[Terrapreta] Soil test and CEC

[joe ferguson]

My recollection is that activated charcoal is produced industrially with 
a final step in which it is heated in a retort to a very high 
temperature (1000C or more) UNDER VACUUM so that volatile material is 
driven off.  It must then be properly cooled and stored in an 
hermetically-sealed container to prevent it from absorbing miscellaneous 
contaminants from the atmosphere.

Kevin Chisholm wrote:
> Dear Jim
> Jim Joyner wrote:
>   
>> Has anyone here ever done or seen a before-and-after (charcoal) soil 
>> test, particularly with an eye to the cation exchange capacity (CEC)?
>>     
> I haven't done such tests,  or seen such results. Such tests would 
> indeed be very helpful
>   
>> Seems to me, that is the issue in a nutshell. If the CEC is increased 
>> then we have a better potential soil, period.  I say potential because 
>> a higher CEC simply indicates greater holding capacity for nutrient. 
>> But if the CEC is higher, we at least know what needs to be done next 
>> and what to add to the soil. The rest is economics.
>>     
>
> Two things seem to influence CEC... surface area and chenmical 
> reactivity. Charcoal is well known for its large internal surface area. 
> As far as I know, the only difference between "regular" charcoal and 
> "activated "  charcoal is the much larger active internal area of 
> activated charcoal. I speculate that the "tars" remaining after low 
> temperature carbonization are  like a "partial paint job" that 
> deactivates some of the adsorption sites.
>   
>> I read somewhere in the list archives that there was a concern about 
>> whether or not the charcoal was created at high or low temps (I'm 
>> speaking of wood or trees.). That might make a difference but there is 
>> no reason to think so. I mean, wood has little or no nutrient in it to 
>> begin with. Maybe a little potassium, but pyrolysis doesn't change 
>> that. Potassium doesn't go away in any event. High temp, low temp, 
>> burn it to ash and the potassium is still there. And most soils have 
>> sufficient potassium, even the sorry stuff I farm in.
>>     
> It is very unlikely that the Primitive Folk in the Jungles of Brazil had 
> the technology to produce activated charcoal. It seems likely that they 
> could only produce Low Temperature Char which they used as part of the 
> Terra Preta Protocol. If it worked for them then, then it should work 
> for us now.
>   
>> There was some comment about the possibility of "resins" being left in 
>> low temp charcoal. So what? That just means there are still some 
>> hydrocarbons left and that just means there some un-combusted 
>> hydrogen. Either way, that hydrogen is going to go away and carbon is 
>> going to be left -- maybe in a less permanent state than charcoal.
>>     
> There is more to "resins" than just hydrogen. There is some suggestion 
> that teh "residual resins and tars" in low temperature charcoal can 
> actually be beneficial.
>   
>> But going back to my original comment, it's the CEC that counts. 
>> Everything else simply follows. If the CEC is greater and more 
>> mutients are available, of course plants will do better and soil 
>> biological life will be enhanced. How could it not?
>>     
> That makes eminent good sense. In moderate quantities, it is hard to see 
> a downside potential. "Too much" by definition is too much.The optimum 
> quantity of char would likely vary, depending on the "starting soil", 
> the crop grown, and growing conditions (water, aeration, temperature, 
> soil life forms present, etc). Additionally, a "support program" of some 
> sort would be required to replace the nutrient demands of the plants, 
> and to nourish the soil life forms.
>
> We should be cautious about forcing their Terra Preta practices to fit 
> into our "modern" growing paradigm. It doesn't matter if the Terra Preta 
> System is right or wrong by our judgemental standards, if the Terra 
> Preta System worked, it is right, on the absolute scale.
>
> Best wishes,
>
> Kevin
>
>
>
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