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Sales of foliar fertilizers have skyrocketed in the last several years, particularly among organic dairy farmers. Foliar products are readily available, easy to store, and many products are approved for organic use and formulated to provide humates, microbiological products, micronutrients, and other popular treatments. Advocates of these products say they offer an environmentally friendly, efficient, and cost-effective way to apply fertilizers. Yet much of the recent research done on foliar feeding has been unable to reliably document benefits to production.
Louceline Fleuridor has spent the last two years studying foliar feeding as part of her Ohio State master’s degree program. She partnered with organic dairy farmers to measure the response of forage and soils to post-cutting foliar fertilization on 19 on-farm sites. As with previous studies in Ohio, Fleuridor found no consistent evidence of benefits from using foliar feeding products.
"In foliar feeding, you apply fertilizer through the leaves, which is contrary to the traditional knowledge that plants will absorb nutrients through their roots,” says Fleuridor, explaining that leaves' primary function is thought to be photosynthesis. "It raises some questions."
On Thursday, December 19, Fleuridor met with participating farmers and Ohio State specialists for a discussion of the research trials and results.
Partnering farmers began the meeting by sharing their experiences with foliar products. Wayne county dairy farmer Jeff Miller began experimenting with foliar feeding on one of his pastures five years ago. He decided to spray half of his pasture to see what would happen and because he couldn’t afford to spray the whole field. But when he noticed how much quicker his herd began to graze in the foliar fed area, he decided he couldn’t afford not to spray the whole field. Other farmers relayed similar experience, noting increases in crop yield, forage health, palatability, and harvested hay quality that coincided with the use of foliar feeding.
Yield gets a lot of attention in studies, but quality and palatability are also important, especially on dairy farms where forage is not the end product. Past studies have noted other advantages to foliar feeds, including decreased nutrient runoff, better absorption efficiency of micro- and macronutrients, reduced instance of disease, and, in a 2000 study on wheat, increased grain protein content.
"Forage quality is where we really expected to see changes, but we didn't," said Ohio State soil fertility specialist Steve Culman, who provided technical assistance on the project.
Fleuridor's study examined a variety of forage quality measurements, including in-field measurements for sugar content (Brix), as well as lab analysis for crude protein, stem:leaf ratio, fiber content, relative forage quality, net energy of lactation, and estimated milk/ton.
In addition to sharing individual and overall test results with the participating farmers, Fleuridor also spent time explaining how researchers use randomized plots and statistics to separate actual treatment differences from differences that happen randomly or from variations in the field. Fleuridor noted that there were some differences between the treatment and control in the studies, but the results were inconsistent and didn’t reveal a cohesive pattern of increased yield, plant health, or milk production for the sites in this study.
Culman cautions farmers to inform themselves before using foliar feeds. “If you’re looking at adding these products, look at the formulation and know what you’re getting. Foliar products tend to supply only a small amount of nutrients.”
Most of the farmers in the study plan to continue using foliar feeding, feeling that these products have caused improvements on their fields. They did note mixed results with some products and a need for additional labor. Several of the participants also stressed that other soil problems need to be fixed before turning attention to foliar feeds.
As for Fleuridor, she feels there are many factors that could have contributed to the mixed results in this study, including weather and soil conditions when the products were applied. She recommended that future studies use a consistent forage composition, and suggested a focus on clover may be advisable, based on farmer feedback.
This study was sponsored by The Ohio State University Paul C. and Edna H. Warner Grants for Sustainable Agriculture, Organic Valley FAFO (Farmers Advocating for Organic), and SoilBiotics. Organic Valley FAFO is currently accepting grant proposals for on-farm research projects. The deadline is February 15, 2020. Read more: https://www.organicvalley.coop/why-organic-valley/power-of-we/farmers-advocating-organics/
|Ohio State researcher Louceline Fleuridor applied foliar feed treatments at spring green up and 10 days after each cutting. Applications were made in the mornings when temperatures were below 75 degrees F.|