Golf Course Management

FEB 2016

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

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106 GOLF COURSE MANAGEMENT 02.16 The high shoot density of the bentgrass helped intercept and store water when com - pared with the lower shoot density and up- right growth of the perennial ryegrass. Inter- estingly, although one could view infltration as the opposite result of runoff (if water does not run off, it should infltrate), grass species was never observed to affect differences in infltration. Methods of measuring infltra - tion are highly variable, and such results are fairly common in research. To further explore this, an additional experiment was conducted. In this experiment, which used small sloped trays of turf, bentgrass retarded the fow of surface runoff through its vegetation signif - cantly longer than ryegrass. It was also found that bentgrass (94 tillers/square inch [1,410 tillers/square decimeter]) intercepted 113% more water than ryegrass (17 tillers/square inch [260 tillers/square decimeter]), and that the high water-holding capacity and increased hydraulic resistance of bentgrass thatch slowed runoff initiation. The bentgrass thus provided a more tortuous pathway for water movement, which increased resistance and, in turn, increased residence time and allowed for greater infltration. In the end, a mature (2-year-old) sward of bentgrass turf managed as a fairway was more effective for reducing runoff than simi - larly managed perennial ryegrass. It should be noted, however, that any turfgrass cover was better than none, as runoff in any treatment was never more than 22.5% of applied water. For golf courses in the vicinity of environmen - tally sensitive areas, this work clearly shows the ability of established turfgrass (and especially creeping bentgrass) to lessen water runoff from fairways. Source: Linde, D.T., T.L. Watschke, A.R. Jarrett and J.A. Borger. 1995. Surface run - off assessment from creeping bentgrass and perennial ryegrass turf. Agronomy Journal 87:176-182. Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn University in Auburn, Ala., and the editor-in-chief for the American Society of Agronomy. She is a 19-year member of GCSAA. Beth Guertal, Ph.D. Twitter: @AUTurfFert Run away with me (verdure) If you want to stop or slow water runoff — and possible subsequent soil erosion — you know what works really well? Turfgrass! Plant residue and vegetative covers have been used for this in road construction and farming for years, and although turf was also known to slow surface runoff and sediment transport, information about the utility of a fairway for this purpose was not well documented. So, in the early 1990s, Doug Linde, Ph.D., and Tom Watschke, Ph.D., at Penn State University de - cided to examine how well creeping bentgrass and perennial ryegrass performed for limiting runoff from fairways. The research plots were located in an area with 9% to 11% slope, and every plot was in - dividually drained into collection chambers designed to measure the varying amounts of runoff over time. Plots were seeded in July to either creeping bentgrass or a perennial rye - grass blend, and they were mowed at 0.75 inch (19 mm) and maintained like a typical fairway. Here's the deal with runoff research: Often, natural rainfall does not produce suf - fcient moisture for substantial measurable runoff to occur, so researchers force runoff by irrigating each plot until runoff occurs. In this case, irrigation was applied on selected dates at 6 inches (152 mm)/hour to create measur - able runoff. This is considered a worst-case scenario, but it allows researchers to compare treatments. For this experiment, forced run - off events were initiated about three months after seeding (October) and then continued for another year. Collected data included run - off volume, time to frst runoff, tiller density and infltration. Greatest runoff, regardless of turf spe - cies, occurred at the frst irrigation event at three months after seeding. At this date, the immature turf had not yet produced signif - cant tillers or stolons (bentgrass). The effects of turf species on runoff differences were not evident until about a year after seeding (May) by which time, the bentgrass had greater til - ler density and had begun to produce stolons. This greater shoot density resulted in reduced runoff volumes from the bentgrass as com - pared with those from ryegrass. An additional help in reducing water runoff from the bent - grass was the fact that the bentgrass produced water-sorbing thatch, which the ryegrass never did during the two years of the study. A mature sward of bentgrass turf managed as a fairway was more effective for reducing runoff than similarly managed perennial ryegrass.

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