Irrigation tech: A look at what’s new for tree nut growers

The industry is moving quickly into a new era of tree nut irrigation technology, where remote sensing through drone and eventually satellite data can inform growers about the real-time stress status of orchards.

“Many researchers see this as the ‘holy grail’ of irrigation tech, and it will revolutionize irrigation management as it becomes more accessible,” said Curt Pierce, Ph.D., area irrigation and water resources advisor for UC Cooperative Extension. “These tools have been in development for some time and have seen some impressive jumps in utility as the technology matures.”

Of course, some challenges on the remote sensing side remain, with cost and resolution being the two most pressing issues.

“Drones are becoming more affordable but remain comparable to other more mature tech such as pressure chamber devices, which haven’t experienced the adoption rates we would expect considering their potential benefits when used effectively,” Pierce said. “Satellite resolution is still too coarse for meaningful use in production, but these temporary challenges should ease as the technology evolves.”

On-the-ground innovations in tree nut irrigation tech

Away from the air, the industry has seen some encouraging developments in microtensiometers, which are plant-based devices that are installed and remain in a plant for the season, delivering real-time water status data to an app that growers can see on their phones.

“They are small, durable and align well with pressure chamber measurements, which I consider the gold standard, but they have struggled to gain widespread adoption,” Pierce said. “These new microtensiometers address the main challenge frequently cited by growers with the pressure chamber, and that is labor.”

Thanks to new in-situ sensors, it’s mostly a once-and-done install for the season, with the data revealed through the app with only periodic re-calibration needed in the majority of cases.

“The challenge there is that these new microtensiometer units are still relatively expensive as far as the initial investment, though I believe some subscription models may be being offered by companies to help ease entry a bit,” Pierce said. “Overall, though, these remain a very exciting innovation that could really fill a gap between the pressure chamber and remote sensing.”

Tom Devol, senior manager of field outreach and education for the Almond Board of California, noted that there is a new area of irrigation tools that are plant-based, taking the measurements off the tree itself rather than measuring the volume of moisture in the soil.

Those include dendrometers, which measure the growth of a tree branch or stem, where some newer systems are inserted into the tree and measuring fluid flow.

“These tools are gaining a larger footprint,” Devol said. “Growers like that they replicate the stem-water potential measurements they would take with a pressure chamber.”

Devol also is seeing more tensiometers being employed to measure soil moisture, especially in the Southeast. However, he warns that they don’t always read a large enough range for tree nut crops, but improvements have been coming.

Regulatory pressures accelerate adoption of irrigation tech

Because of California’s Sustainable Groundwater Management Act (SGMA), the majority of U.S. pistachio growers will be forced to implement new irrigation technologies if they haven’t already done so, said Wes Wilson, director of member services and communications for American Pistachio Growers.

Dendrometers are making a major impact in pistachios and almonds as growers look for tools to meet SGMA requirements, he said.

“Big technology in irrigation has advanced dramatically, and it’s continuing to,” Wilson said.

He noted that having a remote-operated station delivering live weather data is highly popular among nut growers. Soil-moisture probes are also being used more often.

“We’re seeing many remotely controlled irrigation pumps,” he said. “Growers can control irrigation, fertigation and pumping entirely from their phones.”

Remote imaging is another tool that’s making inlays with improving irrigation for tree nut growers, with data being applied to help drive an irrigation schedule.

“Several vendors use satellite imagery to estimate water consumption and provide growers with replacement values,” Devol said. “It’s cutting-edge and not perfect yet, but it reduces the need for field sensors, which is a major benefit for many growers.”

Measuring cosmic rays to determine soil moisture using a neutron detector is being leveraged in research today, and this is intended to measure large areas of soil, as much as a 100-acre footprint.

Building a proper irrigation program

From talking to his clients and doing events in California, Pierce has learned the best way to approach technology in an irrigation program is to first understand the soil.

“So much of a good irrigation program depends on the soil and how it changes across the orchard,” he said. “Many systems are designed without accounting for that, which limits how technologies can be applied later.”

For that reason, Pierce recommends growers should take a “good, better, best” approach to any assessment, or re-assessment, of their systems.

“Soil moisture monitoring through different sensor technology has been around for a long time and only gets better with each passing year and the new technological developments that come with them in that space,” he said. “But soil moisture alone can only tell you so much and misses any accounting of the tree’s ability to effectively access whatever water is stored in the soil. It’s good to have that information, and it certainly can go a long way in informing any irrigation program.”

Devol feels it’s a bright future for tree nut irrigation tech, and growers should stay informed about the latest and greatest from conventions and network of farm advisors.