Collecting moisture readings on greens: One year later

In the summer of 2010 we purchased a TDR 300 Fieldscout moisture sensor from Spectrum Technologies. At first we struggled finding the best way to use the meter but toward the end of 2010 we dialed in on an approach, an approach we put into play for the 2011 golf season. My intent in this article is to recap the moisture collection procedures and corresponding putting surface irrigation highlighted in my January 2011 article, “Visualizing the Final Product.”

I will start by listing our planned approach for 2011. Later I will list ways in which the approach was modified through out the 2012 season.

To recap our planned 2011 procedure:
● Nine readings are taken each morning and recorded on a spreadsheet.
● Each individual putting surface is setup as its own program in the irrigation computer and can be irrigated separately of other putting surfaces.
● Irrigation need on each putting surface was to be determined by reaching a specific moisture number.
● Any irrigation applied to a putting surface would take place as a deep infrequent irrigation cycle.

By moving all putting surfaces to separate irrigation programs and irrigating only those deemed “in need” by the moisture readings, we expected to increase the consistency of the surfaces throughout the course. We also expected to see an increase in bentgrass populations on all surfaces as the typically wet greens with higher Poa annua populations were allowed to achieve the same dry-down as the typically dry greens and their hight bentgrass populations. So, how did it all go?

What was immediately apparent last season as we began keeping moisture readings was that determining the need to water simply through a number was going to be difficult. Some greens seemed able to dry to near 10 percent moisture, while others needed to be irrigated at 15-16 percent. While the number on each individual green was important and certainly helped guide our irrigation decisions, it was only one part of the decision making process. What also needed to be carefully considered was the visual condition of the turf. If the moisture levels were low but visually the turf was strong then we waited on irrigation. In the past, the visual appearance of the turf was really the only indicator used when determining the need for irrigation. As superintendents well know, often times the visual appearance of the turf is very good right up until it is too late. Adding the moisture reading to the visual element allows us to know when the turf is on the edge, even if the visual indicators appear good.

The dual indicators of moisture readings and visual appearance are used in a ratio which is fluid depending on the time of the year. In spring and fall the moisture reading is much less important than visual indicators. During the summer stress months the moisture reading is a much larger portion of our decision making than the visual indicators.

When we started this program at the beginning of 2011 we suspected we would see an improvement in the consistency of the wetter greens. What we also found was a much greater consistency on the other end of the spectrum; the drier greens. In the past, once the drier greens became ready for irrigation we would spend one to three days “nursing” them until we felt a greater number of the other greens had reached our desired dryness. During the middle of the summer this “nursing” could be quite dangerous as the greens were on the edge for one to three days. By using individual irrigation programs and tracking moisture levels we no longer had to “nurse” the dryer greens. When they were ready for irrigation, they received irrigation. Our 14th green is a wonderful example of how our dryer greens became more consistent last summer. The 14th is generally the first green on the course to dry-down to the point of needing irrigation. In the past it always required nursing for one to three days after drying-down while we waited for other surfaces to catch up. By the end of the summer, no matter how well we “nursed” the 14th green it always suffered some scarring from periods when it simply became too dry. In waiting for other greens to dry-down the 14th was forced to suffer. In 2011 the 14th never suffered because when it needed irrigation it got it.

On the other end of the spectrum is the wettest green on the course, our 18th. Before last season the 18th was never able to be dried-down to the same level as other greens on the course. Because it is the last green to dry-down, it always received irrigation based on the schedule of other putting surfaces. By irrigating the 18th green on an individual program last season, along with taking daily moisture readings, we were able to irrigate the putting surface just two times the entire golf season (Note: this does not include occasional short cycles to prep for ferrous sulfate apps and water-in products.) Contrast this will the 14th, which was irrigated a dozen times during the same period.

Realized 2011 putting surface moisture collection and irrigation procedure:
● Nine readings were taken each morning and recorded on a spreadsheet.
● Each individual putting surface is set up as its own program and was irrigated separately of other putting surfaces.
● Irrigation need on each putting surface was determined by a seasonally fluid ratio, described above, of moisture readings and turf appearance.
● Any irrigation applied to a putting surface took place as a deep infrequent irrigation cycle.

Other observations in the first year:
● Bentgrass populations were obviously higher on our dryer greens to begin 2011. The bent populations on our wetter greens, 18, 1 and 5 being three examples, increased dramatically this season.
● The need to hand-water putting surfaces was nearly eliminated. Most of our hand watering in the past came on the surfaces we were forced to “nurse.” One of our goals is to hand-water greens as little as possible. This due both to manpower but also as a method of limiting Poa annua competitiveness.
● Last summer saw the highest incidence of localized dry spot (LDS) in my five seasons at Northland. At this point I am unwilling to say this has anything to do with our irrigation practices. More than likely the higher incidence of LDS is an indication of the need for a core aeration of the putting surfaces and an adjustment to our topdressing shcedule. More on this in another post.
● Rooting on all putting surfaces remained very consistent up to the middle of August. For the majority of the summer it was not uncommon to have the entire depth of the cup-cutter held together by roots. I attribute this to a combination of a spring deep-tining and our moisture/irrigation procedure. I have read and heard the comment: “roots are overrated” in more than one place. My comment to that is they are only overrated when you don’t have them.

Recently I found this quote on my Twitter stream: “When something works, study it. You can repeat excellence only if you understand how it happened the first time.” As a staff we love using this approach and we have done so year after year. Failures are pretty easy to spot and they are wonderful at providing feedback on how not to do something. Successes can also be excellent opportunities for advancement when the reason for the success is carefully analyzed. As we move into 2012 the success of our moisture reading/irrigation program in 2011 is something we will continually analyze in order to improve the quality of our putting surfaces.

Chris is the superintendent at Northland Country Club in Duluth, Minn. Check out his blog at www.northlandgrounds.blogspot.com or visit the clubs website at www.northlandcountryclub.com email Chris at ctritabaugh@northlandcountryclub.com