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 the field is the remaining dried stems and leaves of the crop with limited nutrients which is either chopped and spread on the field or baled for feed and bedding for livestock.