Evapotranspiration Controllers in a Humid Climate

The objective of this article is to present summary findings of multiple research studies concerning evapotranspiration (ET) controllers. Each study provided unique information concerning the performance and implementation techniques necessary to ensure successful integration with irrigation systems to optimize scheduling for water conservation. Based on these studies, ET controllers have the potential for irrigation savings of as much as 63%, without sacrificing landscape quality, when implemented in moderate to high water use scenarios and programmed correctly. Only homes that irrigated more than 450 mm per year had irrigation savings with an ET controller in southwest Florida. The ET controllers that underwent Irrigation Association Smart Water Application Technologies (SWAT) testing experienced oscillations in irrigation adequacy and scheduling efficiency dependent on rainfall. Assuming acceptable levels for irrigation adequacy and scheduling efficiency of 80% and 95%, respectively, there were only a few periods during the Florida SWAT test when both scores were above these thresholds. A maximum of 10% of scores were passing in any of the three evaluation periods with frequent rainfall, indicating that properly accounting for rainfall is a challenge for many of these controllers. The SWAT scores are indicators of water savings only if there is a potential for savings due to excess irrigation prior to implementation of the ET controller.