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How low can you go on nitrogen?How low can you go on nitrogen?

Several studies through the Nebraska On-Farm Research Network address lowering nitrogen use under multiple different scenarios — without giving up on yield.

Curt Arens

March 28, 2023

3 Min Read
Two men, one woman looking at computer in farm shop
WORKING IT OUT: University of Nebraska graduate student Taylor Cross (right), works with Hall County farmers Doug and Tony Jones on sensor-based fertigation strategies aimed at lowering nitrogen use without giving up on yield.Photos by Hannah Gaebel Dorn, HG Images

With the cost of fertilizer and groundwater nitrate issues that can result from overfertilization, farmers these days are curbing nitrogen use as much as they can without giving up on yield. To many, it is surprising how little nitrogen they need to add to get a profitable crop.

Several growers participating in the Nebraska On-Farm Research Network have been testing the limits on lowering nitrogen use over the past several years, with positive results.

Man standing looking at tablet in front of large tractor

MODEL APPROACH: Jon Walz tested the Adapt-N crop model tool in 2022, and he saved 58 pounds of nitrogen and $17 per acre using this technology.

“We have many producers testing a range of nitrogen rates, ranging from 0 pounds per acre to 250-plus pounds per acre,” says Laura Thompson, Nebraska On-Farm Research Network and ag technology Extension educator. “Many of these growers implemented these tests by using prescriptions in their variable-rate application equipment. In this case, the prescriptions are developed by the Nebraska On-Farm Research team and then implemented on the go by the producer,” she explains. “Each rate in the nitrogen-rate ramps is generally 400 feet long by the width of the equipment, and the rates are replicated multiple times in different landscape positions and environments across the field.”

Testing rates

The small size of plots allows producers to study a range of nitrogen rates without having very many acres at extremely low rates. “Yield is determined with a yield monitor,” Thompson says. “These studies have been producing very valuable insights regarding the optimum nitrogen rate and the soil’s inherent nitrogen-supplying capability, allowing producers to make adjustments and reduce their nitrogen fertilizer in future years and better direct variable-rate fertilizer applications.” (See Table 1 for sample results.)

The results from these studies help growers to benchmark their nitrogen management, and those with variable-rate technology are able to easily gain insights into their management strategies with very little hassle, Thompson adds.

Crop model

Several producers, like Jon Walz in Lincoln County, are looking at crop model nitrogen tools, integrating soils, weather and management to obtain site-specific, variable-rate, in-season nitrogen recommendations. Walz, using the Adapt-N crop model in 2022, found that he could save 58 pounds per acre of nitrogen without any yield impact, increasing profit per acre by $17, according to Thompson.

Sensor-based fertigation

With the availability of regular quality aerial imagery during the growing season, sensor-based fertigation through a center pivot has been gaining steam, with good results on irrigated corn, Thompson says. Using imagery to assess in-season nitrogen needs, allowing for data-driven fertigation decisions matching the crop’s nitrogen uptake, has helped growers like Hall County farmers Doug and Tony Jones save up to 98 pounds of nitrogen per acre compared to their typical management system, with no yield impact. Both the sensor-based and traditional management systems yielded 212 bushels of corn per acre, but the sensor-based approach increased profit per acre by $80, Thompson says.

“The sensor-based fertigation method has been tested and improved over the last several years through faculty and graduate students working with farmers in the Nebraska On-Farm Research Network,” she says. “Looking at the same method that the Joneses tested, for 10 study sites, 100% of the sites had more efficient nitrogen use and 70% of the sites were more profitable, with average profit increases of $44 per acre for the sites with a profit increase,” she adds. Learn more about sensor-based fertigation at bit.ly/fptechbreakthrough.

Learn more

These kinds of nitrogen studies are being conducted through the On-Farm Research Network and a grant from the Natural Resources Conservation Service’s Conservation Innovation Grants program titled “promoting adoption of precision nitrogen management technologies.” You can see complete research results at bit.ly/ofrnresultpubs.

About the Author(s)

Curt Arens

Editor, Nebraska Farmer

Curt Arens began writing about Nebraska’s farm families when he was in high school. Before joining Farm Progress as a field editor in April 2010, he had worked as a freelance farm writer for 27 years, first for newspapers and then for farm magazines, including Nebraska Farmer.

His real full-time career, however, during that same period was farming his family’s fourth generation land in northeast Nebraska. He also operated his Christmas tree farm and grew black oil sunflowers for wild birdseed. Curt continues to raise corn, soybeans and alfalfa and runs a cow-calf herd.

Curt and his wife Donna have four children, Lauren, Taylor, Zachary and Benjamin. They are active in their church and St. Rose School in Crofton, where Donna teaches and their children attend classes.

Previously, the 1986 University of Nebraska animal science graduate wrote a weekly rural life column, developed a farm radio program and wrote books about farm direct marketing and farmers markets. He received media honors from the Nebraska Forest Service, Center for Rural Affairs and Northeast Nebraska Experimental Farm Association.

He wrote about the spiritual side of farming in his 2008 book, “Down to Earth: Celebrating a Blessed Life on the Land,” garnering a Catholic Press Association award.

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