Long-term research on extended rotations for corn and soybeans

Crop diversification has diminished in the USA during the past 50 years, and monocultures and short rotation sequences are currently the prevalent cropping systems. 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. 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. In this report we discuss the impacts of cropping system diversification on weed management, predatory insects, soybean sudden death syndrome, and crop productivity, based on results from a long-term crop rotation study in Iowa.