A burgeoning billion-dollar industry woos farmers and gardeners with promises of achieving better, more environmentally friendly harvests through symbiotic fungi that bond with plant roots.
These fungal bonds can help plants thrive and can lock carbon that came from the atmosphere into the soil. But evidence has been piling up that shows buyers ought to eye with some skepticism the products that promise to produce them.
Now, University of Kansas scientists have combed through 250 commercial product trials detailed in peer-reviewed journals. Most of those trials checked to see if the promised fungi materialized on plant roots and helped the plants grow. And 88% of the time, the answer was no.
PROBLEMS THAT have cropped up in peer-reviewed studies at KU and elsewhere include:
• Some commercial products contain a pathogen that harms plants.
• Some contain undisclosed chemical fertilizer.
• Some don’t contain any spores for the beneficial fungi they’re meant to produce.
• Some contain spores that aren’t viable.
“These fungi can do awesome things,” lead author Liz Koziol said. “But not when they’re dead.”
Koziol is an assistant research professor at the Kansas Biological Survey and Center for Ecological Research, where she works with the world’s largest collection of the kind of symbiotic fungi that so many growers want in their soil. These are called arbuscular mycorrhizal fungi.
The paper in New Phytologist concluded with a plea for improving the industry. It said the U.S. “fully lacks regulations” on the quality of these products and on importing or exporting them. And it said these products could pose a risk of introducing invasive species.
THOUGH IT WOULD cost money to enforce rules and independently evaluate products, researchers said they see significant potential for savings compared to how much money farmers and gardeners may be wasting.
Symbiotic fungi give plants vital nutrients. They help plants cope with attacks from insects. And they protect against erosion, which is significant because U.S. farmland is losing soil faster than new soil forms.
All these benefits pique the interest of farmers and gardeners, but how can they browse the dizzying array of fungal inoculants for sale — and pick something that works?
“We need to have more transparency,” said Kirsten Hofmockel, a soil ecologist not involved in the KU research. She’s a senior scientist at the Pacific Northwest National Laboratory and recently served as president of the international Soil Ecology Society.
