Irrigation

Irrigation is the supply of water to the land from artificial channels to make plants grow. In many dry parts of the world where there is not enough rainfall, farmers irrigate their land to grow crops. Even in places where there is good rainfall, farmers often use irrigation to boost the growth of their crops.

Overhead sprinkler systems are one way to irrigate crops

The aim of irrigation is to spread the water evenly across the land so that each plant gets the same amount of water it needs. Many different methods of irrigation are now in use around the world.

On method of irrigation is flood or surface irrigation where the water is allowed to flood across the land through channels. Rice paddies are one place where this method of irrigation is used.

These rice farmers have flooded their fields before planting the rice seedlings.

Another method of irrigation is drip irrigation. Water is pumped through pipes and fed to plants near the roots, drop by drop. This is a very efficient method of watering plants because evaporation and run-off are kept to a minimum. Many people use drip irrigation systems in their home gardens.

Sprinklers are used in another kind of irrigation. Water is pumped to places in the fields where large sprinklers rotate and spray water at high pressure over the crops.

Center pivot irrigation
A variation of the overhead sprinkler method (see picture of overhead sprinklers at the top of the page) is centre pivot irrigation. Pieces of pipe with sprinklers placed along them, are joined together and mounted on wheeled towers. The machine moves in a circle around the field to distribute water evenly to the plants.
The sprinklers can be placed on 'drops' so that the water is deposited on the ground between the plants. The 'drops' also help to stop some evaporation and prevent water being blown about by the wind.

Wheel line irrigation is a series of pipes and wheels with sprinklers attached. Water is pumped through the pipes from a large hose. After enough water has been pumped onto the land, the hose is removed and the wheel line machine is moved to the next section of the field. The hose is attached again and this next section of the field is irrigated.

Water for irrigation
Water used for irrigation can be groundwater taken from springs or pumped from wells.
Surface water can be taken from rivers, lakes, dams or reservoirs.
Treated wastewater is another source of water used for irrigation in some places.
Floodwater harvesting is when flood water is diverted and spread over large areas. The moisture stored in the soil is used to grow crops.

Read more about irrigation here http://home.howstuffworks.com/irrigation.htm

If you use information from this page, acknowledge the source in your bibliography like this:
Thomas, R. & Sydenham, S. Irrigation. [Online] www.

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