From lab to harvest: The development and life of TerraMax’s microbial inoculants for corn

Jan 20, 2023 | How it works

In the 1970s, a young scientist at the University of Minnesota was studying soils. Doug Kremer, now the CEO of TerraMax, an ag-tech company that produces defined microbial inoculants, remembers this time distinctly.

“Our textbook was ‘The Nature and Properties of Soil’ by Nyle Brady, 8th edition,” recalled Kremer, who keeps a copy on the bookshelf in his office. “We didn’t touch chapter five, which was about microorganisms and organic matter.”

Today, farmers understand that soil contains incredible and diverse ecosystems of organic material, physical and chemical elements, and microbes.

In 1973, two biochemists, Herbert Boyer and Stanley Cohen, developed the now-common concept of genetic engineering by inserting DNA from one bacterium into another. Truly, this was an incredible leap.

“[This process] was happening in nature, and we observed it,” Kremer said. “We started to understand that DNA is not this stable thing, but this evolutionary force that is capable of moving information around. That certainly interested me.”

Kremer’s work at the time was attempting to move DNA into plant cells using a bacterial vector. He and others “failed miserably.” It wasn’t until the early 1980s when “some smart folks at Cornell figured they could cover it in gold and build it into plant cells, and that worked,” Kremer said. “For me, it was part of the journey of ‘wow, look what bacteria can do.’”

The lightbulb moment

As Kremer’s career progressed and revolved around the microscopic workings of the natural world, he learned by talking to farmers and began exploring microbiology. There was one challenge in particular that bothered him.

“We didn’t know how to keep microbes alive to do their jobs. If you can’t keep the factory alive, why do you expect to have an impact?” Azospirillum, the microbial star in TerraMax’s Beck’s PFR Proven soil inoculants for corn, “had a well-known reputation of fixing nitrogen, you could brew it up, package it and a farmer had to use it within three to six months. Early formulations had trouble with stability and shelf life.”

From a practical standpoint, this life expectancy makes for an unreliable product.

TerraMax has solved the problem. Today, TerraMax’s corn products are viable and stable for up to two years and are shipped worldwide.

TerraMax MicroAZ-IFVertex-IF and MicroAZ-ST Dry are inoculants for corn that contain Azospirillum — which harvests nitrogen from the atmosphere and fixes it in the soil so it can be used by the plant. Azospirillum also stimulates root growth for healthier corn plants. Both MicroAZ-IF and Vertex-IF are Beck’s PFR Proven, meaning they’ve undergone rigorous testing over a three-year period by Beck’s Superior Hybrids Inc., who developed the Practical Farm Research concept to help farmers determine which products and practices they should implement in their operations. A product can only earn the PFR Proven designation if it has demonstrated that it will provide a positive yield increase over the three-year period of testing and averages a positive return on investment.

Ultimately, everything TerraMax produces must benefit the farmer. “The first thing our products have to do is function,” Kremer said. “They have to provide benefits to the farmer and have a payoff for the farmer.”


Having to constantly purchase and replace expired products is detrimental to a grower’s operations and wallet. “We’ve got to make these things live longer in a jug,” Kremer recalls their thinking at the time. “At TerraMax, that became our focus, and that’s where we put our efforts.”

So how were Kremer and the other researchers at TerraMax able to extend the viability of Azospirillum by four to eight times?

In the lab

Molly Tillman is TerraMax’s director of research. She oversees the lab and all its goings-on, and there’s a lot going on. Laminar flow hoods protect microbes from contamination in one area, while researchers work with them. There’s a large dry lab with bench space where Tillman and her team can examine the plates after they’ve been in the incubator. Here, they look at the number of colonies and the morphology of the microbes. In the wet lab, mixing reagents and messy processes hold center stage.

“It’s a lot of pipetting, diluting, plating and waiting for the colonies to grow,” says Tillman of the process for growing microbes.

“We have a few experiments going on at a time that all have to do with microbial survival,” says Tillman. “I look at strains that we’re interested in, strains that are already in commercial products, and we’re looking at different formulations or different treatments that might help them survive the stabilization process.”

TerraMax’s proprietary stabilization formula is critical to microbial survival and product effectiveness. “Our process allows us to more effectively and efficiently make products and get them to our users in a state and package that they can use,” Kremer said.

Tillman has a strong appreciation for the Beck’s PFR Proven process and the results it yielded for TerraMax’s corn inoculants. “It’s very valuable data for us to have,” she said, “because it was done by a third party. They have high standards that they’re holding it against. It’s not open to loose interpretation. They have a solid bar that we have to jump over, which is … three years positive ROI.”

Azospirillum, the microbe in TerraMax’s corn inoculants, and Bradyrhizobium, which they produce for their soybean inoculants, are not the easiest strains to keep alive. Many bacteria produce spores, which can survive tough environmental conditions and ensure survival of the colony.

Azospirillum and Bradyrhizobium are non-sporulating. “They don’t have the same survival mechanism that other strains do,” Kremer said. “Bacillus (a different genus of bacteria) has a large product history because it can stay alive longer. We tackled the more difficult ones first.”

As a result of their rigorous standards and science, TerraMax has multiple microbial inoculant products for corn that are beneficial to crops, encourage healthy soils and keep bacteria strains alive for an incredible amount of time. “It’s not just that we can get them to survive better in other conditions. It has greater application capabilities. We had to learn that by listening to our customers,” Kremer said.


Out into the world

After Tillman and her team grow the microbes, her team works to stabilize them and put them into TerraMax products. These products are then processed further into the different applications. For TerraMax’s corn inoculants, that means being processed into one of their two wet application products or the Micro AZST Dry formulation.

The products are then shipped to customers. TerraMax has customers across the United States, as well as in Ukraine and Australia.

Now that customers have the inoculants, the products are used prior to farmers planting crop seeds. Farmers are to coat their corn seeds with a TerraMax product, and then plant the seeds.

In the soil

“Soil is frequently a harsh condition that we don’t fully understand,” Kremer said.

TerraMax prepared for many of these conditions as they developed their products. The Azospirillum bacteria can be frozen and unfrozen numerous times. “The formulation is robust enough that it’ll survive until the seed germinates and roots grow,” Kremer said.

The bacteria that coats the seed will grow, reproduce and die as the colony survives and grows. Once the roots begin to grow and elongate, the populations of bacteria grow too, along with the roots.

Kremer describes the relationship between root growth and bacterial population growth as “very interactive,” calling roots the “lunch line” for bacteria. “The growth process is complex, and the bacteria rely on roots actively growing so they can feed,” he said.

The population grows with the roots, moving along the root, reproducing and dying. In return for the free lunch, bacteria provide the critical process of fixing nitrogen for the roots to convey to the rest of the plant.


Over the years, these beneficial populations of Azospirillum will foster healthier, more robust root systems. This provides the corn plans better nutrition, water uptake and nitrogen, and helps build strong roots that reduce soil runoff.

One of the most important benefits of TerraMax products is the increased corn crop yields. TerraMax doesn’t only test its products through the Beck’s PFR Proven process, they have other experimental fields where their products are put to the test. In South Dakota, field trials showed a 12.2 bushel per acre increase in yields when compared to an untreated control field: 181.6 bushels versus 169.4 bushels of corn. At both Colorado State University and the University of Nebraska-Lincoln, TerraMax corn inoculants showed yield increases from 5 to 15 bushels per acre. And as a cost-effective product, it’s worth the investment.

In Kremer’s view, who “wins” with TerraMax products goes beyond even the farmers.

“Our products have to function first,” Kremer said. “The farmer gets to capitalize on that. My job is to figure out which bacteria will contribute best to that, and how to package that. But if we can shift our agricultural system’s dependency from chemistry-based solutions, helping to increase or maintain production, we are all winners.”

As bacteria does what it does in nature, Azospirillum-based microbial inoculants are the result of science harnessing natural processes. And in using science to further apply nature’s own processes, Kremer believes, “If we are successful at what we are doing, not only will people benefit directly, but we can help shift the ever-evolving view of feeding the world.”