Soil Temperatures

As air temperatures reached 111.2 F yesterday at ACC, a soil thermometer shows the temperatures at two different depths within a green's soil profile. At 2 pm the air temperature was 109 F. The soil temperature at 1" down was 96.7 F. Within six inches of the initial probes location, the temperature registered five inches down was 88.7 F.

1" below green surface:

5" below green surface:

Keeping a watchful eye....

Just add water....

In July, we added irrigation to areas lacking adequate coverage on the Driving range tee, #13 tee, #14 ladies tee, #15 behind the green, and the left side of #1 green surround between the green and the start of #13 fairway. These locations had been identified over the past season and a half as having weak or no coverage.

After last season's addressing of every green complex, the priority has shifted to areas of limited or no coverage. For the past few decades these areas have had to be hand watered daily throughout the summer heat to maintain at minimal a stand of turfgrass. Correctly triangulating the head spacing and installing a sprinkler has made the world of difference as illustrated in the photos below:

Left of #1 green shortly after installation:

Left of #1 green now:

#13 Tee Before Installation:

#13 Tee after:

Behind #15 just after installation:

Behind #15 currently:

Bentgrass versus poa

The poa versus Bentgrass debate is always a contested one. Most say that you cannot grow Bentgrass in Southern California and that poa will out compete Bentgrass in the long run. "It is only a matter of time...." they say. We disagree.

For those of you that remember the tense summers at ACC in years past when the poa would struggle mightily or perish in the heat, I pose the question to you, "Which would you rather have, Bentgrass or poa?" Bentgrass can establish itself and be dominant in Southern California given that the correct management practices are being implemented.

One of the major benefits of Bentgrass is that it is more tolerant of abiotic (non-living) stresses on the extreme levels. I will focus on temperature for this post. The photos below illustrate the difference in root depth between a poa green and a Bentgrass green here in Southern California this summer. The poa root depth may be an inch. The Bentgrass, seven inches.

Root depth and mass are very critical to surviving the summer heat. When soil temperatures reach 80 degree Fahrenheit, new root growth ceases and the aging process begins. At above the mid 90 degree mark Fahrenheit, root hairs dye back and fail to function properly. When the air temperature exceeds 90 degrees fahrenheit, the soil temperature in the upper 1/2" can reach reach upwards of 100 degrees on a bright sunny day. When looking at the illustration below of the shallow poa roots, that can be deadly.

We have had a very mild summer to date and our soil temperatures remain in the upper 60's F in the early part of the morning. Those temperatures creep into the mid to upper 70's F in the afternoon.

Poa Green roots in July:

Bentgrass green roots in July:

Summer Irrigation

As many of you are aware, the summer heat can be a bear here in the Inland Empire. We have been fortunate this year to have had a mild June, July, and early August with below average night time temperatures. (especially for this time of the season)

Our irrigation strategy is constantly being modified to provide the best possible playing surfaces and conditions. Many factors influence these modifications with some keys being ET (Evapotranspiration), wind, humidity, and temperature. Turfgrass varieties, soil conditions, sprinkler spacing, and trees also impact our watering procedures.

The Bentgrass greens and their deep, extensive rootzone allow us to stretch our irrigation cycles to greater lengths than say our Common Bermudagrass fairways and tees. We try to water the greens on a less frequent basis, but when the cycle is required, we water for long periods of time to drive the water deeper. The benefit to this deep irrigation cycle is two-fold. It flushes salts building up in the soil profile below the rootzone and out of reach of the plant. I hope this answers the question as to why on occasion the greens may be "wetter" and "better receptive" to low trajectory shots this time of the season.

On the opposite end, the cool season Ryegrass that resides in some shaded rough areas, requires more frequent irrigation. Soil composition and competition from tree roots factor into the irrigation philosophy in these areas. The difficulty with an older, non-single head controlled irrigation system like the one that resides at ACC is that providing enough water to certain areas means applying too much water to another. We try our best to compensate for these deficiencies. We appreciate your patience as we try to better perfect our water management.

August Photography

Appreciation Barbecue

We would like to say "Thank You" to the membership of Arrowhead Country Club for providing an Appreciation Barbecue for the Golf Course Maintenance Staff. We in turn, appreciate the recognition of our day to day efforts to provide quality, consistent, favorable playing conditions. A special thanks to Mr. Dick Williams for organizing the event and to "Chef for the Day" Mr. Steve Henthorn (GM). The staff is already inquiring when the next event will take place.