Golf Course Management

JUL 2018

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

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74 GOLF COURSE MANAGEMENT 07.18 quality (in year 1, especially), with recovery within two weeks. By the second year of the study, turfgrass quality was typically similar among all treatments. Plots that were aerified and received top - dressing sand or reincorporated cores had thicker thatch-mat layers. Over two years, thatch-mat depth was deepest in the spring + summer treatment (89% increase as com - pared to non-cored), followed by the spring- only coring (66% increase), followed by the non-cored bentgrass. Much of this accumu - lation occurred between late summer and the following spring. Total organic matter (amount of organic matter per unit area) was less affected by the various treatments, and was the same among treatments after two years. However, the concentration (amount of organic matter in a gram of soil) of the or - ganic matter in the non-cored bentgrass was substantially greater than that measured in aerified treatments (211% and 298% greater than in the spring-only and spring + summer treatments). So why was total organic matter unaf - fected, but the organic matter concentration substantially changed? Well, when coring was combined with topdressing, the organic mat - ter was diluted by the topdressing sand/rein- corporated cores, and concentration was re- duced within the thatch layer. e take-away messages from this work were threefold: (1) measuring only thatch-mat depth can pres - ent a misleading picture of organic matter ac- cumulation; (2) spring and spring + summer coring reduced organic matter concentra - tions; and (3) summer coring created injury, and it should be used with care or avoided, especially on newer stands of bentgrass. Source: Fu, J., P.H. Dernoeden and J.A. Mur - phy. 2009. Creeping bentgrass color and qual- ity, chlorophyll content, and thatch-mat accu- mulation responses to summer coring. Crop Science 49:1079-1087. Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn Univer - sity in Auburn, Ala., and president-elect of the Crop Sci- ence Society of America. She is a 20-year member of GCSAA. Beth Guertal, Ph.D. Twitter: @AUTurfFert Thatch, mat and coring (verdure) Organic matter accumulation has long been a concern for turfgrass managers, who have adopted many strategies to combat it, including aerification or the application of topdressing or other materials such as wet - ting agents or microbial degraders. Still, organic matter management is often first addressed through cultivation practices, in - cluding aerification. With that in mind, turf- grass researchers at the University of Mary- land (and one author at Rutgers University) examined the practice of coring on the qual - ity and thatch-mat (thatch-mat is the term for the organic layer consisting of thatch and the intermixed topdressing sand) content of a Providence creeping bentgrass putting green. e researchers at Maryland studied the effects of three different coring regimes: (1) spring-only (late April) with cores removed, followed by sand topdressing to fill the holes; (2) spring + summer (three times in early and late June and late July) coring, with the cores ground and reincorporated into the holes as topdressing; and (3) no coring, no topdress - ing. For spring coring, removed cores were 0.5 inch (1.27 cm) in diameter, penetrated to a depth of 3.5 inch (9.0 cm), and were re - moved at equidistant 2-inch (5.0-cm) spacing. For the summer coring treatment, cores were 0.25 inch (0.64 cm) in diameter, penetrated to a depth of 2 inches (5.5 cm), and had a hole spacing of 1.5 × 2 inches (3.8 × 5.0 cm). e location was a sand-based (97% sand) putting green mowed at 0.156 inch (4 mm), and the study was performed for two years. Collected data included turfgrass quality, color and thatch-mat depth. To further study the effect of accumulated topdressing sand, the researchers also collected loss-on-ignition (LOI) data, where thatch-mat samples were combusted in an oven to ignite organic mat - ter. is allowed two different calculations: total organic matter content, which was LOI divided by the surface area of the samples; and organic matter concentration, which was the organic matter (weight of the LOI) di - vided by the dry weight of the cores. In general, plots that had spring coring or spring + summer coring had better spring color (through May) than the plots that were not cored. Summer coring did reduce color in June and July, and it also reduced turfgrass When coring was combined with topdressing, the organic matter was diluted by the topdressing sand/ reincorporated cores, and concentration was reduced within the thatch layer.

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