[Terrapreta] Soil test and CEC

[Jim Joyner]

Thanks all for your responses. I've learned a lot.

I do, however,  have a feeling we're making a mountain out of a mole hill. I'm not a soil scientist but this ain't rocket science. The knowledge to "balance" a soil, regardless of its composition, has been around for about a century.

Carbon is just carbon. It may vary in it's crystalline structure but chemically it is all much like clay.  Charcoal may be activated but it won't be that way for long after putting it in soil. I know Amish farmers who grind up soft (cheap) coal and till it in to there soils. Like charcoal, it's rather long lasting and it increases the CEC. Each particle or face on a grain has a negative charge. All that is typically done to balance the soil is to add enough calcium (and magnesium, if needed) to bring the calcium in the "soup" (CEC) up to 70%. and the
 magnesium to 12%.



In Ohio and Indiana there are muck soils that have so much organic
matter (carbon) in them there appear to have a serious drainage problem. Enough
calcium takes care of that. Sometimes economics enters the picture, but
carbon is not a problem

If we balance the soil this way, the pH will likely be slightly acid (6.5 to 6.8, perfect). pH is a spook. It is a concept we can do without. Plants use nutrients, not pHs. Yes, a neutral pH might indicate a healthy soil, but it might not too. If you raise the pH of an acid soil with potassium, you'll end up with a rock hard parking lot -- but the pH will be OK. If the soil is "balanced", the pH will take care of itself.

Similarly, if we balance the soil, it will be loose (tilthy) and have optimum moisture holding capacity (available to plants) whether the carbon is humus, muck, coal . . . and there's no reason to think charcoal will be any different (if someone has any, I'd love to hear them). What I think is that this balancing process is what is really important to make sure there are no negative affects of the carbon -- whatever its form. Calcium (and to a lesser extent magnesium) is a far greater factor than carbon.



Charcoal in the soil seems to have the virtue of persisting. That's great, especially for farmers with warmer/humid climes and marginal soils. Seems to me, the bigger problem is economics: how to justify spending $10k to $15k per acre applying charcoal. 

Best regards,

Jim





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