Plot Study Comparing Different Irrigation Technologies For Turfgrass

By Kati Migliaccio

From 2015 to 2017, a plot study was conducted in Gainesville, FL, during the growing season. A weather station at the plot site collected weather data and water meters recorded the amount of water applied to each plot. Plots contained established Bermudagrass and were irrigated with four quarter-circle pop-up spray heads.

Figure 1. Picture of turfgrass plots at University of Florida.

Treatments
Eleven different irrigation technologies were used to schedule irrigation: time-based treatment without a rain sensor (WOS), time-based with a rain sensor (WRS), time-based with a rain sensor and a 60% deficit (DWRS), Smartirrigation turf app (APP), Smartirrigation turf app with seasonal water conservation (APPSWC), Baseline soil water sensor (BAS), Rain Bird soil water sensor (RBD), Toro soil water sensor (TOR), Hunter Solar Sync ET (ETH), Rainbird ESP SMTe (ETR), and Weathermatic ET (ETW).

Figure 2. Data collection at the turf plots at the University of Florida Agricultural and Biological Engineering Department (Bernard Cardenas-Laihacar and Ian Hahus pictured)

Results

Results showed that all irrigation scheduling method tested produced water savings as compared to WOS treatment. Average water savings for the soil water sensors ranged from 50 to 61%, for the ET controllers ranged from 19 to 62%, and for the Smartirrigation apps 51 to 64%.

In this plot study, we investigated the use of the seasonal water conservation feature in the Smartirrigation Turf app (APPSWC) where irrigation schedules were provided at a 25% deficit if rainfall exceeded evapotranspiration (ET) the five previous days. This strategy helps reduce irrigation when rainfall is expected to occur and to contribute to plant water needs. During the three years of the study, adding the seasonal water conservation component to the APP schedule resulted in additional water savings. The average water savings over the three years as compared to the WOR treatments for the APP and APPSWC were 51% and 64%, respectively.

During year 2017, a modification was made to the soil water sensor treatments where irrigation was split between two events, a morning and afternoon event. Interestingly, this strategy resulted in only 20% or less events of full irrigation for the three treatments (Fig. 3)

Figure 3. The percent of irrigation events that were full irrigation (pink), percent of irrigation events that were half (green), and percent of irrigation events that were interrupted (gray) for 2017 soil water based sensor treatments

Useful Add-ons
Our results suggest that coupling an irrigation technology with another scheduling feature, such as split irrigation events or irrigation deficits, provide for additional water savings without impacting turf quality. These two add-on features would be useful to implement in locations where rainfall significantly contributes to plant water needs.

For more information on using technology for scheduling irrigation - contact Dr. Kati Migliaccio or Dr. Michael Dukes from the Agricultural and Biological Engineering Department. Additional information is also available in the UF/IFAS EDIS system.