An Examination of Overseeding Species On Athletic Fields and the Fate of the Seed in the Environment.

Throughout the growing season Ontario’s athletic fields are subjected to frequent wear that leads to weaken turfgrass stands.  Overseeding with perennial ryegrass (PR) is used to maintain turf coverage.  However overseeding with PR can lead to a reduction in winter hardiness of the field because of PR’s limited winter hardiness.  An evaluation of supina bluegrass (SB) as a companion species to overseeding with PR was performed at varying rates, frequencies and mowing heights. In addition to a non-overseeded check, treatments were overseeded with 6 kg 100 m^-2 year^-1 PR, in conjunction with SB at 0 kg 100 m^-2 year^-1, 0.5 kg 100 m^-2 year^-1, 1 kg 100 m^-2 year^-1, 2 kg 100 m^-2 year^-1, and 4 kg 100 m^-2 year^-1.  Plots were either seeded one time or seeded at one third the yearly rate three times throughout the growing season.  Turfgrass composition was measured using point quadrats, and soil samples were taken in the fall and spring to determine the effects of overseeding on the seedbank. The data demonstrated that within overseeding rate, the plots overseeded three times a season have greater turfgrass coverage than plots overseeded once.  The no overseeding control demonstrated a steady decline in turfgrass coverage throughout the duration of the experiment.  Recruitment rates of SB correlated to seeding rates; however there was no difference in SB population levels at the 2 kg 100 m^-2 year^-1 and 4 kg 100 m^-2 year^-1.  Supina bluegrass overseeding resulted in SB being the dominant species in the seedbank with a positive correlation to seeding rate.  The higher seeding rates of SB resulted in more PR seed in the seedbank, however overwintering resulted in a 50% drop in viable PR seeds, suggesting spring seedbank sampling is more representative of what species may potentially germinate during the upcoming growing season.