Corn field in Black Hawk County, Iowa.
Iowa State University agronomy professor Matthew Liebman has been experimenting with crop rotation as a means of reducing waterway-polluting fertilizer usage, according to a recent article in National Geographic.
Liebman used a three- and four-crop rotation – consisting mostly of corn, soy, oats, and alfalfa – across 22 acres. The study concluded that crop rotation not only reduced nitrogen levels – a byproduct of fertilizers that pollute waterways – but also produced higher corn yields. These pollutants contribute to contamination in the Mississippi River which has lead to a virtual organic “dead zone” where the river empties into the Gulf of Mexico.