Inspect center-pivot irrigation systems now to prevent issues later

• By Cale Cloud and David Hall •

catch can test in center-pivot irrigation
A pivot uniformity or “catch can” test is conducted to verify that the system is applying water uniformly. Performing irrigation system maintenance during the winter months can ensure the system’s longevity — photo courtesy University of Georgia

With winter just around the corner, now is a good time to winterize and perform some preventive maintenance on center pivot irrigation systems.

Irrigation system maintenance during the winter months is very important because it can ensure a system’s longevity, and regular maintenance can also potentially reduce the risk of experiencing downtime at critical crop stages during the next growing season.

University of Georgia Cooperative Extension recommends checking the following when performing winter maintenance on center pivots:

Conduct a pivot uniformity “catch can” test

Prior to shutting the system down for the year, perform a “catch-can” uniformity test to verify the system is applying water uniformly. Important things to check when doing a uniformity test include leaks, missing or malfunctioning sprinklers and damaged pipes.

If the system has poor uniformity, it would be wise to apply for cost-share assistance through the Natural Resources Conservation Service Environmental Quality Incentives Program for a new sprinkler package.

When performing a catch-can test, it is also important to check end gun settings. Minimal or excessive amounts of water application on the end gun area is a sure sign of improper settings, worn or sticking end gun brake kits, a worn booster pump or a blown-out end gun orifice.

If correct end gun arc settings are not available from the installation package, contact the dealer for the correct setting. All pivots are not the same on the end, and many require special settings.

Drain the irrigation system and check panel boxes

Once you have conducted a uniformity test and are certain you will not be using your irrigation system until the next growing season, the next step will be to drain the system of any remaining water.

Remove the plugs to drain pipes, valves, pumps, sprinklers, booster pumps and anything else on the aboveground portion of the irrigation system that can hold water. Clean out the sand trap on the end of the pivot and drain any condensed water from wheel gearboxes and gear motors.

Ensure there are no loose or damaged connections. Seal any openings to help avoid damage from rodents. Apply rodent bait as needed.

Check the ground rod and grounding connection. Clean up excess vegetation around the pivot point and at the well. This will help make the space less inviting to rodents and other pests.

Service required parts and test the metering equipment

Check all of the wheel gearboxes and gear motors and make sure they have an adequate amount of gear oil and that there are no leaking seals.

Make sure to check the U-joints between the gear box and gear motor. If there is more than a quarter-inch of movement, they should be replaced.

Steel moving on steel without proper lubrication can lead to unnecessary wear and tear on irrigation equipment. Be sure to grease all moving parts, including the pivot point bearing, towable hubs, corner legs and rollers. If it is a diesel-powered motor, change the engine oil, oil filters and fuel filters.

Repair any rutted pivot wheel tracks. Repairing tracks at the end of the season will help reduce erosion during the winter and spring.

Make sure the flow meter on the withdrawal point (usually at the pump) is functioning properly. A properly functioning meter can be used as a means to determine proper operation of the pumping unit.

Note the end reading so that, in conjunction with a starting reading, there will be a record of water used over the growing season. If the flow meter is functioning improperly, contact the Georgia Environmental Protection Division for assistance.

For more information, see UGA Extension Circular 911, “Evaluating and Interpreting Application Uniformity of Center Pivot Irrigation Systems.”

Cale Cloud is the area water agent for University of Georgia Extension in the Southwest District. David Hall is the Bleckley County program assistant/water educator.

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