WORLD CUP RESEARCH UPDATE By Ryan Bearss, Rhys Fielder, Evan Rogers, Jackie Guevara, Jake Kilby, Dr. Trey Rogers, and Dr. John Sorochan
Editor’s note: Tis is the TPI Leadership, Innovation, and Technology (LIT) Committee’s article addressing innovative solutions.
Sod on plastic (or grown in soil on an impervious layer) is a method of sod production that hastens establishment and significantly reduces harvest time. Where conventionally grown sod production typically utilizes laterally spreading species and harvest time is a function of stolon and rhizome development, the harvestability of sod on plastic is dictated by the much faster-developing root system and therefore, not limited by growth habit or species.
For production, seed or sprigs are sowed into a thin layer of growing media (typically a sand-based rootzone), atop plastic sheeting. As the roots of the turfgrass encounter the impervious plastic layer, they become intertwined, hastening establishment. For the past two years, sod on plastic establishment and production has been the focus of research for the Rogers lab (Michigan State University) and Sorochan lab (University of Tennessee).
World Cup Research Process
So, why do we care so much about sod on plastic? In 2021, the University of Tennessee and Michigan State University began research to develop a natural turfgrass playing system that offers uniform playing conditions across all the upcoming World Cup host stadia.
Playing surfaces at eight of the 16 host sites are currently artificial. For these sites, the playing surfaces must be converted to natural grass and be capable of withstanding indoor conditions and gameplay for up to 77 days. Te two cool-season turfgrass species proposed for these conversions are Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.). Te final playing system will most likely consist of three primary components:
Hybrid reinforced, cool-season sod on plastic A sub-laid shock absorbing layer Drainage
To this point, several entries and varieties of each system component have been subjected to rigorous testing. For these tests, we have focused on three basic parameters; i. Ball rebound (Figure 1), ii. Surface hardness, iii. Surface deformation. From this data, we have whittled away several contenders by eliminating those that fail to meet FIFA’s Natural-Pitch Rating System standards.
Figure 2. North Carolina sod on plastic after shipment to Michigan State University—September 2022.
10 TPI Turf News July/August 2023
Figure 1. Dr. Trey Rogers [MSU] (left), Research Assistant Rhys Fielder [UT] (center), and Dr. John Sorochan [UT] (right) measuring ball rebound at Carolina Green Sod Farm, Concord, NC—Spring 2022.
Tanks to our friends at Carolina Green Sod Farm, we have had a convenient location for testing each spring and have maintained a steady supply of sod on plastic. Once summer rolls around, temperatures become too extreme for cool-season growth. All remaining sod is then harvested, and shipped in a refrigerated truck to Michigan State University and the University of Tennessee where it is maintained and tested more extensively (Figure 2). Te cycle continues…
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