—story and photos by Ross Courtney
Precision irrigation tools such as soil moisture probes, dendrometers and sap flow meters must transfer readings to a grower’s smartphone or computer screen — somehow.
Orchard blocks aren’t always close enough to a shop with an internet connection. Cellular service on each device would be expensive, if it’s even available. Satellite signals can be blocked by the orchard canopy.
But for orchards to be smart, they must be connected.
Some growers and researchers are turning to LoRaWAN, an internet of things communication system that uses unlicensed, low-frequency radio waves to transmit small bundles of data across long distances, relatively inexpensively.
“It’s got a lot of applicability in a lot of places,” said Jason Navarrete, information technology director for Allan Bros. in Naches, Washington.
The vertically integrated fruit company is testing LoRaWAN as one of several ideas to solve orchard connectivity challenges. The company hired Yakima internet service provider Data Bridge Technologies to install LoRaWAN nodes in an orchard in the upper Yakima Valley. They communicate with a gateway on nearby Ahtanum Ridge, which is covered with cell towers. Data Bridge has gateways throughout Central Washington, providing an infrastructure for farms to tap into.
In contrast, Allan Bros. has a neighboring block equipped with sensors that communicate via Wi-Fi at a shop, much like laptops and phones connect to a home Wi-Fi router. At one of its Prosser blocks, Allan Bros. physically wired a thermometer under a gravel drive and connected it to a frost alert system inside a shop that has internet.
But no orchard can rely solely on wires, and not all blocks or shops have an internet connection. Meanwhile, spotty cellular service can bog down devices, thwarting a farm’s efforts at automation and precision.
For, example, one Quincy orchard owned by Washington Fruit and Produce Co. is near Central Washington’s Gorge Amphitheater, where thousands of concertgoers clog the bandwidth during weekend events, said Gilbert Plath, an orchard manager and technology team leader.
During those times, managers sometimes wait 40 minutes just to activate an irrigation system outside its normal schedule. In those cases, they usually just turn things on and off manually.
“During those times, we have to go back to irrigation by hand; we’re missing out on the labor savings, which changes the ROI on the system,” Plath said.
How it works
LoRa simply stands for long range. Low-frequency wavelengths travel long distances and through objects such as apple bins, tree branches and sometimes buildings, all using little energy. Batteries last for years.
Here’s the trade-off: Those wavelengths carry small amounts of data at a time. Forget images or video. Even weather stations sometimes need a stronger signal.
The WAN — wide area network — gives each LoRa-enabled node its own identification to prevent interference and maintain privacy through encryption. Farmers might detect signals from a neighbor’s irrigation devices but wouldn’t be able to read their data.
With LoRaWAN, each sensor is wired to a node that transmits its data in bursts, via a low-range radio frequency, to a gateway device either mounted on a trellis post, wind machine tower or on a nearby hillside. That gateway then transmits the data from all those sensors in one package to the internet, either by radio, cellular service or Wi-Fi. In some cases, the gateway may be hardwired to the internet through cable or fiber optic lines.
Then, growers may look at their dashboard to see the information from all their devices.
The system can help in areas with poor internet service. Orchard managers complain all the time about having to drive up a nearby hillside just to make a phone call.
In 2022, 21 percent of farms in the United States still had no internet access, according to the U.S. Department of Agriculture. Oregon, Washington and California fared better at 12 percent, 14 percent and 15 percent, respectively. In Michigan and New York, 21 percent of farms had no internet. In Pennsylvania, the share was 27 percent.
Researchers and vendors
Researchers use LoRaWAN at Washington State University’s Irrigated Agriculture Research and Extension Center (IAREC) near Prosser to monitor irrigation flow meters, sap flow meters, dendrometers and more.
And the data flows both ways. In the Smart Vineyard at the Roza research farm, grape cluster temperature sensors send data via LoRaWAN to a control center, which — if conditions are right — sends a command back to the node to activate automated cooling misters. Then, leaf wetness and soil moisture sensors send more data to the control center, which turns off the misters once a certain threshold is reached.
AgWeatherNet, WSU’s weather station network, also uses LoRaWAN at the WSU Smart Orchard near Mattawa. There, the nodes connect to a gateway that communicates to the internet through the farm’s Wi-Fi.
Srikanth Gorthi, a doctoral student working with AgWeatherNet in Prosser, has placed LoRaWAN-equipped weather sensors in nearby commercial cherry orchards that send data to a gateway hooked to an antenna outside the research station.
Gorthi and Lav Khot, the AgWeatherNet director, want to encourage growers to purchase their own LoRaWAN-enabled temperature, soil or weather sensors and share their data with AgWeatherNet — as a cheaper alternative to hiring a service vendor. They are testing a bank of nodes on the IAREC campus to compare their functionality and reliability.
Service vendors also use LoRaWAN, or something similar.
Wilbur-Ellis, an ag service company, uses LoRaWAN for its irrigation services, installing nodes and gateways throughout the West, said Curtis Pusey, water management team manager.
Company technicians usually install their own gateways, but if the units need to be on a tower, cellular service companies must mount them, Pusey said.
Irrigation probes date back to the 1980s, but each relied on its own cellular signal, Pusey said. LoRaWAN was first released in 2015.
“We were able to drop our prices significantly because of LoRa,” he said.
Some vendors, such as Phytech and Nelson Irrigation, use a system like LoRaWAN but with proprietary low-range frequencies, registered by the federal government only to them. But they still connect many sensors throughout an orchard or vineyard via radio signals to a central hub for analysis and display over the internet.
“The goal in the field is to bring (the data) all to one place, and then you don’t have to pay for many cellular subscriptions,” said Iftach Shalev Rosenbach of Phytech. °
Connect the spots
This gallery shows the internet of things in a vineyard.
(Click an image to enlarge it.)
Sensors with LoRaWAN nodes communicate via low-frequency radio with a gateway connected to the internet.
Some sensors have their own cellular connection.
Either way, growers see data from the devices on a computer or phone dashboard linked to a cloud service.
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