With fertile soils and a major port on the Black Sea, Ukraine has quickly emerged as a powerhouse in the global grain and oilseed export market and as a formidable competitor for U.S. farmers.

This year, the eastern European country is projected to export 32 million metric tons (approximately 1.22 billion bushels) of corn, wheat, soybeans and other crops. That’s more than half of the country’s harvest.

At the same time, Ukraine...