The world produces some 700 million tons of paddy rice each year. This is enough to provide the staple food for more than three billion people, of which some 700 million live in poverty. The majority of rice is grown under irrigated conditions in which the fields are flooded from planting to harvest. Because of this flooding, rice is said to use a lot of water, about two and a half times the amount of water needed to grow a crop of wheat or maize.