Smart technology changes habits, and adds efficiency. Just ask Nebraska farmer Greg Greving, who admits that he, “always wanted to be first to irrigate.” Since he started using an interactive computer model to schedule irrigation, he now holds off watering beans in the early vegetative stage, saving water for grain fill.
Sophisticated irrigation management tools are helping growers make the best use of their water resources. Here’s a brief look at some of the ways irrigators are being smarter about water
Web-based irrigation scheduling
One advanced tool that can help decide when and how much water to apply is Web-based irrigation scheduling. Nebraska’s SoyWater, North Dakota’s NDAWN, and other interactive computer models generate customized irrigation recommendations based on soil type, local weather data, plant growth stage and daily crop water use.
Greg Peters, DeWitt, Neb., uses SoyWater to manage all his irrigated soybean fields. Since he’s been using the scheduling tool, he’s been able to cut one or two irrigation passes a season, per field, saving millions of gallons of water and significant fuel expense.
SoyWater is especially helpful to determine when to do the first irrigation of the season, says Mark Reiman, agronomist at Monsanto’s Water Utilization Learning Center, Gothenburg, Neb. There’s a temptation to start watering too early, particularly soybeans, he says.
SoyWater is also helpful at the end of the season, Greving says, when the goal is to dry down the soil as much as possible without causing yield loss, leaving room in the soil profile for winter and spring precipitation. He farms 3,200 irrigated acres near Chapman, Neb., with his sons Jeremy and Shane.
These programs require growers to enter rainfall and irrigation amounts for each field. Keeping current is a challenge for time-strapped farmers, says Justin Quandt, an Oakes, N.D., farmer who grows corn and soybeans with his father, uncles and brothers. They use North Dakota State University’s NDAWN scheduler.
Remote pivot controls
Remote pivot-management systems give growers control of the pivot without having to drive out to the field. Using satellite, cellular networks, or other telemetry systems, growers can turn pivots and chemigation on and off, change speeds and monitor position.
Quandt stays in touch with 50 center pivots 24/7, using GPS-based systems from Reinke, Zimmatic, AgSense and Rite Control. “We save a lot of time and a lot of fuel manages watering operations on 6,000 acres,” he says. The family operation stretches 17 miles from north to south and 15 miles east to west. “Pretty much everything you would do on-site with the panel you can do remotely.” Remote-control systems also send email and text message alerts if a pivot shuts off or gets stuck.
The computer program he uses calculates crop water needs based on soil type, plant growth stage and local weather. He also is experimenting with variable-rate irrigation, and is looking into wireless soil moisture probes and flow meters. With lower crop prices, we are trying to get more efficient with our water use, he says
Greving also believes in more precise irrigation. “We put in remote controls on all our pivots, because if you’re down for several hours, those can be very, very precious hours for irrigating,” he says. The first time they received a text message from a stopped pivot, “we got there even before the water had drained out. That sold us on remote control then and there.”
The Grevings use Valley Tracker wireless controls on all 18 center pivots. “We still check them morning and night,” Jeremy says, “but they are always being monitored.”
Sensors and variable rate
Soil moisture sensors
The Grevings are experimenting with wireless soil-moisture sensors, which measure changes in soil water content in the root zone. In 2013, Jeremy tried a McCrometer Connect capacitance soil-moisture sensor with wireless telemetry in one soybean field. The probe monitored soil moisture from 6 inches to 3 feet deep, transmitting the data to Jeremy’s iPad.
In other fields, he employed an irrigation scouting service. “Where the agronomist was telling me to apply 1 inch of water, the McCrometer was telling me to speed up the pivot a bit,” Greving says. “I could see the water was soaking in really well in that field and the crop wasn’t using a whole inch.” So he cut the application rate in that field to 0.70 inch per revolution.
“When we got rain, I started the pivot a day or two later than I normally would have because I had the sensor to tell me I still had moisture in the soil. That was real beneficial, knowing when to start back up again after a rain.” He estimates that having a sensor in the field let him cut water application by about 25% in 2013.
One of the limitations of soil-moisture sensors is placement, says Tom Scherer, an agricultural engineer at North Dakota Extension. “Were do you put them? You have 130 acres under the pivot,” so finding a representative location is essential.
It’s a good idea to check soil water conditions in other areas of the field with a hand probe and compare to the sensor readings, says Chuck Burr, an Extension irrigation specialist in west central Nebraska.
Burr also recommends atmometers, which estimate actual crop water use — or evapotranspiration (ET). You read the ET gage on a weekly basis, then compare how much water the crop has used to the amount of rainfall and irrigation the field has received for the past week.
Variable rate irrigation
One water-efficiency technology that’s coming on very strong is variable rate irrigation (VRI), says Scherer, the North Dakota engineer. Quandt is using VRI zone control in two fields where sprinkler water collects in low spots and clay pockets. He puts together watering prescriptions for each 50-foot section of pipe. In zones prone to pooling, banks of sprinklers pulse off at prescribed intervals, reducing water application. That cuts overwatering and runoff, as well as N loss from leaching, Quandt says.
Competition drives efficiency
Competition for water, low grain prices, spark search for irrigation efficiencies
In western corn- and soybean-growing regions, competition for water is intensifying.
In Nebraska, for example, “We’re concerned about the drawdown of the aquifer and potential limits on pumping,” says Gary Zoubek, a Nebraska Extension irrigation expert. Some parts of the state, such as the Box Butte area, the Republican River Basin and the Blue River Basin, have established or are considering pumping restrictions. In other regions, such as Kansas and the Texas Panhandle, wells are becoming depleted as the Ogallala Aquifer dwindles.
But even in regions where irrigation water is ample, “pumping is costing you money,” says Greg Peters, DeWitt, Neb., chairman of the Nebraska Soybean Board. He adds, “Water is a big public issue. We have to be cognizant of efficiency so we are using our water well.”
Meanwhile, lower grain prices spark more interest in strategies that improve irrigation efficiency, says Chuck Burr, an Extension irrigation specialist in west-central Nebraska. As profit margins shrink, “We will need to be more efficient in the coming years.”
Online irrigation management resources
Web-based irrigation management programs