[Terrapreta] Soil Food Web

[Sean K. Barry]

Hi Jim,

... but I think char-in-soil may make no-till more advantageous than it might have otherwise been. It might even be a necessity. After all, It doesn't appear our Amazonian predecessors had tillers and plows.

This is very interesting statement from you.  Are you suggesting that charcoal's ability to accelerate composting of plant material laying on top of the ground may help with your planting right into cut down mulched plant materials?  This sound plausible to me.  Could it even be possible to grab more bulk plant growing season by cutting biomass, mixing in charcoal, and planting into it before it fully matured or "ripened", if you will?  Maybe you can just push the early growth of one planting sooner under another one that way.  Do this, rather than waiting a full season cycle for it to decay more slowly?  Agriculture practice for simple biomass production and nutrients could be different than agriculture for food crops or crop products from fully mature plants.

I've thought that crops like Miscanthus, Willow, and Industrial Hemp, which have large dry tonnage yields per hectare and are fast growing could all be used for "cover cropping" to produce charcoal, dropped right onto that soil, then mixed in with other sorts of "cover cropping" to fill in the for other nutrients (alfalfa and beans for N, etc).   Maybe patches of a single field could be charcoal producing and spread over the other cover crops on other patches.  It sounds like you already spend some years on doing soil remediation on your farmed land.  Charcoal could be just the kind of tool you need to reduce that time you spend doing that.  There is value, I assume, in your bringing an area of land into saleable crop production sooner?

Regards,

SKB
  ----- Original Message ----- 
  From: Jim Joyner<mailto:jimstoy at dtccom.net> 
  To: Philip Small<mailto:psmall2008 at landprofile.com> 
  Cc: terra preta<mailto:Terrapreta at bioenergylists.org> 
  Sent: Saturday, May 10, 2008 11:00 AM
  Subject: Re: [Terrapreta] Soil Food Web


  Phil,

  Well, anticipating at least some of the things you talk about (some just had not occurred to  me), I have (over) planted beans (mostly soy). Most of the these will simply be cut down when they are in full bloom to capture the maximum N value (and left as mulch). In the early fall, without tilling, I will plant rye (grain) and hairy vetch together (they winter over ni9cely here). The bean roots left in the soil should have increased OM but the rye will increase OM in the soil considerably and the vetch will increase N again. I will wait until about (next) mid May to, again, just cut these down and leave them. At that stage both will die and I should capture maximum OM and N. 

  Although maybe a bit unusual, I'm starting with soil conditions and nutrient levels that are about as good as they can be for this soil: CEC and cation balance, N, P, K, OM.

  I'll do soil analysis just before rye/vetch planting. Depending on the soil values in May, I will start planting summer crops or consider other remedial plantings. Typically, I plant right into what I have cut down, again, without tilling. I'm guessing, of course, but I think char-in-soil may make no-till more advantageous than it might have otherwise been. It might even be a necessity. After all, It doesn't appear our Amazonian predecessors had tillers and plows.

  Basically, I've designed this experiment to find a way to enhance the practices I already use -- and hope to learn something about TP in the bargain . . . I'm a farmer, not a scientist.

  The point of this, I think, is that putting charcoal in the soil is just one in many potential steps. Many of the issues you raise may come into play and need to be dealt with to bring the soil up to a point that it can be cropped.

  Thanks for the comments. They give me more to watch for. Given the above, if you have any more . . .

  Jim


  Philip Small wrote: 
    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

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