[Terrapreta] Soil Food Web

[Sean K. Barry]

Hi Phillip,

Increasing CEC in acidic soils could decrease base saturation and increase aluminum toxicity, in sodic soils (and the related grass tetany prone potassium affected soils caused by high manure applications) it could exacerbate the imbalance of monovalent cations relative to divalent cations.

I think Dr. Christoph Steiner addresses this very issue in some of his work.  I think he found significant benefits with charcoal amendments into these specific types of soils, found in the Amazon, right now, in this century.  You might look up his papers (on this site) and/or talk directly to him (he's on the 'terrapreta' list).

Regards,

SKB
  ----- Original Message ----- 
  From: Philip Small<mailto:psmall2008 at landprofile.com> 
  To: Jim Joyner<mailto:jimstoy at dtccom.net> 
  Cc: terra preta<mailto:Terrapreta at bioenergylists.org> 
  Sent: Saturday, May 10, 2008 9:11 AM
  Subject: Re: [Terrapreta] Soil Food Web


  Appreciate that observation. That makes sense to expect a short term reduction in CEC, followed by a significant increase on the back end. Assuming this is the case, the time it takes to get through that trough can be managed: supplemental N source added with char as high C/N soils tend to lose C when shocked/stimulated, condition the char before adding it to the soil, opt for smaller incremental additions of char, place the char deeper in the soil profile than the bulk of the humus, etc. 

  In some situations, increasing CEC without also immediately adding the cations to populate that increased exchange capacity could be asking for soil trouble.  Elaine Ingham has made this point in her concerns with adding charcoal to soil, and, whle she didn't go into detail, I see it as a valid point. Increasing CEC in acidic soils could decrease base saturation and increase aluminum toxicity, in sodic soils (and the related grass tetany prone potassium affected soils caused by high manure applications) it could exacerbate the imbalance of monovalent cations relative to divalent cations.  Thus a measured increase in CEC, as occurs as char conditions in the soil, could be a very good thing, giving the fixed mineral fraction time to mineralize, and to feed a balanced supply of cations into the soil solution. The more I learn from you folks about biochar, the more taken I am by it. -phil


  On Sat, May 10, 2008 at 6:29 AM, Jim Joyner <jimstoy at dtccom.net<mailto:jimstoy at dtccom.net>> wrote:

    Sean K. Barry wrote:


    Charcoal carbon, when added to soil does appear to increase the growth in populations of soil microbes and the activity of soil microbes in the soil, leading to an increase in soil organic matter, and hence an increase in CEC.


    Sean,

    You raise an interesting implied point. While I think your statement is true, it may be critical to see just how that works. The added OM that is broken down into humus must come from someplace. It might come from compost or cover cropping, or it might even come from just the growing of crops. Economics is likely to determine how the addition comes about. 

    Personally, I use no-till with cover cropping and rotations to achieve an optimum level of CEC/humus. (Composts work better but not cost effective for me -- the humus can be greater but the benefits don't justify the costs.) My hope is that the addition of charcoal will elevate that level of CEC/humus with no additional costs (beyond the charcoal introduction), hence, increasing the productivity of my soils. I am also hoping the benefit of charcoal is permanent. If that is true then, the charcoal becomes not a cost but an investment requiring a return. One could then consider the charcoal a part of the real property. But I digress . . .

    The caveat (and my belated point) is, given the additional "activity of soil microbes in  the soil", that only adding charcoal without adding or growing other OM might lead to a reduction in humus and a commensurate reduction in CEC.

    Jim

      Hi Larry,

      You say:
      when charcoal with it's pore spaces are occupied with microbes and when charcoal, consisting of carbon binding sites for nutrient ions, is used then the structure, charcoal, hosts the functions of microbes, fungi, roots and nutrients.

      I like yours and Tony's comments on structure.  The corral reef is an apt analogy to biochar in soil.  It is just a physical thing, though.  There is NO chemical use by organisms on coral reefs of the calcium carbonate in coral reefs.  If there was, then the reef would disappear.  I don't think that charcoal itself interacts chemically with microbes or the nutrient ions in soils, either.  The charcoal has physical impacts on the soil structure (greatly increased "enclosed" surface area I suspect is the greatest addition), but it is not chemically active, per se.

      CEC in soil is generally increased by the addition of soil organic matter and by some clays which both do have more "binding sites" for cations of nutrients like Calcium and Potassium, etc.  The number of "binding sites" (negatively charge sites attracting positively charged cations) is measured in Million equivalents per gram Meq/g, meaning the number of millions of negative charges per gram of the soil.  Charcoal carbon does not have high numbers of negative charges on its surface and so does not increase CEC directly when it is added to soils.

      Charcoal carbon, when added to soil does appear to increase the growth in populations of soil microbes and the activity of soil microbes in the soil, leading to an increase in soil organic matter, and hence an increase in CEC.

      Regards,

      SKB

--------------------------------------------------------------------------
_______________________________________________
Terrapreta mailing list
Terrapreta at bioenergylists.org<mailto:Terrapreta at bioenergylists.org>
http://tech.groups.yahoo.com/group/biochar/<http://tech.groups.yahoo.com/group/biochar/>
http://terrapreta.bioenergylists.org<http://terrapreta.bioenergylists.org/>
http://info.bioenergylists.org<http://info.bioenergylists.org/>


    _______________________________________________
    Terrapreta mailing list
    Terrapreta at bioenergylists.org<mailto:Terrapreta at bioenergylists.org>
    http://tech.groups.yahoo.com/group/biochar/<http://tech.groups.yahoo.com/group/biochar/>
    http://terrapreta.bioenergylists.org<http://terrapreta.bioenergylists.org/>
    http://info.bioenergylists.org<http://info.bioenergylists.org/>




  -- 
  Philip Small, RPSS
  Land Profile, Inc. * PO Box 2175 * Spokane, WA 99210
  509-844-2944 cell * 509-838-4996 fax * 509-838-9860 office
  Profile: http://www.linkedin.com/in/philipsmall<http://www.linkedin.com/in/philipsmall> _______________________________________________
  Terrapreta mailing list
  Terrapreta at bioenergylists.org
  http://tech.groups.yahoo.com/group/biochar/
  http://terrapreta.bioenergylists.org
  http://info.bioenergylists.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /attachments/20080510/1a4add18/attachment.html