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The
Centre Pivot system
represents one of the most efficient and cost effective technologies of
broad-acre irrigation available today (see
pictures). Also, it's the most suitable
irrigation equipment for
effluent irrigation. Provides a uniform depth of water application of the
entire field (see
picture).
Applies water, under
low pressure, from a continuously moving lateral pipe supported by
a series of towers/spans which do not require connecting or disconnecting
to water mainlines. The lateral
is supported by towers and cables or trusses which move on wheel track or
skid support units.
 Water is delivered to the
pivot point usually through buried mainline pipe. The
water enters the system at the pivot point (see
picture). The towers/spans are
self-propelled so that the lateral rotates around a fixed pivot point in
the centre of the irrigated circle.
One pass/revolution time can range from a
half a day to many days, based on application rates. This system can
irrigate from 10-310 ha at pressures ranging from 25-65 Psi (1.7-4.5 bar). The longer the
pivot, the larger the area covered and the lower the costs per hectare.
The water application rate is increased with distance from the pivot to
deliver an even application rate. The slower the pivot irrigates a circle,
the more water is applied.
The centre pivot is kept in a straight line
as it moves around the pivot point by an alignment system that speeds up
or reduces speed or starts and stops movement of the towers as required to
maintain alignment. If the alignment system fails and support units get
too far out of alignment, a safety device automatically shuts down the
entire centre pivot.
Because the centre pivot irrigates a circle,
it leaves the corner of the field unirrigated, unless additions of special
equipment i.e. end gun sprinkler (see
picture) or corner swing arm
(see picture) are made to the system.
The control panel, fertilizer injection equipment are located at the
pivot point.
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