permaculture

[dwoodard@becon.org]

Tallgrass prairie, which I think is the ecosystem from which most of
these species are taken (switchgrass is from the tallgrass) is a
fire-adapted ecosystem and is maintained by fire. Most of its species
take down most of their nutrients to the roots when dormant for the
winter, so they lose as little as possible to fire which normally
occurs in spring and fall.

The massive and deep root development of these species, adapted to
survive summer drought, is what produces the high organic matter of 
prairie soils ("chernozem"). Think of Iowa.

I don't think organic matter is a problem. I expect that multispecies 
mixes close to the species composition of the original tall grass
prairie, can be maintained indefinitely without cultivation which is the 
real problem in maintaining organic matter and preventing erosion.

I understand that monocrop switchgrass has to be plowed and reseeded
after about five years. That's a lot better than corn but not as
good as one would wish.

It would be helpful if the mineral residue from processing the cellulose 
crop could be returned to the soil.

Doug Woodard
St. Catharines, Ontario, Canada



On Fri, 26 Jan 2007, Lawrence F.London, Jr. wrote:

> Rael Bassan <rael@...> writes:
>
> > In a recent [Permaculture Forum (Upper Midwest)] post there was some
> > concern about the proposed harvesting of prairie biomass for energy,
> > suggested by the  Minnesota studies of David Tillman's group. According to
> > their analysis, using a prairie plant mixture of up to 14 species "comes
> > out 6 to 16 times better than corn grain ethanol or biodeisel [sic] ."
> > www.vnps.org/chapters/princewilliam/wildnewsjanfeb07.pdf
>
> Doesn't harvesting prairie plants for conversion to ethanol result in 
> serious
> organic matter and accompanying soil microflora depetion in those soils?
>
> LL