Detailed adjustments

Oscar Wilde once quipped, “It is a very sad thing that nowadays there is so little useless information.” Not sure today’s golf course superintendent would agree, choosing, instead, to take advantage of the massive quantity of extremely useful data available to keep their courses in peak condition.

A great deal of that information is collected in, and dispensed from, the superintendent’s irrigation central control system. Tremendously helpful if the database is accurate and complete, but conversely disadvantageous if it is inaccurate and incomplete.

David Taylor, principal at Bryant Taylor Gordon Golf in Costa Mesa, Calif., says all of the central control systems available today are capable of incredible flexibility compared to their predecessors, which were essentially just timing mechanisms – some more complex than others. But taking full advantage of the system is often ignored.

“To get the most water savings from a control system, watering to ET is the most efficient method,” Taylor says. “ET – or evapotranspiration – is a measure of the water required to be applied to the turf that is lost to either transpiration through the plant stomata, or to evaporation from the soil. ET’s can be measured precisely using on-site weather stations and can be fairly accurately estimated by average temperature or from historical charts. Using ET information, the central computer can calculate exactly how long to run each sprinkler to put back all the water lost to transpiration and evaporation, but in order to do this, the database needs to be both accurate and complete.”

Accurate in terms of the spacing between sprinklers and in terms of the gallons per minute the sprinkler puts out. “This information is used to calculate how much water is being applied to the turf, and is known as the precipitation rate (PR),” he says.

According to Taylor, another major factor used to calculate the run time is the arc of the sprinkler. Is it a full-circle sprinkler or a part-circle sprinkler?

“The difference in arc makes a significant contribution to the run time,” he says. “A sprinkler set to 180 degrees, only needs to run half the time that a full circle sprinkler runs, and a sprinkler set to 90 degrees, only needs to run half as long as a sprinkler set to 180 degrees. Any portion of the database that is not complete or accurate leads to errors in the calculation of the required run time.”

Michael Kropf, superintendent at The Views Golf Club in Oro Valley, Ariz., has a Rain Bird Nimbus II Central Control System with an extensive database containing information for every head on the golf course. There’s a single-wire control on every head so each sprinkler has its own identity in the program and each head is designated to an area – a green, tee, fairway, or rough.

An accurate database is critical to the performance of the whole system, which was installed the year before he became superintendent, Kropf says. Together with his assistant and irrigation manager, they spent months coordinating what the database on the computer says with what was happening on the golf course.

“Heads were not wired correctly so the computer thought Station 1 was coming up when, in fact, Station 5 was coming up,” Kropf says. “We had issues where the computer thought a fairway head was running when a rough head was actually running. Even after we thought we found all the mistakes it still took months to find all the issues. Areas would always be wet and we would find a head that was thought to be running once a night was actually running twice in two programs.

“Accuracy is critical to keep the golf course in good condition and prevent overwatering,” he adds. “Our reclaimed water budget is over $400,000 a year so wasting water is not an option. That performance is also critical because we have to transition back to Bermudagrass every summer and overwatering leads to excess salts in the soil from the reclaimed that kills the Bermudagrass, leaving very poor playing conditions in June.”

While the initial database will include such items as sprinkler type, spacing, GPM and arc, the superintendent or irrigator may occasionally make changes to a sprinkler or its nozzle set to address local conditions.

“Maybe the spacing is compressed and the standard nozzle in the sprinkler ends up throwing water too far, so they put in a smaller nozzle that doesn’t throw as far ... or maybe the sprinkler is on a slope and is not throwing far enough, so they put in a larger nozzle,” Taylor says. “This will generally affect the GPM of the sprinkler. If this change is not noted, and the database is not updated to reflect the change, the computer will be making its calculations based on flawed data. The old adage ‘garbage in , garbage out’ applies here.

“Run times will not be calculated correctly and you will either end up with a dry area or a wet spot because the sprinkler run times are not correct,” he adds. “We recommend that the superintendent or the assigned irrigator audit the system at least once a year. In the audit, they need to confirm that the sprinkler nozzle is noted correctly in the database, that the sprinkler is rotating correctly, and for part-circle sprinklers, that the arc of the sprinkler is noted correctly, and that part-circle sprinklers are oriented correctly to water the turf and not houses, streets or sidewalks.”

For Kropf, communication is key.

“We have a good communication between irrigators and management,” he says. “If the irrigators find a problem they solved by changing a nozzle to a smaller throw to help dry an area out, or use a bigger nozzle to get a dry area, they communicate that change with me to keep the database in the computer accurate. The worst is when someone changes something, but the computer was never told and then more problems are created. We backup the database with Rain Bird GSP (Global Service Plan) on a regular basis to ensure our database is not compromised if the computer crashes.”

According to Taylor, most central control system databases have information for the sprinkler type, the nozzle set installed in the sprinkler, the base pressure of the sprinkler (which affects the GPM delivered from the sprinkler), the GPM of the sprinkler, the number of sprinklers on the station, the spacing between sprinklers and whether that spacing is square, equilateral triangular or something different.

“All of these factors are used to calculate the precipitation rate of the sprinkler and ultimately into the correct run time for the sprinkler,” he says. “Some systems will calculate a run time to the nearest minute, while others can calculate a run time down to the second. Most databases also have the ability to enter the electrical draw for the station, as well, so that the computer can optimize the number of sprinklers operating at any given time and stay within the electrical limits of the system wiring and field controller electronics.”

As for knowing the database is operating at peak accuracy, Taylor says there are several metrics that can be studied to see if the system is operating as intended. The simplest one is to drive the course and look for wet and dry spots.

“These are how most errors in the database manifest themselves,” he says. “Strictly from a measurement standpoint, (superintendents) can check the run log on the computer after an irrigation cycle to see how many gallons the computer says were applied during the irrigation cycle. This can be compared to the gallons reported by the pump station flow meter or by readings from the water meter if they don’t have a pump station. There will always be a difference between these two numbers since one is a theoretical value (the run-time log) and the other is a physical measurement of exactly what happened. As long as they are close, the database is probably in good condition. If the difference is significant or changes over time, then it is time to do a system audit to find where the errors are.” Frequently reviewing the database for adjustments should also be done, Taylor adds.

For superintendents running stand-alone systems – meaning they operate just from the field satellite and there is no central computer – most manufacturers have the ability to retrofit radios for communication so that the satellites can be run from a central computer with a database, Taylor says. These systems have to be proprietary, however, matching the manufacturer of the central system to the satellites. If the field satellites are two or three generations back from the current offerings, this is not necessarily the case and can be an expensive proposition.

Bottom line: Properly maintaining the irrigation database comes down to responsibility – conserving water and money.

“In today’s struggles with the availability of water, taking steps to conserve as much as you can is important, not only as being a good environmental steward, but directly affects the bottom line of the business, particularly in arid climates where water budgets can be in excess of $1 million per year,” Taylor says. “We should be well past the days where the superintendent sets everything to run for 10, 15, 20 or 30 minutes and makes adjustments simply by a percentage increase or decrease from that run time.”