Golf Course Management

JUN 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 Chemical analysis of water 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 (ppm) 400 1300 2200 Magnesium (ppm) 9.8 20.5 30.7 Calcium (ppm) 56 63.8 101 Constituents Sodium (ppm) 48 230 400 Sodium Adsorption Ratio 1.55 6.41 4.6 28.0 51.2 Carbonate (ppm) 0.00 0.00 0.00 Bicarbonate (ppm) 173 392.2 607 Not detected 1.56 2.38 Pesticides The pre-emergent herbicide Pendulum (pendimethalin, BASF) was applied at label rate in April to prevent weed germination. The systemic insecticide Merit (imidacloprid, Bayer) was applied at label rate in June and August to prevent grub damage. 8.94 Potassium (ppm) root growth. The depth of 20-24 inches was also chosen to monitor changes in salinity below the rooting depth because no roots were found below a depth of 16 inches (40 centimeters). Data are presented on electrical conductivity (EC), sodium adsorption ratio (SAR) and sodium (Na) content in the saturated soil paste extract. Residual Sodium Carbonate (milliequivalents/liter) Table 1. Chemical analysis of potable, moderately saline and saline water used in the study. Water samples were collected nine times during the research period (March 2005 to November 2007), and data represent the average of the nine samplings. Sea Spray); and De Anza zoysiagrass. Turfgrass quality was rated monthly, averaged every three months (March to May, June to August, and September to November), and analyzed as three different seasons. Turfgrass color ratings were collected in March and November to evaluate the plots for spring green-up and fall color retention. Plots were assessed on a scale of 1 to 9, where 1 = brown, tan-colored and 9 = dark green turf. Soil The soil at the site consisted of a sandy loam, a sandy skeletal mixed thermic Typic Torriorthent, an entisol typical for arid regions. During the growing season (March to November), plots were mowed twice weekly at a height of 2 inches (5 centimeters) and clippings were collected. Plots were fertilized at a rate of 1 pound nitrogen/1,000 square feet (5 grams nitrogen/square meter) with 15-15-15 quick-release fertilizer in April, June, August and October. A micronutrient fertilizer (Pro-Mate, Helena Chemical Co.) was applied in summer at 2 pounds nitrogen/1,000 square feet (10 grams/square meter). Composite soil samples were collected in midJune 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). Before the beginning of the study, exploratory soil sampling on adjacent golf course fairways with bermudagrass turf revealed that depths of 0-4 and 4-8 inches represent the areas with most of the 82 GCM June 2013 Irrigation Plots were irrigated with potable, moderately saline or saline water. Saline water consisted of water obtained from a saline aquifer that was pumped to the research site. Moderately saline water was prepared by mixing municipal water with saline groundwater to electrical conductivity (EC) of 2 decisiemens/meter. The U.S. Salinity Laboratory (7) classifes moderately saline water as C3-S1 (high in salinity and low for sodium hazard) and saline irrigation water as C4-S2 (very high in salinity and medium for sodium hazard). Water samples were collected monthly to measure EC and three times during each growing season to determine all major constituents in the water. A detailed description of ion concentrations in the irrigation waters are listed in Table 1. Irrigation systems. Grasses were irrigated during the growing season from either a sprinkler or a subsurface drip system at 110% of reference evapotranspiration (ETo) (1). Irrigation was scheduled daily using Nimbus II Central Control System irrigation software (Rain Bird Corp.), which also scheduled the golf course irrigation system. 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 composed 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 for uniform irrigation. Irrigation audits conducted twice during each growing period ensured a minimum distribution uniformity (DU) of 0.7 and provided data necessary to compare the irrigation systems' actual water delivery rates with computer settings. Subsurface drip system. The subsurface drip system consisted of porous emitterless line source

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