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 Sodium 1000 Sprinkler 0-4 inches Drip 0-4 inches Sprinkler 4-8 inches Drip 4-8 inches 900 A Sodium (ppm) 800 A 700 A AB 600 B 500 400 A B B B 300 B B B 200 100 0 June 2005 Nov 2005 June 2006 Nov 2006 June 2007 Nov 2007 Figure 2. Sodium (Na) content (ppm) in soil at depths of 0-4 inches and 4-8 inches (0-10 and 10-20 centimeters) irrigated from a sprinkler or subsurface drip system. Data are pooled over three water qualities (potable, moderately saline, and saline). Letters denote the differences in sodium content between the two irrigation systems and two depths separately for each sampling date. Sodium adsorption ratio 20 18 Sodium adsorption ration (SAR) Potable Moderately saline Saline A A 16 A A 14 B A 12 10 A B B 8 6 4 2 B C C C B B B C C 0 June 2005 Nov 2005 June 2006 Nov 2006 June 2007 Nov 2007 Figure 3. Sodium adsorption ratio (SAR) in soil at depths of 0-8 inches (0-20 centimeters) irrigated with saline, moderately saline or potable water. Data are pooled over two irrigation systems (subsurface drip and sprinkler) and two sampling depths (0-4 and 4-8 inches [0-10 and 10-20 centimeters]). Letters denote the differences in SAR among the three water qualities separately for each sampling date. 84 GCM June 2013 irrigation in leaching salts from the root zone at depths above the drip lines. During the dry spring and early summer of 2005 and 2006, root-zone salinity under drip-irrigated turfgrasses exceeded the levels found under sprinkler irrigation. However, the differences between sprinkler- and dripirrigated soil EC values observed in the summers of 2005 and 2006 did not carry over into the fall and winter. Summer and fall precipitation reduced salts at both soil depths to similar levels for all treatments. Sodium content in drip-irrigated plots at soil depths of 0-4 inches only exceeded that of sprinkler-irrigated plots in June and November 2005. For all other sampling dates, sodium content at soil depths of 0-4 inches did not differ between dripand sprinkler-irrigated plots. As with EC, sodium content did not differ between the two depths in sprinkler-irrigated plots (Figure 2) and sodium content in drip-irrigated plots was either lower (June 2006) or similar to that in sprinkler-irrigated plots at depths of 4-8 inches. Sodium levels measured in November 2006, June 2007 and November 2007 did not differ among irrigation systems, soil depths, or sampling dates (Figure 2). SAR values. SAR values measured at soil depths of 0-4 inches and 4-8 inches refected the SAR of the irrigation waters used in the study, with the highest SAR values measured in plots irrigated with saline water, and the lowest values in plots irrigated with potable water (Figure 3). However, SAR values were not affected by irrigation system at either depth. Root-zone salinity at depths of 20-24 inches At the greatest soil depth (20-24 inches), both water quality and sampling date signifcantly affected EC, sodium content and SAR. The type of irrigation system had no effect on any of the three parameters regardless of water quality. During 2005, water quality did not affect EC, which averaged 2.1 deciseimens/meter in June and 1.3 deciseimens/meter in November. During 2006 and 2007, plots irrigated with saline water had the highest EC levels and plots irrigated with potable water had the lowest (Figure 4). Sodium content and SAR were highest in plots irrigated with saline water and lowest in those irrigated with potable water throughout the research period (Figure 4). Sodium content on saline-irrigated plots dropped between June and November in 2005 and 2006, and no change was measured between June and November in 2007. Turf quality When turf quality data were reanalyzed sepa-

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