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 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. 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.
The ricefield rat (Rattus argentiventer) is a species of rat found throughout Southeast Asia.
The ricefield rat is a medium-sized rat with a grizzed yellow-brown and black pelage. Its belly is gray in the midline with whiter flanks. The tail is uniformly medium brown. They have chisel-like incisor. The ricefield rat is between 304–400 mm long with a tail length of 140–200 mm and a skull length of 37–41 mm. The average weight of Rattus argentiventer is around 97 to 219 g. Female have 12 mammae. Young have an orange-colored tuft in front of each ear.
The ricefield rat lives in large groups which consist of a dominant male and high ranking female. When attacked or disturbed they will make squeals and whistles sound. Rattus argentiventer's main diet includes termites, insects, grasshopper, snails, seeds, nuts, rice, vegetables, and fruits. They feed at night and actively moving at dusk and dawn. During daytime, they can be seen among vegetation, weeds or maturing field. It undergoes 3 week gestation giving birth about 5 to 10 young per litters.