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Though we have been fortunate at this point in time to have not been the subject of water use restrictions, it is important for us to be cognizant of how we use water to irrigate the course.
Our efforts spanning the past two years have been focused on understanding and optimizing a new irrigation system we received as part of a renovation project in 2007. This, along with routine soil moisture readings has given us the data to more accurately fine tune our irrigation applications for more uniform playing conditions and better prepare ourselves for any future water restrictions.
During the 2009 season we began taking an inventory of our system with a goal to operate the system from ET. Taking an inventory of the irrigation components on the course allowed us to enter the correct information into the central control, as well as ensure the correct components were on the course. The first step was to determine the head and row spacing between each sprinkler using a measuring wheel, while also making note of the sprinkler model. From this information we could determine the correct nozzle set for each sprinkler based on spacing. We then retraced our steps to ensure the correct nozzle was in each head, and also set and recorded the arc of each part circle head to within 5 degrees. With this completed, we now have a record of the irrigation specifics that need to be in place. We can refer to these whenever we need to make irrigation repairs to ensure the correct heads and nozzles are in place for the data that is in the computer.
The second step in the process was performing an irrigation audit, starting with the greens, to determine our precipitation rates – which would be used for operating from ET – and application uniformity. As we gathered this information, it was entered into a spreadsheet to record and analyze the data. Through the spreadsheet a graphical representation of the catch-can data was created to easily observe which areas were being over or under-watered. By recognizing that each head on the greens was a part circle and set at differing arcs, thus giving different precipitation rates, we knew we would be able to increase our uniformity across the green by adjusting run times. By only adjusting run times we were able to increase our uniformity across all greens from an average of 73 percent to an average of 80 percent with one green measuring 89 percent. Although we do not irrigate our greens to the daily ET value, we use the precipitation rate and uniformity information to set our program run times to apply 1 inch of water. This allows us to easily adjust the program percentage to apply the amount of water we want as well as an even amount of water across the green.
At the same time we were performing the audits on the greens, we were also tracking soil moisture content with a portable TDR meter. This data was also recorded into a spreadsheet, where we tracked the high, low, mean, uniformity and standard deviation of our soil moisture readings (see chart “April 12”). While watching the data we noticed, even when our greens were at their driest, there were areas that never reached levels that necessitated supplemental watering. In an effort to identify these “wet” areas, we have the spreadsheet identify moisture readings that are equal to or greater than one standard deviation above, or “wetter” than the mean. The heads that irrigated those areas were turned off. In 2010, this accounted for 11 of the 103 heads that irrigate the greens, or 10 percent of the heads. No supplemental irrigation has been needed in these areas and those heads remain turned off.
The greens only account for a small fraction of the water that we use to irrigate the course, so it does not have a large impact on our water usage for the year. However, we are taking the process applied to the greens and applying it to the fairways. Our limited data and experimenting with the fairways is telling us we may be able to turn off 10 percent of those heads, as well. An easy way for us to save 10 percent of our water use seems to lay with the ability to identify which heads on the course do not need to run. Because this irrigation system is new and the variability of environmental conditions, it will be hard to quantify any irrigation savings over previous years.
Our intentions at the beginning of this process were only to achieve a more uniform application of water that would lead to more consistent playing conditions for our members. We believe we are making better use of our water resources with the information we have obtained, which will allow us to avoid some of the initial woes of water restrictions. GCI
Steven Biehl is assistant superintendent at Naperville Country Club, Naperville, Ill.
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