Sod Strength Characteristics of 51 Cool‐Season Turfgrass Mixtures

Abstract

Core Ideas Turfgrass seed mixtures containing fine fescue species can produce sod that achieves equal or greater strength than those containing large amounts of Kentucky bluegrass when harvested 22 mo after establishment. Change in proportion of fine fescues from each initial seed mixture to the resulting final plant community was negatively correlated with sod strength characteristics. Thatch development was only weakly correlated with either maximum tensile load or work required to tear sod. Mixtures with different seed compositions, but resulting in similar or identical final species compositions, often possessed very different mechanical properties. Successful establishment of turfgrass on roadsides often necessitates using species mixtures not typically used for sod production. Evaluating mechanical characteristics of sod produced using such mixtures is necessary to determine if they possess sufficient strength for harvest and handling. The objective of this work was to evaluate tensile strength and work required to tear sod of mixtures of nine cool‐season turfgrass species previously determined to perform well on Minnesota roadsides. Three replications of 51 mixtures were established in a randomized complete block design at St. Paul and Rosemount, MN. Plots were seeded during September 2012 and harvested in July 2014. Tensile testing revealed that plots seeded with 40% strong creeping red fescue (Festuca rubra ssp. rubra Gaudin), 40% Chewings fescue [F. rubra ssp. fallax (Thuill.) Nyman], and 20% alkaligrass [Puccinellia distans (L.) Parl.] resulted in a final plant community comprising 99% fine fescues (Festuca spp.) and produced sod with the highest maximum tensile load to tear of 507.7 Newtons. At St. Paul, maximum work required to tear sod was 16.57 Nm for a final plant community comprising 98% fine fescues and 2% Kentucky bluegrass (Poa pratensis L.). At Rosemount, maximum work required to tear sod was 38.86 Nm for a final plant community comprising 90% fine fescue, 9% creeping bentgrass (Agrostis stolonifera L.), and 1% weed cover. Mixtures currently used on Minnesota roadsides containing high Kentucky bluegrass content were consistently among the weakest in the trial and sod comprising alternative species can match or improve the strength of those mixtures.

Fine fescues: A review of the species, their improvement, production, establishment, and management

“…Therefore, there is a clear advantage of reduced establishment time when using sod vs. seeding. Researchers in Minnesota documented a longer fine fescue sod maturation period of 22 mo (Friell, Watkins, Horgan, & Cavanaugh, 2017); this is in comparison to a typical sod production period for Kentucky bluegrass in Minnesota of 15 mo (Friell et al., 2017), which is similar to a report of 12–20 mo in Wisconsin (Griffith et al., 2017) and 12–18 mo in both Nebraska and Maryland (Shearman et al., 2001).…”

“…(2015) reported that the probability of maintaining at least 60% survival of turf after two years on Minnesota roadsides was increased when hard fescue and sheep fescue were included in seed mixtures. Further research by Friell, Watkins, and Horgan (2012, 2013, 2015, 2017) helped improve the Minnesota DOT seed mixture for low‐maintenance turf on roadsides, which now includes 29% F . rubra ssp., 20% Chewings fescue, 14% hard fescue, 11% sheep fescue, 16% low‐maintenance Kentucky bluegrass cultivars, and 10% perennial ryegrass (Minnesota DOT, 2014).…”

Review of cool‐season turfgrasses for salt‐affected roadsides in cold climates

“…turfgrass growth in salt-stressed conditions (Qian, Wilhelm, & Marcum, 2001 slender creeping red fescue and 40% each of hard fescue and sheep fescue has been estimated to be best suited to that environment based on results of a trial which evaluated 51 mixtures on roadsides over two years (Friell et al, 2015). Those same mixtures were subsequently grown as sod and harvested after 22 mo for tensile strength testing (Friell et al, 2017); nearly all mixtures in the top statistical grouping contained more than 90% fine fescue species in the final plant community composition. Taken together, these trials indicate that mixtures of the fine fescue species have potential for roadside establishment as both sodded and seeded mixtures (Figure 3).…”

“…Furthermore, some authors have implied that the importance of Kentucky bluegrass in salt‐tolerant mixtures is likely restricted to its sod‐forming ability, which often results in higher tensile strength sod than for other species (Butler et al., 1974; Ross, Ennos, & Fitter, 1991). Still, it has been shown that the inclusion of Kentucky bluegrass in seed mixtures is not always sufficient to produce a high‐strength sod (Friell, Watkins, Horgan, & Cavanaugh, 2017).…”

Response of Retail Lawn Seed Products during Acute Drought and Recovery

“…Using mixtures and/or blends helps account for variations in landscape microenvironments, such as sunlight availability, soil physical and chemical properties, seasonal variations in temperature, or even pest resistance. Decades of research involving turfgrass mixtures have been performed to identify which combination of species and their percentages within the mixture can improve turf quality (Hunt and Dunn, 1993;Macolino et al, 2014;Rose-Fricker et al, 1997), increase wear tolerance (Park et al, 2017;Stier et al, 2005) improve sod strength (Friell et al, 2017), enhance disease resistance (Cutulle et al, 2013), and reduce fertilizer or irrigation requirements (Dunn et al, 2002;Reiter et al, 2017).…”