"It takes about a thousand tons of water to produce one ton of grain that, fed to cows, produces only 18 pounds of meat."

James Martin
Meaning of the 21st Century (2006) page 4
http://www.amazon.com/Meaning-21st-Century-James-Martin/dp/1573223239
givemestrength - Amazon have a 'Look Inside' feature where you can read much of the book