Golf Course Management

JAN 2014

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

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Turf quality, 2008 and 2009 Weeks after initial core aeration† Year Core aerations/year 2 4 6 8 10 12 14 16 18 Turf quality (1-9)‡ 5.4 b§ 6.8 a 7.3 a 7.5 a 7.8 a 8.1 a 8.0 a 6.8 a 6.8 b 6.0 a 5.4 c 6.1 c 6.7 b 7.2 b 7.5 b 7.5 c 6.9 a 7.2 a 3 2009 1 2 2008 6.3 a 5.9 b 6.6 b 6.9 b 7.3 b 7.7 b 7.8 b 6.2 b 6.5 b 1 6.6 a 6.7 a 5.3 b 7.7 a 8.1 a 7.6 a 7.4 a 7.8 a 7.6 a 2 5.3 b 6.3 b 6.2 a 7.0 b 7.3 b 7.3 b 7.3 a 7.7 a 7.6 a 3 5.5 b 6.5 ab 6.5 a 6.9 b 7.2 b 7.3 b 7.0 b 6.9 b 6.9 b † Initial aerification occurred on June 1 of each year with subsequent core aeration on July 4 and Aug. 15 (±3 days). Turf quality values range from 9 (ideal turf) to 1 (dead turf). § Values followed by different letters within the same year and weeks after initial core aeration event are significantly different. ‡ Table 3. Turf quality response over time to 1, 2 or 3 core aerations per year averaged across all amounts of surface area affected per year in Clemson, S.C., June−August 2008 and 2009. a core-aeration program to identify the program's potential effects on playability. Overall, two years of core aeration were needed before surface hardness was signifcantly affected by the percent of surface area removed per year. During 2009, removing 25% of surface area reduced surface hardness 4% compared to removing 15% of surface area (Table 2). The effect of the number of core aerations per year on surface hardness was more consistent between years. Increasing the number of yearly core aerations from one to three reduced surface hardness 5% in 2008 and 19% in 2009 (Table 4). Although surface hardness is a topical indicator of soil compaction, superintendents must consider how reducing putting surface frmness affects playability. A frm putting surface may be desirable to encourage fast ball roll speeds and allow predictable ball action on approach shots for skillful players. Conversely, a frm putting surface slows overall play, as fewer balls will hold the green on an approach shot, causing more strokes to be played around the greens complex. Because surface frmness affects playability, it must be considered during the planning stages of a core-aeration program. Allowing adequate time for frming of the surface is necessary to provide conditions appropriate for championship play. Although this study quantifed the overall effect on surface hardness of various core-aeration programs across 144 GOLF COURSE MANAGEMENT 01.14 the growing season, additional research is needed to determine the amount of time necessary to restore frmness to a desired level after soil cultivation. T atc ept Due to the waxy, hydrophobic nature of thatch, soil moisture management can become challenging when thatch depth is excessive. Putting green surfaces typically require relatively high nutrient input to maintain adequate growth. This, in combination with the use of highly stoloniferous turfgrasses, leads to rapid thatch accumulation in the absence of proactive cultivation. In this study, neither increasing the percent of surface area removed per year nor the number of core aerations per year reduced thatch depth. However, thatch depth did not increase throughout the study (Tables 2, 4). Further research is needed to determine how other thatch-cultivation techniques, such as vertical mowing, complement core-aeration programs and affect surface playability. Organic matter content Organic matter is the byproduct of microbial degradation of shoots, thatch and roots. Collecting these byproducts in the upper soil profle is the driving force behind accumulation of soil organic matter. Although soil microbe activity should be encouraged, failure to reduce accumulation of organic byproducts slows soil drainage, increases microporosity and decreases soil oxygen concentration. In this study, reduction of soil organic matter accumulation was not consistent between years. In 2008, increasing the percent of surface area removed per year or the number of core aerations per year did not reduce organic matter accumulation. In 2009, treatments with three core aerations slowed organic matter accumulation 10% more than treatments with only one core aeration (Table 4); however, overall organic matter accumulation was not reduced below pre-study levels. Although research has not consistently quantifed signifcant reductions in soil organic matter following core aeration, numerous studies have shown that core aeration prevents organic matter accumulation above pre-aerifcation values (6,7,8). Long-term observation of soil organic matter accumulation is necessary to determine the cumulative effect of core aeration over several growing seasons. Infltration The resistance water encounters as it travels through hydrophobic thatch and a compacted soil surface typically slows water infltration. Properly constructed putting greens should balance suffcient drainage with adequate soil water-holding capacity to promote healthy turf growth. For newly constructed sand-based putting greens, water should infltrate the turf surface 10 to 15 inches (25-38

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