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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Each growing season, superintendents are conficted between the need for core aeration and commitment to maintaining a consistent, playable putting surface. Over time, reducing or eliminating core aeration will result in deteriorating turf health, soil physical properties and soil chemical properties (6). The trick is fnding the balance between providing suffcient soil cultivation to maintain long-term turf health while limiting disruption to surface playability. Foot traffc and maintenance practices such as mowing and rolling are compressive forces that continually increase compaction. As compaction becomes more severe, the availability of nutrients, water and oxygen is reduced. Severe compaction leads to accumulation of toxic levels of carbon dioxide within the soil and increased incidence of localized dry spot, anaerobic soil conditions, disease and nutrient defciency. Using highly stoloniferous turfgrasses (like ultradwarf bermudagrasses) to increase wear tolerance of high-traffc areas, such as putting greens, increases the need for frequent cultivation to prevent excessive thatch accumulation. Thatch is a slowly decomposing layer of living and dead stems, leaves and roots that develops between turfgrass shoots and the soil surface (3). A limited amount of thatch is desirable to provide resilience to turf and act as a buffer for moderation of soil temperatures (1). Excessive thatch reduces infltration rate, promotes mower scalping, localized dry spot and vulnerability to insect and disease damage (9). Byproducts of microbial thatch degradation accumulate in the soil and increase total soil organic matter. It has been suggested when organic matter content of sand-based putting greens reaches 3%-4% by weight, soil macroporosity begins to decrease (2). Organic matter accumulation within the root zone increases microporosity, lowers permeability of the soil, further slows surface infltration and subsurface drainage, decreases the amount of water available for plant uptake and impedes gas exchange. Core aeration and topdressing are cultivation practices used to improve gas exchange, relieve compaction and slow thatch and organic matter accumulation. Previous recommendations have stated that removing 20% of the surface area on a yearly basis through core aeration is necessary to maintain highquality turf (4). Research has not been able to fnd the perfect balance among core-aeration programs, turf health and surface consistency. The goal of this research was to provide superintendents with a decision-making framework for maximizing benefts to soil physical properties and turf health from core aeration while maintaining consistent playability. Materials and methods A feld study was conducted at Clemson University, Clemson, S.C., during the summers of 2008 and 2009 to evaluate the effect of various core-aeration programs on turf quality and soil physical properties. All research was conducted on a 10-year-old TifEagle bermuda-grass research putting green built to USGA recommendations. The experimental design was developed to explore the effects of removing 15% or 25% surface area per year through one, two or three core aerations on turf quality and soil physical properties. For each treatment, the combination of the percentage of surface area removed and Core-aeration treatments Tine size % surface area affected/year Core-aeration events/year† 25 1 58 25 1 58 25 2 58 25 2 58 25 3 Topdressing‡ Spacing cubic feet/1,000 square feet cubic meters/ hectare 2.5 × 5 63.0 192.0 2.5 × 5 31.5 96.0 5×5 31.5 96.0 2× 2 5×5 15.8 48.0 2× 2 5×5 15.8 48.0 inch centimeters inches / + ½§ 1.59 + 1.27§ 1× 2 / +½ 1.59 + 1.27 1× 2 / +½ 1.59 + 1.27 2× 2 / +½ 1.59 + 1.27 58 / 1.59 centimeters 25 3 58 / 1.59 2× 2 5×5 7.9 24.0 15 1 58 / 1.59 1× 2 2.5 × 5 38.1 116.0 15 1 58 / 1.59 1× 2 2.5 × 5 19.0 58.0 15 2 58 / 1.59 2×2 5×5 19.0 58.0 15 2 58 / 1.59 2×2 5×5 9.5 29.0 15 3 58 / 1.59 2×2 5×5 9.5 29.0 15 3 58 / 1.59 2×2 5×5 4.76 14.5 † Number of core aeration events/year to reach total surface area affected each year. Topdressing amount was the mathematical equivalent of soil removed from core aeration, or half of this rate. § In some treatments, two slightly offset passes with the core aerator were necessary to achieve the correct hole spacing. ‡ Table 1. Treatment list showing percent of total surface area affected per year, core aeration events per year and amount of topdressing applied in Clemson, S.C., June–August 2008 and 2009. 01.14 GOLF COURSE MANAGEMENT 141

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