Published Aug 18, 2025

New Farmer-Led Research Explores Effectiveness of Biological Products
By Elizabeth Wilhelm
More than 80% of trials showed no benefit from biological products

Contact: Elizabeth Wilhelm | Senior Media Relations Coordinator | (515) 232-5661 | elizabeth.wilhelm@practicalfarmers.org

AMES, Iowa (Aug. 18, 2025) — Since 2019, seven farmers in Practical Farmers of Iowa’s Cooperators’ Program have conducted 16 on-farm trials testing various biofertilizer and biostimulant products. These products, derived from living microorganisms or natural substances, are marketed to benefit soil nutrient cycling, enhance soil fertility, stimulate plant growth, improve plant stress tolerance and more.

While these products are promising in theory, the trial results were mixed. Most of the trials (81%) showed no benefit to the use of biological products on the farms that tested them.

“There are countless products marketed toward farmers, and it can be hard to know what’s worth the investment and what’s not,” Stefan Gailans, PFI’s senior research manager, says. “Our members put some of these products to the test and learned what works best for their farms – and what doesn’t.”

Trials included:

  • MycoApply Soil Inoculant for Corn and Soybeans – 2019
  • Holganix Bio 800+ Compost Tea for Corn – 2023
  • Utrisha N Biological Nitrogen Supplement for Organic Corn – 2023
  • Biostimulant Effects on Corn – 2024
  • Biochar Seed Treatment Effect on Corn – 2024
  • Sulfur Fertilizer and Humic Acid Amendment for Soybeans – 2024

However, what works for one farmer may not work for another. That’s why farmer-led, on-farm research has been central to PFI’s mission – helping farmers make informed decisions based on their own conditions.

Keaton Krueger, a frequent cooperator in PFI research trials, says that trials are especially useful to him. “They help me to confirm on my own farm if practices that are shown to elicit a response in the literature hold up,” he says.

Since PFI’s Cooperators’ Program began in 1987, more than 240 farmers have led nearly 1,300 on-farm trials across Iowa and the Midwest, covering topics from cover crops and small grains to horticulture and livestock.

PFI’s farmer-led research empowers farmers to better answer their most challenging farming questions and share that knowledge with others.

To explore the full findings from PFI’s biological product trials, visit practicalfarmers.org/biological-products-for-corn-and-soybean. To view PFI’s Cooperators’ Program Report, visit practicalfarmers.org/2024-cooperators-program-report.

Farmers interested in participating in future trials can contact Stefan Gailans at stefan.gailans@practicalfarmers.org or visit practicalfarmers.org/cooperators-program.

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About Practical Farmers: Practical Farmers of Iowa is a nonprofit with more than 8,000 members that equips farmers to build resilient farms and communities. We create learning opportunities via farmer-led events, on-farm research and educational content through our robust network of farmers. We also provide funding and technical assistance to help farmers adopt regenerative farming practices and grow farm businesses. Our vision is an Iowa with healthy soil, healthy food, clean air, clean water, resilient farms and vibrant communities. To learn more, visit http://practicalfarmers.org.