He said that around 40% of the maize crop would be used for biofuel production to hit US federal mandates, leaving much less of it for food markets. This will mean that biofuels are used to feed cars whilst people go hungry as food prices increase due to the shortages.
As a result, he has has called for the reduction or suspension of the US biofuels mandate.
You can read his full article here: http://www.ft.com/cms/s/0/85a36b26-e22a-11e1-b3ff-00144feab49a.html#axzz2399Yfj5I