What nutritional value does Biochar bring to the table?

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Victor Palkaninec

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May 8, 2013, 5:54:21 AM5/8/13
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Newbie on this topic.

I've read on several pages about Biochar and how it promotes growth in plants in comparison to just plain soil, or soil with NPK. 
I would be very interested learning about any nutritional value that this product can to bring to the plants we eat.  

A large beautiful plate of French Fries looks very appetizing but after we are finished consuming it we have gained nothing, but carbs?

Thanks!


David Hopper

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May 8, 2013, 9:17:25 AM5/8/13
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Victor - Biochar is a soil additive, not a fertilizer. First of all biochar is charcoal; some call it agrichar. This is produced by 'baking' organic matter under high-temp, low oxygen conditions. Char is basically carbon and introducing it to soil contributes to carbon sequestration - meaning that it precludes the release of CO2 from organics that would have occurred without converting it to carbon. When biochar mixed with compost is applied to agricultural soils many trials have found that crop production increases. This is mainly due to the porosity of biochar which enables the char-compost-soil mix to retain moisture and nutrient longer for plants compared to ordinary soil. There are other factors as well - but this enough to answer your question, I hope.          




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Andreas Thomsen

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May 8, 2013, 4:05:48 PM5/8/13
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Hello everybody,
Great that the Biochar group is coming to life.
I absolutely agree with David - biochar itself does not act as a fertilizer, it even may slow down plant growth if not prepared in the right way. Please find a good summary here:
 
 
There you will also find several other articles on biochar and carbon-negative farming.
I am using biochar in my garden for about 4 years now, and I experienced that the best way to charge biochar with nutrients is to mix it with organic waste and to compost it together. If you prepare compost first and then mix it with biochar, much of the nutrients that were released during degradation already got lost, so I highly recommend to add the biochar as early as possible.
 
Concerning your question on nutritional values, Victor - there is not too much data available. Grapes that were grown with Biochar compost tend to have higher contents in anthocyanes and polyphenols, which both have anti-cancer properties:
 
 
My personal feeling is that my vegetable plants and also trees that received biochar compost are at rather good heath.
So far with best regards,
 
andreas
 
 
Gesendet: Mittwoch, 08. Mai 2013 um 15:17 Uhr
Von: "David Hopper" <dber...@gmail.com>
An: bio...@googlegroups.com
Betreff: Re: [Biochar] What nutritional value does Biochar bring to the table?

moretreesplease

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Jul 1, 2013, 6:19:06 AM7/1/13
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I think that the nutritional value of biochar depends on what you load it with - it sounds sensible to mix biochar with compost at an early stage and probably benefit can be gained from adding the rich run-off from worm-composting and also addition of seaweed.  Another value of biochar would be retention of the nutrients in the top soil and absorption of extra nutrients from decaying leaf litter.  In an agroforestry system the charcoal would come from management of the trees and those trees would also be bringing nutrients from the sub-soil and bedrock to be dispersed via leaf litter.  The trees would also catch any excess nutrients that are washed through the top soil.  It would no doubt be useful to know what nutrients the required crop should ideally have, especially trace elements.  Production of certain crops containing specific trace elements or medicinally valuable chemical compounds could be a good selling point - "save money on expensive packaged health supplements by buying our organic vegetables that are carefully grown to consist of their optimum quantity of nutrients ....." (and maybe go on to be more specific)

Nando Breiter

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Jul 1, 2013, 10:18:45 AM7/1/13
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The most plausible benefit in terms of nutrients that biochar provides is that of increased cation exchange capacity - simply stated it stores positively charged plant nutrients in a way and in a location that plant roots can access them, because biochar develops a negatively charged surface as it oxidizes - as long as the biochar is prepared correctly and added to the topsoil. Biochar, when produced at temperatures between say 450 - 550 C, develops a very similar molecular structure to that of humic matter, a somewhat chaotic arrangement of carbon, oxygen and hydrogen. It is that specific structure that facilitates cation exchange capacity, whether in humic matter or biochar. Biochar produced at higher temperatures drives out increasing amounts of O and H, and experiments have confirmed that the cation exchange capacity of these chars falls to almost nothing.

Agricultural plants usually can reach no deeper than 20 to 30 cm. Cations are easily washed down into deeper soil layers when it rains, because rainwater has a negative charge. This is the simple reason why soils with low carbon content have very low plant fertility - they can't retain cations and agricultural plants growing in them can't access the nutrients they need.

Nando



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rongre...@comcast.net

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Jul 1, 2013, 2:36:54 PM7/1/13
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   Nice summation.  Thanks.  Do you have a cite for this?

   Char-making stoves tend to run hotter than your 450--550 C.  Any idea of the lost CEC at 650?

Ron


From: "Nando Breiter" <na...@aria-media.com>
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Sent: Monday, July 1, 2013 8:18:45 AM
Subject: Re: [Biochar] Re: What nutritional value does Biochar bring to the table?

Nando Breiter

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Jul 1, 2013, 5:07:27 PM7/1/13
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Ron,

There was a meta study gathering the data from a variety of research presented at the Rio conference that charted the fall of CEC as process temperatures rose, among other details. I seem to remember it was presented by Saran Sohi, but I also don't find it now looking through the list of presos at http://www.ibi2010.org/agendaagenda.

However, you can take a look at Evelyn Krull's slide deck here, slide 20 demonstrates that significant CEC is lost at 650 C.


I'm not by any means a research expert, but if others claim that high temp chars increase CEC, I'd like to see the evidence behind it. 

Nando

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rongre...@comcast.net

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Jul 1, 2013, 7:14:11 PM7/1/13
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1  Yes -  disturbing decline in CEC in Dr. Krull's figures at higher temps.

2.  But I found contradictory figures by Dr. Lehmann showing monotonic increase with char temp.  Could be in the units.  Highly important.  Lehmann still likes the lower temp range you gave.

3.  In stove terms, the important conversion variable is not total air flow - but rather primary air flow per unit area.  This would argue for shallower wider stoves to get the same power and energy levels.

4.  There is also the issue of post pyrolysis treatments.

More work to do.  Thanks again.


Ron



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Sent: Monday, July 1, 2013 3:07:27 PM

Nando Breiter

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Jul 2, 2013, 6:00:30 AM7/2/13
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Ron,

I don't think it is "disturbing" that CEC declines as process temperatures rise, but rather understandable. Again, the higher the temperature, the longer the residence time, and the more oxygen that is introduced into the pyrolysis zone, the more oxygen, hydrogen and carbon atoms that are not bound in aromatic rings are driven out of the char. Those are the elements needed to form negatively charged functional groups on the surface of the char. The more the evolving char becomes a regularly ordered structure dominated by aromatic rings - or the more it is altered from its original, somewhat chaotic structure, the less it is able to enhance CEC.

It could be that some data shows an increase, say between 400 C and 500 C, but looking at the molecular structure of humic substances and how they enhance CEC indicates that is is very likely we want to preserve a similar molecular structure in biochar if we want it to have the same effect. Data showing a decline of CEC as process temperatures rise seems to confirm this line of thinking.

See attached preso that I developed. The animations are missing in the conversion to PDF, but the only detail that isn't well conveyed is in the slide showing the root and root hairs. A carbohydrate molecule is shown, but what isn't clear is that the plant barters a carbohydrate to the via the hyphae of mycorrhizal fungi in exchange for a needed cation or anion. 

I'm not a soil scientists, but the ones I work with here have reviewed the model in the preso and have told me it represents how cation exchange is understood to work.

Kind regards,

Nando


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BiocharSoilFertility.pdf
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