Chantilly National Golf and Grounds: COURSE CONDITIONS

It looks like your new par 3 tees are facing a long and hot mid-Atlantic summer. If the last month is any indication, we are in for a hot one. As most of you have likely noticed, several of the new tees are already struggling. The two main challenges the young sod is facing is an excess of thatch and hard, compacted soil.

The thatch issue is somewhat common with bentgrass sod. Often, commercially available bentgrass sod is predominately thatch, otherwise it could not be cut and rolled without falling apart. The long term fix for the thatch problem is to core aerify and vertical mow, which mechanically removes some of the thatch, and topdress with sand to help dilute and break down the thatch layer. The heavy thatch, although not ideal and likely adding to our woes, is not what I would consider the main issue, just part of the problem.

Compaction, in my assessment, is the primary challenge your new tees are facing. The top layer of soil, just below the sod and about an inch or so thick, is very compacted. You may have noticed when playing golf this summer just how difficult it is to push a tee into the ground. That is the same problem the turf roots are facing.

On the upside, the compacted layer is only an inch thick. The soil below, in large part, is fine. The cause of this compacted layer is likely a result of the grading and compacting at the time of construction. I am sure it is no surprise to hear me say that compacted soil is not good for a turfgrass plant. It inhibits root growth and slows water infiltration rates leaving the plant gasping for air after a rainfall event. The fix, much like the thatch issue, is aerification and sand topdressing. We need to fill the aerification holes with sand to modify the soil profile.

So, it sounds like an easy fix, right? Punch some holes and add some sand. Yeah, sort of. But we need to consider other factors, specifically the heat and humidity that is likely to continue for the next 90 days or so.

I would love to pull a bunch of cores and fill them with sand, and that is exactly what we will do this fall. But this time of year, with the heat, the turf simply can not handle the added stress that accompanies sand topdressing. Sand is very abrasive and causes wounds to the turf plant. In many cases, on healthy turf, it may be OK to apply light sand layers to a playing surface. In the case of your already stressed tees, a sand application is very likely to cause more damage. Possibly much more.

So what do we do? We need to break up the hard layer and get some sand down into the soil profile but the turf is too weak and the weather too hot to do it for several months. The first step is to punch a solid hole without removing a core and no sand topdressing. That is what you have probably seen us doing for weeks now. If not, there are some pictures below. The holes created are helpful to the turf but it is sort of a short term fix because the holes tend to close quickly when there is no sand to hold them open. So, we will just punch more holes. You can expect to see my team repeatedly punching holes in your tees, maybe even as often as every 7 to 10 days.

Another tactic that will be employed next week is a specialized aerfication and sand injection technique with a machine called the Dryject. This machine uses high pressure water to blast sand into the soil. Much like conventional aerification with sand topdressing, it will leave sand filled cavities in the soil helping to further break through the compacted layer allowing water and air to infiltrate the root zone. But, unlike conventional aerification, very little sand is left on the surface to damage the sensitive cool season turf.

This is a contracted service that, weather permitting, will be performed Wednesday, June 18. I don't want to insinuate this is the "magic bullet" but it will certainly help. As I mentioned before, this fall, once the weather patterns change, we will perform many of the processes, some repeatedly, that I have described. But, this sand injection technique should offer your new sod a fighting chance this summer.

#14 Tee - 5/8" solid tine aerification.

#14 Tee - Close up of aerification holes.

#4 Tee - Verti-quake aerifier in action. This machine cuts 6-7" deep slits but the real benefit comes from the way it shifts back and forth slightly while the blades are in the ground causing fracturing and further relieving compaction.