Agriculture in Iowa owes its immense productivity to an extreme trade-off. Once, perennial prairie covered 85 percent of the state, and its deep root network built and held together a fertile topsoil layer many feet deep. Now, more than 85 percent is in agricultural production, with the majority in row crops.
Iowa State University
Harris, Mary A. and Iyer, Geetha, "Small Changes, Big Impacts: Prairie Conservation Strips" (2014). Natural Resource Ecology and Management Publications. 129.