Every drop of water counts in central and western Nebraska, where Andy Jobman raises soybeans, food-grade yellow and white corn, and cattle with his dad and brother near Gothenburg, in the center of the state. “Irrigation is really big on our farm and really important,” Jobman said. “It’s a resource we can’t afford to neglect or overuse.”
Adopting center pivots and drip tape has allowed the Jobmans to move their entire farm to strip-till, whereas previously, due to historical irrigation practices utilizing gated pipe, they relied on ridge-till. This change has resulted in increased soil organic matter. “Having that extra percent or two of soil organic matter and soil cover from the residue helps with our water usage,” Jobman said.
Traditionally, drip irrigation has been used for high-value horticultural crops such as small fruits and vegetables. But recently, it has been adopted in agronomic crops, including corn, soybeans, and cotton, as a way to improve yield potential.
Bushels of Benefits
Compared with traditional pivot and flood irrigation, drip systems offer multiple advantages, said Chuck Bates, vice president of products and agronomy for Netafim USA. “No. 1 is water use efficiency,” he said. “Generally speaking, you’re going to use less water because you have less evaporative effects than with a pivot, and you’re not wasting water from a flood irrigation system, where you’re creating tailwater.”
The precise application of nutrients is the second and perhaps most important benefit. “Drip irrigation offers a much more uniform application of fertilizer,” Bates said. “That’s a big deal in corn.”
A multi-year study (2019–2023) by Precision Planting’s Precision Technology Institute (PTI) found surface drip irrigation increased corn yield by an average 57.6 bushels per acre (bpa) compared with a non-irrigated control. That translated to an additional gross income by an average $259.70 per acre.
When comparing surface irrigation to subsurface irrigation (SDI), a similar PTI study conducted in 2023 showed an SDI increase of 13 bpa.
“We can put on water when it’s dry, and we can apply the nutrients immediately to the crop,” said Jason Webster, lead commercial agronomist at Precision Planting. “We have the ability to spoon-feed these nutrients every time we turn the water on.”
Irrigating the Irregular
Not all fields can be irrigated with center pivot. In these cases, drip irrigation can be a solution.
Jobman was looking at a better alternative for fields unsuitable for pivot irrigation. “Traditionally, the only way to irrigate those misshaped fields has been with gravity irrigation, like gated pipe, which works, but it is a little bit labor intensive and not as efficient,” Jobman explained. “With a gravity gated pipe, you’re talking 50%–60% efficiency on your water usage.”
N-Drip offered a potential solution for Jobman, using gravity-powered micro-irrigation. The company also offers another product, N-Drip Connect, which uses sensors that generate insights regarding optimal irrigation and fertilization, based on data taken from the root zone. The system monitors the soil’s available water and nitrogen to provide irrigation and fertilization recommendations.
“We were one of the first growers in the area to take the first step with N-Drip,” Jobman shared. “We had a small, 24-acre field, with high-quality soil that we’d been having trouble getting uniform irrigation across the whole field with gravity pipe. We thought that would be a really good field to trial the N-Drip system.”
The Jobmans said they reduced their per-acre pumping costs by 40% and water usage by 39% while increasing their yields by 19% and field revenue by 25%. “It irrigated the field way more uniformly than what we could ever do with ridge till and gated pipe. It was equal to what a center pivot can do,” Jobman said.
The Jobmans were introduced to N-Drip through a cost-share program with Frito-Lay PepsiCo. That program has ended, but N-Drip continues to work on the Jobmans’ farm as a test case to further improve the compatibility of their system with strip-till and row crop production systems. “The infrastructure cost is high; higher than putting a center pivot up,” Jobman acknowledged. “It works best for fields with irrigation where you can’t make a center pivot work.”
The system at the PTI farm includes a reservoir that recycles drainage-tile rainwater to pull for irrigation as needed. With the cost of digging the reservoir plus the irrigation system, Precision Planting has invested about $4,000 per acre on an 80-acre field, Webster of Precision Planting said. “But with the yield increases we’ve gotten with both the drainage tile, as well as the irrigation, we’re on a 10-year payoff,” he said.
Learning Curve
For farmers who are used to center pivots or flood irrigation, there is a learning curve moving to drip irrigation, said Bates of Netafim USA. “When you’re turning on a center pivot, there’s a very visual depiction of what is happening,” he said. “Water is spraying, the pivot is turning, or you can see the water flowing in a flood field,” he said. “With drip, you don’t see any of that. You’re relying much more on equipment and technology to tell you what’s happening in the field.”
There are additional maintenance learnings as well. “You need to understand how to repair leaks and prevent plugging of the drippers and what chemicals to use at what times throughout the course of the year,” Bates said. “We’ve got agronomists across the country that will help a farmer through that learning curve.”
Advanced technology options can help farmers mitigate the learning curve. Netafim’s Growsphere Operating System offers a new digital solution to help farmers monitor pressure and flow rates and turn on fertilizer injection systems. “You can control, monitor, and even receive agronomic recommendations, all from Growsphere,” Bates said.
Courtesy of Netafilm USA
Potential Kinks in the Tape
Aspects of the surface micro-irrigation system didn’t work as well with Jobman’s standard crop and livestock rotation. For example, cattle typically graze corn stover after harvest. “We couldn’t really do that with the tape out there, near the surface of the soil; the cows will trample and drag it around in their grazing patterns,” Jobman shared. That left more residue to contend with the following season, complicating strip-tillage passes.
Also, with SDI, fields have to be minimum-till or no-till. The depth of the system depends on soil type and ranges from 6–14 inches deep. “What’s typical for corn and soybeans is 30-inch lateral spacing,” Bates explained. “That gives good flexibility to do any crop rotation, including alfalfa, in most areas.”
Rodents can also be an issue with above- and below-ground drip systems. “Most people do a pretty routine course of repellent throughout the season,” Bates said. “If there’s damage incurred during the course of the season, they go through after harvest and repair the damage.”
The trick with subsurface drip is you have to get rid of the air pocket, Webster explained. “When you lay the tape, you have to backfill it with soil to get it covered up. If you leave an air pocket, there’s a water source there for voles. They’re also going to nip at the tape, and you’ll have a blowout there the following year,” he said.
Webster has seen the benefits of drip irrigation in the research at Precision Planting. “It’s an easy way to irrigate because of your instant access,” he said. “It’s like an IV right into the corn or soybean plant. You can get to it faster.”
Jobman also sees the potential of this technology. “We’re not quite to a point where we can just put it everywhere yet,” he said. “It’s a great irrigation system, but we’re working to figure out how to make it mesh really well with our row crop systems.”