Growing corn and soybean supplies in South America are creating new challenges for U.S. producers. The USDA increased production estimates for both Brazil and Argentina in its latest supply-and-demand report. Brazil’s corn crop is now projected at 138 million metric tons, while soybean production remains at a massive 180 million metric tons. Argentina’s corn and soybean forecasts also moved higher. The Wall Street Journal reports the larger crops contributed to weakness in Chicago grain futures as traders factored additional export competition into price forecasts. Analysts say abundant South American supplies could make it more difficult for U.S. exporters to gain market share during the coming marketing year. Farmers continue to monitor export demand and weather conditions as they assess potential marketing opportunities ahead of harvest.