Field evaluation of very low pressure center-pivot sprinkler devices in the pacific Northwest, U.S.A
Abstract
The continued viability of center-pivot sprinkler irrigation in the
Pacific Northwest may depend on increasing the efficiency with which water
and energy are used. Very low pressure sprinkler devices can contribute
greatly to energy savings of center-pivot systems.
In the Hiddle Columbia Basin of the Pacific Northwest eight medium and
high pressure center-pivot sprinkler systems were completely or partially
converted to very low pressure systems (69-138 kPa (10-20 psi)). Field
tests were conducted under a variety of field conditions to compare three
center-pivot sprinkler devices. The sprinkler devices evaluated were very
low pressure fixed-head spray sprinklers (top sprays, drop sprays, and
spray booms) and bubblers (furrow drops). These very low pressure sprinkler
devices were compared with high to medium pressure impact sprinklers with
standard or Flow Control Nozzles. The combined effects of spray losses,
uniformity coefficient, soil water and yield were studied.
Under similar conditions, spray loss values from high or medium
pressure impact sprinklers ranged from two to three times the spray loss
values obtained under lower elevation spray sprinklers. Wind speed and
spray head elevation influenced spray loss as much as the very low pressure
sprinkler devices. Bubblers (furrow drops) effectively eliminated spray
loss but their use in low pressure center-pivot conversion in Pacific
Northwest is questionable.
A full season comparison between these sprinkler devices showed that
for low spray head elevations (0.9-1.8 m (3-6 feet)) from the soil surface
or crop canopy and low pressures (70-140 kPa 00-20 psi)), and at dealer
recommended sprinkler spacings, the spray heads on center-pivot systems
appear to be a promising alternative for reducing irrigation energy
requirement. This energy reduction is due to a reduction both in sprinkler
operating pressure and spray loss.
Citation
Master of Science in Agricultural EngineeringPublisher
GRADUATE SCHOOL UNIVERSITY OF IDAHO