The combine harvester, or simply combine, is a machine that harvests grain crops. It combines into a single operation process that previously required three separate operations (reaping, threshing, and winnowing). Among the crops harvested with a combine are wheat, oats, rye, barley, corn (maize), soybeans and flax (linseed). The waste straw left behind on . . . → Read More: The Basic’s of Combine Harvesting