Golf Course Management

JUL 2019

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07.19 GOLF COURSE MANAGEMENT 69 damages could be associated with its fine leaf texture and slow growth characteristics. Pre- vious research has shown that under drought conditions and with or without traffic, buffa- lograss maintained higher turfgrass quality at fairway and rough mowing heights than Ken- tucky bluegrass (Poa pratensis) and tall fescue [Schedonorus arundinaceus (Shreb.)] (4). Minimal information is available on the traffic tolerance of buffalograss under vary- ing nitrogen fertility management programs. ‚e goal of this study was to determine whether differences in nitrogen fertility lev- els influenced the traffic tolerance of Cody buffalograss. The experiment We conducted a two-year field study that consisted of three separate studies at the Rocky Ford Turfgrass Research Center in Manhat- tan, Kan., from 2014 to 2015. ‚ese studies were conducted on mature Cody buffalograss that had received no fertility, pesticides or sup- plemental irrigation in the last five years. Our experiment included 16 whole plots and 20 strip plots arranged in a 4 (nitrogen fertility) by 5 (traffic) treatment factorial in a strip-plot design with four replications (Figure 1). To simulate a low-maintenance golf course rough environment, the buffalograss was mowed twice per week with a rotary zero-turn mower, and supplemental irrigation of 2 inches (5.08 centimeters) was applied only to water-in fer- tility treatments. Nitrogen treatments during the study were applied with urea at 0, 1, 2 and 3 pounds ni- trogen/1,000 square feet/year (48.8, 97.6 and 146.4 kilograms/hectare). Over the 14-week experimental period, nitrogen applications were split into two half-rate applications, with applications occurring at the beginning of the trial and then again eight weeks after the ini- tial nitrogen application. After both nitrogen applications, the fertilizer was immediately watered-in with 0.25 inch (0.635 centimeter) of irrigation. Simulated golf cart traffic treatments were run twice per week for the duration of the ex- periment, with weekly passes totaling zero, two, four, eight and 16 passes/week. ‚e traf- fic simulator consisted of two trailers, each weighing 1,000 pounds (453.59 kilograms) and supported by a solid axle and five golf cart tires (Figure 2) (2, 8). At certain times dur- ing the experiment, two rollers weighing 390 pounds (176.9 kilograms) each were pulled in tandem because of mechanical issues with the original traffic simulator. When in use, both simulators were pulled in straight lines with no turning, which we deemed was similar to the traffic imposed on the turf near where golf carts enter or exit cart paths. Percent green color measurements were taken every two weeks throughout the 14- week study period. Images were taken with a camera light box and then analyzed using a software program to determine the percent of green pixels in the image (0% to 100% scale). Additional ratings of visual turf color (0-9 scale, 6 = acceptable color), visual turf qual - ity (0-9 scale, 6 = acceptable color), soil pen- etration resistance and soil volumetric content were also collected. Nitrogen rate effect on buffalograss green cover, quality and color ‚rough data analysis, we found that the interaction between nitrogen rate and traffic rate was not significant. ‚erefore, nitrogen rate and traffic rate will be discussed separately. We observed that when higher rates of nitrogen were applied, Cody buffalograss typically had better-than-acceptable percent green cover and visual quality regardless of traffic rate (Table 1). During the first half of the study, we observed that applying 2 or 3 pounds nitrogen/1,000 square feet/year pro- duced higher percent green cover than when 0 or 1 pound nitrogen/1,000 square feet/year was applied. However, for the majority of the study period, any nitrogen application rate re- sulted in higher percent green cover than no nitrogen application, regardless of traffic rate (1). Similar results were observed for visual quality and color. When no nitrogen was ap- plied, the buffalograss never achieved accept- able visual quality or color, regardless of traffic level (Figure 3). Effect of traffic rate on buffalograss green cover, quality and color We observed that when higher levels of traffic were applied, percent green cover, quality and color decreased over time. After the initial rating period, buffalograss receiv- ing 16 passes of traffic per week had the low- est percent green cover and visual quality of all applied traffic treatments. ‚is is similar to observations in an earlier study on buffalo- grass, where 16 passes/week of traffic reduced percent green cover to around 40% to 50% (4). However, in that same study, it was also noted that the buffalograss quickly recovered (to approximately 75% green cover) after traffic had stopped. Figure 2. Traffic simulator used throughout the study consisted of two 1,000-pound trailers, each with a single axle and five golf cart tires.

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