The irrigation water is not received from river diversions, storage reservoirs or deep wells, but from rainfall or runoff from a local catchment area. The prevailing climatic and soil conditions in shallow rain-fed rice areas are extremely variable. Fertilizer use is low, stand establishment difficult and pest control almost impossible, and yields are poor. In Brazil, a major part of the rice crop is upland. In India and throughout Southeast Asia, upland cultivation is common along river banks as waters recede at the end of the rainy season.
Soils are commonly heavy and residual moisture alone sustains growth.
Upland rice farming ranges from shifting cultivation of forested hilly or mountainous areas that are cleared and burned to large-scale mechanized operations. Between these two extremes is farming of sloping hill regions that are subject to serious erosion and frequent drought, by hundreds of thousands of the poorest of rice farmers. The environmental damage here is very serious. In South and Southeast Asia some 13 percent of the total rice area is upland, but in some countries in Africa and Latin America upland rice exceeds 50 percent of the national total rice area. In deep-water rice, water depth is at least 1 m during a significant portion of the growing season.