The agricultural practice of planting only one or two crops over large areas. In the United States, corn and soybean are the only crops grown on most farms in the central Midwest, while on the Great Plains wheat is almost exclusively grown. Although it minimizes farmers' investments in large, expensive implements, the practice exposes crops to the risk of being wiped out by a single predator. This happened with the Irish potato blight of the 1840s and the corn leaf blight of 1970 in the United States, which destroyed millions of acres of corn. Ecologists warn against monoculture's over-simplification of the food chain/web, arguing that complex webs are more stable.