To Joel & all who dragged out "Loomis and Connor" to try to figure this
out,
I was quite bothered by the question of why the pesticides would have a
higher embodied energy per kg. than fixed nitrogen. That really didn't
make sense, so I went over that chapter in Crop Ecology pretty
carefully. I found that the authors had made some assumptions about
embodied energy calculations which would have to be clarified before
comparing to what other authors call embodied energy. There was no
reference to the source data, so I was ready to send email to the
authors for clarification and hopefully a reference.
Then I noticed in Table 15.3. (a) on page 404 what I did not see the
first 10 times I read it, which was the italicized "Heats of combustion"
under the heading "Material." It probably should have been under the
heading "Energy content."
Anyway, the answer to this small mystery is, I believe, that these
numbers are NOT "embodied energy" at all.
Now I am very curious about how others think of embodied energy, since
what I have just read suggests a departure from what I have always meant
by "embodied energy." It seems as if there is a potential here for a
lot of confusion if these two divergent ideas are being discussed under
the same subject heading.
Joel B. Gruver wrote:
> get out my copy of "Crop Ecology" by Loomis and Connor. On pages 404 and
> 405, Loomis and Connor present a table of the energy costs of a wide array
> of field operations as well as embodied energy costs of agricultural
> inputs.
>
> The embodied energy costs of paraquat and glyphosate (roundup) are listed
> as 460 MJ/kg (Megajoules/kilogram) and 450 MJ/kg.
> BTW Why is the energy cost of producing a kg of paraquat/glyphosate so much
> higher than the cost of producing a kg of N fertilizer ?
Loren Muldowney
loscott@envsci.rutgers.edu
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