Rice: Encyclopedia II - Rice - Rice cultivation

Rice - Rice cultivation

Rice is a dietary staple of more than half of the world's human population, making it the most consumed cereal grain. Rice cultivation is well suited to countries and regions with low labour costs and high rainfall, as it is very labour-intensive to cultivate and requires plenty of water for irrigation. However, it can be grown practically anywhere, even on steep hillsides. Rice is the world's third largest crop, behind maize (corn) and wheat. Although its species are native to South Asia and certain parts of Africa, centuries of trade and exportation has made it commonplace in many cultures.

Rice is often grown in paddies — shallow puddles carefully controlled to ensure the appropriate water depth (typically 15 cm). Rice paddies sometimes serve a dual agricultural purpose by also producing edible fish or frogs, a useful source of protein. The farmers take advantage of the rice plant's tolerance to water: the water in the paddies prevents weeds from outgrowing the crop. Once the rice has established dominance of the field, the water can be drained in preparation for harvest. Paddies increase productivity, although rice can also be grown on dry land (including on terraced hillsides) with the help of chemical weed controls.

In some instances, a deepwater strain of rice often called floating rice is grown. This can develop elongated stems capable of coping with water depths exceeding 2 meters (6 feet).

Rice paddies are an important habitat for birds such as herons and warblers, and a wide range of amphibians and snakes. They perform a useful function in controlling insect pests by providing useful habitats for those who prey on them.

Whether it is grown in paddies or on dry land, rice requires a great amount of water compared to other food crops. Rice growing is a controversial practice in some areas, particularly in the United States and Australia, where rice farmers use 7% of the nation's water to generate just 0.02% of GDP. However, in nations that have a periodical rain season and typhoons, rice paddies serve to keep the water supply steady and prevent floods from reaching a dangerous level.

Rice blast, caused by the fungus Magnaporthe grisea is the most significant disease affecting rice cultivation.

Adapted from the Wikipedia article "Rice cultivation", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki