Growers have long had the ability to estimate crop evapotranspiration, but work a few years ago by a University of California, Davis graduate student and others opened that world to give farmers actual ET rates through a simple sensor.

Tom Shapland, chief executive officer of Tule Technologies, co-developed a system during his graduate and post-doctoral work at UC Davis to help growers discover actual ET across a larger area. Good growers who already understand how weather and water stresses affect plants will quickly see value in an app-based approach that does not require time-consuming testing of single plants or trees with expensive pieces of equipment.

The sensor technology co-developed by Shapland at UC Davis is novel in its approach. Arriving at actual ET, versus estimates and conjecture through mathematical equations and the use of California Irrigation Management Information System (CIMIS) stations that may not be in the same microclimate, is more accurate, and easier to attain. It does so through hardware installed above the plant canopy and communicates through servers using a cellular connection. From there, growers can use a smart phone app to see the actual ET in their field and make more timely irrigation systems.

Actual ET vs. Reference ET

Shapland's sensor technology is the first to record actual ET. The long-time standard method for farmers has been to calculate "reference ET" based on CIMIS stations located throughout the state. This requires mathematical calculations and estimations of water use by a hypothetical, fully irrigated crop field.

The calculations are just that – estimations of probably crop water usage that do not factor microclimate conditions and other conditions that can increase or decrease crop water usage. The calculations can get a grower close, but not exact in a world where farmers are closely managing every drop of water applied.

Related: Southern Ore. wine grapes could get by on less water

According to Shapland, water used by plants is influenced by the weather, the size of its canopy, and how water stressed the plant is. Stressed plants will use less water as they move through a biological mode to protect their energy use.

When Shapland first introduced the sensor technology at a University of California field day several years ago it garnered some interest because for the first time, actual water use by a plant could be measured more effectively. The technology was quite new at the time and wanted some time to test the efficacy of the technology and its practical application on the farm.

How it works

Shapland describes the system as two product lines. The first is the sensor, which can survey a larger area than technology that involves pressure bombs and soil sensors. The second is the app-based Tule Vision, which compiles data from the sensors and gives growers a real-time picture of plant water use.

He demonstrated the app in a wine grape vineyard in the rolling hills just south of the city of Paso Robles, Calif. The app walks users through the correct use with the smart phone's camera. Instructions advise to point the camera at the sunny side of the canopy, within a couple feet of the vines. Through the app, users learn the midday leaf water potential measured in bars.

Vineyard application

Randy Heinzen, president and owner of Vineyard Professional Services in Paso Robles, Calif., uses the technology in his vineyards to manage irrigation sets in several varietals of wine grapes, including Cabernet Sauvignon, Petite Syrah, Malbec, Cabernet Franc and Merlot.

Heinzen's intention with the sensors and Tule Vision app was to test it on a few plots of wine grapes with different configurations. Sensors were installed over north/south oriented vines, and over east/west oriented vines. The idea: "to challenge the technology to see how it would ultimately perform," Heinzen said.

Ease-of-use and the ability to collect data while Heinzen's field scouts are already out walking the vineyard, inspecting for pest, disease and other issues is one of the aspects Heinzen likes about the system. As those scouts are inspecting vines, they can access the app and check the actual ET of the vines to ensure the proper amount of irrigation water is being delivered.

"Here's an example of where I'm not having to send someone out to get a specific data point," Heinzen said. "They're already out there. It's informing our management decisions on how we judiciously use water."

Together, the system is saving Heinzen water and labor resources.

Heinzen likes the Tule technology for its ease-of-use. Not all gadgets and gizmos farmers are pitched these days are as intuitive.

"Technology has to be accessible and have utility to every level of employee in the field," he said. "There's some cool technology out there, but if you have to hire an IT expert to manage it or dedicate weeks of training for your top managers to understand it, that doesn't do it for what we need."

Unexpected benefits

Shapland continues to be amazed at how the technology he helped developed is being used by growers. He points to Heinzen's studies of north/south vs. east/west vineyard configurations as he determines how to plant his vines for the best light interception.

Heinzen wants to better understand how these configurations can affect the vines and the quality of wine produced from the grapes. Using the system to collect data on light interception in a practical manner is one of many things Shapland didn't consider when designing the Tule Vision app.

Shapland also likes to talk up the technology coming out of Land Grant institutions like UC Davis, versus some of the tech introduced in Silicon Valley. There is a culture and science behind farming in California. The connection between farmers and Cooperative Extension across the state lends credibility to the technology farmers are asked to adopt.

"I think that there's a lot of noise in the ag tech marketplace where anyone with a drone thinks they can start an ag tech company and provide value, but they have no background or understanding in how these crops work, or the economics, culture and science behind farming," Shapland said.

Visit https://www.tuletechnologies.com/ online for more information.