[Terrapreta] Effect of Washing Charcoal

[Philip Small]

On Fri, Jun 27, 2008 at 6:10 AM, Richard Haard <richrd at nas.com> wrote:

> Philip we had no change in pH with our block study, with two types of
> charcoal . Our charcoal home made had high ash content.
>
With a little soil data and application rate data, you and I could calculate
the reasonable (assuming an informed scientific wild-*ssed guess =
reasonable) increase, and see if it is enough to show up against background
noise.

>
> Buffering properties of soil comes into play in the explanation. Typical
> result is pH 5.4, buffer pH 6.2  - no correlation of pH with treatment.
>
Laboratories perform the buffer pH test in order to develop lime
recommendations.  The lower the buffer
pH<http://hubcap.clemson.edu/%7Eblpprt/bobweb/BOBWEB8.HTM>,
the higher the lime requirement.

Five basic methods (using five different buffer solutions) for lime
requirement are now being used in the United States. They are selected based
on the dominant soil characteristics of the region.

   - Shoemaker, McLean, and
Pratt<http://extension.oregonstate.edu/catalog/html/fg/fg52-e/#anchor919910>(SMP)
(most accurate for alfisols requiring >2 tons of lime per acre, having
   <pH 5.8, containing <10% organic matter, high exchange capacity clays
   (such as monmorillonite and illite) and having appreciable quantities of
   soluble Al - SMP is in the widest use)
   - Adams-Evans <http://hubcap.clemson.edu/%7Eblpprt/diagnosis.html> (most
   accurate for oxisols and ultisols with low exchange clays (kaolinite) where
   SMP would drastically overestimate lime requirement - in wide use)
   - Woodruff (most accurate for classic mollisols - used in midwest,
   otherwise not in wide use)
   - Mehlich <http://www.ncagr.com/agronomi/buffacid.htm>. (can be modified
   regionally, use is expanding due to low restrictions on reagents used)
   - Sikora <http://soils.rs.uky.edu/sikora_smptechreport.htm> (mimics SMP,
   replacing SMP due to carcinogenicity concerns with SMP reagents - use is
   expanding)

Your lab likely used the SMP buffer.  Using a table from
OSU<http://extension.oregonstate.edu/catalog/html/fg/fg52-e/#anchor919910>,
we should be able to figure out the lime requirement (or maybe the lab
already informed you of this?), and with that, we can back into how much
your charcoal application should/could increase your pH assuming we can
reasonably guess the charcoal's ash content and its CCE.

>
> I think the potential for pH change by charcoal in soil addition needs to
> be qualified.
>
We should identify a laboratory to work with to characterize charcoal CCE.
Would the laboratory you use be capable of this?  I would use Dellavalle
Labs <http://dellavallelab.com/analyticalcatalog.html> (Fresno, CA): They
test ash for CCE (see
PDF<http://dellavallelab.com/forms/Soil_Amendment_Analysis.pdf>
).

>
> Our pH is getting a bit high for our native plants and we are contemplating
> a sulphur treatment. Linked to this we would like to apply rock phosphate as
> sulphur treatment releases P to plants. I wonder if this combination with
> charcoal might be a good practice?
>

That makes good sense to me, especially for offsetting increased pH. -Philip

>
>
>
> Rich
> On Jun 27, 2008, at 12:00 AM, Michael Bailes wrote:
>
> I managed to kill some acid loving plants with pyrolysis charcoal from rice
> hulls and other sources.
> (I stole it from BEST)
> Perhaps traditional charcoal would have ash which would raise pH
> The phrase "Lowered soil acidity", is a little ambiguous.
> Does it mean pH goes up or down?
>
> Rarely people test the char- or soil- before they add char to soil/ potting
> mix etc.
>
> I am not even sure if I know what pH means any more.
> The more I learn about soil science the more confused I get.
> m
>
> 2008/6/27 Philip Small <psmall2008 at landprofile.com>:
>
>> Re: [Terrapreta] list of benign effect
>> On Thu, Jun 26, 2008 at 2:05 PM, Michael Bailes <
>> michaelangelica at gmail.com> wrote:
>>
>>>
>>> I am not sure about "Lowered soil acidity", that has not been my
>>> experience.
>>
>>
>> Alkalinity is a well established characteristic of charcoal.  The
>> following is from The Charcoal Vision: A Win–Win–Win Scenario for
>> Simultaneously Producing Bioenergy, Permanently Sequestering Carbon, while
>> Improving Soil and Water Quality<http://agron.scijournals.org/cgi/content/full/100/1/178>
>> *Importantly, charcoal is hypothesized to have several positive impacts
>> on soils (Glaser et al., 2002). First, charcoal is ...  Fourth, charcoal
>> is a liming agent that will help off set the acidifying effects of N
>> fertilizers, thereby reducing the need for liming. *[emphasis added]
>>
>> Michael, was your charcoal washed prior to your use? If you soaked the
>> char and then tossed the soak water, this could help explain your
>> experience.
>>
>> Normally, adding charcoal raises soil pH (aka lowers soil acidity) and is
>> thus considered a liming material.  "Lime" and "liming material"  are
>> interchangeable terms for any material that will raise soil pH<http://www.soils.wisc.edu/extension/shortcourse/New_course_materials/SOILPHANDLIMING.pdf>.
>> Calcium carbonate equivalent (CCE<http://hubcap.clemson.edu/%7Eblpprt/bobweb/BOBWEB2.HTM>)
>> is a measure of liming ability relative to finely ground limestone.  Ash has
>> a CCE of between 50% and 100%, which is fairly high, higher than coarse
>> limestone.
>>
>> It is the ash content of the charcoal that drives its CCE<http://hubcap.clemson.edu/%7Eblpprt/bestwoodash.html>,
>> and even charcoal made to minimize ash content (by burning off as little of
>> the charcoal as is practical) will have a dry weight ash content starting at
>> about 3%. Less efficient processes, such as my home-made charcoal, probably
>> yields starting out at about 10% ash.  The alkaline constituents in ash have
>> a reputation of being fast acting on soil due to their high solubility in
>> water. Thus the CCE of charcoal is fairly easy to reduce with water
>> processing.  This is likely why Dr. Reddy is using washed charcoal to
>> help improve alkaline soils in India<http://terrapreta.bioenergylists.org/Saibaskharalkaline>
>> .
>>
>>
>> --
> Michael
> Most gods throw dice, but Fate plays chess,
> and you don't find out til too late that he's been playing with two queens
> all along.
> Terry Pratchett
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>
>
-- 
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
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