We recently had physical soil testing done on three of our greens to help determine the cause of the isolated setbacks we had this summer. The greens tested were #7, #3 & #12. Seven and Three were tested because of their chronic year to year mediocrity in the summer months, and twelve was sampled as one of our healthier greens.
The testing did not reveal anything we did not already know but did provide scientific validation of how we need to move forward to provide the consistent, firm and fast putting surfaces you desire. As I have explained in previous updates, the bottom line is we have excessive organic matter or thatch accumulation in the top two inches of our putting surfaces needs to be removed by more aggressive core aeration and deep vertical mowing. The good news is that the USGA greens mix below the top three inches is what should be expected with 16 year old greens and should be able to sustain a healthy surface once we get caught up with thatch removal.
The following are experts from the summary of the ISTRC testing. As you will see they recommend a minimum of 20% surface area displacement per year. We plan to target 25% to 30% for the next couple of years to get caught up. Good news is we can accomplish this using smaller 1/2" holes in a tighter pattern rather then using the larger 5/8" holes which take longer to recover. More details on how we plan to accomplish these goals to come.
"All three tested greens have an accumulation of plant-deposited organic matter & thatch within their upper 3 to 4 inches, which is the source of the high water holding & water porosity properties. Without open aerification holes we would estimate the root zone would support infiltration rates at or below 2 in./hr."
"A build up of organic matter and/or thatch is often a gradual process that occurs when the rate of plant-deposited biomass exceeds the rate of microbial decomposition and the physical removal through hollow coring & verti-cutting. As cumulative 1st tier organic contents (sum of the upper 4”) exceed 7 to 8 percent or 2 to 2 ½ percent, by inch, our testing & research has shown it becomes increasingly more difficult to keep the root zone open & breathing as well as maintain desirable firmness & green speed."
"Over the years we have been conducting an ongoing study into the annual displacement percentage and its impact on the aging of greens. Frequency has been a common measure of aerification; however with the wide range of tines & setups it provides very little information as to the true impact of aerification."
"Our goal through this study has been to establish a quantifiable measure for aerification and through its correlation to the physical properties help establish appropriate short & long-term programs. Given the current conditions, age of the greens, and their turf-type an excellent goal for your greens would be at least 20 percent annual surface area displacement (calculation based on the OD of the tines)."
The newer aerifiers, quadtines, blocks, and deep verticutters have allowed many superintendents to significantly increase their annual displacement without increasing the frequency per year. For example, the Toro ProCore using 10 tine block and a ½ inch tine provides a good balance of displacement, ease of fill and recoverability."
"With greens that are prone to sealing off, it will be important that you also supplement the larger tine aerifications or deep verti-cuttings with regular venting using non-disruptive equipment such as the HydroJect, Planet Air, needle/pencil tines, hollow/solid quads, bayonet tines, star/cross tines, slicer, or deep spiker. Venting has proven to be extremely beneficial to the health of the turf and promoting gas exchange, particularly when done on a regular basis." "Improving the ability for the root zone to breathe will not only encourage a deeper, more sustainable root system but also enhance microbial activity to aid in the natural decomposition of the organic matter & thatch."
"The current testing has established an initial benchmark of your greens. We would recommend that you continue to monitor your greens with regular testing. The information derived from regular testing will allow you to monitor the aging process of the greens, evaluate the effectiveness of the current cultural practices, modify the program based on hard data, make adjustments to the program to meet the individual needs of specific greens, and detect problems before they affect the health of the greens."
Matt Pulis, M.S.