Center Update: Testing Drought Tolerance

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Evaluation Of Drought-Tolerant Warm-Season Turfgrass Response To Water-Saving Irrigation Scheduling Methods

PI: Chadi Sayde; Student: Ryan Ackett


With increased urban demand for irrigation water coupled with increased municipal restrictions on irrigation frequency for residential turfgrass to mitigate draught impact on available water resources, water conservation is becoming increasingly important when selecting turfgrass cultivars (Xiang et al., 2018). Limited information or guidance on irrigation scheduling for novel water-saving turfgrass cultivars exists in North Carolina. To effectively formulate the needed irrigation scheduling guidance, comparative data on consumptive water use and lawn quality response to restrictive irrigation scheduling of novel drought-tolerant turfgrass cultivars is needed (Wherley et al., 2015). The objectives of this work are 1) to establish a state-of-the-art turfgrass irrigation research site, 2) evaluate the performance of a drought-tolerant warm-season turfgrass cultivar under eight different water-saving irrigation scheduling methods, and 3) Compare various methods of assessing turf quality, including visual rating, vegetation index (NDVI) measurements, and Green normalized difference vegetation index (GNDVI) measurements.

Method/Results and Discussion

During the first phase of this project a state-of-the-art turfgrass irrigation research site has been planned at Lake Wheeler Turfgrass Field Lab. The installation of the site has been initiated in May, 2020 and expected to be completed by the end of June, 2020. The new site is being established to replace the previous site (established in 2006) that has been impacted by the expansion of Lake Wheeler Road by the City of Raleigh.

The new site consists of twenty-four 15-ft by 15-ft plots with 3-ft separation between plots. Each plot is independently irrigated by an automated sprinkler system. Prior to irrigation system installation, the area has undergone land preparation and delineation. An underground irrigation system was installed in May, 2020 to irrigate the plots. The irrigation system is plumbed into an existing line connected to a pump supplying water from a nearby pond. The headwork system includes pressure regulation, filtration, and pressure and flow measurement system with remote access and data logging capability. Each plot is irrigated by 4 quarter circle 15-ft radius pop-up spray heads located at plot corners. The pop-spray system is equipped with 30 psi in-stem pressure regulator and can deliver high water distribution uniformity. The irrigation system for each the 24 plots is independently controlled by a solenoid valve. Each plots were also equipped by a pulsed flowmeter connected to Campbell Scientific data logging system to continuously monitor and log water applied at each of the 24 plots.

All solenoids are wired to a Baseline BL-3200X irrigation controller. Additionally, a soil moisture sensor was installed at 3” depth in the middle of each plot. The soil moisture sensors were also wired to the Baseline irrigation controller. The system setup provided extended flexibility in term of allocating specific irrigation scheduling method at the level of every single test plot. The irrigation of each Plots can be managed independently or in conjunction with any other plot. The following irrigation management methods can be executed at the individual plot level: 1) weather based irrigation scheduling, 2) from soil moisture sensors feedback , and 3)user defined schedule. A remote sensing system will be installed at the site in June/July, 2020, to continuously monitor at sub-daily frequencies turfgrass quality at the level of each test plot. The remote sensing/imaging system consists of a near-infrared camera with a wide angle lens and triple bandpass (R/G/NIR) filter C-mount. Two of the imaging system will be installed on top of two 17-ft height stationary poles at the opposite sides of the site. This system is expected to generate high-resolution data to calculate vegetation indices (NDVI, GNDVI) for each test plot. The quantitative estimations of turfgrass quality will be compared to visual assessments and other ground-based measurements. The Baseline irrigation controller, the Campbell Scientific data logger, and the remote sensing system will be connected to a WiFi system that is in the process of being established at the site. The remote connectivity will allow real-time data monitoring as well as remote operation/intervention. This capability will allow the site to be integrated in distant classroom and extension activities.

Due to the impact of Covid-19 on the availability of the desired zoysiagrass cultivar, an available draught-tolerant bermudagrass cultivar will be used for this experiment. The sod will be installed during the third week of June, 2020. After turfgrass establishment the site is expected to be fully operational to conduct the irrigation scheduling trials.

irrigation layout

Figure 1:New site irrigation layout

Xiang, Mingying; Fry, Jack D.; and Kennelly, Megan M. (2018) “Evaluating Zoysiagrass-Tall Fescue Mixtures in Kansas,” Kansas Agricultural Experiment Station Research Reports: Vol. 4: Iss. 6.

Wherley, B. & Dukes, Michael & Cathey, S. & Miller, Grady & Sinclair, T.. (2015). Consumptive water use and crop coefficients for warm-season turfgrass species in the Southeastern United States. Agricultural Water Management. 156. 10-18. 10.1016/j.agwat.2015.03.020.

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Written By

Grady Miller, N.C. Cooperative ExtensionDr. Grady MillerProfessor Call Dr. Grady Email Dr. Grady Crop & Soil Sciences
NC State Extension, NC State University
Updated on Dec 17, 2020
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