Crop diversification: Impact on weeds, soybean sudden death syndrome and crop productivity

Crop diversification has diminished in the USA during the past 50 years, and monocultures and short rotation sequences are currently the prevalent cropping systems (Brummer, 1998; Cook, 2006). Simplification of cropping systems has been accompanied by greater reliance on synthetic pesticides and fertilizers to manage weeds, diseases and soil fertility, creating concerns about contamination of underground and surface water by nitrogen, herbicides and soil sediment (Hartwig and Ammon, 2002). Learning how to reduce reliance on synthetic fertilizers and pesticides without compromising farm productivity and profitability is a key priority for Iowa and other parts of the U.S. Corn Belt (Gomez et al., 2012; Cruse et al., 2010). In this report we discuss the impacts of cropping system diversification on weed management, soybean productivity, sudden death syndrome, and root health, based on results from a long-term crop rotation study in Iowa