First, let’s clarify what we mean when we’re talking about biological products. This is a broad group that includes both naturally occurring substances (such as humic or fulvic acids, seaweed extracts and enzymes) as well as beneficial microbes (such as nitrogen-fixing bacteria, phosphorus-solubilizing microbes, plant growth promoting rhizobacteria and mycorrhizal fungi). These products aren’t fertilizers themselves, but often claim to increase nutrient availability, improve nutrient uptake, improve stress tolerance or support plant growth.

Since high fertilizer prices have prompted some renewed interest in these products, I’ll focus mainly on nitrogen-fixing biologicals.

A quick note on regulation (and why it matters)

In Canada, most of these products are regulated under the Fertilizers Act. That means they must be properly labelled and prove that they are safe, but they do not need to prove efficacy before being sold. This makes replicated, independent research particularly important to test whether a product increases yield or can replace fertilizer under Manitoba conditions.

What has local research found?

Through our Research on the Farm program, MCA has tested a nitrogen-fixing biological product (Envita®) in several replicated, field-scale strip trials. In the eight corn and two spring wheat trials, we did not find a statistically significant yield increase when the nitrogen-fixing biological product was used.

Through their On-Farm Network, our colleagues with Manitoba Pulse and Soybean Growers (MPSG) have also tested many biological products. In 46 trials evaluating a range of microbial and non-microbial products, no statistically significant yield increases have been observed.

That doesn’t mean these products can never work. It does mean that predictable ROI has been hard to find under Manitoba conditions.

Does small‑plot research tell a different story?

Not really.

University and independent research in Western Canada and the North Central United States to date has largely lined up with what MCA and MPSG have found in on-farm trials. There are occasional positive responses, but they’re sporadic and can be hard to predict. For example:

• The Indian Head Agricultural Research Foundation tested two foliar-applied nitrogen-fixing biological products (Envita® and Utrisha^TM-N) on spring wheat. Across the five locations and two years tested, they did not find a statistically significant impact on grain yield or protein. Similar results were found in canola.
• In 2022, researchers from several land grant universities in the North Central United States performed 61 trials testing eight nitrogen-fixing biological products in corn, wheat, sugar beet and/or canola. Only two site-years in corn had a statistically significant yield increase with the use of a nitrogen-fixing biological product.

Why are results so inconsistent? Formulation challenges, competition with the native microbial population and environmental differences all influence whether a product will find success. For those interested in learning more on this topic, Andrew McGuire with Washington State University has an interesting article.

So, should you use biologicals to offset high fertilizer costs?

Biologicals are an active area of research, and some products may eventually find a fit in our cropping systems. But based on local on‑farm and small-plot research to date, they are unfortunately not a silver bullet for high fertilizer prices.

If you do want to try a biological product, think about what problem you’re trying to solve. Is it a nutrient deficiency? Are you hoping to mitigate environmental stress? Are you trying to improve your long-term soil health? Consider the product claims, what the active ingredient is and how the product claims to work. Finally, if you do decide to try a product on your farm, I encourage you to consider conducting a replicated strip trial. Replicated strip trials let you test a product on your own farm, with your own management, and give statistically valid results. If you want to learn more about conducting on-farm trials, reach out to us for more information on the MCA Research on the Farm program.

The bottom line: For now, I recommend approaching biologicals with curiosity, caution and solid, on‑farm testing. To ensure you’re making efficient use of your fertilizers, use the 4Rs of nutrient stewardship (the Right Source @ the Right Rate, Right Time, and Right Place®) to guide your decision making, and check out this helpful factsheet on stretching fertilizer dollars and supplies from Manitoba Agriculture.