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There once was a microbe attached to corn roots in a Missouri cornfield teeming with zillions of other microscopic microbes. This microbe differed from the others, though. It nabbed atmospheric nitrogen (N) to make ammonia that helps corn plants grow and yield more bushels.
Sound like a fairy tale? It’s reality, say officials for Pivot Bio, an agricultural microbial firm. “We isolated that naturally occurring bacteria from the corn roots,” says Ernie Sanders, Pivot Bio vice president of product development. Then, Pivot Bio scientists determined this microbe could be reproduced into a microbial product. Pivot Bio now markets Pivot Bio Proven that can be mixed with starter fertilizers or other liquid products in-furrow at a .1-gallon-per-acre rate.
“This product adheres to the root system and does not wash away,” says Sanders. Three years of company, university, and third-party data indicate a yield increase range of 3 to 20 bushels per acre, with an average 6 bushels per acre yield increase, says Sanders. He adds that farmers can also opt to retain their existing yields and cut commercial N rates by 25 pounds per acre with the atmospheric N that Pivot Bio Proven converts.
The cost of such microbial products pales when compared with a farmer’s seed or chemical bill, but it is an extra expense in these days of tight margins. The manufacturer’s suggested retail price for Pivot Bio Proven is $20 per acre before incentive programs and discounts, says Sanders.
Such products are part of the biostimulants market, which has a market value of $1.5 billion and is annually growing 15%, says Marcus Meadows-Smith, CEO of BioConsortia, a microbial firm. These products are commonly applied as seed treatments or in-furrow with starter fertilizers and other components.
Beneficial microorganisms are part of this space, which includes substances like rhizobia bacteria and fungi such as mycorrhizae.
Farmers have used some beneficial microbial products for years.
“We’ve known for a long time that rhizobia bacteria are essential for fixing nitrogen in legumes,” says Carl Rosen, a University of Minnesota soil scientist. Agronomists often recommend them for areas where soybeans have not been planted for a time.
Newer products tout benefits ranging from capturing atmospheric N to reducing plant stress to boosting yields. Scientists isolate many of these products from the rhizosphere – the area surrounding roots where microbes reside and where chemical and biochemical processes occur.
“Companies are extracting microbes from the rhizosphere and then purifying those microbes to make these products,” says Rosen.
It’s not easy to do so, however.
“If you’re extracting one from a corn plant, it may not be useful for wheat or potatoes,” he says. “Then if you isolate one from a clay loam soil, will it have the same impact in a sandy soil? Then there are questions about formulation and if microbes will withstand the formulation, or if it will survive mixing with fertilizers.”
Some biological products don’t mix well with certain components, says Sanders. Pivot Bio’s Proven, for example, cannot be mixed with nonchelated zinc or copper. Chelated zinc or copper do work well.
Microbes can also face a battle when introduced into the soil with existing microbes.
“Many microbes in the soil have actually evolved to kill one another,” says Meadows-Smith. “They compete for nutrients and space.”
Plant microbes that work with the crop’s microbiome are different, though.
“Plants do not thrive without these beneficial microbes,” he says. “The moment the [crop] seed germinates, it starts to produce an exudate that feeds its microbiome. What we’ve done is put the most beneficial microbes on the seed treatment, and those microbes get their competitive advantage because they are the ones that are actually fed by the plant and can be among the first to colonize the plant.”
These microbes track through the crop plant’s root system and help direct the plant toward putting its energy into positive benefits like substantially increasing yield, points out Meadows-Smith.
What to Do
Microbial products first need a sound agronomic program in order to work, Sanders says.
“Yield is a complicated equation,” he says. “It takes more than just nitrogen to make yield, so make sure you have a good balance of what is going on in your field.”
Lack of consistency has traditionally plagued biostimulants, says Rosen.
“Base evaluations of these products on multiple years and replicated studies,” he says. “Don’t just rely on testimonials.”