Josh Landreth, Vice President Ace of Blades • 479-530-7001 aceofblades@cox.net
Jay Randolph Sebastian County Park Admin. & Golf Course Superintendent jrandolph@co.sebastian.ar.us
Ricky Self Cypress Creek r.self@yahoo.com • 501-605-8000
Make an Impact
Who is the most famous turfgrass manager you can think of? James Beard, the father of contemporary turfgrass science? A.J. Turgeon, author of many turfgrass textbooks? Robert Frase, inducted into National Golf Hall of Fame for his work as a golf course superintendent and contributions to the GCSAA? For most people in the world, it’s probably Carl Spackler, the lovable character played by Bill Murray in the movie Caddyshack!
Sadly, it was really Carl that put our profession on the radar for most of the rest of the world. Who doesn’t relate to the hatred for a mole that singlehandedly destroys every piece of your hard work. Who wouldn’t go to every extreme to eradicate that nuisance? I know I “would”.
If you know Dr. Mike Richardson, whom some might argue is the most famous turfgrass manager in our state, you know that man is a stone-cold mole killer! Dr. Richardson is my professional mentor. I owe so much to him. I recently attended the University of Arkansas Turfgrass Field Day and got to spend some time with my mentor. After being in the presence of turfgrass greatness for an entire day, I went home, walked outside…and killed a mole. I just don’t believe this could be a coincidence! We all need a mentor.
That’s just a funny story to make the point, we need each other. Do you have a mentor? Are you mentoring anyone else in the industry? Are you intentional with your desire to see the industry grow, improve, move forward with the respect we receive from those outside the industry? I’m thankful for Dr. Richardson and Dr. Karcher for pouring so much into me. But also, I’m thankful for Kyle Sanders and Richard Covert and Jeremy Kyle and Keith Ihms and Jay Randolph and Amy Matthews and on and on and on and on. Men and women that are friends because we share a passion for growing grass. I just hope I can give back an ounce of what I’ve received from this industry.
We have a few opportunities coming up for you to get involved and build relationships. First, there is an ornamental workshop that is going to be led by Dr. Anthony Bowden on November 4th in Little Rock. Information for the workshop is in this publication and on our website. Also, don’t forget that we are gearing up for our annual conference in January. You never know who you might meet that changes your career, or better yet, who you might be able to help along their career path.
We’re not all destined for turfgrass stardom like Carl Spackler, but you never know who you might have impact on in their career. I promise, I daily remember and thank my lucky stars for those that impacted me. Be intentional. Give back. Grow the industry. Maybe one day we’re not known as Carl Spacklers!
Josh Landreth ATA-Vice President
Mike Richardson, Ph.D. Professor 479-575-2860
mricha@uark.edu
Wendell Hutchens, Ph.D. Assistant Professor of Turfgrass Science University of Arkansas, Department of Horticulture Cell: 276-952-8186 Office: 479-575-6205
wendellh@uark.edu X / Twitter: @HutchensWendell
Hannah Wright Smith Weed Specialist-Turfgrass, Specialty Crops, & Forestry 501-251-4416
hw044@uark.edu
John H. McCalla Jr. Program Technician III 479-575-5033
Hot Springs Convention Center in Hot Springs, Arkansas
Don’t miss out! The ATA Annual Conference and Trade Show offer great opportunities for networking, education and certifications. Stay tuned for more details and registration information!
Register for the conference and reserve a room at Hotel Hot Springs or Embassy Suites Hot Springs on the ATA website: arkansasturf.net
Companies that would like to be a part of the Trade Show, contact: Courtney Landreth • ataturfgrass@gmail.com • (479) 301-5534
SAVE THE DATE FOR THE
This workshop tackles Arkansa’s top landscape challenges – soil health and compaction, drainage and irrigation issues, pest and disease pressures, nutrient imbalances and improper plant selection – and equips you with practical solutions like soil amendments, optimized watering strategies, integrated pest management and guidance on selecting regionally adapted plants to create healthier, more resilient landscapes.
DATE: Tuesday, November 4, 2025
TIME: 9 AM – 2 PM
LOCATION: U of A Cooperative Extension Office 2301 S. University Ave. Little Rock, AR 72204
PRICE: $50 Per Person with Lunch Included
SPEAKER: Dr. Anthony Bowden
Scan the QR Code or go to www.arkansasturf.net
REGISTRATION
IS NOW OPEN
linkedin.com/company/theturfzone
x.com/theturfzone
THE DATA, NOT THE MARKETING
Turfgrass Research Shows No Differences in ‘Penetrant’ and ‘Retainer’ Wetting Agents LOOK TO
Wetting agents used to counteract hydrophobic sandy soils on putting greens
By John Lovett
After several years of research, the results are in on the difference in turfgrass soil surfactants that are marketed as “penetrants” and “retainers.”
Mike Richardson, professor of horticulture with the Arkansas Agricultural Experiment Station, says putting greens built to United States Golf Association standards with 12-inch-deep sand root zones require meticulous water management to promote both plant health and playability. Among the most important tools for managing water in putting greens are soil surfactants, often called wetting agents.
Despite their critical role in turf maintenance and because they aren’t pest management tools, wetting agents do not go through the same federal registration and labeling process as herbicides, fungicides, or insecticides, resulting in less research data about what they are and how they work. In the absence of such data, marketing terminology such as “penetrant” or “retainer,” along with anecdotal evidence, have been used instead, Richardson explained.
To help clear up the confusion, a study by turfgrass scientists with the experiment station, the research arm of the University of Arkansas System Division of Agriculture, and the Dale Bumpers College of Agricultural, Food and Life Sciences at the University of Arkansas, was recently published by the American Society for Testing and Materials. Co-authors of the study include researchers at Texas Tech University, The Ohio State University and Pennsylvania State University.
The study titled “Penetrants Versus Retainers: Comparing Soil Surfactant Terminology to Performance in Sand-Based Putting Greens” found that differences between soil surfactants marketed as “penetrants” or “retainers” were inconsistent, if present at all. It was published in the ASTM “Pesticide Formulation and Delivery Systems 43rd Volume.” ASTM stands for Advancing Standards Transforming Markets.
Arkansas Agricultural Experiment Station turfgrass researchers led by Doug Karcher began looking at wetting agent products marketed as “penetrants” and “retainers” in 2017. Karcher, now the horticulture and crop science department chair at The Ohio State University, was assisted by Daniel O’Brien, Ph.D., as a graduate student. O’Brien carried on the work as a Ph.D. student while in Arkansas and served as the lead author of the recently published study. He now works for U.S. Golf Association as a Green Section Research Manager.
The study was supported by the Golf Course Superintendents Association of America.
As part of their investigation, the researchers compared turfgrass soil surfactants marketed as penetrants to those marketed as retainers for their ability to affect rootzone volumetric water content and surface firmness. Volumetric water content, a measurement of how much water a given volume of soil contains, is especially important in sand-based putting greens with their limited water-holding capacity.
Multiple studies were conducted on sand-based putting greens in Fayetteville from 2018 to 2021, and Lubbock, Texas, from 2019 to 2020. The studies included the turfgrass species creeping bentgrass and ultradwarf bermudagrass.
Photo 1. Research on wetting agents marketed as “penetrants” and “retainers” showed no major differences. Visual symptoms of localized dry spot are seen in this aerial view of turfgrass at the Milo J. Shult Agricultural Research & Extension Center in Fayetteville. (U of A System Division of Agriculture photo)
Soil surfactant treatments were applied according to label recommendations and evaluated over a range of rootzone moisture conditions. Volumetric water content was measured at multiple depths using portable moisture meters and surface firmness was assessed through multiple methods.
At the Fayetteville location, during 2018 to 2019, there were no significant differences in volumetric water content between penetrants and retainers on any date or at any depth. In 2021, both penetrants and retainers could produce volumetric water content greater than nontreated controls. Likewise, both product types also resulted in volumetric water content less than nontreated controls. Similar inconsistencies were documented at the Lubbock location.
Collectively, the results reinforced the need to establish soil surfactant classifications based on performance data from field testing rather than marketing terminology, the study concluded.
Co-authors included Joseph Young, associate professor of turfgrass science at Texas Tech University, Michael Fidanza, professor of plant and soil sciences at Pennsylvania State University, and Stanley Kostka, a visiting scholar at PSU.
To learn more about the Division of Agriculture research, visit the Arkansas Agricultural Experiment Station website. Follow us on at @ArkAgResearch, subscribe to the Food, Farms and Forests podcast and sign up for our monthly newsletter, the Arkansas Agricultural Research Report. To learn more about the Division of Agriculture, visit uada.edu. Follow us on at @AgInArk. To learn about extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit uaex.uada.edu
About the Division of Agriculture: The University of Arkansas System Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. Through the Agricultural Experiment Station and the Cooperative Extension Service, the Division of Agriculture conducts research and extension work within the nation’s historic land grant education system.
The Division of Agriculture is one of 20 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on three campuses.
Pursuant to 7 CFR § 15.3, the University of Arkansas System Division of Agriculture offers all its Extension and Research programs and services (including employment) without regard to race, color, sex, national origin, religion, age, disability, marital or veteran status, genetic information, sexual preference, pregnancy or any other legally protected status, and is an equal opportunity institution.
MICROWAVE RADIOMETRY
for A IRRIGATION PRECISION NEW TOOL
As
By Madan Sapkota, Chase M. Straw, Weston W. Floyd, and Elia Scudiero
global demand for freshwater intensifies and the environmental impact of water use becomes more apparent, golf course superintendents face increasing pressure to manage water resources more efficiently. Conventional irrigation scheduling methods may result in overwatering or underwatering, leading to water waste and negatively affecting turfgrass health and playability. Precision irrigation has emerged as an advanced approach that applies water precisely where and when it is needed, using technologies that monitor soil moisture and optimize irrigation practices.
Accurate soil moisture data are crucial for precision irrigation, as they provide real-time information necessary for refining irrigation schedules, minimizing water waste, and maintaining healthy turfgrass. However, current sensor technologies face challenges in covering large areas like golf course fairways. While traditional methods, such as gravimetric techniques, are accurate, they are also labor-intensive and impractical for large-scale use. Time domain reflectometry (TDR) sensors, commonly used by superintendents in the United States, provide real-time data with less labor but are limited to point-specific measurements, making them less efficient for extensive areas. To overcome these limitations, new solutions are needed to improve the accuracy and reliability of soil moisture measurements over large areas, ultimately enhancing water conservation and promoting healthier turfgrass.
Introducing Microwave Radiometry
To address the limitations of current soil moisture sensing technologies, microwave sensing emerges as a promising solution for large-scale, accurate soil moisture measurement on golf courses. Microwave sensing can be categorized into active and passive methods. Active microwave sensing, such as synthetic aperture radar (SAR), involves emitting microwave signals to the ground and measuring the reflected signals. This method is effective for mapping surface features but can be complex and resource-intensive. In contrast, passive microwave sensing, or microwave radiometry, measures the natural microwave emissions from the surface. This passive approach is particularly effective for assessing soil moisture content, as it directly responds to the water present in the soil.
Microwave Radiometry in Golf Course Management
Microwave radiometry is emerging as a promising technology for soil moisture measurement, with significant potential for large-scale applications in golf course management. An example of this technology is the Portable L-Band Radiometer (PoLRa), commercially known as turfRad (TerraRad Tech AG, Zurich, Switzerland). Although PoLRa represents a new tool for golf course superintendents, the principles of microwave radiometry could transform how soil moisture is monitored and how highresolution soil moisture maps are created.
Figure 1. a) Portable L-band Radiometer (PoLRa, i.e., turfRad) sensor mounted on a fairway mower at the golf course.
b) Time domain reflectometry (TDR) measurements (ground truth data) from the data collection conducted on August 14, 2023.
A B
Microwave radiometry detects natural microwave emissions from the surface, allowing for soil moisture measurement up to four inches below the surface. This non-invasive method enables rapid data collection over large areas, making it ideal for managing extensive golf course fairways, where traditional soil moisture-sensing methods are often labor-intensive or limited. The radiometer sensor can be mounted on a mower or strapped to the bed of a utility vehicle, measuring soil moisture about 14 times per second while traveling up to 10 mph. Sensors can also be arranged in an array for broader coverage.
Although microwave radiometry is still relatively new and has not undergone extensive testing in golf course management, it has already been implemented at several golf courses in the United States. Technologies like PoLRa show promise but are still in the early stages of exploration. For precision irrigation, any geospatial sensor technology, including PoLRa, must be rigorously evaluated by assessing soil moisture measurement accuracy and improving soil moisture mapping.
The preliminary research discussed in the next section focuses on the first step: enhancing measurement accuracy through calibration techniques. Calibration involves adjusting the sensor readings to match those from reliable reference measurements, such as those obtained from TDR sensors, to ensure the data collected are accurate and reliable. Factors influencing accuracy include soil moisture content, leaf water levels, brightness temperature (how much microwave radiation is reflected back to
the sensor), temperature fluctuations, and surface roughness (how smooth or uneven the surface is, affecting the scattering of microwave signals). Different turfgrass species may also affect readings due to variations in leaf water content and surface characteristics. Therefore, site-specific calibrations are essential for ensuring reliable measurements. Significant effort is needed to develop and apply effective calibration techniques to achieve precise and dependable results.
Preliminary Research at Champions Golf Club, Houston, Texas
On August 14, 2023, Texas A&M University researchers conducted a study at Champions Golf Club (Jackrabbit Course) in Houston, Texas, focusing on fairways 2, 6, and 13, which feature ‘Tifway 419’ hybrid bermudagrass in sandy loam soil. Two methods to measure soil moisture were used: the PoLRa (turfRad) microwave radiometer and handheld TDR 350 sensors (FieldScout TDR 350 Soil Moisture Meter, Spectrum Technologies, Inc., Plainfield, IL, USA). The PoLRa was mounted on a fairway mower about one meter above the ground (Figure 1a) and driven at speeds of 3.5-4.5 mph. The mower made three passes per fairway—two near the edges and one down the center—while data were collected at twelve randomly chosen points per fairway. After each pass, the points were flagged and exact times were recorded using the ‘Unix Time’ app.
Previous research has shown strong correlations between TDR and gravimetric soil moisture measurements, especially in coarse, non-conductive soils. Since TDR is practical for golf course superintendents, it provides reliable data for calibrating the PoLRa sensor. After using PoLRa to take measurements, soil moisture readings were collected at marked points using handheld TDR sensors at depths of 1.5, 3.0, and 4.8 inches (Figure 1b). The PoLRa data were then matched with the TDR readings based on the recorded times to ensure accurate comparisons.
For calibration, we used ANCOVA regression, a statistical method that helps understand the relationship between different variables while controlling for other factors. In this method, TDR readings were treated as the dependent variable (the outcome we are measuring), and the brightness temperature from PoLRa’s vertical polarization was the independent variable (the factor we are testing to see its effect). This method enabled more accurate estimation of soil moisture levels. We assessed the model’s performance using metrics such as R², which indicates how well the model explains the variation in soil moisture, and mean absolute error (MAE), which shows the average size of the prediction errors.
Our initial calibration using PoLRa’s off-the-shelf (i.e., factory) settings showed an R² value of 0.60 (P < 0.01) and MAE of 0.06
(Figure 2a), indicating that 60% of the variability in soil moisture readings could be explained by PoLRa data. While promising, these results highlighted the need for further refinement to improve accuracy. Using an advanced ANCOVA calibration approach that incorporated additional factors such as brightness temperature, the model’s performance significantly improved. The R² value increased to 0.78 (P < 0.01) (Figure 2b), explaining 78% of the variability in soil moisture, and the MAE was reduced to 0.03. These results demonstrate the effectiveness of advanced calibration techniques in enhancing the accuracy of PoLRa’s soil moisture measurements.
Future Direction for Accuracy and Reliability
The improved soil moisture measurement accuracy from using ANCOVA to calibrate microwave radiometry technology highlights its potential to improve golf course irrigation. While effective, ANCOVA requires further refinement. Future research should explore additional factors, such as different soil types, turfgrass species and varieties, management practices, and various climatic environments. Considering temporal factors, including seasonal variations, will also help enhance the model’s year-round accuracy.
Figure 2. a) The relationship between off-the-shelf PoLRa (turfRad) volumetric water content (VWC) and ground truth time domain reflectometry (TDR) measurements from three golf course fairways during a survey at Champions Golf Club (Jackrabbit Course) in Houston, Texas.
b) A comparison of observed vs. estimated VWC using the ANCOVA regression approach.
Fine-Tuning Microwave Radiometry and Improving Soil Moisture Mapping
After improving soil moisture measurement accuracy, the next step in optimizing precision irrigation is enhancing soil moisture mapping across large areas like fairways. These maps help visualize soil moisture variability, as shown in Figure 3, and hold great potential for precision irrigation. By integrating PoLRa, which utilizes both microwave radiometry and GPS for georeferencing soil moisture data, with digital job board technology, real-time georeferencing of soil moisture readings can be achieved as a PoLRa moves across fairways. The resulting maps can reveal patterns of soil moisture variability, which can be more effectively addressed once the soil moisture calibrations are fully applied (Figure 3a and 3b).
Conclusions
Microwave radiometry holds potential to transform precision irrigation on golf courses. Its ability to provide accurate, large-scale soil moisture measurements could revolutionize water management for superintendents. By overcoming the limitations of current sensors and offering a non-invasive, efficient method for real-time data collection, microwave radiometry could become essential in modern golf course management. Although further research is needed to improve accuracy and reliability, the final step to ease the implementation of precision irrigation is integrating this technology with irrigation systems. This integration could reduce the need for manual adjustments of irrigation schedules by allowing the system to recommend adjustments based on soil moisture and possibly other turfgrass or soil data. Superintendents would then be able to simply approve or adjust these recommendations as needed. This approach could ultimately lead to more sustainable water use, improved turfgrass health, and enhanced overall golf course quality. •
Figure 3. a) Soil moisture maps generated by integrating PoLRa (turfRad) data with digital job board (ASB taskTracker) for fairway 2 and 6 (a and b, respectively) at Champions Golf Club (Jackrabbit Course) in Houston, Texas, during a survey on August 14, 2023.
M. Sapkota, C.M. Straw, and W.W. Floyd, Department of Soil and Crop Sciences, Texas A&M University 3100 F and B Rd • College Station, TX 77845
E. Scudiero, University of California Riverside West Big Spring Rd • Riverside, CA 92507
Acknowledgement: The authors gratefully acknowledge Chris Ortmeier, Director of Agronomy at Champions Golf Club, and Cliff Morris, Superintendent of the Jackrabbit Course, for providing space for our research. We are also thankful to the United States Golf Association and the South Texas Golf Course Superintendents Association for their financial support. Special thanks to Dr. Derek Houtz, Founder and CEO of TerraRad Tech AG, for his technical support with the PoLRa sensor.
