Rink peg interfering with sprinkler
worn impellers. Centrifugal pumps are generally very reliable but, over time, will eventually need servicing. A pump expert can test your pump for you. For those clubs with town water supply,
pressure losses are common. Large draw offs in summer from domestic use (especially early evening) can reduce pressure at the sprinkler resulting in substantially poor uniformity. Schedule irrigation after midnight when water pressure is optimum. By irrigating more efficiently you should see reduced disease problems, and an added bonus of irrigating at night generally means less wind influence on the irrigation sprinkler patterns. Uniformity problems can also be
related to a mish-mash of sprinkler types around the same green. When a system is originally installed typically the same make and type of sprinkler is used. The early systems normally used impact sprinklers but, in recent years, these have been superceded by new technology, e.g. gear drive sprinklers. As those original impact sprinklers have become obsolete/faulty/aged it has been common practice to replace them with a modern gear drive sprinkler. It is important to match the application rates of all the sprinklers when these changes are made.
Sprinkler scheduling (runtimes)
A common fault we often see with typical 8+1 pop-up sprinkler configurations is incorrect sprinkler runtimes. In many cases we find that the corner and middle sprinklers are set to run at the same time. A corner sprinkler (90°) set up this way will apply twice the amount of water as the middle sprinkler (180°). Dry and wet areas are easily distinguishable on greens when runtimes are set incorrectly. Ideally, all runtime decisions should be
Damaged sprinkler head with poor water distribution
based around what runtime you give the centre sprinkler.
Misaligned, damaged or incorrect sprinkler arc settings
Incorrect sprinkler arcs may seem insignificant but they can actually cause problems with uniformity. I recall testing a system where two sprinklers had their arcs realigned to water the flower gardens nearby. The club wondered why the corners and one side of the green were so dry! The key requirement when setting sprinkler arcs is to make sure you allow for the prevailing wind.
How good is your irrigation system?
Winter or early spring is a good time to review, check and adjust your irrigation system. Always look at the simple things first. Here’s a checklist:
• Observe the operating arcs of the sprinklers on a calm day.
• Check the operating water pressure directly from the sprinkler (Pitot gauge).
• Check the pressure at the pump. • Look for potential nozzle blockages.
• Make sure the runtimes of each sprinkler are accurately set.
The next step to finding out how efficiently water is being applied to the green is to do an irrigation system survey (pot test). One way to do this is to place 2 litre ice cream containers at 4 metre centres across the green. The centre sprinkler is set to run for a
predetermined time, e.g. twenty-four minutes. Accordingly, the middle and corner sprinklers are set to run at twelve and six minutes respectively. The water caught in the ice cream containers is calculated in a spreadsheet programme and will show the average
application rate and co-efficient of uniformity - this is measured as a percentage, e.g. 75-80% is regarded as reasonably good. The test can be done in-house or you can contact your local agronomist.
Conclusion
Changes to the quality of your green during the season can be related to irrigation coverage issues. Don’t take for granted that your old (or new) sprinklers still operate the same as they did when first installed. Over time nozzles do wear out, internal components malfunction and arc settings can be altered for whatever reason. Poor irrigation efficiency often doesn’t happen suddenly. It sneaks up on us over time. A tune up of your irrigation system and an irrigation survey (WOF) to measure the performance of your irrigation system is probably one of the best investments of time to improve or maintain optimum efficiency. Don’t leave those recurring irrigation issues until late spring/summer when you don’t have time. A half day test this autumn/winter will save a lot of heartache down the track.
The above schematic diagram shows a typical 8 + 1 sprinkler layout on a bowling green with proper runtimes
Proper arc setting is a fundamental requirement. How good is your irrigation system?
Irrigation survey to test coefficient of uniformity (CU) and application rate
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