Nutrient producing microbes win over farmers but skeptics doubtful

a man holding a small boy in a farm field
Colin Wegner stands in front of farming equipment with his son Cash during spring planting at their farm in Wells, Minn.
Courtesy Colin Wegner

On his south-central Minnesota farm, Colin Wegner adds bacteria to the corn seeds he plants, and cuts back on the synthetic nitrogen fertilizer traditionally applied to corn.

The live bacteria are selected for their ability to pull nitrogen out of the air.

“They live on the corn roots, the corn root releases sugars and carbohydrates throughout the growing season,” explains Wegner. “And what the microbes do is they convert nitrogen out of the atmosphere, and they convert it to plant-available ammonia.”

Wegner is a fifth generation farmer, and he’s so convinced microbes are the future of farming that he became a sales representative for Pivot Bio, the company that makes the bacteria he uses on corn.

green corn plants turning brown
Companies are identifying and reproducing the best nitrogen producers to add to corn and other crops.
Dan Gunderson | MPR News

Symbiotic process

The early 1900s discovery of a process to create synthetic nitrogen fertilizer revolutionized agriculture.

But the process has a big carbon footprint, using large amounts of natural gas. And nitrogen fertilizer applied to soil but not used by plants can leach into water or turn into nitrous oxide gas and escape in to the atmosphere.

Nitrous oxide accounts for only a small fraction of worldwide greenhouse gas emissions, but according to the Environmental Protection Agency, the impact of 1 pound on warming the atmosphere is 265 times that of 1 pound of carbon dioxide.

There are billions of bacteria in soil. Some already produce nitrogen in a symbiotic relationship with plants such as beans and other legumes.

Companies are identifying and reproducing the best nitrogen producers to add to corn and other crops. Some are genetically edited to enhance nitrogen production.

“We know that our microbes have the capability of producing perhaps 40 or more pounds nitrogen equivalent for most growers,” said Pivot Bio Vice President Dan Poston.

“Our goal is constantly to move that number up with new and improved microbes.”

Farmers are interested and they’re buying.

Pivot Bio released its first product in 2019, and this year the company reported that the microbes it sells were used on 5 million acres across the U.S., while revenue grew 60 percent, surpassing $100 million. And Pivot Bio is only one of many companies entering this potentially lucrative market.

Skeptical analysis

a man smiles
North Dakota State University Extension soil specialist Dave Franzen authored a paper compiling research on nitrogen producing bacterial supplements at a dozen Midwestern universities.
Dan Gunderson | MPR News

But skeptics abound. Soil scientists at a number of universities across the Midwest tested some of the bacteria supplements.

“So it turned out that the performance wasn’t all that great,” said Dave Franzen, an extension soil specialist at North Dakota State University.

Franzen authored a paper compiling research on nitrogen producing bacterial supplements at a dozen Midwestern universities.

“I think the most important thing for farmers to get out of it is, don’t believe everything you hear,” he said.

Franzen tried to buy nitrogen producing microbes to test last year, and the products were sold out. He was shocked farmers were so quick to go all in on what he believes is an unproven technology.

“How could you do this without seeing some kind of really positive research from people where their retirement program isn't tied to this? But they bought it all up. And that was crazy,” said Franzen.

Franzen tells farmers if they want to try biological replacements for fertilizer they should first rigorously test the product on their farm.

He hopes these products will be successful but said the data just doesn’t support the benefits companies are claiming.

green seeds falling into a bin
Corn seeds treated with live bacteria, which has specific temperature needs, flow into a hopper.
Courtesy Colin Wegner

“I understand the skepticism,” said Pivot Bio’s Poston, who suggested that as the industry developed there were challenges.

“Where you’re trying to deliver living organisms to the field. And a lot of that inconsistency and kind of doubt or skepticism has come from the fact that in hindsight, we realize that a lot of these things have not made it to the field alive,” he said.

The bacteria needs to be kept within a specific temperature range, and it doesn’t have a long shelf life. Poston said those supply chain issues have been resolved.

The company pushed back against the article authored by Franzen, saying in a blog post that the research was poorly designed and the article showed “a misunderstanding of what Pivot Bio is striving to achieve and why more and more growers are replacing synthetic fertilizer with our technology.”

Franzen stands by the research and analysis, but said much more research is needed to understand how the very complex soil microbiome works and how it reacts to added microbes.

Pivot Bio points to reams of data it says proves the product works, and shows that farmers like Colin Wegner reduced nitrogen fertilizer use with no loss of crop yield.

But that might be the result of good marketing, said University of Minnesota associate professor Daniel Kaiser, who has also tested the nitrogen producing bacteria.

“These companies know that most growers are already a little aggressive on their nitrogen, that they can cut back, put the product on and still get the same yield. But it doesn’t necessarily prove that the product works,” he said.

Kaiser also urges farmers to test the products in carefully designed trials on their farm before using the products broadly.

“Because some of these claims are pretty fantastical in terms of what some of these things can do,” said Kaiser. “You’ve got to be careful with some of this and just not trust it.”

an ear of corn
The bacteria can cut back on the synthetic nitrogen fertilizer traditionally applied to corn.
Dan Gunderson | MPR News

Companies are also selling microbes to help suppress crop diseases.

Kaiser said there’s little regulation of the rapidly expanding industry which he worries could lead to companies selling modified products that might have negative environmental effects.

But the ag industry is ripe for change as farmers feel pressure to be more sustainable.

“You see a lot of interest right now especially with a lot of the emphasis on sustainability and environmental stewardship,” Kaiser said. “[Farmers are] trying to figure out what is out there that can help us better manage nitrogen."

Colin Wegner believes microbes are a key to the future of farming.

“It’s really fun and cool to be, in my opinion, on the front end of a really large change in agriculture and see it happening,” he said. “And I’m really excited to see what farming looks like in 10 to 20 years. I think there’s going to be drastic shifts in production agriculture.”