Seed ratios for optimum turf quality of mixtures of kentucky bluegrass, creeping red fescue, and alkaligrass subjected to deicing salts

Abstract

Deicing salts often are applied to sidewalks and roadways to enhance pedestrian and driving safety during freezing weather. For example, in eastern North Dakota, average annual snow days and amount are 29 days and 40 inches, respectively. This study was conducted in Fargo, ND, to investigate the population dynamics of turfgrass mixtures composed of kentucky bluegrass [KB (Poa pratensis)], creeping red fescue [RF (Festuca rubra)], and alkaligrass [ALK (Puccinellia sp.)] with the goal of optimizing turf quality by selecting seed ratios containing these species in home lawn mixtures and subject to frequent applications of deicing salts. A total of 21 mixtures were generated based on simplex-lattice design with KB, ALK, and RF contributing to 0%, 20%, 40%, 60%, 80%, and 100% of their respective full-seeding rate of 150, 150, and 300 lb/acre, respectively, after pure live seed (PLS) adjustment. The mixtures were tested at annual deicing salt rates of 0, 160, 320 lb/acre, which represent typical application. The results showed that the botanical component of the stands of grasses shifted over a 2-year period for all salt levels. Despite the good salinity tolerance of ALK reported elsewhere, it did not contribute to the improvement of turf quality in mixtures receiving deicing salts at 320 lb/acre per year. Therefore, ALK is not recommended for lawn, but mixing KB and RF in 48% and 52% of their respective full-seeding rates was recommended for areas adjacent to deicing salt applications.