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Fine tuning irrigation efficiency

Learning to rely on moisture sensors for irrigation.

Forrest Laws

February 15, 2022

Farmers can face a steep learning curve when they begin installing soil moisture sensors, surge valves, well monitors and other technologically advanced tools to help improve the irrigation efficiency on their farms.

Fortunately, there are resources they can call on such as Mike Hamilton, an irrigation instructor with the University of Arkansas System Division of Agriculture and an irrigation specialist with USDA’s Natural Resources Conservation Service.

“In 2017, I had an opportunity to work with Mike Hamilton and learn from him,” said Jennifer James, a corn, rice and soybean producer from Jackson County, Ark. James, a recognized conservation leader in the rice industry, was a presenter for the 24th annual Arkansas Soil and Water Education Conference, which was held online this year.

“When we started to learn and refine our processes while working with Mike, we quickly learned that we really didn't know what we were doing,” she said with a laugh. “There was a lot more to learn, and a lot more to do out there.”

Example: The installation of soil moisture sensors in one of her family’s corn fields.

“Mike, our county Extension agent Matthew Davis and some NRCS technicians came out to teach me how to install those moisture sensors in our corn,” she said. “We were using Watermark Soil Moisture Sensors with a Precision King Monitoring System.”

Moisture deficit

She and one of her employees were monitoring the sensors, which were placed in the row in the corn field, when the sensors indicated a moisture deficit in the soil. (The sensors are placed to indicate the amount of moisture available to the plant at the 6-, 12-, 18- and 30-inch depths in the soil.)

“We had performed an irrigation on June 29th and saw that immediately all of the sensors were telling us to irrigate again,” she said. “We went out to the field and the soil was just sopping wet. Above the red line

It appeared there was no need for irrigation. But on July 6, the 18-inch sensor was above the red line, which indicated that it was time for irrigation.

“I called Mike Hamilton and told him this sensor’s not working. He came out, and pulled it up and said, ‘No, it’s just that hot and that dry. Your corn is actually using more water from the 18-inch depth than from the top,’ which made sense after he told me that because that’s where most of the roots were at that time.”

James and her employees continued to irrigate each time it was necessary throughout the rest of the season.

“We learned a lot about the sensors after that season,” she said. “We could see that understanding what the plant needed under the surface was very important. Simply to know that the surface was dry was no longer an accurate way to irrigate for the needs of the plant.

“The next few summers I tried several types of moisture sensors with different telemetry packages, and it was really overwhelming. There are a lot of companies out there who are making excellent products, and we were trying to decide which one would work better on our farm.”

The James farming operation has four distinct areas. Rather than buying sensors for each field, she has been purchasing enough soil moisture sensors to be representative of each area.

“We chose the Watermark system with the Precision King telemetry,” she noted. “One of the main reasons was they have a lot of historical data behind how to trigger your irrigation and a lot of folks that understand how they work. So we could get help through the process.

“It’s all about you and your folks who are managing your irrigation. They all will help you, and they all will make you more efficient and improve your yields.”

About the Author(s)

Forrest Laws

Forrest Laws spent 10 years with The Memphis Press-Scimitar before joining Delta Farm Press in 1980. He has written extensively on farm production practices, crop marketing, farm legislation, environmental regulations and alternative energy. He resides in Memphis, Tenn. He served as a missile launch officer in the U.S. Air Force before resuming his career in journalism with The Press-Scimitar.

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