Good point Horace.
----- Original Message -----
From: "Horace Heffner" <[EMAIL PROTECTED]>
To: <vortex-l@eskimo.com>
Sent: Friday, March 10, 2006 8:21 PM
Subject: Re: Farrell responds to Pimentel regarding ethanol
On Mar 10, 2006, at 4:57 AM, Michel Jullian wrote:
Again thanks for the teaching Fred, I had no idea it was the case!
The only biofuels that are ever mentioned here in France are Colza
oil and ethanol.
Then nitrogen fertilizing is indeed a moot point wrt biofuel such
as soydiesel, or what am I missing again in my presomptuous
reinventing of the biofuel wheel? ;)
The problem with regard to nitrogen fixation and other soil depletion
is the not that it *can* be circumvented by judicious management, but
rather what *may* actually happen and what is actually proposed to
happen. For example, elephant grass is touted as the solution to
ethanol production in northern latitudes. However, see:
http://www.fao.org/ag/agp/agpc/doc/Gbase/DATA/Pf000301.htm
"A complete fertilizer mixture may be needed for establishment
according to soil fertility. In Tobago, West Indies, a crop of
elephant grass removed 463 kg nitrogen, 96 kg phosphorus and 594 kg
potassium per hectare per year. The optimum phosphorus content of the
dry matter for growth was determined as 0.248 percent for the purple
type and 0.215 percent for the green variety (Falade, 1975). High
rates of nitrogen generally give good responses (Walmsley, Sargeant &
Dookeran, 1978) especially in the third and subsequent years when the
native soil nitrogen has been exhausted (Vicente-Chandler et al.,
1953). The latter authors suggested that the highest yields could be
expected from cutting at 12-week intervals and applying nitrogen
after every cut."
If oil hits $150 a barrel then it will be more expedient to buy
fertilizer and make a killing in a market which may not last than to
worry about crop rotation.
Horace Heffner
