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permaculture - Re: [permaculture] Harvesting of prairie biomass for energy?

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  • From: dwoodard@becon.org
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] Harvesting of prairie biomass for energy?
  • Date: Fri, 26 Jan 2007 18:29:07 -0500 (EST)

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




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