A soybean field near Campo Verde in western Brazil in January 2011. Researchers argue that enough arable land is already under cultivation to feed the planet for the next several decades. Yasuyoshi Chiba/AFP/GettyImages hide caption

itoggle caption Yasuyoshi Chiba/AFP/GettyImages

A worker piles sacks of corn at a market in Guatemala City. Daniel LeClair/Reuters /Landov hide caption

itoggle caption Daniel LeClair/Reuters /Landov