Some numbers.
The Green Revolution increased the energy flow to agriculture by an average of 50 times the energy input of traditional agriculture.5 In the most extreme cases, energy consumption by agriculture has increased 100 fold or more.6
In the United States, 400 gallons of oil equivalents are expended annually to feed each American (as of data provided in 1994).7 Agricultural energy consumption is broken down as follows:
\ufffd 31% for the manufacture of inorganic fertilizer
\ufffd 19% for the operation of field machinery
\ufffd 16% for transportation
\ufffd 13% for irrigation
\ufffd 08% for raising livestock (not including livestock feed)
\ufffd 05% for crop drying
\ufffd 05% for pesticide production
\ufffd 08% miscellaneous8
Energy costs for packaging, refrigeration, transportation to retail outlets, and household cooking are not considered in these figures.
To give the reader an idea of the energy intensiveness of modern agriculture, production of one kilogram of nitrogen for fertilizer requires the energy equivalent of from 1.4 to 1.8 liters of diesel fuel. This is not considering the natural gas feedstock.9 According to The Fertilizer Institute ([link|http://www.tfi.org|http://www.tfi.org]), in the year from June 30 2001 until June 30 2002 the United States used 12,009,300 short tons of nitrogen fertilizer.10 Using the low figure of 1.4 liters diesel equivalent per kilogram of nitrogen, this equates to the energy content of 15.3 billion liters of diesel fuel, or 96.2 million barrels.
There are huge advantages to using nitrogen fertilizers, especially for corn. The [link|http://www.calciumproducts.com/record_yield.htm|record] for non-irrigated fields is 442 bushels/acre. (Typical averages for the US are about 130 bushels/acre.) The [link|http://www.gocorn.net/mag_Fertilizer6.htm|usual recommendation] is about a pound of nitrogen per bushel so Francis Childs is using a lot of fertilizer.
Cheers,
Scott.