It’s common knowledge among soybean growers that bacteria in the soil are responsible for absorbing nitrogen (N) from the air — where it is abundant but not usable by plants — and converting it to a form that is. This process, called “fixing” nitrogen, helps the soybean plant itself, and it’s also what makes soybeans such an excellent rotation crop with nitrogen-hungry corn.
The bacteria most commonly responsible for fixing N in soybeans is Bradyrhizobium japonicum, a naturally occurring soil microbe that has been selectively grown to be more efficient at fixing N. To increase populations of the bacterium in the soil, seeds are treated with it, or it is applied in-furrow — sometimes both. B. japonicum has been used effectively in soybean production for more than 80 years. Now, a new species of N-fixing bacteria, Bradyrhizobium elkanii, is being introduced to the market that is an improvement over B. japonicum and can provide extra yield even when used in combination with it.
B. elkanii (prounounced “el-CANE-ee-eye”) is more aggressive in entering and forming nodules on soybean roots, so it means earlier greening and ultimately, increased yield. Two separate strains of B. elkanii are included in LALFIX DUO® SL PROYIELD, a new biofertilizer developed by Lallemand Plant Care.
“What’s exciting about this new inoculant is often when you add another strain of B. japonicum to a field where it is already present, you don’t often see a yield response,” says Matt Pfarr, Technical Sales Support and Market Innovation Manager at Lallemand. “But last year in trials with the Independent Professional Seed Association, we saw a nearly 2 bu./acre yield increase with the addition of B. elkanii. There was already B. japonicum in the soil, but we saw this two-bushel increase consistently across the trials.”
2 +1=4: Delftia Boosts Nodulation in Symbiotic Relationship with N-Fixing Bacteria
Another microbe in LALFIX DUO® SL PROYIELD that adds an additional boost is Delftia acidovorans, a plant-growth-promoting rhizobacteria, or PGPR. Delftia stimulates root growth through the secretion of phytohormones. By stimulating more roots and the nutrient-and-water-absorbing root hairs, there are more sites for nodulation by the Bradyrhizobium in the soil. The combination of the three microbes (two strains of B. elkanii plus the Delftia) is unique in the industry and creates a symbiotic relationship that boosts plant health and yield.
“One way to think about LALFIX DUO® SL PROYIELD is that it’s a probiotic for plants,” says Nathan Wright, Broad Acre Crop Commercial Director of North America for Lallemand. “In humans, science is revealing how important it is for our health when our gut bacteria is in good alignment, and the same thing is true for plants. The plant’s root system is its digestive system. When it has everything it needs to work properly, the result is a much healthier plant.”
The two-bushel increase took place in fields with a heavy rotation of soybeans, so there was already a high population of B. japonicum. In certain situations, Wright says trials showed an increase of 15% to 20%. To make sure the difference was due to B. elkanii, Dr. Meghan K. Rains, Product Development Manager with Lallemand’s Technical Marketing team, grew soybeans in nitrogen-free soil and added B. elkanii and B. japonicum to separate plantings. Afterward, she extracted N from the plants and measured it.
“The results showed large and statistically significant increases in the amount of plant N, proving B. elkanii is indeed more efficient than B. japonicum at N production,” Wright says.
Trouble-free Mixing Allows Ease of Use
LALFIX DUO® SL PROYIELD can be applied as a seed coating or as a liquid in-furrow. It was first launched during the 2019 season, and has proved popular with retailers for its ease of handling.
“It has really gotten the attention of the industry,” Wright says. “One brand, one bladder, one product, and a low use rate make it very easy to use. The retailer is the one usually doing the treating of seed with the inoculant and fungicides and insecticides. Many of the liquid products they handle are coming in two bladders or even three or four, with a lot of mixing required. We have just one. They can open a box, apply, and it’s done. There’s no guessing in mixing or additional agitation required.”
Because LALFIX DUO® SL PROYIELD contains living organisms, retailers need to store and use it within certain parameters, but they aren’t unduly restrictive, Pfarr says.
“These are living organisms that prefer the types of conditions you’d find in a soil environment, where they are fairly protected from high temperatures and temperature spikes.” Pfarr says. “The optimum storage temperature is 40°F to 70°F. We guarantee the product will live to the expiration date printed on the box, and that you will have a guaranteed minimum amount of cells per liquid volume at the time of expiration. We count the bacterial cells to establish that guaranteed amount.”
Pfarr says once the seed is treated, it should be kept out of direct sunlight, high heat, and drying winds.
“B. elkanii is very hardy. As long as the pretreated seed is stored and handled properly, we’ve seen it retain efficacy for six months,” Pfarr says. “While many times the seed is treated and planted within 24 to 48 hours, if someone needs more time between treating the seed and planting, there is a really long, flexible application window compared to most other seed treatments in the market.”
The only soil conditions at planting that could be difficult are very dry conditions, Wright says. Any condition that will stop or slow the plant from germinating and growing will be difficult for the bacteria as well.
“If you can establish the plant, the bacteria will thrive alongside the plant,“ Wright says. “If conditions are hotter or drier than desired at the time of planting, or if it has been several years since soybeans have been planted, we recommend double inoculation, using LALFIX DUO® SL PROYIELD on the seed and another liquid application in-furrow. Or if a grower can put down a granular product in-furrow, that’s fine, too. It’s really helpful to make sure the bacteria are distributed and the plant can access them through the growing season.”
The Truth Behind the Technology
Lallemand has been a global leader in the development, production and marketing of microorganisms and their derivatives since it began producing yeast for the baking industry in 1923, and both Wright and Pfarr stress that the company is dedicated to knowing the science behind how its products work. The company has worked with the University of Regina and Dr. Chris Yost, founder of the Institute for Microbial Systems and Society, to research the mode of action behind how the bacteria work and why they provide the increased yield and plant health. All of this work is peer-reviewed, independent research.
“Our public partnerships are so important to us — this area is the frontier of ag technology right now,” Pfarr says. “Dr. Yost’s team looked at the entire genetic sequence of the Delftia acidovorans. He found that when this bacteria is living in the soil next to soybean roots, it upregulates genes that are important for things like attachment to the plant roots, and it secretes plant stimulating molecules called phytohormones. There is a whole host of genes and proteins that are prolific in D. acidovorans that make it compare well or even better than a lot of other PGPRs.”
Lallemand produces all of its products in-house in its Canadian facility. Detailed compatibility testing is done with LALFIX DUO® SL PROYIELD and fungicides and insecticides to ensure there are no negative effects on efficacy.
“We are taking the extra step to work with good research and show the value of these products at the most basic biologic level, and it’s really powerful,” Pfarr says. “I think our customers are really impressed with what the product does and how it performs under stressful conditions like cold, wet soils and later planting. We’ve had a tremendous response from customers this year.”
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