Big crops weigh on prices, which have slumped to the lowest levels since 2020.

Iowa and U.S. farmers are expected to harvest record corn yields this year as favorable weather across most of the Corn Belt helps plants pack on grain, the U.S. Department of Agriculture (USDA) said last week.

Nationwide, the USDA said corn yields will average a record high 183.1 bushels per acre. U.S. soybean yields are also expected to set a...