The starchy cassava root has long been an important ingredient in everything from tapioca pudding and ice cream to paper and animal feed. But last year, 98 percent of cassava chips exported from Thailand, the world’s largest cassava exporter, went to just one place and almost all for one purpose: to China to make biofuel.(..)During the second half of 2010, the price of corn rose steeply — 73 percent in the United States — an increase that the United Nations World Food Program attributed in part to the greater use of American corn for bioethanol.