The nine-year Marsden Farm study—conducted by researchers from the USDA, the University of Minnesota, and Iowa State University—replicated the industrial corn-soy midwestern
farming system alongside two multi-crop alternatives. A three-year rotation incorporated another grain plus a red clover cover crop (pictured here), and a four-year rotation added
alfalfa, a key livestock feed, into the mix. The more complex systems enhanced yields and profits, controlled weeds, and reduced chemical fertilizer, herbicide, and energy use.