Page 42 - Grapevine May-June 2020

Around The Vineyard

The DU score improved from 0.88 to 0.91 of plugging due to precipitates from bicarbonates,
between the two evaluations. Problems due to bacteria, algae, or other biological slimes. Correct
pressure were reduced by about 20% in the retest these issues before sending water into the system.
evaluation. High pressure losses at the pump sta- Precipitates can be managed by adjusting the pH
tion were not present in the retest, and the differ- of irrigation water. Biological issues are often man-
ence between riser pressures decreased by 5 psi, aged with chlorine. It is easy to overlook the impor-
from 7 to 2 psi even though average set pressure tance of water treatment for the functioning of the
between the two tests was unchanged. On average, system. If there is a water quality issue, however,
emission devices performed about 8% better after it is the most effective way to reduce plugging of
chemical remediation and flushing. emitters and maintain a high DU score.

This is an excellent example of how small chang- Distribution Uniformity evaluations are offered by
es and a more aggressive maintenance regime many Resource Conservation Districts, County ag
improved system efficiency without major changes departments, State ag agencies, and USDA offices
to the system itself at an affordable cost. Costs as mobile irrigation lab services. Simplified versions
were $35/acre to treat with strong acid, plus his can also be performed by growers themselves.
labor to flush. Water treatment was done based on
water quality analysis and with the help of a profes- Other metrics like water use over time, changes in
sional water treatment company. system pressures, and frequency of filter flushing
over time can indicate changes in system efficiency.
Recommendations By monitoring the system’s performance, it is pos-
sible to reduce the amount of water used over time
When troubleshooting irrigation system per- and reduce pumping costs thereby saving money
formance issues, start at the pump. Determine if and resources.
the pump is operating properly. Confirm that the
pressure supplied by the well pump is sufficient to
deliver water to the highest point in the system or
the farthest point from the well pump. If not, install
a booster pump.

Then, investigate whether the quality of the
water coming out of the well is the source of irri-
gation system problems. This can be in the form

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