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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Page 152 of 196

Two weeks after treatment removing 25% of the surface area with one core aeration. Increasing the amount of surface area removed through core aeration reduces bulk density, improves surface water infltration and decreases surface hardness, while increasing healing time. Photos by Jeff Atkinson the number of core aerations dictated the tine size and tine spacing. The actual amount of surface area affected per year varies slightly from the target values because of mechanical limitations. In some treatments, two slightly offset passes with the core aerator were necessary to achieve the correct hole spacing. Following each core aeration, treatments received one of two topdressing rates — either the mathematical equivalent of soil removed by aerifcation or half this rate (Table 1). The frst core aerations were performed on June 1, the second on July 4 (±3 days) (where necessary), and the third on Aug. 15 (±3 days) (where necessary) of each year, using a tractor-mounted core cultivator. Topdressing material similar to that used in putting green construction was measured by volume and applied by shaking it evenly over individual plots. Topdressing was incorporated by hand with a shop broom. A 20N-8.8P-16.6K fertilizer was applied throughout the growing season to provide 1 pound nitrogen/1,000 square feet (48.42 kilograms/hectare) each growing month. Plots 142 GOLF COURSE MANAGEMENT 01.14 were mowed fve times per week and maintained at 0.125 inch (3.18 millimeters). Plots were evaluated for turf quality, bulk density, surface hardness, thatch depth, soil organic matter content and surface-water infltration rate. Turf quality was visually evaluated every two weeks on a 1-9 scale, where 1 was dead turf; 9 was dark green, dense turf; and a rating below 7 was unacceptable. Bulk density was measured at the end of each study year by removing an undisturbed soil core, drying it in an oven at 221 F (105 C) for 48 hours and then dividing dry soil core mass by total soil core volume. Surface hardness was determined as the average of three Clegg impact values (CIV) per plot, a measurement of deceleration of a 5-pound (2.25-kilogram) weight dropped from a height of 18 inches (45 centimeters). Thatch depth was measured two weeks after each core aeration by removing four soil cores from each plot and measuring the distance between shoots above the thatch layer and roots below the thatch layer. Thatch samples were dried at 221 F (105 C) for 48 hours and weighed. Dry cores were then combusted in a muffe furnace to provide ashed organic weight and organic matter content determined by the difference between these two measurements. Infltration was measured 14 days (±2 days) after each aerifcation using a doublering infltrometer. Infltration (inches/hour) is reported as time for water in the center ring to empty from an initial height of 3 inches (8 centimeters) while maintaining a consistent hydraulic head in the outer ring. Results and discussion Topdressing rate did not affect any measured parameter in either year of the study, and interaction between percent surface area removed per year and the number of core aerations per year was inconsistent. The remainder of the article will focus on the effects that the amount of surface area removed per year and the number of core aerations per year had on turf quality, bulk density, surface hardness, thatch depth, soil organic matter content and infltration rate.

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