Superintendent Magazine - November, 2012


Extra Sensory

Soil sensors put real data behind course conditions.
By Patrick White

In this Internet-focused world, we've become accustomed to being able to look up any bit of information at any time. From Yogi Berra's career batting average (.285) to the correct part numbers for your ancient rough mower, it seems that the supply of data available to us is limitless. So it's only natural that we feel a little lost whenever we encounter a void in the information web.


That's sometimes the case with golf maintenance: There's certainly a science to turfgrass, but management decisions often come down to visual observation and gut feelings. Some superintendents are using soil sensors to generate real data about what's happening on the course, and using that information to make more informed decisions.

Data wows superintendent and club's members

"I was intrigued when I first heard about the soil sensor technology, but it was too expensive," recalls Alan FitzGerald, superintendent at LedgeRock Golf Club in Mohnton, Pa. "But when Toro came out with theirs, the cost was at a lower price point and it was worth it to us to try them out."

FitzGerald initially got just two sensors to experiment with in 2009, but they quickly proved their value. The course ended up purchasing 18 sensors, with two set in each of the three challenging greens on the property; two in each of the layout's three best greens; and the rest spread throughout other greens on the course.

"On the greens we put one in a high spot and one in a low spot so we could average those. Altogether, this gave us a good description of all the different growing environments that we have," FitzGerald says.

Installation of the sensors was timely, because the hot summer of 2010 hit the then 4-year-old course hard just as the layout was maturing.

"We were starting to learn how to really get it up to speed for play and we had three greens that were really heavily pocketed with no air movement, just not a good growing environment for grass," FitzGerald explains, noting that he had one gas-powered fan to help promote air circulation, but kept having to move the fan from green to green on alternating days.

The capital outlay for more fans would be large, "and trying to convince people that buying fans is going to make grass grow better is a tough sell anyway," FitzGerald says. "But thanks to the soil sensors, we could see the temperatures would drop on the greens where the fan was by 3 to 4 degrees, and that was 2 inches below the surface, so we could see the fan was doing even more at the surface. So I had the proof and that was a big selling point."

Having the data to back up the visual evidence helped convince the club to purchase a total of five fans. "People love seeing data," FitzGerald says.

Since then, FitzGerald has continued to primarily utilize the sensors' soil temperature function. For example, when he sees the soil temps drop into the upper 50s and low 60s, he knows it's time to start getting the course ready for winter by adjusting mowing and fertility.

"We still use a hand-held moisture sensor; we're not completely comfortable using the moisture part of the soil sensors yet," he says. "It's very good for the greens; it helps us know when a green is about to wilt. But we're just not ready to use it to compare one green to another for moisture content. For that we still rely on our one hand-held unit, so we know it's consistent between each green."

The sensors can also be used to track salinity, but that's not an issue at LedgeRock.

"That data automatically comes up on the screen, and though we don't use it, it's nice to know that we can check on that if we need to," FitzGerald says. "For example, one time I saw a huge spike in salinity and I looked at our records and we had fertilized the day before. So it definitely does work."

The sensors at LedgeRock are independent of the irrigation system. However, last year the club invested in Toro's Lynx system, and FitzGerald says that software can communicate with the sensors and allows sensors to be "tagged" to sprinklers.

"I could see a time in the future when the sensors could really run the irrigation system this way," he says. "I'm sure that capability will be there, but it will take time for everyone to get used to this technology and get comfortable with it. I don't think I personally would ever get to that point of completely relying on it, but it's nice to have the sensors to make you aware of things that you might need to check on."

FitzGerald thinks that soil sensor technology will play a larger role in golf course maintenance in coming years.

"This is still new technology that people are getting used to, but I think the potential is there to base fertilizer and chemical applications on the data," he predicts. "For example, crabgrass is heavily influenced by soil temperatures, so I'm sure someone could do a study that shows that you'll start to see crabgrass at X-number of degrees. If you could perfectly time your crabgrass control, it might mean just one application and you're done."

It will take time to understand the exact correlations between soil temperatures and moisture levels and the appearance of disease and insect pressure, he adds.

"I think that potential is there," FitzGerald adds.

For the moment, he uses the technology more as a warning system.

"I'm all about being out on the course and seeing and feeling what's going on," he says. "I think you have to do that. But having indicators to give you a heads-up earlier than you can see things is really nice."

Creating precise green speeds at Merion

Back in 2005, Merion Golf Club in Ardmore, Pa., was preparing to host the U.S. Amateur in the midst of a brutally hot stretch of summer weather. Matt Shaffer, Merion's director of golf course operations, was approached about trying out a new soil sensor technology from UgMO Technologies.

"I wasn't interested in trying anything new at that point. I was just trying to salvage turf for the championship," Shaffer recalls.

But, on the recommendation of his mentor, former Merion Superintendent Paul R. Latshaw, Shaffer decided to give it a shot.

"I'm kind of an early adopter, so I was curious," he explains. "As soon as we got them in the ground, we realized what a valuable tool they were."

Merion started with just a few sensors and gradually that number expanded to 68. More recently, that number has dropped a little.

"They are expensive," Shaffer says. "They also do make some challenges for when you aerify. That's the reason we're using less. As the technology evolves and they become smaller and cheaper, we'll use them everywhere." (When aerifying, Shaffer says the sensors need to be removed or the aerator needs to go around the areas where they're located, adding to the time that maintenance task takes.)

The UgMO sensors send a signal from the ground through a repeater, and that data ends up on Shaffer's computer screen.

"It's not integrated at all with our irrigation system. We're pretty hands-on, so that's fine," he says. "We don't use the data as much for irrigation as we do for playability."

Putting together up-to-the-minute moisture levels with separate firmness readings, for example, gives Shaffer greater control over creating precise green speeds.

Merion's renowned firm and fast playing conditions make the moisture level capabilities of the sensors particularly important.

"We push turf right out to the end every day, but we could never quantify what 'dry' was," Shaffer says. "We would predicate it on ball marks or sticking a knife in the ground, but we didn't really know. In reality, firmness is all about moisture. I used to think that dry was dry. From the sensors I've realized that dry is about 15 percent, and crazy dry is like 11 percent, and 5 percent is write-your-résumé time."

With such a fine line between optimum playability and the unemployment line, having precise data is critical.

"You can't discern 6 percent difference with your eye - you just can't," Shaffer emphasizes. "You need a sensor."

Even at courses without a firm-and-fast philosophy, Shaffer says the sensors can be a valuable water-saving aid.

"Many golf courses overuse their irrigation system," he says. "I think I'm a pretty good waterer, but this technology has made me better."

Assuming greens construction is uniform throughout the course, Shaffer advises dividing up the putting surfaces by orientation (north/south, etc.). Putting sensors in the best and worst greens in each of those categories, as well as one or two in fairways, one in tees and approaches and maybe even the rough, can provide a representative sample of what's happening on the course, he explains.

Shaffer also installed soil sensors in some of his bunker banks, one of the most difficult parts of the course to manage, he says.

"Water is critical in those and we have drip irrigation there," he states.

One challenge to using soil sensors is potential data overload, Shaffer says.

"We have millions and millions of data points," he adds. "We had an assistant who devoted an entire summer to correlating that data. He says there still needs to be a lot of work done to model all of the data produced and that takes time and money.

"The stuff we learned is just amazing," Shaffer continues. "We'd leave at night and our greens would be at 13 percent [moisture]. We wouldn't run any irrigation and when we came in the next morning they'd be at 18 percent. If you get the porosity in your greens right, the cool air can wick moisture to the surface. I never knew that and probably would never have known it because you can't see that with your eyes."

Shaffer thinks the technology was just beginning to unfold when the economy and the golf industry began to contract, which has delayed the more widespread adoption of soil sensors.

"I think if that hadn't happened, more people would be using them now. I don't think soil sensors are fully understood or fully implemented anywhere," Shaffer says.

As more courses begin to use soil sensors, there may be a greater overall understanding of how to use the data they generate to determine maintenance practices and schedules, he adds.

"It's great technology," Shaffer says. "There's so much to discover, but you need the time and [the manufacturers] need the funding to be able to do that."

Keeping the greens "on edge" with the help of sensors

Grand Cypress Resort in Orlando, Fla., has been using Rain Bird's soil sensors for about two years.

Soil sensors at Grand Cypress have allowed the resort to reduce maintenance costs, among other things.

"We were just trying to dial in our watering practices a little better," explains Tom Alex, director of golf course maintenance, of the impetus for adopting this technology. "And these have done a pretty good job for us in that regard."

One of the main ways that Grand Cypress uses the sensors is to better understand when the greens will get to the wilt stage in the afternoons. The maintenance staff starts to look at moisture readings around late morning to get a sense of what the afternoon's program should be.

"What we learned is that once we dip down into the high teens, we'd better get out there and start syringing," Alex says. "Because if we get down to 17 or 18, we're going backwards."

The data is also analyzed at the end of the day, along with information from an on-site ET weather station, to determine the irrigation schedule for the night. The goal at the end of an irrigation cycle is to get the moisture reading back up to about 22 to 23, he notes.

Having data on moisture levels helps safeguard the health of the turf and also the playability of the course, Alex says.

"Greens are built to drain, and down here in Florida, where it's always over 90 degrees, it doesn't take them long to dry out," Alex says. "We want to keep them on the edge; we want them firm and fast."

Having the sensors allows him to more comfortably walk that line, Alex says, adding that it also helps to reduce maintenance costs. "With irrigation, you're paying for water and paying for electricity, so these sensors are one tool to help us in that regard," he adds.

Alex says that, given the variability of weather from year to year, the sensors haven't been in place on the course long enough to quantify exact water savings, but he feels it's there.

"Are we going to see millions of gallons of reduction? I hope not, because that would mean we haven't done anything right in past years," he says. "But I think we are going to see some savings in water and energy. And, at the same time, hopefully the health of our greens will be a little bit better and playability will be a little bit better."

The Rain Bird sensors are hard-wired to a data logger, which sends the information to the central irrigation control system via an antenna. The ability of these particular sensors to directly communicate with the irrigation system is one of the reasons they were chosen at Grand Cypress.

"If we allow it, we can say, 'Irrigate the soil back to 22 percent,' " Alex explains. "We've done some of that and it's pretty neat technology. I don't quite have enough sensors to be able to do that throughout the three courses, but certainly where we have the sensors we can do that."

Beyond helping to refine the irrigation program, Alex says the sensors have proven valuable in helping to understand soil temperatures. Grand Cypress has about 12 sensors spread over the resort's three courses.

"We have as many as three in one green; we have a fairway sampled, and we also have some tees sampled," Alex notes. "We use soil temperatures around our pre-emergence applications in February or March."

In the past, he would occasionally use a hand-held unit to capture those temperatures, if at all. Now that data is readily available at all times.

Alex says the sensors can be installed anywhere from 2 or 3 inches up to 1 foot deep.

"The depth is more important to the guys who are using them for salinity, so when they're flushing their root zones, they know if they've flushed it all the way through," he explains. "We're not really using them for that here, but it's amazing how quickly the salinity comes up after you fertilize. Within minutes you start to see it rise."

Soil sensors are one more tool to help superintendents get the job done, says Alex, adding that they're "definitely a good investment." But, he cautions, they are not a silver bullet to solve all maintenance challenges and can't replace getting out on the golf course.

"It's good information; you can come in and at a glance see where you are and give you an idea of what you need to look at," Alex says. "But I don't have guys sitting there staring at the computer all day. We're techie here, but we don't go overboard."

Patrick White is a freelance writer based in Middlesex, Vt. He spent several years working in golf maintenance, and over the past 16 years has served as an editor and writer for numerous regional and national golf publications.