NUMBERS Racket

Water is liquid gold these days. More and more states require water-withdrawal permits and water use must be reported annually, requiring proper recordkeeping and data management.

However, those numbers have other uses, too, and can be mined for valuable insight to improve the quality of your turf management program and strengthen your budget.

Five key metrics to record irrigation and water usage are evapotranspiration (ET), plant water requirements, soil type, soil moisture and precipitation rate, says Steve Sakurai, data management and irrigation systems for Ewing Irrigation.

“All of these five metrics depend upon each other in the context of irrigation and water usage,” he says. “Evapotranspiration showcases how much water is lost during the day due to current weather conditions. You need to determine what kind of turf you are caring for to understand its plant water requirements.”

ET is calculated using weather station data to estimate water loss from the plant/soil system, says Dr. Doug Soldat, associate professor in the University of Wisconsin-Madison Department of Soil Science. He adds any factors – such as grass type and course microclimates – influence the actual water loss from an area, but estimated ET puts a superintendent in the ballpark.

Soldat recommends superintendents set their irrigation to run off ET data, which is a more “quantitative and efficient way” to irrigate than using run times to schedule irrigation.

“At first, some areas will be too wet and others will be too dry,” Soldat says. “But by using a soil moisture probe you can find them and percent adjust heads up or down accordingly.”

Annual ET, precipitation and irrigation use can be compiled at the end of the year to represent irrigation efficiency. The data is useful for demonstrating the efficiency of irrigation water use on a course and can be used as a target to base future improvements, Soldat says.

Soil type dictates how many cycles a runtime needs to be separated into to achieve a plant’s water requirement, Sakurai says. For example, a sandy soil might be able to handle 15 minutes of consistent watering, while a heavy clay soil would require three five-minute watering cycles. The existing soil moisture levels determine how often the soil needs watered.

“A precipitation rate is the rate that sprinkler heads apply water in a given period of time, Sakurai says. “Another factor to be considered is the distribution uniformity (DU) of the rotor. A sprinkler with a higher DU will put water down more efficiently, saving water and time.” He adds these metrics work together, and recording and interpreting the data will make an irrigation system run more efficiently.

Irrigation data collection should focus on the amount of water applied, weather readings, chemicals applied, cultural practices undertaken, and soil moisture and temperature, says Paul Standerfer, product marketing manager for Toro Golf Irrigation. However, he adds these data elements are most likely at the top of most superintendents’ lists, as they all impact each other.

“Turf health and vigor is based on recognizing what Mother Nature is doing and using the tools available,” Standerfer says. “At times of the year, the superintendent is very reactionary and at others very anticipatory. With experience and information, you can read the conditions and have the correct action plan.”

The time of the year and the length of days have a significant impact on plant needs, Standerfer says, adding measuring environmental components is more important today than ever.

“What we used to think was normal is increasingly abnormal,” Standerfer says. “You can no longer time an application or cultural practice based upon when you’ve always done it. Soil temperatures are warming sooner. Frost dates are moving. Putting down materials at the wrong time is wasteful and expensive.”

Water use per source is another key metric that must be monitored and data collected on, says Brian Vinchesi, design engineer for Irrigation Consulting Inc.

“To manage water, you have to measure it,” Vinchesi says. “Without useful information you are just guessing, or worse, assuming. All water sources should be measured with a flow meter to get the total picture of how much water is used to support the course’s water needs.”

For example, measure pump station water use with regard to the amount of water coming out of the pump station per cycle and per day, week, month and annually, Vinchesi says. “If you have only one water source, it may be the same as what you measure from the source,” he says. “But, if you have multiple sources, measuring all will show you the inefficiencies inherent in the water supply system. That will allow you to identify the efficiencies and improve overall water management strategy.”

When considering electricity usage the irrigation pump system is “far and away” the largest energy consumer on the golf course. And in some regions, such as the Northwest, variable utility rates can have extreme effects on course budgets.

“Optimizing pump station use and narrowing a watering window, watering during off peak times, or managing the flow through a modern pump system can impact annual electricity bills,” says Tory Perren, senior marketing manager for Toro Golf Irrigation. “Monitoring metrics like these help a superintendent dial in systems to maximize resources and provide the balance between usage and turf quality, thus lessening overall environmental impact.”

Water withdrawal data is another important element of proper water management, says Ian Williams, national specification manager for Rain Bird’s Golf Division. Consider that a course’s irrigation activities could draw water from various sources, such as wells or other private sources, municipal water supplies, a reclaimed water source, or natural streams where water must be transported to a holding area by mechanical means. Accurate metering is essential. In many cases, metering may be done by the provider. Sometimes the property is responsible for self-recording. Records of withdrawal quantities can be manually collected or accessed remotely and entered into software to generate reports, he says.

Water usage metering includes measuring what is being discharged through the irrigation system, Williams says. To ensure accurate measurements, superintendents must install flow meters on the discharge line of the pumping source according to manufacturer guidelines and calibrated them correctly. While superintendents can collect these values manually, Williams says computer software can also generate detailed reports that include power consumption, hours of operation, as well as detailed pressure and flow values at any time throughout the irrigation cycle.

Understanding the distribution uniformity (DU) of sprinkler heads on a golf course helps superintendents make decisions regarding irrigation system maintenance and upgrades.

“Routine water audits performed by a certified golf course irrigation auditor expose uniformity deficiencies that can lead to over-usage of both water and energy,” Williams says. “Poor-performing sprinklers can, at times, be corrected inexpensively, which will lead to better performance.”

Soil moisture and temperature – either measured throughout the day by permanently installed soil sensors or periodically by portable sensors – is arguably the most important data used by a turf manager to make irrigation and other maintenance-related decisions, Williams says.

Permanently installed sensors offer data throughout the day at user-defined intervals. Reading and interpreting more data points received throughout the day during periods of plant stress permits the superintendent to document climate and turf-reaction trends.

“Understanding predictive trends in turf grass behavior from the data gives the manager the ability to develop a proactive water management plan,” Williams says. “Understanding volumetric soil moisture content can be used to guide irrigation scheduling.”

Measuring water fraction volume “as the turf sees it,” or more importantly as utilized in the most active region of the turf system, is vitally important, says Carmen Magro, vice president and chief agronomist for Stevens Water Monitoring Systems Inc.

“The balance of air and moisture is critical for the efficiency of photosynthesis (Ps) and respiration (Rs),” Magro says. “These processes are not givens in turfgrass growth and performance. Each depends on very specific variables, such as the availability of free diffused oxygen in soil solution, available moisture for the plant to take from the rootzone, free exchange of CO2 that comes from the soil, and several other factors including how the turf utilizes nutrients.”

Just because nutrients are present, does not mean the plant will utilize them, Magro adds. An imbalance of moisture in the most dominant upper region of the rootzone will negate any efficient uptake or use of those nutrients, and will hinder the fundamental, basic physiological functions of the turfgrass system.

“The best way to measure water fraction volume is by using scientific grade, precise and accurate moisture monitoring technology designed to be capable of measuring accurately through changing turf conditions over time,” Magro says.

Electro-conductivity (EC) – aka salinity – is very important in understanding what impact free ions have on the turf system, Magro says. “Basically, any ion in solution impacts EC as the turf sees it,” he adds. “Understanding what the turf sees on a consistent basis from day to day and throughout the year will indicate the health of the system from a salinity perspective. Since higher EC levels indicate higher salinity levels, and because salts are very good at stealing moisture from the plant and making any available moisture harder to take up, EC has an impact on water management. Everyone and anyone managing turfgrass, irrigation and/or nutrition (all turf managers) should be mindful of EC so that they not only know the consistent (or lack of) availability of nutrients to their turf and to understand the impact these (salts) have on the availability of moisture to the turf.”

In golf irrigation, most inefficiencies are in the database that is operating the system, Vinchesi says. For example, the database’s data assumes the installed sprinklers are operating at a specific pressure and at a specific spacing and it then uses that information to calculate the sprinkler precipitation rate and the operating time which effects water use. If the database has the wrong sprinklers, nozzles, pressure or spacing, it will most likely use more water.

“To be efficient with water and to keep your use minimized, database management is essential as it operates the system and keeps the superintendent feedback to make decisions,” Vinchesi says.

John Torsiello is a Torrington, Conn.-based writer and frequent GCI contributor.