As researcher Udayakumar Sekaran sees it, soil-moisture sensors help farmers irrigate more efficiently but are limited by the wires to which they are attached.

Limited reach and the need for a power source are among those limitations. And farmers who use wired sensors have to visit fields frequently to check on them.

Sekaran is getting rid of the wires.

“We are using wireless technology to measure soil moisture,” said Sekaran, an irrigation and soil fertility specialist at the Oregon State University Malheur Experiment Station south of Ontario.

Targeted benefits go beyond getting real-time values on a mobile phone application and further automating irrigation.

Since a wireless sensor network can be placed anywhere, “you can cover more spots and create more irrigation zones,” Sekaran said. Fields, including small parts of them with unique characteristics, can be managed more precisely.

Onion experiment

Drip-irrigated onions are the focus of the project, though wireless soil moisture sensor networks have the potential to be used with other crops and irrigation delivery systems, such as center-pivot sprinklers.

The work aims to build on research that Sekaran participated in as a post-doctoral research fellow at Clemson University in South Carolina. Soil moisture in cotton, corn and soybeans was monitored throughout the growing season. That study, now in its late stages, found that irrigating at optimal levels increased the value of the crops.

“We’re expecting the same result in Oregon,” Sekaran said.

“The technology is working well,” he said.

Compared to cotton, corn and soybeans, onions are shallow-rooted and planted at shallow depth.

In onions, a medium-water-use crop, “most of the water we apply is in the top three to four inches of soil,” Sekaran said. Loss can be high due to evaporation into the atmosphere and percolation into deeper layers of soil.

Researchers are measuring soil moisture at six inches and one foot. Goals include determining depths at which moisture is high or low, and how well onion plants take up water at different depths.

Threshold moisture levels, at which onions are over- or under-irrigated, also are being sought. Irrigating too little can reduce quality and yield. Applying too much water, to the point at which the plant’s usage efficiency declines, can cost growers more and increase nutrient leaching.

The project also involves Erik Feibert of the OSU Malheur station staff, former McCain Foods agronomist Kyler Beck and Jim Klauser, retired Clearwater Supply irrigation equipment specialist.

Southeast Oregon and southwest Idaho comprise a major onion-growing region. The area has low rainfall. Some growers incorporate mulch to keep the soil from getting overheated and reduce water loss, the focus of another project in which Sekaran is involved.

Precision irrigation

Making irrigation as precise as possible in this arid environment can help save water and increase crop production, he said.

In the future, Sekaran, a fairly recent hire, intends to use artificial intelligence in studying irrigation and soil health.

The approach holds promise in creating models to predict how management decisions — such as those dealing with irrigation, fertilizer and chemical application — impact total production, he said.

“With the growing population, the demand for and usage of water is increasing,” said Sekaran, who grew up on his grandfather’s farm in the state of Tamil Nadu, India. “Irrigation is part of the management system, and so we’ve got to take care of it.”

Udayakumar Sekaran

Udayakumar Sekaran

Age: 32

Title: assistant professor and irrigation/soil fertility specialist, Oregon State University Malheur Experiment Station.

Home: Ontario, Ore.

Education: Bachelor’s degree in agriculture, master’s and Ph.D. degrees in soil science, all from Tamil Nadu Agricultural University, India, 2017. Post-doctoral fellowships, South Dakota State University and Clemson University.

Family: Wife Jemila Chellappa, one child. Chellappa works at Eastern Oregon University, under OSU’s agriculture program, as a crop and soil science instructor.

Hobbies: Volleyball, travel, photography.