January 03, 2024
By Adrienne Held

The buzz around biologicals in corn and soybeansBoring Science

PHOTO: ILLUSTRATION BY PÂTÉ

Biological products promise to enhance soil nutrient supply, improve fertilizer efficiency, mitigate plant stress, and suppress pests. But the quagmire of options, formulations, and application timings promotes confusion surrounding biologicals and how to use them on the farm.

Dale Downey has been using biological products on his southwest Indiana farm for a couple seasons. “Everyone is trying to understand it, and that’s where I am at,” he says. “I’m so fascinated by what’s going on under the soil.”

What's the buzz?

Biological products are the fastest-growing segment in agriculture. L.E.K. Consulting, which provides research in market dynamics, reports that the growth in crop biologicals is now forecast to outpace that of conventional agricultural chemicals, with a compound annual growth rate of 14% through 2029.

Interest is being driven by the potential to help farmers produce higher yields while also promoting environmental sustainability. High input costs in 2022 and 2023 paved the way for growers to turn to biofertilizers to lower costs without sacrificing yield or soil fertility.

“With climate change, drought, and other abiotic stressors posting increasing challenges to crop production, biostimulant technologies can provide needed support by boosting nutrition, mitigating stress, and helping plants recover faster after a stress event,” says Mike Eiberger, U.S. biologicals portfolio marketing leader with Corteva.

Clayton Nevins, a senior agronomic scientist and new venture lead at Pivot Bio, sees a shift in the marketplace toward resilient and sustainable practices. “I think the need is there, but I think it’s also a desire among growers to have better solutions so we can optimize our resources, minimize our environmental impact, and ensure the long-term viability of our farms and our land.”

Richard Fordyce, a farmer in northwest Missouri, shared that fertilizer prices played a role in his choice to try biofertilizer on his farm. “In 2021 and 2022 we saw an uptick in nitrogen costs,” he says. “The claim is you can replace 40 pounds of synthetic nitrogen if you use Pivot Bio’s Proven 40 product and the price point of Proven 40 was lower than the equivalent 40 pounds of nitrogen.”

Les Anderson farms in Minnesota and was first interested in trying N-fixing biologicals as a time-released source of nitrogen compared to traditional synthetic fertilizers to combat nitrate leaching.

“We have 10,000 lakes in Minnesota, but we are also the head of three major watersheds. No water runs into Minnesota, it all runs out. We might as well take the lead and be proactive on some of these nitrate issues in groundwater,” says Anderson.

How do they work?

Biologicals aren’t new to agriculture. Products like Bt and spinosad have been used to combat caterpillar pests for decades. Bradyrhizobium inoculant has been used for nearly a century and is still popular among organic and conventional growers for establishing legume crops. Biological insecticides and fungicides are popular alternatives for pest management in the organic specialty crop market. Pheromones are used in fruit production to disrupt the normal mating patterns of insect pests, thus reducing insect damage.

The mode of action varies depending on the product. Many biofertilizers are living bacteria or fungi, also referred to as microbes. The biofertilizers are making the most buzz in the market.

Proven 40 is labeled for corn and contains N-fixing bacteria that can take atmospheric N and convert to plant-usable N. The product is marketed to replace up to 40 pounds of N or 20% of a N budget in a typical Midwest corn field.

Corteva’s Utrisha N contains another N-fixing bacteria. Utrisha N is applied to plant postemergence and lives within the plant cells, producing N inside the plant. Utrisha P is a new bacterium from Corteva with the goal of increasing the availability of phosphorus to promote plant growth.

Mosaic Biosciences has two biofertilizer offerings: BioPath and Powercoat. Both contain Bacillus strains and both are liquids. “The key difference between the two products is how they’re applied. Biopath is for liquid applications and Powercoat for dry applications. Biopath is water-based, so it can go into starter fertilizers or Urea Ammonium Nitrate (UAN) as a pre blend. Powercoat is applied at the retail level onto the dry fertilizer that they’re ordering,” says Dion Pierce, sales operations lead, Mosaic BioScience.

Examples of biostimulant products.*

Biologicals defined

The Biological Products Industry Alliance (BPIA) defines biologicals as “naturally occurring compounds or synthetically derived compounds that are structurally and functionally similar to natural counterparts.” Biologicals fit into three broad categories: biopesticides, beneficial microbes (also sometimes referred to as biofertilizers), and biostimulants.


“Biologicals are a little bit of a gray area and are not extremely well-defined. Biostimulants, biocontrol, and biofertilizers are all used interchangeably in some cases, which can add to the confusion. I would say anything that is natural or derived from natural origin and used to mitigate or control a pest and/or to enhance plant growth or nutrient use efficiency. However, this doesn’t mean that it’s organic,” says Pierce.

Biopesticides help control insects, diseases, nematodes, and weeds. These are regulated by the EPA.

Nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and mycorrhizal fungi are all part of the beneficial microbes category.

There are several categories of biostimulants, which include humic substances, amino acids and other nitrogen compounds, chitosans, seaweed extracts, and beneficial microorganisms, such as bacteria (plant growth promoting rhizobacteria) or fungi (often mycorrhizae). These substances give a boost to a plant’s natural processes, growth, and defense mechanisms to help the plant more effectively use what is already present in its environment. These effects may, in turn, help enhance the growth and yield of crops.

Beneficial microbes and biostimulants are the most common products currently used in row crops.

How can biological products be used?

Biologicals can be applied many times during the growing season, depending on the desired outcome. Application options include as seed treatments, in-furrow with starter fertilizer, foliar-applied at vegetative stages (with postemergence herbicide) and reproductive stages (with fungicide or insecticide), with dry fertilizer, or on crop residues. The flexibility of application is one of the greatest assets of these products.

“Overall, most of these are relatively inexpensive,” says Conner Sible, a postdoctoral research associate at the University of Illinois. “Most have a free ride of application.”

The success of biologicals is largely dependent on a sound agronomic base of seed choice, soil fertility, and crop protection, he adds. Once these factors are set, biologicals can be a next step in improving crop yields.

What does research say for use in corn?

Many products are marketed as a way to reduce synthetic fertilizer inputs without reducing yield or profit. Sible’s research at the University of Illinois recommends a slightly different approach. He found that applying Proven 40 can improve corn yields when applied N is limited. However, when N rates were low, yield potential for the corn crop was also reduced.

“Our program here is high yield,” says Sible. “What we are seeing in our data is at the standard fertility rates, adding a biological tends to get you a little more bushels out of the standard rate. If I reduce the fertilizer rate, I’m already reducing the amount the crop can have. In a year with heavy N loss conditions, I’m even further behind.

Les Anderson's on-farm strip-trial photo of corn at the 220-pound N rate and 80-pound N rate plus Proven 40 shows
 no distress at the significantly lower N rate.  Photo: LES ANDERSON

“There are always parts of the field that have high N supply power and parts of the field where N is more subject to loss,” he continues. “If you put something that can fix N, it brings those low spots up to field average. With today’s results we are seeing that maintaining a standard fertility rate and adding a biological can keep the whole field average up.”

Sible’s biological research spans the state of Illinois and includes four years of data including 103 site years for corn trials.

From 2019 to 2022, North Dakota State University compiled results from 12 trials in 10 states across the north central region looking at the asymbiotic N-fixing products in corn, spring wheat, sugar beet, and canola. Products tested can be seen in the table on page 18. Dave Franzen, Extension soil specialist at North Dakota State University, says, “Of the 51 sites, 49 did not show a statistical yield benefit to using a biological product and the two that had a yield benefit was about half of what was advertised.”

Summary of corn trials with N rates with and without biological N-fixation products from 10 north central states. Number indicates site years evaluated. “Yes” indicates a trial with overall yield advantage to product use over N rate alone. “No” indicates no yield advantage to product use over N rate alone.

“The research had multiple N rates that span N rates above and below the optimal within a given field with and without the product,” says Dan Kaiser from the University of Minnesota, giving a synopsis of his work in the north central research. “A majority of the data shows the same yield no matter if you have the product or not.” Minnesota trials were conducted at six locations over the three-year study (2019-2022). Five locations show no yield benefit. The sixth at Waseca, Minnesota, in 2020 showed a 9 bu/acre yield benefit using Proven, which was equivalent to a 20 pounds of N per acre benefit to Proven.

The north central region studies focused on yield, which is not the only benefit of biologicals as Pivot Bio and Corteva shared in their response to the research.

"At many trial locations summarized in the extension research studies, plots with Pivot Bio microbial products applied with reduced nitrogen rates achieved parity yield with the full-rate synthetic nitrogen check. This supports what we have told farmers all along – they can replace some of their synthetic nitrogen with Proven 40 and maintain yield," says Nevins.

“Corteva data supporting our yield improvement claims for Utrisha N [2.5 bu/acre in soybean and 5 bu/acre in corn] reflects a two-year, multilocation analysis of more than 300 field trials across U.S. corn-producing states. These university studies 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,” says Eiberger.

What about research specifically for soybean?

Science for Success, a collaborative effort of soybean specialists across Extension in several states, conducted a study evaluating biological seed treatments in soybeans in 2022. The study spanned 17 states and 49 locations. There were nine treatments with a range of genus and species of microbial products as well as a control.

In summary of the research, Fabiano Colet, a doctoral candidate at The Ohio State University who is leading the project, shared that yield differences from biological seed treatments in soybeans ranged from –6.5 bu/acre to 4.5 bu/acre. When results were combined, there were no significant differences in yield by treatment. There was a higher probability of a positive yield response in the southern United States.

“These are preliminary results,” he explains. “We know there is this trend in Southern states with particular products. We want to see if that’s going to happen again in 2023.”

At the time of this writing, 2023 results were not yet available. When completed, results can be found at soybeanresearchinfo.com. This study is funded by the United Soybean Board and USDA.

Beck’s Hybrids has also researched biological products at multiple locations. Products were evaluated to determine the return on investment (ROI), and Beck’s labeled products with a positive ROI as Practical Farm Research (PFR) Proven. “PFR Proven products have a minimum of three years of data, multiple locations, have to provide a yield increase every year, and a positive average ROI over that period of testing,” says Travis Burnett, field agronomist with Beck’s Hybrids.

For 2022, PFR studies included nine biological products: seven corn products and two soybean products. The PFR biological products in corn offered a range in yield benefit of 3.3 to 9.8 bu/acre and a ROI range of $3.97 to $39.66. For soybeans, the yield benefit range was 1.1 to 1.4 bu/acre and ROI range of $1.99 to $13.07 per acre. For more information on these results, go to beckshybrids.com.

When evaluating research results, Laura Lindsey, soybean and small grain specialist at The Ohio State University, recommends paying attention to statistical significance.

“When we do field research, we need to distinguish between yield differences due to natural field variability (fertility, drainage, organic matter, etc.) versus yield differences due to a treatment (e.g., biological seed treatment). Our statistical analysis gives us a probability of response due to the treatment (vs. field variability). So, a probability value of 95% means we are 95% confident that the soybean yield is different due to the biological seed treatment,” explains Lindsey. “Most university research will include statistical comparison, but industry research may not. We encourage farmers to reach out to Extension when they see information about these products.”

Farmer experiences

Anderson has four seasons of strip plot research on his farm looking at the returns in both yield and nitrogen cost savings.

Anderson started his on-farm plot research with Proven 40, varying N rates from as high as 220 pounds down to 80 pounds. He has noted visible differences in growth some years. “In 2020, I noticed plants were darker green in the part of the field where Proven 40 was applied. It showed an 8-bushel advantage when we had heavy rain where there was leaching of N. That’s where this product is going to shine,” he says.

In-season field health imagery shows striping within field plots. Photo: LES ANDERSON

But what Anderson found most intriguing was the results from 2022 that included a pass with an 80-pound nitrogen rate. “I thought the 80 pounds of nitrogen would be a yellow streak out in the field, but it looked green and healthy. With 80 pounds of nitrogen and Proven 40, it yielded 218 bushels to the acre and without Proven 40 was 208,” he explains.

Yield isn’t the only factor that Anderson considered.

"In 2023, I had about 160 acres of tests. Strips included 120 pounds of N preplant with Proven 40 versus 160 pounds of N without Proven 40. There was about a 2-bushel yield increase for the Proven 40, but I was more impressed with the $35+ acre return when figuring reduced N and application costs,” explains Anderson.

Les Anderson's 2020 on-farm research plot is illustrated in a field map of treated vs. untreated strips with Proven 40. Photo: LES ANDERSON

In-season aerial photo showing darker green striping within the field where Proven 40 was applied. Photo: LES ANDERSON

Anderson is a believer in what his research has shown, and he now uses Proven 40 on all his corn acres.

Tips for on-farm research
“I think everyone should do their own research,” Anderson says. “I think you really have to replicate and be careful about how you set your plots up. If you don’t have good data, you aren’t going to make good decisions.”

“If you are doing testing, make sure you set up your tests properly,” says Kaiser. “If you’re following the industry protocol where you have your rate, your rate minus 40 pounds N plus the product, don’t stop there. Do another strip with that minus 40 rate without the product. Then you’ll have that direct comparison at that reduced rate.”

“I think the take home message from this is: If you are going to look at biologicals, what are their claims? What is its purpose? Is it for root growth, overall plant growth, nutrient related?” says Shaun Casteel, Extension soybean specialist at Purdue University. “Find the solution to a problem you are facing and put it in your worst case. I look at these as trying to be workhorses to help you with tools you need in your field. Put it to the test in those tough soils or disease pressure scenarios.”

Soils are a complex and living biome and adding a biological to the system is more challenging than chemistry because so many more things interact. “The thing about a biological product is it’s so much harder to predict what’s going to happen since there are so many factors that can affect it once it gets into the soil itself,” explains Kaiser.