Thursday, January 23, 2020

Dynamic Viscosity!

Hello and welcome to The Greenkeeper!  Today is Thursday, January 23rd and our fourth consecutive morning with temperatures below freezing.  Prior to this cold snap's arrival we had endured 29 consecutive days with above average temperatures dating back to before Christmas.  In fact, our Bermudagrass tees and fairways began to show signs of waking from their annual winter's slumber.  Yes, the color you see and enjoy is natural, nothing has been applied.
Brad Panovich, WCNC
We are also in the midst of our driest stretch this winter (since Dec 1) with only 0.14" rainfall in the past eight days.  Unfortunately our area is forecast to receive more than one inch of rain starting sometime late tomorrow.  Also, we have already received 9.46 inches rainfall this winter (since Dec 1) which is well above average.  The record winter rainfall total is 19.46 inches set just last year (Dec '18-Feb '19).

It has rained 119.03 inches on Carolina Golf Club since Jan 1, 2018!  And that total is approximately equivalent to three years average rainfall, but in just two.  I tell you this only to give you a greater perspective and understanding to the unusually wet conditions of late.  For those curious the most recent wet winter prior to last year was four years ago (Dec '15-Feb '16) when we received 15.48 inches.

Needless to say, during periods of extreme wet weather we receive comments about drainage.  And the information I'm sharing is not meant as an excuse, the committee and I are always evaluating the golf course, playing conditions and our resources to determine the best ways to improve and enhance your experience.  I'm merely trying to help you better understand the context of why things are softer and slow to dry this year and last.

The golf course is built on native Piedmont clay soil and is mostly surface drained, that was a strong suit of Donald J. Ross.  We added a modest network of inlets and below ground drains during the restoration, and have added and modified that network over the years.  We've also sand topdressed fairways the past five years in an effort to modify the soil profile and improve water infiltration.  

In the summer months Bermudagrass is actively growing and takes up plant available water through the roots.  Long days and warm temperatures help promote evaporation.  In the winter months the turf is dormant (hibernating) and the short days and colder temperatures greatly reduce the rate of evaporation.  But there is also another phenomenon that negatively impacts the removal of water from our clay soils - viscosity.  

Viscosity is a fluid's resistance to flow and everyone understands liquids such as motor oil, molasses and honey are much thicker and have a greater viscosity than water (the higher the viscosity value the more resistance to flow).  But viscosity is not static, and temperature alters the viscosity of liquids, including water where flow is reduced in colder temperatures.
Chart Courtesy of Cale Bigelow, Ph.D.

Another question I've been fielding lately is why the wet area on No. 8 fairway seems to defy gravity and is on the slope.  For starters it doesn't help the area in question is shaded (see pic below), but that's not all.  In the book Practical Drainage for Golf, Sportsturf and Horticulture by Keith McIntyre and Bent Jakobsen, Chapter Four, The Capillary and Lateral Movement of Water in Soils provides two key factors.  First, the lateral movement of water in soils is extremely slow.  Second, the downward force of gravity on water is reduced once it reaches where the slope begins to flatten.  The slower rate of lateral movement then causes the water to back up and we encounter the phenomenon that seems to defy our logic.
Wet Area Marked by Small Stakes

Hopefully this update gives you a better understanding of how the changing seasons impact our daily conditions, and lately the seasons have been a little extreme.  In the meantime you can help by exhibiting caution and avoid the lower lying and wetter areas with your traffic.  All traffic compacts wet soils and the increase in compaction slows even more the internal movement of water.  We will continue to examine the needs of the course and make improvements when and where possible, and I encourage you to reach out to me and/or members of the Green Committee with your questions and comments.  All feedback is helpful. 

That's all for now.  Next week I'll be at the annual Golf Industry Show where I'll be co-teaching a seminar on Monday and participating in a panel discussion on Tuesday.  Looking forward to networking and collaborating with my peers, and catching up with Matt Claunch!

See you on the course,

Matthew Wharton, CGCS, MG

1 comment:

  1. Tangentially related to drainage...Whois responsible for sending out notifications regarding conditions and cart restrictions? Ideally, these notifications would be sent out as early in the morning as possible.