Straight from the USDA website, the US plants about 90 million acres of corn annually. One square mile is 640 acres, so that’s >140,000 square miles. The IO9 article says 50,000 square miles of ‘lawn’ are out there (which sounds crazy high). In any case, 140,000 > 50,000

http://www.ers.usda.gov/topics/crops/c…