More and more, growers are looking to find the sweet spot of when to start irrigating and striving to understand how to assess trees’ water needs more accurately throughout the year. And, more and more, technology is stepping up and playing a significant role in answering those two questions. Satellite imagery and sensors that measure moisture levels or leaf temperature, for example, may sound like tools of the future, but in reality they’re already providing critical information to growers today – and there is much opportunity to greatly increase adoption of irrigation technology throughout the industry.
Such was a key theme during The Almond Conference 2020 session “New Perspectives in Irrigation Management,” which featured experts across a variety of fields who each provided insight on how irrigation technology may advance the industry towards the almond orchard of the future.
Here’s a brief recap of the research updates offered during this session.
NASA expert shares new tool
Research into “Open ET,” which combines satellite and meteorological information into one interface, will soon be launched in collaboration with NASA, the Environmental Defense Fund, and Google, among other co-funders, according to Forrest Melton, who works at the NASA Ames Research Center in Mountain View. This research project is part of an effort to improve irrigation scheduling tools and calculators in the almond industry and beyond.
Melton said the ongoing research is analyzing actual evapotranspiration (ETa) data from more than 150 sites across the western United States, including two almond orchards from the San Joaquin Valley. The system then measures total monthly ETa in inches to create a fever chart for any orchard, which can be compared year over year as the orchards age and trees grow. Growers also can compare their results to state averages.
“We want to give farmers better information about when they should and shouldn’t have their water on,” he said.
Melton characterized the results from the almond orchard tests as “encouraging,” and the system is expected to go live later this year; validation in almonds is an ongoing process.
UC research uncovers more precise water needs
Isaya Kisekka of the University of California, Davis, described how growers can use zone irrigation management techniques that rely on sensors placed in the ground to measure soil moisture over an entire orchard. The data, he said, can help growers more accurately identify how much water is needed in different parts of an orchard based on soil type.
Kisekka also shared the results of a recent research project that looked specifically at the water needs of almond trees in their first, second and third leaf. He found that trees needed about 35 inches of water through their third year and then 40 to 43 inches after that.
A surface renewal approach to calculate ETa
Another UC Davis expert, Andrew McElrone, discussed the ways in which California irrigation technology is being used to determine trees’ water needs. Sensors that measure the temperature of leaves as well as moisture in the ground provide information on how much radiation is being absorbed by the orchard canopy, how much energy is coming in via the sun and how much that natural energy source heats the air and ground.
“What we’re trying to do is manage the water budget for an orchard,” McElrone said. “We’re trying to match the water needed in an irrigation system with water losses.”
The goal of this technology (ETa calculation), McElrone explained, is to determine how much water trees need and help pinpoint when and where to apply it. He said his team is considering a variety of methods to increase grower adoption of this available system, ideas including developing an online tool and instructional videos to facilitate adoption of what he described as a “citizen science model.”
Trial in walnuts piques interest for almonds
Beyond research in almonds, one speaker presented information based on research being performed in walnuts. While this research is very much in the initial stages in almonds and no results are available at this time, once the research is complete the California almond industry may be able to garner insights into early-season irrigation.
Ken Shackel, water expert and professor at UC Davis, presented this research, which he said addresses “the Goldilocks question,” that which growers often ask themselves when considering when to begin irrigating: “Am I starting too early, too late or just right?”
For many growers, this question nags at them throughout the season. The answer, Shackel said, often depends on a number of variables including weather, soil structure, root health and even the almond varietal itself.
“Obviously, we want the answer to be ‘just right,’” Shackel said.
His team’s research in walnuts has shown that too much water applied too early in the season can lead to some mid-summer disease symptoms. Shackel believes that there is room for water savings in almonds by starting irrigation a bit later than usual, but that remains to be confirmed. The Almond Board will continue to monitor Shackel’s research in this area to determine what learnings may be applicable to almonds.
Growers with questions regarding irrigation practices are encouraged to reach out to ABC’s Senior Manager in Field Outreach and Education, Tom Devol, at tdevol@almondboard.com.
Presentation slides from this conference session may be found here.
