason to believe charcoal directly raises CEC. CEC is essentially an electrical measurement of the capacity to hold nutrients in a suspension from plants can draw them. Charcoal does not seem to be a part of the electrical  or chemical equation.

  We can't have it both ways.

  It may me that charcoal yields a type of mechanical (if you will) structure that will hold nutrients in place while the biological processes proceed -- without them be washed away by rain or oxidized by the presence heat and humidity. 

  I don't think we have the measurement tools (or maybe just a good theory) yet to determine what is going on in the soil with charcoal or to what extent. Empirically, we may see better growth (or more worms), but that gives us no universal set of principles to apply what we know to other soils and climes. This empirical view, when compost is applied, just distorts what we see.

  And, most of what we have been saying about charcoal's benefit in the soil is still speculative. The tools we have just don't tell the whole story.

  Jim

  Kevin Chisholm wrote: 
Dear Tom

Tom Miles wrote:
  Capacity of the soil, but that Torrified Wood has the Cation Exchange 
sites tied up, and that it would not work a effectively as char.
    
      So what's the marginal value of CEC? I don't think we know this yet.
  
    This paper shows that an increment of charcoal to a soil increased the 
CEC from 24.9 to 47.2.:
http://www.georgiaitp.org/carbon/PDF%20Files/Posters/ChengPoster.pdf<http://www.georgiaitp.org/carbon/PDF%20Files/Posters/ChengPoster.pdf>

I am not certain of the quantity they used in their test. They state:
"An incubation experiment was performed in which either water-washed 
charcoal or a charcoal-soil
mixture in a ratio of 50:1 was incubated at either 30°C or 70°C."

I find this confusing. This suggests the test mixture was either 100% 
water washed charcoal, or 98% water washed charcoal and 2% soil mixture. 
However, their Table 2 lists the tests they performed with variables as 
follows: Soil, Soil + Char, Soil + Char +Fertilizer, Soil + Char + 
Microbes, Soil + Char + Manure, Soil + Charcoal+ Fertilizer+Manure.... 
This suggests that they measured the changes to the soil with additions 
of various ingredients.

If we ASSUME that the actual tests involved soil as the starting point, 
and that there were 2% additions of each ingredient, we can calculate 
the marginal or incremental value for the CEC of Char. If this was the 
case, then a 2% addition of char increased the CEC of the soil from 24.9 
to 47.2, a change of  22.3 mmole/kg. From this we calculate that the CEC 
for the Char alone would be about 50 times greater, or about 1,115 mmole/kg.

Would you think that these assumptions are reasonable? Is this a 
reasonable interpretation of the data presented?

Best wishes,

Kevin
  Tom




  
    


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