Research Summary
The Heating Characteristics of Tall Fescue/ Kentucky Bluegrass and Bermudagrass Sods Virginia Tech Researchers: Mike Goatley Jr., Ph.D., Professor and Extension Turfgrass Specialist; Whitnee Askew, Turfgrass Program Manager; and Jon Dickerson, Senior Research Specialist Research Cooperators: Jeff Everhart and Scott Woodward (Woodward Turf Farms, Remington, VA), the Virginia Turfgrass Foundation and the Virginia Agricultural Council
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nowing more about the effects on sod-pallet heating — as influenced by turfgrass sod-harvest timing (morning vs. afternoon), turf cutting height and soil moisture at harvest — will allow producers to make informed decisions regarding the anticipated shelf life of cool-season turfgrass sods. This study was conducted in May, August and October of 2015 on an 85/15 (% by weight at seed establishment) mixture of tall fescue [Festuca arundinacea L. (Schreb.)]/Kentucky bluegrass (Poa pratensis L.) sod at Woodward Turf Farm (Remington, VA) and on a tall fescue sod at the Virginia Tech Turfgrass Research Center (Blacksburg, VA). The research utilized small-roll sizes (8.5 ft2) stacked on a pallet (540 ft2 total) at Remington or as individual rolls on a pallet at Blacksburg. For the sod farm site, remote temperature sensors set to record temperatures on 15-minute intervals for periods of at least 3 days were installed to record temperatures at specified lower, middle and upper locations of the sod on the pallet for sod harvested in either the afternoon or morning of the same or consecutive days (Photo 1). At the Blacksburg site the pre-harvest treatments included varying mowing height (7.5 cm vs 5 cm) and dry (soil % volumetric water content targets of 15-20%) vs. moist (> than 25% VWC) at harvest. The sod was either immediately replaced in the field or hand-rolled with a sensor installed in the center of the roll and placed on a
pallet for 1, 8 or 24 hours when it was returned to the field and irrigated to monitor recovery. Time of harvest data varied for the three harvest months, with the afternoon harvest having the highest temperatures recorded for May and October. As anticipated, heating was less in October than for other harvest months. While not part of the planned research, rain events on the
harvested sod on the pallet in the field impacted internal heating characteristics, seemingly trapping the accumulated heat load. While moist soil warmed more than dry when left on the pallet for 24 hours, moist soil at harvest was highly beneficial for sod recovery (Photo 2). There were no significant differences in heating or recovery characteristics based on variable cutting heights in these trials. c
Photo 1. Temperature sensors were installed near the bottom, middle and top layers of stacked sod in order to monitor sod-pallet heating characteristics over three or more days in the field at Woodward Turf Farms, Remington, VA.
Photo 2. Greater % volumetric soil water (VSW) contents at harvest provided much better recovery in the field trials at the Blacksburg Turfgrass Research Center.
26 | Virginia Turfgrass Journal May/June 2016 www.vaturf.org