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Almond Facts
MARCH | APRIL 2017
Up-to-date irrigation system
performance evaluation is
essential to efficient irrigation
water management. An
orchard’s irrigation system
should be tested at a minimum
of every three years to ensure
the system is performing at its
highest potential. Evaluating an
irrigation system has a similar
result to all other annual farm
equipment maintenance: it
allows for the system to work
properly, and frequent system
checks help to avoid issues.
“Common system performance
problems that I see include emitter
plugging or line pressure that
isn’t uniform or within system
specification,” said Spencer Cooper,
senior manager, Irrigation and
Water Efficiency, Almond Board
of California. “Variation in your
system performance could be caused
by extra pressure and plugging
throughout the irrigation line.”
Impact Sprinkler
Pressure Testing
The easiest way to measure the
operating pressure of an impact
sprinkler is to use a pressure
gauge fitted with a pitot tube. The
pitot tube is a small, hollow brass
tube that should be available for
purchase from your local irrigation
equipment supplier. A 0–60 psi or
a 0–100 psi liquid-filled pressure
gauge works well for taking the
measurements.
It’s recommended that the same new
pressure gauge be used to measure
all the pressures when sampling. A
new pressure gauge is advantageous,
because pressure gauges often
become less accurate with use. If
multiple pressure gauges are to be
used, confirm that they all read the
same pressure by measuring a single
location with each gauge.
Once the pitot tube is fitted with
a pressure gauge, hold the tube
in the water stream just outside
the sprinkler nozzle, and read the
pressure on the gauge. Move the
pitot tube around in the water
stream until the maximum pressure
is noted. With practice, the pressure
can be measured at a sprinkler head
in only a few seconds. When the
measurement is taken, record its
location within the orchard on an
orchard plot map, or write a good
description of its location.
The variability of the pressure
measurements is an indicator
Does Your
Irrigation
System
Need a
Tune-Up?
A performance test
should be performed
frequently to improve
irrigation efficiency.
Irrigation technician Devin Power, Power Hydrodynamics, Inc., Modesto,
measures and records irrigation drip-line pressure. Line pressures that are not
within system design specifications can be a common problem when addressing
nonuniform irrigation water distribution, regardless of system type.
IN YOUR ORCHARD
