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Cover Story
Aerification for UltraDwarf Bermudagrass Putting Greens
By Marco Schiavon, PhD Assistant Professor Ft. Lauderdale Research & Education Center
Aerification is a crucial turf management technique that helps prevent the buildup of organic matter (OM) and soil compaction in golf greens. Core aerification, which involves the use of hollow tines, entails the removal of numerous shallow soil cores from the turf. This process involves physically extracting small plugs of the upper turf layer, thatch, and surface soil, replacing them with sand. While this intensive practice can be disruptive for both golfers and maintenance crews, its significance for long-term turf management cannot be overstated. Neglecting aerification can lead to increased OM accumulation and reduced drainage capabilities.
When performed at the appropriate times, aerification can mitigate these problems and minimize soil compaction. Currently, hollow tine core aerators are the standard for this practice. They are specifically designed to remove plugs of soil closest to the surface of the turf, where OM predominantly tends to accumulate. Various styles of tines exist, offering a range of core sizes and shapes, including solid tines, which perforate the surface of the greens without removal of any material. Additionally, alternatives to core aeration, such as sand or air injection, aim to enhance soil properties with minimal surface disruption. Sand injection, for instance, utilizes high-pressure water to create perforations that are subsequently filled with sand through the Venturi effect.
Recently, a two year-experiment (2021-22) was conducted on a mature ‘TifEagle’ hybrid bermudagrass putting green. This green was established in 2016 at the University of Florida Institute of Food and Agricultural Sciences, Fort Lauderdale Research and Education Center in Davie, FL, USA to determine if different aerification methods alter turfgrass performance and soil properties. The green was aerified monthly from the end of May to August. The experiment was set up to compare tine-aerated treatments with sand and air injection. Tine-aerated treatments were performed with an aerator [eight sets of four tines (ProCore 648; The Toro Company, Bloomington, MN, USA)] with either hollow tine four times per year [This is the industry standard for south Florida, USA] and was considered as control), twice with hollow needle tines, and twice with hollow tines, or with hollow needle tines four times per year. Sand injection was performed using DryJect 4800 four times per year and air injection was performed using Air2G2 four times per year. Plots were tested for recovery after aerification events and for improved soil characteristics i.e. surface firmness, saturated hydraulic conductivity (Ksat), volumetric water content (VWC) and organic matter content.
Traditional aerification methods can temporarily compromise the aesthetics and performance of putting greens due to their disruptive nature. Research has shown that the quality of ‘TifEagle’ hybrid bermudagrass may decline for up to four weeks following aerification. Findings indicate that hollow tines have a longer recovery time compared to other aerification techniques, attributed to the larger area impacted. In contrast, alternative methods like sand injection cause minimal surface disruption and shorten recovery time.
Additionally, putting surfaces treated with sand injection were approximately 12% firmer compared to those treated with tine aeration.
While all plots aerated with tines exhibited an increase in Ksat (the rate at which water drains through the green), those treated with hollow tines—either alone or in combination with hollow needle tines—demonstrated higher Ksat values by the end of the season compared to plots treated only with hollow needle tines. This difference may be linked to the higher organic matter content found in the plots aerated solely with hollow needle tines. plots aerated with hollow tines showed a lower VWC (Figure 1) towards the end of summer likely due to reduced organic matter content and higher saturated hydraulic conductivity. Overall, the results indicate that hollow tines are more effective in reducing organic matter than hollow needle tines alone.
In summary, while aerification with hollow tines, either by themselves or alongside hollow needle tines, successfully decreased surface firmness and organic matter content while enhancing Ksat, it also led to a reduction in green cover. Under the conditions of this study, air injection (Air2G2) did not ameliorate any soil properties compared to tine aerated treatments. Results may be different on sites with greater soil compaction. Although disruptive, the use of hollow tines for aerification remains the most effective tool to ameliorate soil characteristics in hybrid bermudagrass putting greens. More research is needed to identify if alternating or combining sand, or air injection, with hollow tines could reduce the amount of core aerifications through the year while keeping benefits on soil properties and reducing greens’ recovery times.
