Voice of America: The growing demand for food worldwide has helped push the price of many commodities to record levels. Besides demand, prices are influenced by other factors such as weather patterns and pollutants that can affect crop yields. At the University of Illinois in Urbana, researchers are studying the effects pollutants have on crop growth. As VOA’s Kane Farabaugh reports, the researchers say they can accurately predict future carbon levels in the atmosphere and in the world’s farm fields. …