[Terrapreta] volatile matter and char

[Richard Haard]

Good summary Sean

We had an analytical lab conduct proximate analysis on both samples we  
used in our soil tests we used this spring. I am wondering if this VM  
content is what makes charcoal hydrophillic and after introduction  
into the soil, microbes use this material as substrate to eventually  
allow water and beneficial organisms to inhabit over time.

Some of our charcoal still has not wetted as it  still makes powder  
when scraped  and others after Larry's pretreatment is waterlogged  
and  fungus/critter friendly. Part of our interest is to see if these  
properties change over time and if there is any pretreatment for fresh  
charcoal, perhaps some kind of composting to speed up this conversion  
process.


On Dec 20, 2007, at 8:43 PM, Sean K. Barry wrote:
> Hi Gerrit,
>
> What is the source/cause of high volatile matter in char?  Does this  
> VM (since it is 'volatile') decrease/volatize by itself over a short  
> time?
>
> According to the article "VM" content is "a measure of the  
> susceptibility of charcoal to further decompose and form carbon when  
> heated."
>
> Translation, please??
>
> We've asked Dr. Michael J. Antal this very question, when he was  
> subscribed to the list.  He was vague about what VM actually is  
> then, too.  It is measurable as the percent weight (VM%) of a  
> charcoal sample (this is done using a "proximate analysis" test),  
> but its chemical analysis is a mystery.  Some others have recently  
> mentioned VM has an insecticidal effect (Dr. Reddy).  Edward Someus  
> also says high VM% content on charcoal is a problem in soil.  People  
> working with Eprida, Danny Day, Dr. Christoph Steiner, etc., were  
> wondering if the VM% was a benefit as "food for microbes".
>
> From what I have read about pyrolysis reactions, the VM% content is  
> be dictated primarily by maximum internal particle temperature in  
> the char bits (this can be somewhat related to residence time in the  
> reactor).  Low VM% is obtained at high temperatures, basically.   
> Higher temperatures produce a more "activated" charcoal too  
> ("activated" charcoal has a high adsorption surface area).  Now,  
> charring biomass on a forest floor or in the soil will not likely  
> allow such high temperatures (~1000C) to be achieved, so one wonders  
> how the original Terra Preta soil was made with low temp char and  
> does not suffer from toxicity.  Perhaps any toxicity in fresh low  
> temperature charcoal is lost over time once it is in the soil.
>
> As you suggest, VM is "volatile", so I imagine it does dissipate  
> somewhat off the surface of the charcoal, through reduction by  
> oxygen from the air, or water.  This has been recognized as a  
> "storage" problem for fresh charcoal.  Fresh charcoal can  
> spontaneously ignite!  THis occurs when the VM reacts and creates  
> heat).  Another question I had was,  ... What about charcoal from  
> natural forest fires that are quenched out by rain, for instance?.   
> Wouldn't these be low temperature and leave toxins in the soil?   
> But, as has been observed, soils on which forest fires have run  
> across do not stop plant growth.  In fact, there is a "bloom" of new  
> growth.  So, what's up? (with this "toxicity of of high VM% on low  
> temperature charcoal" scare).

Interesting is that with Deluca's laboratory experiments he found  
collected wildfire charcoal to be superior to laboratory produced  
samples


' In our second experiment, we grew K. macrantha in soil amended with  
charcoal made at 350°C from ponderosa pine and Douglas-fir bark.  
Growth of K. macrantha was significantly diminished by both of these  
charcoal types relative to the control. In our third experiment, we  
grew K. macrantha in soil amended with six concentrations (0, 0.5, 1,  
2, 5, and 10%) of charcoal collected from a wildfire. The data showed  
increasing growth of K. macrantha with charcoal addition, suggesting  
some fundamental differences between laboratory-generated charcoal and  
wildfire-produced charcoal.'

His experiment is on  Koeleriia macrantha, a grass that thrives after  
wildfires and he showed in his tests that

' that charcoal increased N mineralization and nitrification when  
glycine was added, but reduced N mineralization and nitrification  
without the addition of glycine.' and the concentration of soluble  
phenols in the soil was reduced by charcoal in soils, a compound that  
acts as a natural inhibitor to germination of some species , obtained  
for their experiments with extracts of Arctostaphylos uva-ursi, or  
knicknick a native shrub.

This result is an interesting look a dynamics of plant forest  
understory plant communities and a natural adaptation to fire. Here is  
the same plant community as Deluca studied after a fireThese  
germination and growth inhibitors are very common in nature and are  
used by plants to control the growth of plants in direct competition  
with the species

What is especially interesting to me is that Larry's charcoal  
pretreatment is based on what he intuits the conditions of original  
peoples handling of charcoal in Amazon basin and includes extracts of  
cooked meat and urine. An exact parallel with Deluca's work and as  
result of Larry's work case anecdotal  evidence of beneficial effect  
and of direct observation of charcoal hydration and utilization by  
microbes and plant roots. :>)

So here we have a report on a test that screened the properties of  
different charcoals on soil natural processes, both mineralization,  
nitrification and degradation of germination inhibitors found in a  
natural setting.

Here is another abstract on these natural inhibitors in tropical and  
subtropical plants and the effects of extracts of germination and  
growth of crop plants , cucumbers, corn, sorghum and bean in Puerto  
Rico.

http://www.blackwell-synergy.com/doi/abs/10.1111/j.1399-3054.1969.tb07374.x


>
> I think this premise needs testing.  I think no none who has  
> provided any "field results of using charcoal in soil" here yet, has  
> known that the charcoal they used was low VM% or even what  
> temperature the char was made at (no data on this presented).  I can  
> make charcoal with my reactor and control the max temperature inside  
> the reactor core.  I can do a "proximate analysis" test on any  
> charcoal produced and make measurements of VM%.  I cannot discover  
> any ways yet to characterize the chemical analysis of the VM in any  
> way.  Dr. Antal got short with me when I asked him about doing  
> this.  He told me, like in the paper, Volatile Matter is only  
> quantifiable, not characterize-able.  (Who gets to say, "That's  
> bunk!" to a PhD?).


No need to get hoof in mouth disease because we do not need to know  
exactly what this VM is only that if natural soil dynamics eventually  
will eat this stuff and if its presence/absence effects function of  
charcoal in soil.


Here is a nice description from wikipedia of  Allelopathy

' or the natural process plants use by releasing chemicals into the  
environment and subsequently influence the growth and development of  
neighbouring plants. It is important to keep in mind that allelopathy  
involves the addition of a chemical compound or compounds (secondary  
metabolites) into the environment, while resource competition involves  
the removal or reduction of some factor or factors in the environment  
(such as nutrients, water, or light).'




>
> It may be that the processes required to produce low VM% charcoal  
> are more expensive than otherwise, so these producers are trying to  
> play up the value of their product.  I think the premise needs  
> testing.  I think most testing occurring now is NOT seeing this  
> detriment in their plant growth results.
>
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