Golf Course Management

SEP 2013

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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research Turfgrasses Seven cool-season turfgrasses were established in 2004: Southeast and Tar Heel II tall fescue [Festuca arundinacea (Schreb.)]; Brightstar SLT and Catalina perennial ryegrass [Lolium perenne (L.)]; Fults and Salty alkaligrass [Puccinellia distans (L.) Parl]; and Dawson fne fescue [Festuca rubra (L.)]. Turfgrass quality was rated monthly on a scale of 1 to 9, where 1 is dead turf and 9 is dark green, uniform turf. The monthly ratings were averaged every three months (March-May, June-August and September-November) and analyzed as three different seasons. Digital photographs were taken monthly from March to November at full sunlight from one hour before until one hour after solar noon. Digital images were analyzed for percent green coverage. Coverage data were averaged every three months and correlated with visual quality. During the growing season (March-November), plots were mowed biweekly at a height of 3 inches (7.5 centimeters) and clippings were collected. Plots were fertilized at a rate of 1 pound nitrogen/1,000 square feet with 15-15-15 quickrelease fertilizer in April, June, August and October. A micronutrient fertilizer (Pro-Mate, Helena Chemical Co.) containing calcium (1.0%), magnesium (4.3%), sulfur (18.2%), copper (0.3%), iron (14.3%) and manganese (2.6%) was applied in the summer at a rate of 2 pounds/1,000 square feet (10 grams/square meter). Soil The soil at the site consisted of a sandy loam, a sandy, skeletal, mixed, thermic Typic Torriorthent, an entisol typical for arid regions. Composite soil samples were collected in mid-June and mid-November from depths of 0-4 inches (0-10 centimeters), 4-8 inches (10-20 centimeters), and 20-24 inches (50-60 centimeters). Data are presented on electrical conductivity (EC), sodium adsorption ratio (SAR) and sodium content. Irrigation Plots were irrigated with potable, moderately saline or saline water. Saline water was pumped from a nearby saline aquifer to the research site. Moderately saline water was prepared by mixing municipal water with the saline groundwater to EC of 2 decisiemens/meter. According to the U.S. Salinity Laboratory (17), the moderately saline water is classifed as high in salinity and low for sodium hazard (C3-S1), and the saline irrigation water is classifed as very high in salinity and Chemical analysis of irrigation water used in the study Constituents Water quality Potable Moderately saline Saline pH 7.98 7.69 7.52 Electrical conductivity (decisiemens/meter) 0.6 2.0 3.5 Total Dissolved Solids (milligrams/liter) 400 1,300 2,200 Magnesium (milliequivalents/liter) 0.8 1.68 2.52 Calcium (milliequivalents/liter) 2.8 3.19 5.05 Sodium (ppm) Sodium Adsorption Ratio (SAR) 48 230 400 1.55 6.41 8.94 Potassium (milligrams/liter) 4.6 28.0 51.2 Carbonate (milliequivalents/liter) 0.00 0.00 0.00 Bicarbonate (milliequivalents/liter) 2.84 6.43 9.95 Not detected 1.56 2.38 Residual sodium carbonate (milliequivalents/liter) Table 1. Chemical analysis of potable, moderately saline and saline water used in the study. medium for sodium hazard (C4-S2). A detailed description of ion concentrations in the irrigation waters are listed in Table 1. Irrigation systems. Grasses were irrigated with either a sprinkler or a subsurface drip system. From February to November, irrigation was scheduled daily at 120% of reference evapotranspiration (ETo) (1) using Nimbus II Central Control System irrigation software (Rain Bird Corp.) that also scheduled the golf course irrigation system. During December and January, irrigation was scheduled manually twice weekly for approximately 10 minutes. Climate data used to calculate ETo were collected at a weather station located on the golf course near the study site. Irrigation for each sprinkler and subsurface-drip main block was regulated by a separate solenoid valve and pressure regulator. Sprinklers. The sprinkler system was made up of eight Walla Walla MP2000 Rotators (Walla Walla Sprinkler Co.) operated at 30 psi (200 kPa) and spaced 12.5 feet (3.8 meters) apart to allow uniform irrigation. Irrigation audits conducted during each year ensured that distribution uniformity was never lower than 0.7 and provided data necessary to compare actual water delivery rates with computer settings. Subsurface drip system. The subsurface drip system consisted of porous emitterless line source pipes (Precision Porous Pipe) with a diameter of September 2013 GCM 77

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