In its World Agricultural Supply and Demand Estimates (WASDE) report last week, the U.S. Department of Agriculture (USDA) raised its projection for U.S. corn-ethanol output and slashed its outlook for Argentina’s soybean harvest.

The U.S. corn crop is forecast at 14.6 billion bushels, the report said. And more of that big crop will headed overseas,

The department increased its estimate for corn exports by 175 million bushels to 2.23 billion, citing “U.S. price competitiveness, record-high outstanding sales and reduced exports from Argentina.”

Soybean farmers will harvest...