COURSE CARE
Stop The Cold With A "Dead Air Gap" February 3, 2017 By Patrick O'Brien, agronomist, Central Region

Using drainage pipe to create a “dead air gap” is an effective strategy for maintaining higher root zone temperatures during cold weather.

A blast of arctic cold roared through the Southeast Region from Jan. 6-9, 2017. Air temperatures dipped into the mid to low teens in many locations, and even into the single digits in others. Often, turf covers are deployed on bermudagrass putting greens when low temperatures occur to prevent winter injury. Sometimes, superintendents also create a “dead air gap” under the covers for extra protection during extremely cold weather events.

Pine straw is an effective but labor-intensive way to create an air gap.

Creating a space for stationary air between a cover and turfgrass improves the effectiveness of the cover because the air acts as an insulator. Using a turf cover alone allows heat to directly move from the root zone to the colder turf cover. Trapping a pocket of air under the turf cover will keep the putting green surfaces warmer than covers alone. However, the gap between cover and turf shouldn't be more than 1/2 inch; otherwise the air will circulate and become a less-effective insulator. 

Temperatures at the ninth and 12th putting greens during a period of cold temperature between Jan. 6-9, 2017 at The Peninsula Club in Cornelius, North Carolina.

 
9th Green
  Treatment Jan. 6, 2017 Jan. 7, 2017 Jan. 8, 2017 Jan. 9, 2017
Low Air Temp.   28.9 21.4 16.7 17.4
Soil Temp. Cover Only 44 * 36 35
Soil Temp. Cover + Pine Straw 44 * 41 41
Soil Temp. Cover + Drain Pipe 44 * 41 40

All temperatures in Fahrenheit, soil temperatures measured at 2-inch depth, * No measurement

12th Green
  Treatment Jan. 6, 2017 Jan. 7, 2017 Jan. 8, 2017 Jan. 9, 2017
Low Air Temp.   28.9 21.4 16.7 17.4
Soil Temp. Cover Only 44.8 * 38 36
Soil Temp. Cover + Drain Pipe 45.2 * 40 40

All temperatures in Fahrenheit, soil temperatures measured at 2-inch depth, * No measurement

 
  • Soil temperatures never dropped below 35 degrees at any putting green site, even with the turf cover alone.
  • It takes about the same amount of time and labor to place the pine straw or drainage pipe onto the putting greens.
  • It is much easier to remove the drainage pipe. It took eight hours to remove the pine straw; it only took four hours to remove the drainage pipe.
Turf covers are an effective tool to help prevent cold weather injury to bermudagrass putting greens. The protection provided by covers can be enhanced by creating an air gap between the cover and turf. New ideas are on the way that may make these programs even more successful, stay tuned for further updates on this topic.
 

Southeast Region Agronomists:

Chris Hartwiger, director, USGA Course Consulting Service - chartwiger@usga.org

Steve Kammerer, regional director – skammerer@usga.org

Patrick M. O’Brien, agronomist – patobrien@usga.org

Todd Lowe, agronomist – tlowe@usga.org

Information on the USGA’s Course Consulting Service

Contact the Green Section Staff

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