8 bushels (400 lbs) of corn/maize per human year for pure calories. 200 bu/acre yield for corn/maize nowadays, so 25 people supported by an acre of industrial

8 bushels (400 lbs) of corn/maize per human year for pure calories. 200 bu/acre yield for corn/maize nowadays, so 25 people supported by an acre of industrial agriculture. 43560 sq ft in an acre. Intensive dirt farming would require 2000 sq ft/person, at a minimum, fudging up for protein and nutrients. Looks like a decimal error on their part.