providing critical and timely information relating to the long-term sustainability of turfgrass systems, this project meets TLI’s second objective of Environmental Awareness of Turfgrass identified in the previously mentioned TLI Research Areas.
Tis study will be conducted on the urban landscape runoff facility located at the Texas A&M University (TAMU) Scotts Miracle-Gro Center for Turfgrass Research in College Station, TX. Te facility consists of 24 individually irrigated 13 ft x 27 ft. (3.96 m x 8.23 m) plots established with 5-year old ‘Raleigh’ St. Augustinegrass. Te proposed study began on April 1, 2018, and will continue through March 31, 2020. Each plot has its own runoff collection system composed of an ISCO flow meter and sampler that provides full documentation of the amount of water lost to runoff as well as water samples for subsequent measurement of the chemical content of the runoff.
Tis approach will determine water requirements of various landscape conversions composed of variations in traditional lawns to ‘water-efficient’ alternative landscapes. Similarly, this project examines converting the existing St. Augustinegrass plots to either entirely or varying mixtures of turfgrass and water-efficient residential landscapes using regionally adapted native drought-tolerant shrubs or water conserving plants. In this way, the effects of different residential landscapes on the runoff volume,
the chemical content of runoff, and soil properties can be evaluated. Plant areas within alternative landscapes will be irrigated twice weekly using drip irrigation, while turfgrass plots will be irrigated twice weekly at 60 percent of reference ET. Following conversations with landscape design architects, this research will compare the following landscape types: • 100 percent natural turfgrass (existing 6-year old ‘Raleigh’ St. Augustinegrass)
• 100 percent xeriscape (decomposed granite surface with 50 percent area composed of native plants)
• 100 percent dark hardwood mulch (shredded hardwood mulch surface with 50 percent area composed of native plants)
• 100 percent hardscape concrete pavers (allowing for comparing runoff mitigation potential offered in comparison to turf)
• 100 percent sand-capped turf (4-inch sand-cap placed below the turf in order to determine benefits of sand- cap layer on water retention and runoff mitigation)
For the water-efficient landscape, Texas native drought- tolerant plant selection will be based on mutually agreed upon materials between Scotts and TAMU, potentially selected from Earth-Kind plant selector (
ekps.tamu.edu).
Data to be recorded include reflective landscape canopy- to-air temperature, FLIR thermal imaging infrared cameras, weed pressure, runoff dynamics and water quality, water budgets, and overall landscape performance. Runoff characteristics will be evaluated for all naturally occurring rainfall events from April through October. Peak flow rates as well as total runoff volumes from each landscape type will be compared to determine the influence of landscapes on runoff characteristics. Additionally, runoff water samples will be collected and analyzed for pH, EC, Nitrogen (Total N, NO3 NH4
-N, -N, organic N) and orthophosphate-P concentrations
throughout both years. Chemical analysis of samples will be performed for at least six events (two spring, two summer, two fall) from naturally occurring rainfall- induced events.
Te majority of research studies evaluating alternative landscape benefits have focused primarily on water use, but it is also of interest to evaluate runoff volume and chemistry dynamics following various types of landscape conversions in comparison to established turfgrass systems, which have been shown to slow runoff and serve as a biological filter. Such research could provide valuable data documenting ecosystem services of various landscape types beyond simply water use, as well as shed light on the unintended environmental consequences of conversion to alternative landscapes.
TPI Turf News September/October 2018
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