On Wednesday, in article
Post by Damien R. Sullivan Post by Alan Braggins
"Keith heard it claimed" is pretty weak as cites go though, even by
typical Usenet standards. Anyone got actual numbers?
"The Oil We Eat", Richard Manning, Feb 2004 Harpers. Says in 1940 the average
US farm produced 2.3 calories of food energy per calorie of fossil fuel
consumed. In 1974 it was 1:1; allegedly no one has looked closely since then.
David Pimentel at Cornell, "has estimated that if all of the world at the way
the US eats, humanity would exhaust all known global fossil-fuel reserves in
just over seven years. Some [detractors] have accused him of being off on
other calculations by as much as 30 percent."
Here in the UK, for wheat, a yield of 10 tonnes per hectare is currently
taken to be the target. Farmers paying rent, or paying off a mortgage,
would need to better that.
This is about 4 tons per acre.
I understand that US wheat yields are about half that.
Of course, that extra yield doesn't come free. The fertiliser and
pesticide element of the energy cost is increased, and so is harvesting.
Combine harvesters used in the USA operate with much wider headers than
in the UK, and at what appear to be higher ground speeds.
But it certainly seems plausible, from my experience, that US farming is
less energy-efficient. And I have seen articles in the agricultural
press which suggest some US farmers are following a more European
approach to get higher yields, and by getting more grain from a reduced
cultivated area they are making a better profit. I can't give a
detailed cite for the reports I read, but I think it was in a magazine
called "The Furrow", published by John Deere.
Regular posters to RASFF have described agricultural practices in some
parts of the US, involving pesticide use, which are illegal in the UK
under the basic safety rules, and which would make a crop here
unsellable. So I believe that the energy efficiency of US agriculture
could be improved.
I wonder how much food the US imports?
In any case, food calories are not the significant figure for biofuel
production. Fermentation can produce alcohol from plant components we
cannot ourselves consume. Also, a significant proportion of US meat
production uses human-edible plantstuff. We are omnivores, and a diet
with a high meat content is less than optimal, with more risk of food
deficiency diseases. Likewise, a wholly vegetarian diet. The risks can
be dealt with, but a wholly vegetarian diet, widely adopted, would
damage the economics of milk production. Half of all cattle born are
male, only useful for meat production.
Unless you can get milk from a bull.
And meat animals can be fed to convert food we cannot ourselves eat, and
be fed from land which cannot grow crops.
David G. Bell -- SF Fan, Filker, and Punslinger.
"History shows that the Singularity started when Sir Tim Berners-Lee
was bitten by a radioactive spider."