Wednesday, September 19, 2007

Sean Barry on the Antiquity of Terra Preta.

Sean Barry gives us this post on the antiquity of Terra preta in Brazil and its living history from the terra preta group.

The people who live in Brazil, the families who have farmed land with Terra Preta soil on it for 500+ years generation after generation, will attest to it, though. Some grow world record productive papaya and mango groves. They do not buy or use industrial fertilizers. They, like the generations of ancestors before them, put back into the soil, those parts of the harvest, which are not eaten. They value the land for its fertility. They guard it closely. There are laws that prohibit "mining" and "selling" TP soil. It is truly valuable land for them because of it productivity. They are not corporate entities, with huge capital assets, and armies of PR people, making things sound so good, that you can hardly believe it. They are truck farmers, peasant farmers. They do what they do and it works for them. That is all the evidence they need.

I grant you that most of these people are not scientists and they could not tell you why the TP soil they live on and grow crops in can do what it does. They just know from experience over their lifetime and the lifetimes of the generations before them that TP soil provides them a bounty for the growth of crops. Some have documented ownership and cultivation for 500+

I, like many, including the people who use TP soil, do not know what the"recipe" is. From what I have read, the cultivation practice that makes most sense to me, for maintaining the soil fertility under continuous cultivation, is that they "return" to the soil all of the plant wastes from the harvest. They compost the food wastes back into the soil, also. My belief is that the charcoal carbon in the soil pays large dividends for their deposits. They give back the plant nutrients that they do not use and the soil/micro-organism ecology in the soil gives it to the plants in their next crop.

I do not know that anyone has come up with a definitive, scientifically arrived at understanding as to how it all works. It is from generations of experience that they "know" that it works. They might not know "why" or "how" it works, but they will protect it as an asset, nonetheless. They do not abandon it because they do not know how it works.

So, I guess I am saying it's anecdotal. This is very like what Dr.A.D. Karve says. He has a hypothesis about why what he is doing works.

He is trying to develop theories as to "why" and "how". He has many village farmers that rely on his methods, practice his methods, and believe that "it works", because it does for them. Maybe, someday, he will be able to show (the damned nit-picking (I'm kidding)) scientists why.

I would say, though (and you have pointed this out yourself recently), there are two camps in here about Terra Preta; 1) those that want it for its enhanced agricultural benefit, and 2) those that want this for carbon sequestration.

I think 1) is possible and hard to know why. I think 2) is obvious and absolutely clear by virtue of the mere existence of 2500+ year old charcoal carbon in the Amazon rainforest. It was put there by people long ago. It is still there. It has been sequestered for 2500+ years ... No doubt about it (not in my mind). This is like 15 times the duration of our entire Industrial Revolution and 15 times the amount of time that it has taken humankind to pump all the 300 million year old fossil fuel carbon into the atmosphere! Clearly, we can sequester carbon by putting charcoal carbon into the soil, don't you think?


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