Actually, Pollan's research is correct in terms of how nitrogen fertilizer is made today by industry. These days, part of the actual source of hydrogen needed in the chemical process comes from a reaction between natural gas (methane) and water (part of the natural gas is burnt to heat water and produce steam, which, when combined with the methane, produces hydrogen gas and carbon monoxide). The haber-bosch process only gets more complicated after that...John's right in saying that it would be possible to do this without fossil fuels, but it would still take an incredible amount of energy to get a source of hydrogen gas and then a little more energy to get hydrogen and nitrogen to react with one another, even though this part does release heat on its own like John said.
Why not just promote the much more elegant process used by certain legume species and their best buddies---the fertilizer making microbial symbionts who do it all with a little sugar from the plants and some magical enzymes?
I found this to be a useful link estimating how much fossil fuel is in a bushel of corn, strictly in terms of the fossil fuel used in the haber-bosch process.
Thanks for the intellectual honesty,
John Warner <daddyoat@...
Michael Pollan, quoted in full below, says, "When I've done research on
nitrogen fertilizer . . . [I've found] that we've learned how to turn
fossil fuel into food for our plants."
This is not correct. As a small farmer who practices alternative
agriculture, I feel poorly represented by a number of self-appointed
spokespeople who claim they are championing my interests. I prefer
Industrial nitrogen is generated by the Haber process which goes like this .
Hydrogen and nitrogen gas, when subjected to heat and pressure, will yeild
ammonia plus heat [which is put back into the process].
So where's the fossil fuel? None required. Heat and pressure can easily be
generated from renewable resources such as hydroelectric or perhaps even
wood. It would be interesting to know, however, how much net energy is
required to keep the process going. It's quite likely that in practice
petrofuels are used, but they are not required.
Today I was listening to audio of a panel discussion entitled Fast Food
World: Perils and Promises of the Global Food Chain. Below is a rough
transcription of an astute question from an audience member along with
answers from three of the participants.
Q: Do you think that we have changed the carrying capacity of the earth
through fossil fuels to the extent that we could not support the current
population with organic agriculture free of synthetic fertilizers?
Michael Pollan: That is a very hard and scary question. When I've done
research on nitrogen fertilizer, which in a way is the key 20th century
invention driving the whole industrialization of food, is the fact
that we've learned how to turn fossil fuel into food for our plants. I
learned that there are 2 billion people on this planet whose very
substance is nitrogen that came from those fertilizers. So whether we
can undo that is a real question. That is the limiting factor in so
much agriculture and therefore in so much population is this limitation
on the nitrogen in our soil--and we've exceeded that artificially. Now
there is a margin, Wes Jackson says there is a kind of margin of error
because we're feeding so much food to animals. If we truly went to
organic and could eliminate all the fertility we are giving to our
cattle, it might help. I don't think it is at all clear that going
to organic agriculture as we know it could support a population of 8
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