What are Biostimulants?

Will biostimulants be the next ticket to a higher yield?

There is a lot of press about biostimulants today and the number of products and companies marketing them continues to expand. It is getting more and more difficult to see through all the haze that come with so many companies and products competing in this arena, discerning what works and when it works. You must trust they are doing the right science and validation and not just marketing ‘me-to’ products.

I think of biostimulants in terms of either soil or plant categories and how they are produced. Biostimulants can be produced synthetically, biologically (think fermentation and extraction), mined (such humates) or originate as by-product like spent cake. And even composts or manures could be considered a biological biostimulant since they induce a biological response in the soil in addition to providing fertility.

The Biological Products Industry Alliance (BPIA), an association for the bioproducts industry characterizes biologicals in two formal categories and multiple subcategories:

  • Biologicals are naturally occurring compounds or synthetically derived compounds that are structurally similar (and functionally identical) to their naturally occurring counterparts.
  • Microbial products are products derived from various microscopic organisms.

For plants, biologicals can stimulate a plant, protect a plant or induce a plant protection response. In soil, biologicals can add to the microbial community, stimulate the community or feed the community.

Plant Based: Many of the science-based companies are focused on delivering plant-based biologicals either providing protection or PRG (plant regulator growth) properties. Many of these products will be conveniently delivered as part of a seed treatment package, in-furrow or can be applied foliarly.

Probably the most commonly recognized biopesticide or biological insecticide is Bt (Bacillus thuringiensis), an insecticidal bio-protein that kills Lepidoptera insect species. While today it’s largely available as a trait in corn or cotton, it can also be purchased as a liquid insecticide that is biologically produced.

Plant Impact’s Fortalis for soybeans, cotton, peanuts, and alfalfa is a product that acts as a biostimulant by mobilizing calcium. It is synthetically derived to improve the movement of calcium in soybean plants by enhancing a process that is naturally limiting. It is applied over the top at early reproductive stages alone or with a fungicide, nutritional product, and/or insecticide.

Another example is Bayer’s Acceleron Seed Treatment and BioAg business (formerly Monsanto BioAg) which combines fungicides, insecticide, nematicide and bioenhancers (bacteria, fungicide and stimulants) into a seed treatment application.

It is impossible to list all the companies and product possibilities in this area, and especially as they continue to expand with new product discoveries.

Soil Based: There are many soil-based biological products on the market, and I have tested many on our farm. I categorize them as byproducts, biostimulants or live organisms.

Many industrial byproducts are available that can improve the structure of the soil and add sulfur and other nutrients (byproduct gypsum, compost), add structure, fertility improve the water holding capacity and stimulate the microbial community (diatomaceous earth based spent cake filter), dried distiller grain (DDGs) from ethanol plants that have feed, biostimulant and nutrition properties and fish processing byproducts that have nutritional and biostimulant properties. Companies are looking to find land to apply these products rather than pay to dispose of them at landfills and can often be very economical to apply and beneficial for the soil.

Other biostimulants can be biologically fertilizer and stimulant additives that enhance plant growth and soil health. They can improve nutrient-use efficiency and abiotic stress tolerance. This group comprises a diverse group of products including microbial inoculants, biocatalysts, amino acids, humic acids, fulvic acids, seaweed extracts, sea salt minerals, etc. And biocatalysts stimulate the native microbial community, enhance their utility and increase the availability of nutrients already in the soil or being released by organic matter.

Microbial-based biostimulants (bugs in a jug) are microbe-containing inoculants that contain live microbial organisms instead of the byproducts they produce. They can be added to the soil to stimulate the community, shift the community or enhance microbial functionality. For example, growers can add mycorrhizae products to the soil via the seed or in-furrow to enhance root mycorrhizal association. Mycorrhizae hyphae effectively expand the soil rooting volume a crop can occupy. Rhizobia species are routinely applied with legume seed to ensure greater nodulation and nitrogen fixation. And live microbial cocktails of fungi and bacterial can be applied at planting, banded around the seed zone to increase nutrient availability.

However, a word of caution. Ask yourself if applying 2 pints, 2 quarts or 1 gallon per acre of live microbes to 2 million lbs. of soil with trillions of organisms per acre will effectively shift the naturally entrenched native population. Microbial products can be effective in localized situations on the seed or around the roots but may disappoint across the broad acre swath.

Biostimulant products are here and play a role in production agriculture. They are often considered more sustainable since we are harnessing nature instead of relying on synthetic products. However, as a producer you still must do your homework on the product and company. Always consider on-farm testing to validate and don’t rely on testimonials. To start with, make sure the company and product provide you with replicated test data and that the data defines a clear return on your investment.


Dan Davidson is a PhD agronomist, part-time farmer and soybean expert from Nebraska who consults with soybean checkoff and industry on crop production, marketing, and product development projects.

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