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Next generation inoculant technology

At present, about 60 percent of soybean fields in Ontario receive an annual application of inoculants, which are placed on seeds to help the crop fix sufficient amounts of nitrogen.


November 30, 2011
By Treena Hein

Topics

At present, about 60 percent of soybean fields in Ontario receive an annual application of inoculants, which are placed on seeds to help the crop fix sufficient amounts of nitrogen. However, older research has shown that yield gains with inoculants were inconsistent, and relatively small, on fields that had successfully grown soybeans in the past.

ETCM-13-10-soybean-combine12 
According to the results of a three-year research study, growers using a pre-inoculant could see return of up to $9.17 per acre, based on a conservative price of $10 per bushel for soybeans and a yield gain of 1.25 bu/ac. Photo by Ralph Pearce.


 

That is why companies have introduced “pre-inoculants” for soybeans (and forages as well), that are applied to the seed by custom treatment companies or larger seed houses. Pre-inoculants are different from commonly used inoculants in that the grower does not apply the pre-inoculant but purchases the seed with the inoculant already inconvenient applied rather than applying at the time of planting.

“These products contain two or even three highly efficient strains of bacteria as well as “extenders” that prolong the viability of the inoculants,” says Horst Bohner, soybean specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs. “Extenders are a food source to keep the bacteria alive on the seed, and also, without them, the rhizobia would dry out within a relatively short time: hours to days, depending on the conditions.”

Companies have gone beyond just extenders, however, and now offer “next generation” inoculants with additives that promote better crop performance. Becker Underwood’s HiStick NT product, for example, features the standard Bradyrhizobium japonicum bacteria, an extender and another strain of bacteria (Bacillus subtilis) in spore form, says Piran Cargeeg, Becker Underwood’s technical team leader of seed enhancements/biologicals. “In addition, HiStick NT’s Nodulating Trigger technology releases a phytohormone on the root surface,” he notes, “which is perceived by the plant, and results in increased root development and increased above-ground vigour, a reduced number of days-to-canopy closure, larger leaves and greater yield.”

The liquid version of HiStick NT with extender has an on-seed shelf life of up to 30 days. For the company’s HiCoat N/T S225 pre-inoculant, it is 225 days. Use of pre-inoculants started in Quebec in the 1990s with dairy farmers, who were quick to take notice of them because of the convenience; their use has only expanded into Ontario during the last couple of years. “Using pre-inoculants involves reduced procedures at planting time and excellent coverage, compared to traditional drill box application,” Cargeeg notes. “Current high-quality pre-inoculants provide between 800,000 and 1,400,000 bacterial cells per seed, which are much higher concentrations than were previously available.”

Cargeeg points out that along with boosted soybean yield through helping with nitrogen uptake, pre-inoculants also increase soil nitrogen for the benefit of rotational crops.

Inoculants are produced, stored and delivered in water, peat or clay. “These forms have been developed to adapt to the grower’s application equipment and specific agronomic conditions,” says Cargeeg. “Thus growers must choose the inoculant carrier type that is most compatible to their situations.”

In Eastern Canada, he says about 60 percent of Becker Underwood customers choose peat and 40 percent choose liquid inoculants.

Latest results also encouraging
Much has been made of secondary or complementary effects of various seed treatments and inoculants in the past few years. Since 2007, it has been common knowledge that certain name-brand seed treatments for soybeans and edible beans enhanced the growth of the plant. However, it was also discovered to offer secondary protection against pests such bean leaf beetles and the damage they can do, to both plant and bean, as well create infection sites for diseases. That is another of the benefits that Dave Townsend, product manager with Becker Underwood, is seeing, beyond the aboveground effects. “The NT is providing that protective zone around the root that is displacing or not allowing damping-off diseases, like Fusarium or Rhizoctonia to be able to come into the root.”

Although some of this is anecdotal, it follows along the same lines as the seed treatment and bean leaf beetle effect, where the inoculant’s properties enhance and increase root activity through the
mycorrhizae.

Ontario trial results
Bohner and Dr. Hugh Earl, an associate professor in the Department of Plant Agriculture at the University of Guelph, have released the results of a three-year, 38-trial study of inoculants. “We tested two of the most popular products at the time of the study,” says Bohner.

However, the average statistical yield gain in fields with inoculants compared to untreated control was 1.25 bushels per acre across the three seasons. “We found that at a conservative selling price of $10 per bushel and a yield gain of 1.25 bushels per acre, a return of $9.17 per acre would be realized when using a inoculant, assuming a cost of $3.33 per acre (cited in the study) for the inoculant,” explains Bohner. “It should also be noted that the average yield gain in 2009 was higher than it was in the previous two years, probably due to the fact that it was a very cool growing season.”

Further studies will be designed to assess possible yield correlations to soil nitrogen levels, pesticide seed treatment use, and soil potassium levels.

Bohner definitely foresees more pre-inoculant developments to come. “I think we’ll see new strains of bacteria and new combinations of products such as fungicides, insecticides, biostimulants and more,” he says.

Cargeeg goes even further, calling these technologies “the next area of growth” in agriculture. “There’s an increased recognition of the power of biologicals to help promote growth and fight off pests and disease,” he states. “They can work in concert with existing pesticide usage and other agronomic practices that help prevent pesticide resistance as well.”

Cargeeg also predicts the power of seed treatments and shelf-life of pre-inoculants will be extended. He adds that because seeds can only carry so much material, “concentrations will also be increased.”