Jackie Lyn Guevara, Jacob Kilby, Ryan C Bearss & John N Rogers
Abstract
Sod grown on plastic (SOP) is a popular choice among sports field managers due to its dense rooting system, allowing play immediately after installation. Kentucky bluegrass (KBG; Poa pratensis L.) is a commonly used cool-season turfgrass species in sod production and sports fields. However, growing a pure KBG SOP is challenging due to KBG’s slow germination rate, rendering the initial stages of sod production vulnerable to washouts. The researchers hypothesized that incorporating perennial ryegrass (PRG; Lolium perenne) will mitigate washouts as PRG can stabilize the soil while KBG is in its germination phase. Although KBG and PRG mixtures have been extensively studied in golf courses, sport fields and home lawns, the optimal KBG and PRG ratio for sod production has yet to be explored. Thus, the objective of this study was to evaluate the stability and harvestability of cool-season SOP seeded with varying KBG and PRG seeding ratios. The study was conducted at the Hancock Turfgrass Research Center in East Lansing, MI in the summers of 2022 and 2023. The experimental design was a randomized complete block design with 3 replications. Six KBG: PRG seeding ratios (100:0, 98:2, 96:4, 92:8, 84:16 and 0:100), which all followed a pure live seeding rate of 3 seeds cm -2 , were evaluated at 4 months after seeding. To assess stability, shear strength was determined by averaging three shear vane measurements. To quantify the harvestability, tensile strength was measured using a digital force gauge while a 0.30 m x 0.45 m sod piece was pulled apart by a sod puller. In 2022, the shear strength of 92:8 and 84:16 was higher than 100:0. The tensile strength of 84:16 ratio is 60% and 40% higher than 100:0 in 2022 and 2023, respectively. The 84:16 seeding ratio is recommended to minimize washouts and expedite production.
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