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ALMOND ORCHARD 2025 GOAL Scientists have known how to calculate potential crop ET for almonds for a long time (ETc) but actual ET (ETa) is a new and revolutionary approach that will improve precision irrigation management. "If we add high resolution remote sensing to visualize and map evapotranspiration, then we get two critical pieces of information together: Eta and its spatial orchard variability," said Saa. The idea is to make ETa field-scale, accessible and affordable to all California almond growers. This precludes solutions such as purchasing expensive hardware to install in each orchard or paying services to fly over orchards to collect data. To deliver a solution to growers that is accurate, accessible, and affordable, the strategy is to rely on a technology that is already available on all California almond orchards: satellite imagery. However, there is still a need for validated almond-specific models so that growers can irrigate based on this satellite data with confidence. That's exactly what has brought this team of researchers to Olam's orchard – to develop accurate models for remote sensing of evapotranspiration. The project goes by the name T-REX: Tree Crop Remote Sensing of Evapotranspiration EXperiment. 1 Building a model from the ground up The idea for the T-REX project was inspired by a similar project for the California grape industry called GRAPEX. 2 Initially launched in partnership with E.&J. Gallo, the goal of GRAPEX was to build a multi-scale remote sensing ET toolkit for all California vineyards. The success of this project and the multi-disciplinary approach caught the attention of the Almond Board to answer related questions for almond growers. "The Almond Board has been critical in making this happen because they have the ability to get researchers to work together," said USDA-ARS plant physiologist Andrew McElrone. "They saw the example from the GRAPEX project of 20 to 30 researchers from around the world working together, and they had the ability to transfer that model over to almonds." Like GRAPEX, the basis for T-REX begins with collecting very precise measurements of the amount of transpiration that's occurring in the orchard using something called a flux tower. This futuristic-looking tower stands taller than the tree and provides continuous measurements of actual evaporation as well as the entire orchard energy budget. "The flux tower allows us to collect data at an individual tree or sub-tree level," said McElrone. "We're looking at how, when you go from a measurement like that to something larger like a satellite at 30-by 30-meter resolution, how well does the data match up?" With these sophisticated measurements and some complex math and physics, McElrone and colleagues will be able to determine how accurate the satellite Continue on page 11 1 "New Perspectives in Irrigation Management" https://bit.ly/2ZrRd2c 2 GAPEX Overview https://bit.ly/3uimoIw Plant Physiologist Andrew McElrone uses a handheld device that tracks the evapotransporation of the tree from the lower-canopy level. Utah State University's AggieAir UAV Research Program team launches its experimental fixed-wing drone with a wingspan of 10 feet. Almond Board of California 10