Study looks at benefits of wheat in corn-soybean crop rotations Access The United States grows a lot of corn and soybeans. Some researchers think it’s a good idea to add wheat into that mix. A new study shows that including wheat once every 4 years in rotations with corn and soybean can have many benefits. The research was recently published in Agronomy Journal. In 2019, farmers across the U.S. harvested corn from 81.5 million acres of farmland. That’s just smaller than the areas of Nebraska and Iowa combined. More than half the corn harvested in the U.S. came from just four states in the Northern Corn Belt — Iowa, Nebraska, Illinois and Minnesota.