[Terrapreta] Catalyst: Carbon Bigfoot

[Duane Pendergast]

Thanks for that calculation Chuck,

I guess even if I make it for another 30 years, I won't have to lose too
much sleep over terra preta sucking excessive CO2 from the atmosphere.

Maybe there is some potential for increasing the arable land count in the
long run.

Duane

-----Original Message-----
From: terrapreta-bounces at bioenergylists.org
[mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Chuck Yokota
Sent: December 10, 2007 12:29 PM
To: Terrapreta
Subject: Re: [Terrapreta] Catalyst: Carbon Bigfoot


The Earth's atmosphere holds roughly 800 billion tons of carbon in 3000
billion tons of carbon dioxide.  Field experiments mentioned on the list
use 5 to 10 tons of char per hectare.  There are 5 billion hectares of
agricultural land in the world.  If every farmer applied 10 tons of char
per hectare, that would take 50 billion tons out of the carbon cycle.
This would still leave carbon dioxide levels far above pre-industrial
levels.  Farmers would need to apply more than 50 tons per acre to bring
carbon dioxide levels back to pre-industrial levels.  I would expect
that the agricultural value of more char would hit an economic limit of
diminishing returns long before it reached that point.  We are not in
danger of depleting the Earth's atmosphere of carbon dioxide.

Kevin wrote:

Dear Lou

lou gold wrote:
> Hi Duane,
>
> del...
> The only thing that I question is your assertion that we must continue

> to generate CO2 in order to feed the plants. It seems to me that there

> is a huge reservoir already available. Do you know of any studies or 
> models that might suggest when CO2 will "peak" and require replacement

> inputs, perhaps from fossil fuels?
The Greenhouse Industry has done alot of work, and research papers, on 
the benefits and economics of CO2 to greenhouse atmospheres in teh 
winter, when greenhouse ventilation is low. The plant canopy strips the 
CO2 from teh closed atmosphere very quickly. Commonly propane or natural

gas is burned, with products of combustion vented into teh growing 
space, to enrich CO2 to enhance plant growth.

A Google search for "greenhouse CO2 Enrichment" gives 21 hits; with no 
quotes, you get about 340,000 hits.

Best wishes,

Kevin


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