Research examines potential water savings of automated and remote irrigation systems.
• By Vicky Boyd,
Nowadays, computer and smartphone technology allows users to monitor home security, adjust thermostats, and automatically turn on and off lights and appliances while they’re away.
Drew Gholson, a Mississippi State University Extension irrigation specialist, is conducting farm-scale research trials to determine whether growers potentially can save water by using similar technology to automate well operations. The system under evaluation also allows users to remotely monitor water levels in fields and, if needed, turn wells on or off from a smartphone or computer.
“Our goal was not to let one drop of water go over the levee gate,” he said about the first year of trials. “From a university standpoint, we’re just evaluating these technologies to see if we can not only save water and money but also are these something that can help farmers make decisions and save time doing that.”
Gholson is using a simple automation system from PrecisionKing of Yazoo City, Mississippi, consisting of ultra-sonic water level sensors, actuated valves to shift water from one field to another and a pump controller. If the pump just serves a single field, the valves aren’t needed. The fields in the trial were irrigated using side-inlet irrigation and alternate wetting and drying, or AWD.
Based on previous small-plot research conducted at MSU’s Delta Research and Extension Center, Gholson said growers using side-inlet irrigation and AWD can let the water drop to about 4 inches below ground level – or minus 4 — before reflooding without losing significant yield. In those trials, average water use was reduced by 39% compared to a conventional flood-irrigated field.
“Can we even increase that further by automating it?” he said. “I think you could save an additional amount of water and make management decisions a lot easier.”
Farmers may have scattered fields with some several miles from home, the office or shop. Driving to each field to turn the water off and on or to check water levels is time consuming, and growers or irrigators may hesitate to venture out in the middle of the night to turn off wells when a 4-inch flood is reached. Instead, they may wait until the following morning.
But the automated system will turn off wells when the trigger is reached, eliminating additional hours of water use. Users also can check water levels and well status from their smartphones or computers without having to drive to each field, saving time and fuel. In addition, users are able to bypass the automation settings if, for example, they see a large rainstorm coming and want to shut off the well beforehand to prevent water from spilling over the levees.
After the first year
For his trials, Gholson set the top flood depth at 4 inches and the trigger to reflood at minus 3. The actual trigger points can be entered based on user goals. A single ultra-sonic sensor in the field measures water levels in a pani pipe sunk in the soil. The sensor communicates via telemetry with the pump controller to turn on or turn off based on water levels in the pipe.
If the well serves two fields, a valve actuator will open or close to divert water based on the sensor communication. All of the wells in the trials were electric for ease of turning them on and off.
One of the challenges was positioning the single sensor to collect representative water-level readings from throughout the field, Gholson said. Initially, they placed it near the well inlet pipe. But they found it quickly reached the 4-inch trigger point and shut off the well prematurely even though much of the field still hadn’t been adequately flooded. This season, he said they plan to put the sensors farther away from the inlet pipe.
Another challenge is building faith that the system will work as designed. Gholson visited each site during the different functions to ensure the wells were turned on, shut down or the valves switched water to different fields. As with any new technology, he said building confidence comes with experience.
During the 2020 season, Gholson had three sites comprising five fields and three wells in the trials. Each field with automation was paired with one the farmer irrigated as usual.
Austin Davis, who farms near Benoit, Mississippi, is a long-time MSU cooperator. He said he volunteered a 160-acre field for the project so he could see the automation first hand.
“It’s kind of in its infancy right now, and I don’t think it’s quite feasible from a cost standpoint for a lot of acreage,” he said. “I think that with the climate change thing being a big talking point, if this seems to be a more efficient way of doing things or as a water-savings tool and this is something that would be ‘heavily encouraged,’ at some point in my life it’s something I’d use.”
Although the results are preliminary, they are encouraging, Gholson said. Farmer-irrigated fields averaged 219 bushels per acre compared to 223 bushels per acre for the automated irrigation fields. The big difference was in applied water use, with the automated fields averaging only 18.8 acre-inches compared to the farmer-irrigated fields averaging 28.6 acre-inches.
He plans to repeat the trials this season and expand them to include additional sites to take in variability in soil, microclimates and farmer irrigation practices. Gholson said he also hoped to continue the project for a few more seasons to account for weather differences.
As part of the research, he said he plans to conduct an economic analysis to determine automated system costs, break-even points and potential payback.
Gholson’s trials also are being funded in part by the Mississippi Rice Promotion Board.
Arkansas brothers see real-world water savings with automation
Jim Whitaker and his brother, Sam, who farm near McGehee, Arkansas, have become big devotees of irrigation automation.
Not only are they expanding installation in their rice fields, but they’re also implementing it in cotton and corn.
The water savings is the most obvious benefit, but the technology also saves electricity and allows them to make more efficient use of their labor, said Jim Whitaker.
Their rice fields are zero grade, and they use alternate wetting and drying or AWD. As a result, they had reduced water use to 12 to 15 acre-inches of applied water per year even before the technology.
During the past six to seven years, the Whitakers have adopted automation as the systems have evolved. They started with PrecisionKing and still use the company’s systems for row crops. For rice, they’ve started using aQuarius Farm Controls, although Whitaker said both companies make good products.
They’ve also worked with Dr. Merle Anders, consultant, and Drs. Joe Massey and Michele Reba with the U.S. Department of Agriculture’s Agricultural Research Service in Jonesboro, Arkansas, to quantify water savings and greenhouse gas reduction.
During the first year of adoption, Whitaker said he wanted to see if he could control irrigation using his phone. That evolved into automating risers serving multiple fields. Much like Gholson, Whitaker has installed a moisture sensor in each field and set thresholds for turning on and off the water.
With the technology, he’s been able to stretch the interval between irrigations to 10 to 14 days, depending on the weather, without affecting yield. At the end of the season, the Whitakers typically apply 20% less water using the automation than manually turning on and off the wells.
“The first thing we figured out was we were able to save a lot of water because it was shutting the wells off in the middle of the night,” Whitaker said. “Normally by the time the guys get to the shop and we have a morning meeting, it might be 8 or 9, maybe even as late as 10, before the guys make it around to check those fields.”
He said they still have a ways to go to fully automate irrigation on their farm, with cost being one of the hurdles. But Whitaker credited the Natural Resource Conservation Service Regional Conservation Partnership Program for providing cost-share funds to help with their efforts.