[Terrapreta] Charcoal costs

[Richard Haard]

Jim

Could the difference be the be the characterization of the charcoal  
itself.? Mine are 2 sources , made from a covered heap and made in an  
industrial pyrolyser.

If so also are there pretreatments, such as aging to oxidize and leach  
the char sample before using. To determine impact of your charcoal on  
CEC is only a $8 test.  We have our surplus 2 lots of charcoal aging  
under a tree since May. There is also the question whether my charcoal  
treatment blocks will have changed CEC after next years cropping.

After all the compounds responsible for making charcoal hydrophobic  
are most likely biodegradable. Wood chips incorporated into the soil  
retain their integrity for 1-2 years and eventually disappear.

There could be a biological process here that may show up. With  
Larry's charcoal tests on swiss chard he showed a intimate association  
of fungal mycelium and plant roots with the charcoal.
<http://www.flickr.com/photos/rchaard/336553821/in/set-72157594444994347/ 
 >
  My tests had mycelium but was associated with the wood chips used in  
making the commercial compost we used. (mostly from Nidularia - Birds  
nest fungus found on rotting wood).
<http://www.flickr.com/photos/rchaard/2098572906/in/set-72157594444994347/ 
 >

Rich


On Dec 9, 2007, at 7:42 AM, Jim Joyner wrote:

> There is something missing here. I suspect it is tools.
>
> In Richard's tests the CEC does not increase with the application  
> charcoal. It does increase the OM but that is probably not a true  
> reading but a deficiency in our soil analysis.i.e., the test is  
> reading the carbon in charcoal as organic when it is not.
>
> The CEC increases with compost and charcoal (in Brazil)  . . . well,  
> of course it does. The compost yields a type of carbon that is acted  
> upon through biological processes . . . but not the charcoal. The  
> benefit of charcoal is that it pesists, but that is because it is  
> not a part of the chemical (electrical, ionic).
>
> There is no reason to believe charcoal directly raises CEC. CEC is  
> essentially an electrical measurement of the capacity to hold  
> nutrients in a suspension from plants can draw them. Charcoal does  
> not seem to be a part of the electrical  or chemical equation.
>
> We can't have it both ways.
>
> It may me that charcoal yields a type of mechanical (if you will)  
> structure that will hold nutrients in place while the biological  
> processes proceed -- without them be washed away by rain or oxidized  
> by the presence heat and humidity.
>
> I don't think we have the measurement tools (or maybe just a good  
> theory) yet to determine what is going on in the soil with charcoal  
> or to what extent. Empirically, we may see better growth (or more  
> worms), but that gives us no universal set of principles to apply  
> what we know to other soils and climes. This empirical view, when  
> compost is applied, just distorts what we see.
>
> And, most of what we have been saying about charcoal's benefit in  
> the soil is still speculative. The tools we have just don't tell the  
> whole story.
>
> Jim
>
> Kevin Chisholm wrote:
>>
>> Dear Tom
>>
>> Tom Miles wrote:
>>
>>>> Capacity of the soil, but that Torrified Wood has the Cation  
>>>> Exchange
>>>> sites tied up, and that it would not work a effectively as char.
>>>>
>>>>
>>> So what's the marginal value of CEC? I don't think we know this yet.
>>>
>>>
>> This paper shows that an increment of charcoal to a soil increased  
>> the
>> CEC from 24.9 to 47.2.:
>> http://www.georgiaitp.org/carbon/PDF%20Files/Posters/ChengPoster.pdf
>>
>> I am not certain of the quantity they used in their test. They state:
>> "An incubation experiment was performed in which either water-washed
>> charcoal or a charcoal-soil
>> mixture in a ratio of 50:1 was incubated at either 30°C or 70°C."
>>
>> I find this confusing. This suggests the test mixture was either 100%
>> water washed charcoal, or 98% water washed charcoal and 2% soil  
>> mixture.
>> However, their Table 2 lists the tests they performed with  
>> variables as
>> follows: Soil, Soil + Char, Soil + Char +Fertilizer, Soil + Char +
>> Microbes, Soil + Char + Manure, Soil + Charcoal+ Fertilizer 
>> +Manure....
>> This suggests that they measured the changes to the soil with  
>> additions
>> of various ingredients.
>>
>> If we ASSUME that the actual tests involved soil as the starting  
>> point,
>> and that there were 2% additions of each ingredient, we can calculate
>> the marginal or incremental value for the CEC of Char. If this was  
>> the
>> case, then a 2% addition of char increased the CEC of the soil from  
>> 24.9
>> to 47.2, a change of  22.3 mmole/kg. From this we calculate that  
>> the CEC
>> for the Char alone would be about 50 times greater, or about 1,115  
>> mmole/kg.
>>
>> Would you think that these assumptions are reasonable? Is this a
>> reasonable interpretation of the data presented?
>>
>> Best wishes,
>>
>> Kevin
>>
>>> Tom
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
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>>
>
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