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Why haven’t microbial products been more widely adopted by farmers?

This is a question that drives me each day. Microbial products have been around for a long time; starting with rhizobium in legumes, dating back 125 years. Yet, in the United States, rhizobium inoculants have not been widely adopted by soybean farmers – some indicate less than 15% use overall in the United States. Why?

Is it limited or variable yield increases, issues with handling and application, compatibility with fungicides?

For those of us in the industry, we know the promise of microbial products to provide farmers with improvements in crop vigour, stress tolerance, disease suppression, yield and quality, along with the opportunity to reduce synthetic fertilizer and pesticide use. Biologicals, in general, are seen as safer for the environment and necessary for promoting sustainable agriculture. Those reporting the markets say biologicals are here to stay and expect double-digit market growth over the next 10-15 years. Yet, many farmers remain sceptical of biological products in general, microbials in particular. If farmers aren’t adopting microbial products more widely, there’s not much of a market.

So how does the microbial industry get more farmers interested in microbial products? 

Foremost, farmers want to see data showing the products work, preferably from university trials and not paid for by the company. Some (many?) university extension researchers – as trusted sources of research-based information – are unfamiliar with microbial products, and worse yet may be sceptical that they work, leading to unfavourable impressions with farmers. Extension researchers need funding to conduct microbial product trials, across different crops, geographies, and conditions. While sources of funding are difficult to come by these days, funding could come from a government program, commodity groups, or an industry coalition. For example, something similar to the IR-4 program, which exists for university testing of biopesticides in speciality crops, could be beneficial for biological products in general.

Second, as an industry, we need to keep showing up and educating farmers, extension agents, government officials, the public – basically anyone who will listen. For example, this year at Commodity Classic – the largest farmer-led, farmer-focused trade show in the United States – there were several microbial product companies in attendance, which is great, but we need more.

With effective education comes messaging. Microbial products don’t work everywhere all of the time and are not a promise of increased yield. With that said, microbial products do show their greatest advantages when conditions are least favourable, helping crops overcome abiotic stresses and poor soil conditions in lower-yielding areas. Our messaging, therefore, becomes increasingly important. For example, in corn, yield increases from microbial products reported by industry range on average between 4-7 bu/acre with win rates approximately 70% of the time. The reality is in a good or even average season, yield advantages from a microbial product may be minimal if at all. Thus, messages to the farmer about microbial products need to highlight the ability to help decrease risk due to stresses such as nutrient, drought, and heat, improve germination rate, early vigour and stand, and so forth – and not just about yield.

So why is there so much scepticism about whether or not microbial products actually work?

Ultimately, efficacy depends on the quality of the product produced. Issues surrounding product quality have been raised for many years. Product quality in part involves the effectiveness of the strain(s), the number of viable cells, and absence of contamination. Recent studies evaluating the quality of commercial microbial products have shown <20% are meeting their guaranteed numbers of viable cells on the label (ODA, 2016), and <40% contained the expected strain(s) without any contamination (Hermann et al 2015). We should all be concerned about these numbers.

During the early stages of research and development, when the effectiveness of the strains are typically established, pure highly viable cultures absent of any contamination are field-tested for efficacy. During scale-up of the production process, however, the ability to maintain pure highly viable cultures absent of contaminates becomes increasingly more challenging. Industrial fermentation processes have been largely designed to grow microbes for producing a byproduct such as enzymes, organic acids, or antibiotics. Typically, the liquid culture produced undergoes separation and extraction processes to purify the byproduct, and the biomass itself is discarded. For a microbial product, the biomass is the product. During scale-up of the fermentation, 4-5 step-ups or more are involved going from shake flasks to large scale production vessels, requiring extensive quality control practices to ensure no contaminants are introduced at any of the steps. Transfer and mixing of material during formulation and filling into final packaging introduces additional points for contaminates to be introduced.

As the production scale gets larger, variations in dissolved oxygen (for aerobic microbes), available nutrients, temperature and shear stresses from mixing in the large vessels create stressful conditions for the microbes. Microbes respond to the stress through the accumulation of phenotypic variants (otherwise known as mutants) and display variable gene expression patterns, which can present a challenge in maintaining the genetic stability of the microbes being produced. As more genetic engineering approaches are explored that influence gene expression by the microbes, the challenges of maintaining genetic stability and lessening stress to microbes during scale-up become even more important. Not only is a highly viable microbial product important in terms of numbers of living cells, but its fitness to perform the intended function is also important and requires the minimization of mutants and maintenance of genetic stability during production.

With challenges come opportunities

Issues with microbial product quality can (and will) be overcome with innovation. One area of innovation we are working on at 3Bar Biologics is improving the approach to biomanufacturing and packaging using a small batch fermentation approach to eliminate the issues of microbe stress and contamination during scale-up. Another area of innovation involves synthetic biology; as discovery work continues in applying genetic engineering approaches, improvements in the microbes and their performance will be realized. Through advancements in biotechnology and biomanufacturing, the ultimate winner is the farmer who will see more high-quality microbial products reaching the marketplace. With widespread university product testing, education and appropriate messaging, as with any new technology, increased farmer adoption should follow – but only if the product works and farmers find value in using it.

Jane Fife is Chief Technology Officer at 3Bar Biologics.

The Microbiome for Agriculture Congress: USA will take place in October 2021. Click here to download the agenda.


  • Oregon Department of Agriculture. 2016. ODA finds big problems with little organisms.
  • Herrmann L, Atieno M, Brau L, Lesueur D. 2015. Microbial quality of commercial inoculants to increase BNF and nutrient use efficiency. Biological Nitrogen Fixation, Volume 2. De Bruijn FJ (ed). John Wiley & Sons, Inc.

2 Responses to “Why haven’t microbial products been more widely adopted by farmers?”

  1. Thanks for sharing such amezing content

    Increasing trends towards the consumption of organics products for a healthy life is a prominent growth factor of the agricultural biologicals market. people are preferring natural products instead of fancy chemical products which is boosting the agriculture industry.

  2. Yet, in the United States, rhizobium inoculants have not been widely adopted by soybean farmers – some indicate less than 15% use overall in the United States


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