By Adam Thoms and Thomas Gould, Iowa State University
With the end of 2022 in sight and colder temperatures in the forecast, it is time to think about how your turfgrass will survive winter. Irrigation systems have been blown out and the turfgrass is waiting on snow cover or rainfall to keep the turfgrass crowns hydrated. One of the biggest struggles for turfgrass stands throughout the Midwest is when there is no snow, a dry weather pattern, and relentless winds. At the Horticulture Research Station at Iowa State, we are in a joint project with the Iowa State University Athletic Department growing sand-based sod for their football stadium field in 2022 and soccer field for summer of 2023. We get asked often about what we do to prepare the sod field for winter, so here is an explanation.
The sod field is a three-inch sand cap of 100% sand that meets United States Golf Association specifications; it has Kentucky bluegrass growing on a loam soil (Figure 1). The sod field used to be a corn field, so there is nothing around the field to slow the wind, and the rolling hills of the field make some spots more prone to drying out than other parts of the field. The biggest struggle is keeping the sod hydrated during the periods of time we don’t have irrigation. We have taken steps to try to keep the sod hydrated during the winter dormancy period.
We started by stopping mowing of the sod two weeks before blowing out the irrigation system. The sod had been mowed at 1.25” before that; allowing a little more leaf tissue to grow would help with lowering the stress of the plant. This also allowed us to water a couple more times before we would no longer have water. The day before we blew out the irrigation system (Figure 2), we applied a wetting agent to the sand that would hold as much water as possible. With the lack of organic matter in the top three inches we know that there is very little moisture-holding ability, so the addition of the wetting agent should help with maintaining the moisture for at least the first 30 days. After the irrigation system is blown out an application of an antitranspirant is applied to cover the leaf blades with a thick film that prevents evapotranspiration. The benefit here is to limit the loss of water from the plant during a period of reduced to no growth as well as not worrying about the loss of product from mowing. In the winter of 2021-2022 these steps proved helpful to maintain soil moisture and crown hydration until the snow cover in January. We are hopeful for a similar scenario with no winterkill this upcoming year. We are also testing a small area to see if we will experience winterkill without treating it. Additional information will be presented next year, with a follow-up replicated study looking at timing and inputs for sod grown on sand to survive winter stresses.
