Aboveground responses of cool-season lawn species to nitrogen rates and application timings

Lawns are the largest managed turf acreage in the USA. This large acreage of fertilized turf has generated public concern regarding nitrogen (N) fertilizer misuse. This 2-yr field study evaluated the effects of eight N programs that varied by N amount, 0 to 196 kg N ha^-1 yr^-1, and seasonal application timing on the aboveground plant responses of three cool-season lawn species: Kentucky bluegrass (Poa pratensis L.; KBG), perennial ryegrass (Lolium perenne L.; PRG), and turf-type tall fescue (Festuca arundinacea Schreb.; TTTF). Significant cumulative species dry matter yield differences were measured for the study, with 9426, 7750, and 7011 kg ha ^-1 for TTTF, KBG, and PRG, respectively. Kentucky bluegrass generally possessed the greenest canopy when averaged across all N programs, followed by TTTF and PRG. Annual turfgrass quality (TQ) was highest and most seasonally consistent for TTTF, followed by KBG and PRG. Although, KBG overall TQ was lower than TTTF, primarily due to slow spring green-up, KBG was superior to TTTF on many ratings during active growth. Perennial ryegrass produced the lowest TQ compared with TTTF and KBG. This was due to summer disease in both years and substantial turf cover losses, 24 to 81% in 2005. If the goal in lawn management is to maximize turfgrass response with the fewest N inputs, the species that met this goal was TTTF, which provided acceptable TQ and color, and had less disease at relatively low, 73 to 123 kg ha^-1 yr^-1, N levels.