Felix Reinders
Agricultural Research Council
Institute for Agricultural Engineering
D
rip irrigation is considered as the most efficient irrigation system, but there is proof
from literature and through testing that this
system can also be in-efficient, due to bad
water quality, mismanagement and maintenance problems. Clogging of the emitters is one of the most serious problems associated with drip irrigation and various approaches in preventing the clogging of emitters
include filtration, flushing and chemical treatment of
the irrigation water. Complimentary to this, ultrasonic
sound is also used very successfully to maintain drippers
functional. As they say, prevention is better than cure.
Through intensive laboratory and field testing by the
ARC- Institute for Agricultural Engineering, results were
obtained and analysed that gave some insight into the
performance of drip irrigation systems under field conditions. Studies have also been conducted on the usage
of ultrasonic sound to clean the drippers.
Figure 1: Dripper testing in the laboratory of ARCIAE
With the evaluation in the ARC-IAE’s laboratory (see
figure 1), new drippers’ coefficient of variation (CVq)
varied from an excellent 2, 1% to a good 4, 2% with an
average of 3, 1%. The CVq of the recovered drip lines
from the field was a fair 6, 5% in the first year and it
worsened to a poor 8, 2% in the second year - a clear
indication that it was clogging regardless of maintenance and treatment with chemicals. There was a tendency that the Emission Uniformity (EU) as measured in
the field of all the dripper types deteriorated over time
from a new pipe EU of 92% to 87, 1% in the first evaluation to 82,4% in the fourth and last evaluation one
year later. With regard to the statistical discharge coefficient (Us), on average, the drippers met the requirements in only 69%.
Innovative technology that uses ultrasonic sound to
clean drip pipes was developed by a South African
farmer, Mr Leon Lingnau. He has been a farmer for
Figure 2: Cleaning of the drippers with ultra-sonic
sound.