Paddy Field

A paddy field is a flooded parcel of arable land used for growing semiaquatic rice. Paddy cultivation should not be confused with cultivation of deep water rice, which is grown in flooded conditions with water more than 50 cm (20 in) deep for at least a month. Genetic evidence published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) shows that all forms of paddy rice, both indica and japonica, spring from a single domestication of the wild rice Oryza rufipogon that occurred 8,200--13,500 years ago in China During the twentieth century, paddy field farming became the dominant form of growing rice. Hill tribes of Thailand still cultivate dry-soil varieties called upland rice. Paddy field farming is practiced in Cambodia, Bangladesh, China, Taiwan, India, Indonesia, Japan, North Korea, South Korea, Malaysia, Myanmar, Nepal, Pakistan, the Philippines, Sri Lanka, Thailand, Vietnam, and Laos, as well as Piedmont in Italy, the Camargue in France, the Artibonite Valley in Haiti, and Sacramento Valley in California. Paddy fields are a major source of atmospheric methane and have been estimated to contribute in the range of 50 to 100 million tonnes of the gas per annum