To irrigate is to water crops by bringing in water from pipes, canals, sprinklers, or other man-made means, rather than relying on rainfall alone. Places that have sparse or seasonal rainfall could not sustain agriculture without irrigation. In areas that have irregular precipitation, irrigationimprovescrop growth and quality. By allowing farmers to grow crops on a consistent schedule, irrigation also creates more reliable food supplies.
Ancient civilizations in many parts of the world practiced irrigation. In fact, civilization would probably not be possible without some form of irrigation. The earliest form of irrigationprobably involved people carrying buckets of water from wells or rivers to pour on their crops. As better techniques developed, societies in Egypt and China built irrigationcanals, dams, dikes, and water storage facilities. Ancient Rome built structures called aqueducts to carry water from snowmelt in the Alps to cities and towns in the valleys below. This water was used for drinking, washing, and irrigation.
Modern irrigation systems use reservoirs, tanks, and wells to supply water for crops. Reservoirs include aquifers, basins that collect snowmelt, lakes, and basins created by dams. Canals or pipelines carry the water from reservoirs to fields. Canals and pipelines, just like the ancient Roman aqueducts, often rely on the force of gravity. Pumps may also move water from reservoirsto fields.
Crops are irrigated by several methods: flooding an entire field, channeling water between rows of plants, spraying water through large sprinklers, or letting water drop onto plants through holes in pipes.
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