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Biostimulants are not exclusive to organic systems, but they are a common input for organic growers. Ohio State vegetable production specialist Matt Kleinhenz has spent many years studying microbial-based biostimulants (MBBS). Few agricultural input markets have seen the kind of explosive growth that has occurred with MBBS.
“These products are widely available, relatively inexpensive, are said to offer interesting and appealing benefits, and rarely put users at significant risk, unlike some other products,” says Kleinhenz.
Nicole Wright, program coordinator for the Vegetable Production Lab’s MBBS project, also attributes market growth to increased interest in microbiology.
“I think growers are applying them and thinking about soil and soil microbiology,” she says, “They are thinking ‘everything I hear says that having healthy soil means having lots of living things in them and if I can contribute to that, it’s a good thing.’”
With a constant stream of products entering and exiting the market, Kleinhenz and his team are less interested in testing specific products and more interested in answering the bigger questions surrounding this subset of agricultural inputs. Their research has focused on identifying which factors are important to product efficacy, such as the effect of timing and application rate.
Kleinhenz and Wright have this advice for growers interested in or already using MBBSs on their crops:
- Do background research. Just because a product is OMRI-listed does not mean it’s been found effective. Set aside time to read up on the product. Take a critical look at label instructions. What details are provided about the timing, application rate and application methods? What can the manufacturer tell you about mixing it with other products or using it in specific conditions or crops?
- Be wary of claims that seem exaggerated. Most of these products create modest, gradual, and/or inconsistent yield improvements. Growers should have realistic expectations for MBBS products.
- Product consistency can be an issue with MBBSs. If a product only works some of the time, the cause may be related to the user, the manufacturing process and product itself, or production conditions. For example, environmental factors like soil fertility, pH, or cropping history might influence the product’s effectiveness.
- Use storage and handling procedures that acknowledge these are living products. Avoid temperature extremes and chlorinated water, for example.
- Track what happens. Referrals from other users of the product are valuable. But remember that their success won’t necessarily be repeated in your farm’s unique conditions. When trying a new product or practice, maintain a similar untreated part of your field to compare. Do your own experiments with rate and timing. Keep records on what you applied, where, and take notes on any differences you see in growth, yield, quality, etc.
- Use good cultural processes to increase microbials in your soil too. Wright likens MBBS products to taking a vitamin vs. eating healthy foods. Cultural practices that favor soil biodiversity, organic matter, and good drainage are also needed to provide food and conditions that allow microbial life to thrive.
Change is coming
So far, these products are largely unregulated. For the first time, the current farm bill includes language defining a biostimulant--an important first step in creating better uniformity in the industry, says Kleinhenz. Some manufacturers are concerned about the overall image of MBBS products and are pushing for a more narrow definition along with efficacy testing.
Kleinhenz feels regulation will usher in increased product consistency and better information for consumers, but regulation may also limit the number of products available. Testing product efficacy requires time, expertise, and/or expenses that smaller manufacturers may find challenging.
He also questions if it is truly appropriate to apply the same efficacy standards used for many mainstream agricultural inputs. Based on averages and standard, proven statistical analysis, a comparison of treated and non-treated plots failed to show that inoculation (product use) significantly influenced yield. However, the Vegetable Production Systems Lab team observed many times when a MBBS did increase yield (and a few times when it lowered it).
“If you went out to your truck and it only started half of the mornings, you’d be pretty annoyed and conclude it’s unreliable, that it’s not working,” Kleinhenz says. “However, if you apply a product to your crops or soils and see measurable improvement say, 30% of the time, you might still find the application worthwhile if the costs and other risks were low. Our goal as a team is to provide growers and others with information they can use to distinguish worthwhile from unwise investments and practices.”
There are many additional practical questions to answer that could involve microbiology and decision-making. For now, Kleinhenz and his lab are enjoying the conversation and questions stimulated by this growing and changing industry.
This research is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Organic Transitions Program under award Number 2016-51106-25714 and also under award number 2016-38640-25381 through the North Central Region SARE program under subaward number LNC16-380.