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 deepwater rice, which is grown in flooded conditions with water more than 50 cm (20 in) deep for at least a month. Genetic evidence shows that all forms of paddy rice, both indica and japonica, spring from a domestication of the wild rice Oryza rufipogon that first occurred 8,200–13,500 years ago South of the Yangtze River in present-day China. However, the domesticated indica subspecies currently appears to be a product of the introgression of favorable alleles from japonica at a later date, so that there are possibly several events of cultivation and domestication. Paddy fields are the typical feature of rice farming in east, south and southeast Asia and the Northern Marianas; as well as taro farming in Micronesia, Melanesia, and Polynesia. Fields can be built into steep hillsides as terraces and adjacent to depressed or steeply sloped features such as rivers or marshes. They can require a great deal of labor and materials to create, and need large quantities of water for irrigation. Oxen and water buffalo, adapted for life in wetlands, are important working animals used extensively in paddy field farming. During the 20th 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 Asia, namely in Cambodia, Bangladesh, China, Taiwan, India, Indonesia, Iran, Japan, North Korea, South Korea, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, Vietnam, and Laos, and in Europe, Northern Italy, the Camargue in France, and in Spain, particularly in the Albufera de València wetlands in the Valencian Community, the Ebro Delta in Catalonia and the Guadalquivir wetlands in Andalusia, as well as along the eastern coast of Brazil, the Artibonite Valley in Haiti, and Sacramento Valley in California, among other places. 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.Studies have shown that this can be significantly reduced while also boosting crop yield by draining the paddies to allow the soil to aerate to interrupt methane production. Studies have also shown the variability in assessment of methane emission using local, regional and global factors and calling for better inventorisation based on micro level data. The word 'paddy' is derived from the Malay word padi, meaning 'rice plant'. It is derived from Proto-Austronesian *pajay ('rice in the field', 'rice plant'), with cognates including Amis panay; Tagalog paláy; Kadazan Dusun paai; Javanese pari; and Chamorro faʻi, among others. Archaeologists generally accept that wet-field cultivation originated in what is now China, although it wasn't invented by Sinitic peoples. Rather they were the inventions of the precursors of modern Austronesians and Southeast Asians who inhabited southern China prior to the Han expansion. Paddy field agriculture was especially highly developed among the pre-Austronesian Hemudu, Majiabang and Liangzhu cultures of the wetlands of the Yangtze Delta and may have originated there. The earliest paddy field found dates to 4330 BC, based on carbon dating of grains of rice and soil organic matter found at the Chaodun site in Kunshan County. At Caoxieshan, a site of the Neolithic Majiabang culture, archaeologists excavated paddy fields. Some archaeologists claim that Caoxieshan may date to 4000–3000 BC. There is archaeological evidence that unhusked rice was stored for the military and for burial with the deceased from the Neolithic period to the Han Dynasty in China. There are ten archaeologically excavated rice paddy fields in Korea. The two oldest are the Okhyun and Yaumdong sites, found in Ulsan, dating to the early Mumun pottery period. Paddy field farming goes back thousands of years in Korea. A pit-house at the Daecheon-ni site yielded carbonized rice grains and radiocarbon dates, indicating that rice cultivation in dry-fields may have begun as early as the Middle Jeulmun pottery period (c. 3500–2000 BC) in the Korean Peninsula. Ancient paddy fields have been carefully unearthed in Korea by institutes such as Kyungnam University Museum (KUM) of Masan. They excavated paddy field features at the Geumcheon-ni Site near Miryang, South Gyeongsang Province. The paddy field feature was found next to a pit-house that is dated to the latter part of the Early Mumun pottery period (c. 1100–850 BC). KUM has conducted excavations, that have revealed similarly dated paddy field features, at Yaeum-dong and Okhyeon, in modern-day Ulsan. The earliest Mumun features were usually located in low-lying narrow gullies, that were naturally swampy and fed by the local stream system. Some Mumun paddy fields in flat areas were made of a series of squares and rectangles, separated by bunds approximately 10 cm in height, while terraced paddy fields consisted of long irregular shapes that followed natural contours of the land at various levels. Mumun Period rice farmers used all of the elements that are present in today's paddy fields, such as terracing, bunds, canals, and small reservoirs. We can grasp some paddy-field farming techniques of the Middle Mumun (c. 850–550 BC), from the well-preserved wooden tools excavated from archaeological rice fields at the Majeon-ni Site. However, iron tools for paddy-field farming were not introduced until sometime after 200 BC. The spatial scale of paddy-fields increased, with the regular use of iron tools, in the Three Kingdoms of Korea Period (c. AD 300/400-668).