Do N-Fixing Biological Products Work?

University Research Casts Skepticism on Nitrogen-Fixing Biologicals

Jason Jenkins
By  Jason Jenkins , DTN Crops Editor
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Biological nitrogen-fixing products have been marketed as an option for reducing fertilizer rates while maintaining yields, but new university trials found little benefit. (DTN photo by Pamela Smith)

JEFFERSON CITY, Mo. (DTN) -- In the wake of skyrocketing fertilizer prices, nitrogen-fixing biological products have gained headlines as an alternative means of feeding the crop. But these products may be more hype than help, according to a new report from a group of land-grant university researchers.

A committee on nonconventional additives and amendments organized by the North Central Regional Association of State Agricultural Experiment Station Directors recently summarized 61 nitrogen rate trials with and without biological nitrogen-fixing products to determine their possible value to farmers.

Of the 61 trials, 59 showed no significant yield increase with the use of the products compared to nitrogen alone.

"It's been the perfect storm. Nitrogen prices were through the roof, so anything farmers could do that might help get the cost down, they were all in," said Dave Franzen, University of North Dakota Extension soil specialist and head of the North Central Extension Research Activities committee that conducted the research. "So, our committee decided to do some work on these products. All of my colleagues hoped it would work, but the results weren't there."

The trials were conducted in 10 states within the North Central region, including Illinois, Indiana, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, North Dakota and Ohio. While a majority of the trials were conducted in corn, the products also were evaluated in spring wheat, sugar beets and canola.

Products tested included Azotic's Envita, Corteva's Utrisha N, Pivot Bio's ProveN and ProveN40, and TerraMax's MicroAZ-ST in both liquid and dry formulations. Products were either foliar-applied, applied as impregnated urea, used in-furrow or as a seed treatment.

"We followed the label rates exactly like a farmer would see," Franzen said. "We didn't mess around with rates. We just wanted to see if the label was effective.

"Almost everyone used a range of nitrogen rates and not on the high end," he explained. Rates in North Dakota trials in corn ranged from 113 to 150 pounds per acre. "Some of the companies urged us to use it at the 160- to 200-pound rate. I thought that was ridiculous. If you wanted to know if this stuff was really working, you'd want to do it at the lower end."

The products in this category of "biologicals" contain asymbiotic nitrogen-fixing organisms, usually species of bacteria. In theory, the bacteria can pull nitrogen gas from the air and provide it as inorganic nitrogen fertilizer to the crop.

"These things are in the soil already," Franzen said. "There's a whole slug of them, maybe 50 species in any given field. They're limited by food and housing. When you stick another one in there, they're still limited by food and housing, so there's a war going on in the soil. The one you add may not be all that competitive."

When queried about the university trials, Corteva provided a statement to DTN, noting that data supporting its yield improvement claims for Utrisha N reflect a two-year, multi-location analysis of more than 300 field trials across U.S. corn-producing states. The company stated its biological product is intended to be a supplement to fertilizer rather than a substitute.

"Corteva Agriscience stands behind our long-running commitment to deliver farmers with reliable products that provide proven, predictable performance," the company asserted in the statement. "The university studies referenced would need to include comparable levels of data -- and be aggregated together -- to account for the large number of uncontrolled environmental variables, such as pest pressures, weather conditions, soil factors including fertility and manner of use or application."

Tom Tregunno, global market manager for Azotic, also referenced research, including hundreds of peer-reviewed papers, that demonstrates the bacteria in Envita colonizes and fixes nitrogen in many crops.

"Biologicals have significant potential to increase crop yields and quality," Tregunno wrote in an email to DTN. "As an industry, we are learning together. For example, Azotic's first focus was on seed treatments and in-furrow applications. Today, we know the foliar application provides the most consistent results. After four years of large-scale commercial trials, we see an average (increase) of 8 bushels per acre, 80% of the time on corn. We know Envita works. We offer a performance guarantee. This provides growers an opportunity to test Envita on their farm."

In its response to DTN's request for comment on the university trials, Pivot Bio stated that first-to-market technologies naturally attract interest and questions, which is why it has worked with multiple academic and independent research organizations to rigorously test our products.

"We have multiple, independent third-party studies that demonstrate the efficacy and environmental benefits of Pivot Bio's products," the company stated. "Pivot Bio's microbial nitrogen is a reliable replacement for synthetic fertilizer, and no nitrogen product on the market is judged on yield alone. Our product can efficiently and reliably replace up to 40 pounds per acre of synthetic nitrogen while maintaining yield and boosting a grower's return on investment."


In an April 27 blog post discussing the summary report, Dan Kaiser, a University of Minnesota Extension nutrient management specialist who participated in the research, suggested that growers interested in adding biological soil fertility products should conduct on-farm field trials to see if a product works.

"One important component of testing is to make sure you have a direct comparison where all factors are controlled equally," Kaiser wrote. "Avoid making comparisons using just a standard rate versus a reduced rate with the biological product.

"There is a substantial amount of data I see presented that claims product efficacy of a reduced rate with the product yields the same as a farmer's normal practice," he wrote. "An important comparison that is missed in this situation is the reduced rate without the product, as that would provide a direct comparison."

Franzen agreed that farmers should be curious, but "also be skeptical."

"Do replicated strip trials on the farm before diving in," he said. "It's easy to do with yield monitors and GPS, so do it."

The North Dakota researcher indicated he would not be repeating the product evaluation trials this year.

"If the result had been 50/50, I'd consider it, but only two out of 61 trials showed a yield benefit," he said. "Would you ever go to Vegas with those kind of odds?"

The complete research summary report can be found here:….

A primer for setting up and conducting on-farm research can be found here:….

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Jason Jenkins