[Terrapreta] Soil test and CEC

[Kevin Chisholm]

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