[Terrapreta] Soil test and CEC

[Jim Joyner]

Michael,



Stephen Joseph says that NSW DPI have done work on CEC.(
contact Yin Chan who is at the Ag station at Richmond. )

>From what I can see, The CEC is going to respond about the same way to
charcoal as it will to any other organic (carbon) material such as
humates,  coal, stable humus . . . That's good enough for me. 

$15,000 per acre for charcoal.!How much are you adding?The Japanese are getting by with 100g per sq metre per year an tea trees
That is based on about 1.5 to 2 inches, although, I suspect any amount will be beneficial. That is my own calculation for raising the CEC an optimum amount. Soils vary a lot. but I think I also saw that this is close to wht the folks at Cornell recommend. But the question you raise is a good one.

Seems to me the prime benefit to using charcoal is to raise the CEC. If the soil is sandy (very low CEC), then one needs a lot more to have much of an effect. I my case, I have a silt that is similar to sand and needs a great deal. In the case of a heavy clay soil or a muck soil (large amount of biomass already), I'm  not
 sure what exactly the benefit of charcoal would be, especially in a northern, cold clime. It wouldn't hurt anything, but considering the marginal benefit, it might be a waste of money.

Looking at the pictures of TP in the Amazon, the soil appears to be
sandy, which, I think, meant they had to apply a great deal of
charcoal. Plus, they had to add large amounts of calcium, maybe with
fish/animal bones to make sure that nutrients and moisture weren't tied
up like they would be in a low calcium, heavy clay.

Ultimately, what can make the investment a good one is the fact that it may not only be spread over many years but many generations. Even at $15,000/acre, if it improves the soil's structure by leaps and bounds -- and stays that way -- that is nothing spread over a 1000 years! Even a hundred years.
.
I think one of the things a study of TP does is forces you to see the soil as a dynamic living, interacting community of unnamed and numerous terrestrial beings.
So does all soil. Nice sentiment, but a little overly romantic for a farmer. Now with gardening (I assume from you signature statement, you are a gardener), when you consider that gardening is and always has been the most efficient form of agriculture (never mind the other, less tangible benefits), the investment has even much greater potential
 returns.

It is Terra preta's effects on this community which is of interest.  
I guess I don't quite understand the context of your statement. 

How do we make soil, as well as plants, grow?
Depends. If you have a good soil in a cold clime, just take care of it by returning what is taken out. If you have beach sand, there's not much you can do, practically. If you have a heavy clay soil, you make sure you have sufficient calcium/magnesium applied even down into the sub soil. Most of us are somewhere in among these.

Jim








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