North American Fruit Explorers mailing list at ibiblio

[Geoffrey Tolle <Gtolle0709@wowway.com>]

I'd also like to point out that biochar is formed by the incomplete 
combustion of organic matter. While the periodic prairie burns do 
relatively completely burn the surface "grass", the root masses, 
protected as they are by soil and other organic matter will tend to 
incompletely combust. Over the millenia, even a little biochar after 
each burn will build up.

                                    Geoffrey Tolle

On 2/6/11 4:14 AM, Douglas Woodard wrote:
> The consensus on the black soils of the U.S. midwest is that they were 
> formed by the massive root systems of (especially tallgrass) prairie 
> and savanna grasses and other plants, and the residue of thousands of 
> years of the seasonal growth and decay of the roots of these plant 
> communities, which are maintained by fire.
>
> The fire is encouraged by seasonal dryness, and by cyclical droughts 
> every few decades, which also kill trees.
>
> Such grasses are adept at drawing stored nutrients into the roots for 
> the dormant season leaving mostly cellulose above ground, to minimize 
> the loss from burning.
>
> [Deletions]
>
> Doug Woodard
> St. Catharines, Ontario, Canada