[Terrapreta] a braoder theory of torrefaction and TP

[Sean K. Barry]

Hi Jim,

Taken to the extreme, just knock trees down and bury them whole into the subsoil, right?  Why go to all the trouble of chipping it and pulverizing it into sawdust at all?

There are possibly two differences with using charcoal in topsoil (or in subsoil), I think.  One, when making charcoal from biomass, one can harvest some of the biomass energy in the form of heat and/or some fuel gases, leaving the charcoal as a byproduct for use as a soil amendment .  Two, charcoal has the potential to persist in the soil for much longer than the raw biomass.

If you know now where that subsoil containing sawdust was buried in Missouri 25 or 30 years ago, you might consider digging it up and seeing how much is left of it?  Was there any subsidence of the ground level in those areas?

Regards,

SKB
  ----- Original Message ----- 
  From: Jim Joyner<mailto:jimstoy at dtccom.net> 
  To: Undisclosed-recipients:<mailto:Undisclosed-recipients:> 
  Cc: Terrapreta preta<mailto:terrapreta at bioenergylists.org> 
  Sent: Monday, December 10, 2007 8:47 PM
  Subject: Re: [Terrapreta] a braoder theory of torrefaction and TP


  You know, We've all been looking at the sexier uses of various forms of burned wood in the top soil, but if you want a cheap way to sequester carbon, burying sawdust or chips in the subsoil accomplishes the same thing (burying charcoal below the topsoil makes no economic sense, serves little or no purpose). It  works because there is little or no biological activity in the subsoil.

  I don't know how long it lasts but it gotta be at least decades. But it might be forever. I was always involved with the farming side, not the research, but I know of experiments that were started 25 to 30 years ago in Missouri. They took sawdust, mixed it with subsoil and buried it as much as six feet deep in long trenches. The purpose was to give certain deep rooted perennials (grapes, in this case) more root room and create a moisture reservoir. 

  The moisture reservoir is a good idea for not only plants but for good water shed. And, it buries a lot carbon waste product that doesn't need to be processed.

  There are even less invasive ways to bury woody material in the subsoil too. For example, I subsoil my beds for annuals to about 3 feet. I balance the subsoil by adding limestone (I built a device that subsoils and adds lime at the same time. Not all soils need the lime) so that it will be lose not only physically but electrically. Then, every year a crop sends a new set of roots down and leaves them behind. The blackness of the soil gets deeper and darker every year. The water holding capacity of the subsoil increases every year. 

  Jim

  Gerald Van Koeverden wrote:

    I like your idea....we 'soils peoples'  have to broaden our scope of interest from 'biochar' to the whole range of "torrefied wood".  Let me try to build a new 'theory."


    Torrefaction does something to the wood so that it lasts much longer in the soil than non-torrefied wood.  What happens in torrefaction?  "This process removes all naturally occurring resins, sugars and oxygens while collapsing the cells. This accomplishes two things: First, it gives the lumber a deep, rich brown color...Second, and more importantly, it alters the wood to make it extremely stable, moisture resistant and decay resistant."


    This extended life effect is not just because it drives out enough moisture to inhibit decomposing organisms, but it also provides a suitable habitat for non-decomposing soil-dwelling organisms - not dependant on as high moisture contents - which in turn protect their habitat from rapid decomposition.  If these MO don't completely inhibit decomposition, they at least have a significant effect in slowing that process down.  It is the biological activity of these micro-organisms inhabiting the torrefied wood, which increases the fertility of those soils and make TP's what they are.
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