Water Application Methods - Practices of Irrigation and On-farm Water Management - page 49

is selected so that the axle clears the crop as it is moved. A drive unit (usually an
air-cooled gasoline-powered engine located near the center of the lateral) is used to
move the system from one irrigation position to another by rolling the wheels.
Traveling Gun System
This system utilizes a high volume, high pressure sprinkler (called “gun”) mounted
on a trailer, with water being supplied through a flexible hose or from an open ditch
along which the trailer passes (Fig. 2.7 ) . The gun may be operated in a stationary
position for the desired time and then moved to the next location. However, the most
common use is as a continuous move system, where the gun sprinkles as it moves.
The gun used is usually a part-circle sprinkler, operating through 80-90% of the
circle for best uniformity and allowing the trailer to move ahead on dry ground.
These systems can be used on most crops, though due to the large droplets and high
application rates produced, they are best suited to coarse soils having high intake
rates and to crops providing good ground cover.
Fig. 2.7 Traveling gun type sprinkler
Center Pivot and Linear Move Systems
The center pivot system consists of a single sprinkler lateral supported by a series
of towers. The towers are self-propelled so that the lateral rotates around a pivot
point in the center of the irrigated area (Fig. 2.8 ) . The time for the system to revolve
through one complete circle can range from a half a day to many days. The longer
the lateral, the faster the end of the lateral travels and the larger the area irrigated by
the end section. Thus, the water application rate must increase with distance from
the pivot to deliver an even application amount. A variety of sprinkler products