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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Response of soil physical properties to core aeration Year No. of core aerations/year Bulk density (grams/cubic centimeter) Surface hardness (gMax)† Thatch organic matter content ounces/ square inch‡ grams/ square centimeter Thatch depth inch millimeters Infiltration inches/ hour centimeters/ hour 1.25 a§ 48.0a 0.22a 0.96a 0.56a 13.9a 57.5a 146a 1.25 a 46.7ab 0.23a 1.01a 0.57a 14.5a 65.7a 167a 3 2009 1 2 2008 1.15 b 45.4b 0.22a 0.98a 0.55a 13.9a 61.0a 155a 1 1.43 a 57.6a 0.27a 1.19a 0.52a 13.3a 76.0a 193a 2 1.37 b 53.4b 0.26ab 1.17ab 0.51a 12.9a 52.0b 132b 3 1.36 b 46.9c 0.24b 1.07b 0.48a 12.1a 61.0b 155b † Relative surface hardness value quantifies deceleration of 4.96-pound (2.25-kilogram) weight dropped from height of 17.7 inches (45 centimeters). Ashed organic weight of thatch layer per square inch of surface area § Values followed by different letters within the same year are significantly different. ‡ Table 4. Soil physical properties response to one, two or three core aerations per year, averaged across all rating dates and percent of surface area affected each year in Clemson, S.C., June−August 2008 and 2009. centimeters)/hour (5). Thatch accumulation and byproducts of thatch decomposition combine to slow infltration over time. As infltration is reduced, the proportion of water lost through runoff increases, the amount of plant-available water is reduced, and saturation of the thatch layer is encouraged. Removing thatch through core aeration has long been relied on to reduce or slow thatch accumulation, thereby improving infltration rate. In this study, increasing the percent of surface area removed per year did not increase infltration speed in 2008 or 2009. Increasing the number of yearly core aerations did not affect infltration speed in 2008; however, in 2009 increasing the number of core aerations from one to two decreased the speed of surface water infltration 32%, and increasing the number of core aerations from one to three decreased surface water infltration speed 20% (Table 4). The season-long effect of increased infltration in treatments with only one core aeration in 2009 may be explained by the initial removal of a large percent of surface area early in the growing season. Increasing the number of yearly core aerations to remove the same percent of surface area reduces the size and number of channels opened through the turf 146 GOLF COURSE MANAGEMENT 01.14 surface to facilitate infltration. When single core-aeration treatments were repeated in consecutive years (2008 and 2009), numerous channels to facilitate water movement through the turf surface were opened early in the growing season, improving season-long infltration speed. Conclusions The research shows that superintendents should develop core-aeration programs that ft their needs while keeping in mind agronomic considerations and playability. Generally, as the number of core aerations per year and the percent of surface area removed per year increase, soil physical properties improve. As the number of core aerations per year and the amount of surface area removed per year decrease, average turf quality across the entire growing season improves, but soil physical properties show less improvement. Regular monitoring of bulk density, surface-water infltration, surface hardness, thatch depth and organic matter accumulation is necessary to identify soil physical properties in need of amelioration through core aeration. These properties — as well as consideration of the effects of core aeration on turf quality — should be used to determine amount and frequency of core aeration nec- essary to provide a healthy growing environment for turf. Developing a framework for superintendents to balance agronomic practices with maintaining a consistent playing surface is an ongoing process. Continuing research is needed to refne timing, spacing and tine size selection to minimize putting surface disruption while maximizing the benefts gained through core aeration. Additional research is also needed to gain an understanding of the long-term effects of various cultivation programs on turf health. Funding Funding was provided by the Clemson Agricultural Research Station. Acknowledgments The authors would like to acknowledge Alan Estes, Ray McCauley and Jeff Marvin for their assistance conducting this research. Literature cited 1. Butler, J.D. 1965. Thatch: A problem in turf management. Pages 1-3. In: Illinois Turf Conference Proceedings, Lemont, Ill. 1965. University of Illinois Cooperative Extension Service, College of Agriculture and the Illinois Turfgrass Foundation, University of

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