Spray irrigation is a modern and commonly-used system of irrigating, but it also requires machinery and a greater use of energy (power). Spray irrigation systems are in use on many farms today throughout the world. The systems can simply be long hoses with sprinkers along the length or a large scale center-pivot system that traverses a circle in the paddocks.
This picture shows a simple sprinkler irrigation system commonly used on farms. It is unfortunately one of the less efficient models because a large part of the water shot into the air evaporates.
The center-pivot systems have a number of metal frames (on rolling wheels) that hold the water tube out into the paddocks. Electric motors move each frame in a big circle around the field squirting water from a tube fixed at the water source at the center of the circle.
This picture shows the distinctive pattern from the air of a very common center-pivot sprinkler irrigation system in operation.
The depth of water applied is determined by the rate of travel of the system. Single units are ordinarily about 1,250 to 1,300 feet long and irrigate about a 130-acre circular area. In high-pressure systems, there can be very big water guns along the tube.
A more efficient alternative to the high-pressure water guns is the low-pressure sprinkler system, seen in the picture below.
Here, water is gently sprayed downward onto plants instead of being shot high in the air. Low-pressure systems are more efficient in that much less water evaporates or is blown off the fields if there is a strong wind present.
Although still widely in use today, high-pressure spray irrigation system can be quite inefficient. A lot of water, (up to 35 percent) in high pressure systems, is lost because of evaporation and the blowing winds. More efficient irrigation systems are starting to be used more often as people come to appreciate the real value of water and the costs of irrigation.
For information on other irrigation systems refer to the articles;
