according to all I have read, there are two main causes for the observed rise in the prices of corn, wheat, and rice. first cause is the diversion of large quantities of grains into biofuels. second cause is the change in eating habits of many humans from vegetables and grains to Meats. It takes tremendous amounts of grains to feed cattle to a point that they can be slaughtered. As more and more humans choose to eat more meat, and gain enough money to do so, the human race requires more grain production to feed the cattle, pigs and other livestock. This is a very simple supply and demand situation. If you desire to reduce your impact on our planet it terms of greenhouse gases and the preservation of ecosystems for other species, it is important to eat as little meat as possible (and in the western world most of us eat far more than we need, and far more than is healthy). It is also important to reduce the amount of fuel we use, be it fossil fuel or biofuel. Most biofuel uses a large amount of fossil fuel in production anyway, other than ethanol from sugar cane. The benefits of biofuels were oversold, and the potential negative impacts were undersold, because we feel our oil addiction and see biofuels as a magical answer. the true magic answer is to use renewables such as solar and wind to fuel battery vehicles and public transit.