It's a great time to tackle irrigation system maintenance. Irrigation problems are not always apparent during the cooler times of year, but once summer heat arrives, the system will be providing a lifeline to pastures and crops. The Smarter Irrigation for Profit project conducted "catch can" tests on three centre pivots during the 2015/16 irrigation season finding that two of the older pivots tested weren't performing to industry standards and as a result were wasting water and potentially limiting pasture production.
Before irrigation begins for the upcoming growing season, ensure the centre pivot irrigation system is functioning properly. Take the time to service power units and before starting up, check electrical systems, pumps, piping and intakes, pivot gearboxes and drivelines. It also pays to inspect the anchor bolts and grease the pivot point.
Next, operate the power unit and pumping system to fill pipes and bring centre pivot up to operating pressure. Check pressures at the pump, pivot point, and end of pivot. Always check pressure with pivot parked in same spot.
With pivot fully operational, check the system flow rate and compare with the design flow rate on the sprinkler chart. Verify flow meter is working properly. Walk the pivot looking for malfunctioning sprinklers, including clogs, worn impact plates, missing sprinklers, etc. If possible, verify each sprinkler matches the sprinkler specified in the sprinkler chart. Consider performing a "catch can" test to evaluate water application uniformity. Visually verify regulators are working properly. Replace missing or malfunctioning regulators. Take note of any leaks anywhere in the system and repair. Verify centre pivot operates with towers in proper alignment. Test safety circuits to verify proper performance. Check tyres for wear, cracking, low pressure, etc. Make sure all lugs are tight. Test the control panel settings for autostop, autoreverse and end gun coverage areas. Make sure end gun watering angles are set properly.
Losses from a pivot that is not working correctly can mount up quickly. Tim Powell from Integrated Irrigation estimates that a 40-hectare pivot operating at a Distribution Uniformity (DU) of 51 per cent and a Coefficient of Uniformity of 86 per cent (the field performance target for pasture is DU greater than 90 per cent and CU greater than 85 per cent) could potentially lose $11,000 per year on a dairy pasture if growth was inhibited by 25 per cent due to under or over watering.
If struggling for time remember that an irrigation supplier can conduct system checks and catch can tests for the farmer.
For further information on the Smarter Irrigation project, contact Monique White, phone 0400 972 206 or email firstname.lastname@example.org.
The Smarter Irrigation for Profit project is supported by funding from the Australian Government Department of Agriculture and Water Resources as part of its Rural Research and Development for Profit Programme, and Dairy Australia.