Divot Resistance of Thick Cut Sod as Influenced by Pre-Harvest Nitrogen and Sand Topdressing

For sports played on turfgrasss, stable footing for the athletes is paramount to player performance and safety. High-level athletes possess exceptional size and speed and their studded footwear can shear portions of turf away from the rootzone as they change directions. These sheared portions of turf have been termed divots. Resistance to turfgrass divoting is a primary concern of high-level sports field managers. Professional facilities in the U.S.A. are now frequently installing thick-cut sod during the playing season. This newly installed sod is often played upon days after installation. Due to the thickness of the sod and the short duration between installation and use, the rooting of the sod layer into the rootzone has little to no effect on surface stability. Field performance immediately after sod installation is primarily determined by the maintenance practices of the sod farm prior to harvest and installation. The objective of this research was to investigate the influence of six N programs (98-245 kg N ha^-1 yr^-1 applied spring or fall) and two sand-topdressing rates (0 and 8.5 kg m^-2 yr^-1) on KBG grown as sod. In 2013 and 2014 KBG was established from seed in September and grown for 7 months at a commercial sod farm (Hammonton, NJ) and then transported as sod and grown for another 7 months under the 6 by 2 treatment combinations at University Park, PA. Sod was harvested 14 months after seeding and evaluated for divot resistance and sod strength in relationship to turfgrass characteristics (color, shoot density, below ground biomass, and thatch). Divot resistance was measured with a weighted pendulum where smaller divot lengths indicate less sod displacement and greater divot resistance.” Topdressing reduced divot resistance by 6% in 2014 and had no effect in 2013. Nitrogen treatments significantly affected divot resistance which varied with year of the study. In 2013 all N treatments were similar in divot resistance except at the highest N rate which exhibited the lowest divot resistance. In 2014, the lowest divot resistance was observed with 49 kg N ha^-1 applied 3 times in the spring (147 kg total N) or using the same N program with another 49 kg ha^-1 applied in September (196 kg total N). The results of this research suggest that some sod growers can maximize divot resistance by reducing N inputs in the year immediately following seeding the previous fall.