Trends in Bioproduct Use on Organic Vegetable Farms: A 2009-2014 Survey of Ohio Organic System Plans

Growers increasingly seek biological alternatives to chemical inputs in the form of microbe-containing bioproducts (e.g., biofertilizers, biostimulants, biopesticides) (MCBPs) applied to seeds, plants, roots, or soils to promote growth, or limit disease or abiotic stress. Trends in MCBP use were tracked from 2009-2014 by surveying the organic certification records of 86 Ohio organic vegetable farmers. A total of 22 biofertilizer products from 12 different manufacturers, and 10 biopesticide products from 8 manufacturers were reportedly used over the 6-year period. Biopesticides were used by 65% of farmers and accounted for 4.3% of all inputs by number. Similarly, biofertilizers were used by 51% of farmers and accounted for 4.8% of all inputs by number. Biopesticides were grouped into three categories: BT (Bacillus thuringiensis), other insecticides, and fungal antagonists, which accounted for 65%, 13%, and 21% of all uses, respectively. All biopesticide products contained a single species as the active ingredient, which was identified at the strain level in every case. In contrast, the most widely used biofertilizers were products containing mixtures of different bacterial and/or fungal species. These mixed products accounted for 40% of all biofertilizer use, and products containing unspecified “beneficial microorganisms” accounted for 28% of all biofertilizer use. Rhizobia and mycorrhizal fungi accounted for 21% and 10% of use, respectively, and asymbiotic nitrogen fixing inoculants accounted for the remaining 2%. These patterns of MCBP use are consistent with what is available commercially. A potential biopesticide strain must go through extensive testing in order to be registered by the EPA, whereas there are virtually no regulations for biofertilizers. The vast majority of commercially available biofertilizers are mixed inoculants, and many products have imprecisely labeled ingredients and unclear application instructions. Furthermore, little independent, research-based, and publically available information is available to substantiate claims of product efficacy. That so many farmers use biofertilizers despite the present lack of reliable information about them suggests a need for more research and extension.