Em4885 irrigation management practices to protect ground water

4 CHAPTER
Description
One of the great advantages of micro-irrigation is the ability to control both the placement
and amount of fertilizers and other chemicals. Fertigation and chemigation is widely
practiced with micro systems. However, due to the small passages in the emission devices
and the flow characteristics of the piping systems, incorrect combinations of particular
nutrients/chemicals and irrigation water may cause clogging of the system.
Fertilizer and chemical dealers in an area with significant micro-irrigated acreage should
know which formulations will work and which will not. Also, contact local WSU
Cooperative Extension personnel for information.
Do not take chances with clogging a micro-irrigation system. When in doubt, contact a
reputable laboratory to run tests of chemical/nutrient/water combinations at the pressure
and temperatures within the system.
IP 2.04.05 - Practice Good Maintenance Procedures to Ensure
That the System Performs as Designed
Objective
Maintain design emission uniformity, thus potential application efficiency.
Description
Design of micro-irrigation systems many times involves the use of pressure regulating
valves. These valves must be set correctly and maintained. Pressure gauges that are
installed at strategic points in the system can identify problems with pressure regulation
or with the pumping plant.
Even with the best of maintenance, filtration, and chemical treatments, some clogging may
occur. In these cases, emission devices will be replaced. Or, it may be a situation where as
the crop develops, additional emitters are added to the system. It is essential that the
devices at each plant have the same operating characteristics. That is, they will emit the
same flow for a given pressure.
One of the tradeoffs in using micro-irrigation systems is that labor for maintenance
increases. The system should be regularly inspected for leaks and clogged or worn
emission devices. A flow meter at the pump and pressure gauges at strategic spots
in the system can help indicate when problems are developing.
The best filtration will not remove fine silts and clays. These sediments may settle out in
the piping system at points of low flow velocity. Periodic flushing of all pipelines in the
system is needed to make sure that the sedimentation does not build up to harmful levels.
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