Irrigation
![Irrigation of agricultural fields in [[Andalusia](https://upload.wikimedia.org/wikipedia/commons/5/51/Fields_SW_from_Sevilla.jpg)
There are several methods of irrigation that differ in how water is supplied to plants. Surface irrigation, also known as gravity irrigation, is the oldest form of irrigation and has been in use for thousands of years. In sprinkler irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure water devices. Micro-irrigation is a system that distributes water under low pressure through a piped network and applies it as a small discharge to each plant. Micro-irrigation uses less pressure and water flow than sprinkler irrigation. Drip irrigation delivers water directly to the root zone of plants. Subirrigation has been used in field crops in areas with high water tables for many years. It involves artificially raising the water table to moisten the soil below the root zone of plants.
Irrigation water can come from groundwater (extracted from springs or by using wells), from surface water (withdrawn from rivers, lakes or reservoirs) or from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection. Irrigation can be supplementary to rainfall, which is common in many parts of the world as rainfed agriculture, or it can be full irrigation, where crops rarely rely on any contribution from rainfall. Full irrigation is less common and only occurs in arid landscapes with very low rainfall or when crops are grown in semi-arid areas outside of rainy seasons.
The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme. The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme. Amongst some of these problems is depletion of underground aquifers through overdrafting. Soil can be over-irrigated due to poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution. Over-irrigation can cause deep drainage from rising water tables that can lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage. Provided by Wikipedia
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1Report bibliotecaCGIAR
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3by National Irrigation Administration, Sri Lanka, International Irrigation Management Institute
Published 1991Book bibliotecaCGIAR -
4by National Irrigation Administration, Sri Lanka, International Irrigation Management Institute
Published 1991Book bibliotecaCGIAR -
5by National Irrigation Administration, Sri Lanka, International Irrigation Management Institute
Published 1991Book bibliotecaCGIAR -
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7Texto bibliotecaUAAAN MX
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8by International Irrigation Management Institute, Punjab Irrigation Department, Water and Power Development Authority
Published 1995Report bibliotecaCGIAR -
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11Irrigation management in latin America; present situation, problem areas and areas of potential improvement / Irrigation management in latin America; present situation, problem areas and areas of potential improvement /by International Irrigation Management Institute
Published 1990Texto bibliotecaCOLPOS -
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14Planning the management, operation and Maintenance of irrigation and drainage systems : a guide for the preparation of strategies and manuals. Planning the management, operation and Maintenance of irrigation and drainage systems : a guide for the preparation of strategies and manuals.by International Commission on Irrigation and Drainage.
Published 1989Texto bibliotecaCOLPOS -
15Texto bibliotecaFAO IT
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16Texto bibliotecaFAO IT
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17Texto bibliotecaFAO IT
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19Texto bibliotecaFAO IT
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