Hybrid Bluegrass Nitrogen Timing and Rates for the Southeast.
E. A. Guertal, Agronomy & Soils, Auburn University, Auburn, AL 36839
Hybrid bluegrass (Poa arachnifera Torr. x Poa pratensis L.) is a newer turfgrass option for homeowners in the southeastern United States. Typically seeded cultivars, the grasses are marketed for enhanced heat and drought tolerance when compared to other cool-season turfgrasses. Little is known about best management practices for fertilizer nitrogen (N) rates and timings for this newer grass, especially in the humid SE United States, where cool season grass plantings often fail in the summer months. The objective of this study was to evaluate N rate and timing impacts on the growth and turf quality of two cultivars of hybrid bluegrass. The plots were established in October, 2004 in Auburn, AL, on a Marvyn fine sandy loam soil. Fertilizer treatments were initiated on May 13th, 2005. Fertilizer treatments consisted of various spring and fall programs, with fertilizer (a homeowner type 29-3-4 product) applied at total N rates of 146, 195 and 292 kg N ha-1, with the N split throughout the year. Treatments were arranged in a randomized complete block design with 14 N rate/timing treatments and 4 replications of each treatment, for each cultivar. Data collection started in June, 2006, one year after all fertilizer treatments had been applied, with treatments continued for all subsequent data collection. Collected data included monthly turf color and quality, quarterly clipping yield, and twice-yearly shoot density and root-length density. Findings to date indicate that a total of 146 kg N yr-1 is not sufficient to maintain quality hybrid bluegrass in the southeast, regardless of the application timing. Best hybrid bluegrass performance was observed when N was applied throughout the year, and not just as a fall program. Hybrid bluegrass fertilized at 292 kg ha-1 yr-1 had the best color, quality, and resistance to bermudagrass encroachment, but it also had the lowest root mass.