[Terrapreta] CEC
Sean K. Barry
sean.barry at juno.com
Tue Dec 11 09:43:15 CST 2007
Hi Wayne,
Oh, oops you are right, Sodium (Na+) cation bonds with a single Chlorine (Cl-) anion to make NaCl, salt! I think I carried over the two pluses from the Calcium (Ca++) label. Yes, 10 milli-mole (10 x 0.001) equals one centi-mole (0.01). I was getting sloppy with my memory on this stuff.
Your ideas about charring forest arisings is just great! I agree that it could be a tremendous boon for carbon sequestration, soil enhancement, and fire safety.
Regards,
SKB
----- Original Message -----
From: teelws at jmu.edu<mailto:teelws at jmu.edu>
To: Sean K. Barry<mailto:sean.barry at juno.com> ; Tom Miles<mailto:tmiles at trmiles.com> ; 'Terrapreta'<mailto:terrapreta at bioenergylists.org>
Sent: Tuesday, December 11, 2007 4:42 AM
Subject: Re: [Terrapreta] CEC
Sean, Tom and all,
Just a couple corrections to Sean's otherwise correct notions of CEC. Na (sodium) has a single charge, not a double charge. The measure meq/100ml and cmol/kg are equivalent (not cmol/100mg). It is easy to get these units confused. It gets even worse when switching between English and metric, the latter being far easier, if awkward for Americans.
Organic matter buried in soil does have a variable but very high CEC. Generally it varies between 100 and 450 meq/100mg. In low CEC situations you would get a bigger kick by adding compost to the char, though for long term carbon storage the char is essential. Organic matter stability in the soil is dependent upon water. It you have a saturated subsoil the orgnanic material in it remains stable for centuries or longer. Some organic soils on Boreo are 70 feet thick, a wonderful carbon storage. However, take away the water the carbon will slowly be consumed, respirated to CO2. Even worse, if the saturation is intermittent you get methane. Char, whether agrichar or forest char, is likely far more stable in both wet and dry conditions.
One final comment. Though I don't like the idea of charring trees, forests commonly produce a lot of woody material that outside the wet tropics will remain as forest floor debris for a long time. Anti-fire advocates would love to see that cleaned up to prevent the huge fires we have seen in the west in the past two decades. Why not char that? You could reduce fire risk and improve soil at the same time. To increase the soil organic matter you could compost the leaves and twigs, just charring the slightly bigger material.
Wayne
---- Original message ----
>Date: Mon, 10 Dec 2007 22:43:21 -0600
>From: "Sean K. Barry" <sean.barry at juno.com<mailto:sean.barry at juno.com>>
>Subject: Re: [Terrapreta] CEC
>To: "'Richard Haard'" <richrd at nas.com<mailto:richrd at nas.com>>, "'Kevin Chisholm'" <kchisholm at ca.inter.net<mailto:kchisholm at ca.inter.net>>, "Tom Miles" <tmiles at trmiles.com<mailto:tmiles at trmiles.com>>
>Cc: "'Nikolaus Foidl'" <nfoidl at desa.com.bo<mailto:nfoidl at desa.com.bo>>, "'Terrapreta'" <terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org>>, "'Todd Jones'" <tjones at nas.com<mailto:tjones at nas.com>>
>
> Hi Tom,
>
> I think it is fair to infer that CEC is a measure of
> the health of the microbial community, but somewhat
> indirectly. The primary factor for determining CEC
> in soil is the clay and/or organic matter content of
> the soil. In general, higher quantities of clay and
> organic matter means higher CEC. But, different
> types of clays have different exchange capacities.
> The issues of soil pH and the concentration of base
> cations, like Potassium (K+), Calcium (Ca++),
> Magnesium (Mg++), and Sodium (Na++), so called base
> saturation, play a role too, along with CEC, in the
> actual fertility of soil.
>
> But, organic matter alone has a CEC like ~150
> mEq/100g, so a healthy population of soil
> microorganisms; bacteria and fungus, etc., plus
> things like glomalin - all organic matter, do
> increase the CEC of the soil. If the pH is in an
> acceptable range for these microbes to persist and
> live and the base saturation of things like plant
> useless Sodium (Na++) ions and Aluminum ions are low
> enough, too, then the organic matter CEC can provide
> a significant nutrient holding and nutrient
> delivering capacity to the roots of plants growing
> in the soil.
>
> I'm not a soil scientist, Tom (but I could play one
> on TV? hehe...), so I might not have this all
> entirely correct. I've just learned about CEC in
> this past year from reading and I only think I
> understand mostly about how it works. But I've
> never been tested? So, consider the source and get
> some other opinions, maybe?
>
> Regards,
>
> SKB
>
>
>
> ----- Original Message -----
> From: Tom Miles
> To: 'Sean K. Barry' ; 'Richard Haard' ; 'Kevin
> Chisholm'
> Cc: 'Jim Joyner' ; 'Nikolaus Foidl' ; 'Terrapreta'
> ; 'Todd Jones'
> Sent: Monday, December 10, 2007 10:20 PM
> Subject: RE: [Terrapreta] Charcoal costs
>
> Can it be inferred from previous posts that the
> CEC increases with charcoal as microorganisms
> inhabiting the charcoal provide more binding sites
> compared with soil? Is CEC a measure of the
> "health" of the microbial community?
>
>
>
> Tom
>
>
>
> From: Sean K. Barry [mailto:sean.barry at juno.com]
> Sent: Monday, December 10, 2007 6:57 PM
> To: Richard Haard; Kevin Chisholm
> Cc: Tom Miles; Jim Joyner; Nikolaus Foidl;
> Terrapreta; Todd Jones
> Subject: Re: [Terrapreta] Charcoal costs
>
>
>
> Hi Kevin, et. al.,
>
>
>
> Described qualitatively, the Cation Exchange
> Capacity (CEC) of soil, is the ability of soil to
> attract positively charged ions (cations) to
> negatively charged sites on molecules or atoms of
> the substances in the soil. Quantitatively, CEC
> is a measure (or an estimate) of the number of
> negative charges per unit weight of the soil. The
> dimensions of this measurement are conventionally
> in milli-Equivalents per 100 grams (mEq/100g).
> This means one thousandth (milli = 0.001 = 10E-3)
> of an "Equivalent" per 100 grams of the sample.
>
>
>
> An "Equivalent" is the term usually given as a
> measure of positively charged ions, because it
> means how many grams of a substance that will
> react with one mole (6.02 E 23) of electrons.
> This also applies for negatively charged atomic
> ions, considering the number of negative charges
> of magnitude -1 (or again, e-) contained in the
> ions. It brings together the concepts of both the
> atomic weight of the ion and its charge or
> valence.
>
>
>
> However, when speaking of CEC in soil, the # of
> negative charges does not pay regard to the atomic
> weight of the molecules or atoms which hold those
> negative charges. So, 1 mEq is equivalent to 1
> mole of negative charges (e-), period.
>
>
>
> So, a CEC measurement of ...
>
>
>
> "1 mEq/100g" is the same as "10 mmole/kg" (10
> milli-mole per kilogram) or "1 cmole/100g" (1
> centi-mole per 100 grams of sample)
>
>
>
> The "mEq/100g" value represents the number of
> cation binding "sites" in a 100 gram sample of the
> soil, to which that same number value of
> monovalent cations (ions with a valence charge of
> +1, e.g. H+) could attach. For divalent and
> trivalent cations (+2 and +3), the number of
> "sites" is reduced to 1/2 and 1/3 of the
> "mEq/100g" value, respectively.
>
>
>
> I hope this helps everyone understand the units of
> measurement used for CEC measurements?
>
>
>
> Regards,
>
>
>
> SKB
>
>
>
>
>
> ----- Original Message -----
>
> From: Kevin Chisholm
>
> To: Richard Haard
>
> Cc: Tom Miles ; Sean K. Barry ; Jim Joyner ;
> Nikolaus Foidl ; Terrapreta ; Todd Jones
>
> Sent: Sunday, December 09, 2007 10:34 PM
>
> Subject: Re: [Terrapreta] Charcoal costs
>
>
>
> Dear Richard
>
> Richard Haard wrote:
> > S,K,J,N and Tom
> >
> > Jim and I have been discussing CEC and soil
> nutrition and charcoal for
> > a few rounds offline and the apparent anomaly
> of my data not showing a
> > boost in CEC with charcoal addition.
> Could it be that with low temperature char,
> still containing volatiles
> and/or products of incomplete charring, the
> future CEC sites are
> presently blocked, but that with some
> combination of microbial action
> and weathering over several years, the tars and
> volatiles still on the
> char will be decomposed or removed to yield an
> "active" char?
> > Rereading Steiner etal tonight I have
> concluded my first year data is
> > consistent with first year results obtained by
> Steiner in Brazil.
> >
> > It seems that charcoal addition to soil does
> not make terra preta and
> > that terra preta itself is the product of a
> long term biological,
> > chemical and physical process. The process we
> used to make our
> > charcoal 2 was identical to the local
> production method where Steiner
> > obtained his charcoal.
> >
> > Jim or anyone do you have a citation that
> supports your statement in
> > an earlier posting
> >
> > Jim Joyner wrote:
> >> The CEC increases with compost and charcoal
> (in Brazil) . . . well,
> >> of course it does.
> I don't have any specific references to support
> this on its own, but
> washed char tests by Cheng Lehmann and Thies
> http://www.georgiaitp.org/carbon/PDF%20Files/Posters/ChengPoster.pdf<http://www.georgiaitp.org/carbon/PDF%20Files/Posters/ChengPoster.pdf>
> shows that char will increase the CEC.
> They used char which was much smaller than the
> lump and stick charcoal
> you used. Two differences between your protocol
> and theirs were washing
> and finer size.
>
> This is a big reach, but is it possible that
> there was sampling bias?
> Specifically, is it possible that when taking
> samples, the large lumps
> of char were removed inadvertently in the field,
> or perhaps by screening
> at the Lab?
>
> Note also that your units for CEC seem to be
> cmole/kg while Cheng et al
> use mmole/kg. How does one convert between teh
> different units.?
>
> How did you measure crop yields? Did you see
> much difference between the
> various plots?
>
> Best wishes,
>
> Kevin
>
> >
> >
> > Here are some quotes from Steiner et al (2007)
> and my comments that
> > might be interesting for this topic of CEC and
> charcoal in soil.
> >
> > Paper cited: Long term effects of manure,
> charcoal and mineral
> > fertilization on crop production and fertility
> on a highly weathered
> > central Amazon upland soil
> >
> > abstract here<
> >
> >
> ------------------------------------------------------------------------
> >
> > >
> >
> > from Steiner et al et al p 2
> >
> > Terra Preta research has shown that oxidation
> on the edges of the
> > aromatic backbone and adsorbtion of other OM
> to charcoal is
> > responsible for the increased CEC, although
> the proportion of these
> > two processed is unclear (Liang et al 2006)
> >
> > cited Liang B et al Black Carbon increases
> cation exchange capacity
> > in soils Soil Sci Soc Am J 70:1719-1730
> >
> > and from page 12 - ' the period of this study
> might have not been
> > sufficient for oxidation'
> >
> > 'and SOM was only effective at increasing CEC
> levels above pH 5.5
> > which is consistent with the blockage of
> exchange sites by either Al
> > or Fe at lower values ---- In our study only
> plots fertilized with CM
> > had pH values higher than 5.5 and increased
> CEC. '
> >
> > His charcoal was derived from a secondary
> producer and manually
> > crushed ( not special charcoal and made with a
> technique identical to
> > our charcoal 2 = heap burn)
> >
> > Definitions of his treatment blocks
> >
> > C control
> > L leaf litter
> > LB simulated slash and burn (burned litter)
> > F inorganic fertilizer
> > CM chicken manure
> > 2CO compost
> > 2CC charcoal
> > 2CO+F compost +F
> > 2CC+F charcoal + F
> > CC+CO Charcoal + Compost
> > 2CC+CO Charcoal + Compost
> > 2CC+CO+F Charcoal + Compost + Fertilizer
> > 2CCp charcoal pieces
> >
> > From Table 2 page 11 of Steiner et al soil
> Chemical Properties after
> > first harvest (CEC only)
> >
> > (cmole+kg-1)
> >
> > Steiner et al after first harvest values
> first - then my own after
> > first harvest (charcoal 1 then charcoal 2)
> > C 1.61 9.85
> > L 1.52
> > LB 1.73
> > F 2.16 12.05
> > CM 12.55
> > 2CO 1.94 11.9
> > 2CC 1.80 10.4,11.9
> > 2CO+F 2.45 12.3
> > 2CC+F 1.94 10.1, 11.25
> > 2CC+CO 1.8 10.95, 12.3
> > 2CC+CO+F 2.11 12.7, 12
> > 2CCp 1.65
> >
> > Interesting pattern here. Charcoal 1 showed
> the best indication of
> > enhanced growth above ground and roots. I
> might speculate the lower
> > CEC values represent greater nutrient
> utilization. Additionally, CEC
> > may be incidental to the role of charcoal in
> soil. We should include
> > also biological factors in our considerations.
> >
> > In terms of biological contribution to
> beneficial effects of charcoal
> > additions Steiner et al concluded
> >
> > The conditions of ADE (Amazon Dark Earth) are
> ideal for maximum
> > biological N2 fixtation. About 77% of the ADE
> sampled showed positive
> > incidence of /Aspospirillum sp./ compared to
> only 10 % of the
> > Ferralsols. Charcoal provides a good habitat
> for the propagation of
> > useful microorganisms such as free living
> nitrogen fixing bacteria and
> > mycorrhizal fungi. Ogawa holds the charcoals
> weak alkalinity, porosity
> > and ability to retain water and air
> responsible for stimulation of
> > microbes (citations excluded).
> >
> > Steiner et al did conclude that
> >
> > 'Charcoal proved to sustain fertility if an
> additional nutrient source
> > was given. Even though significantly more
> nutrients were exported from
> > the charcoal plots (with higher yields) the
> available nutrient
> > contents of the soil did not decrease in
> comparison to just mineral
> > fertilized plots'
> >
> > In addition he demonstrated highest mineral
> losses in plots treated
> > with Chicken Manure, followed by compost, then
> litter and control.
> >
> > Rich H
> >
>________________
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Wayne S. Teel
MSC 4102 ISAT
James Madison University
Harrisonburg, VA 22807
Tel: 540-568-2798
Fax: 540-568-2761
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