This analysis delves into the contentious topic of foliar fungicide application on soybeans, specifically examining whether scientific evidence supports its widespread use. For years, farmers and researchers have explored direct nutrient application to boost soybean yields. However, extensive, multi-state trials indicate that routine, prophylactic foliar fungicide treatments offer little to no economic advantage unless specific nutrient deficiencies are visibly present. This insight challenges conventional wisdom and underscores the importance of evidence-based agricultural practices to optimize economic returns.
Detailed Report: The Science Behind Soybean Foliar Fungicides
In a pivotal two-year investigation spanning 2019 and 2020, leading soybean researchers operating under the \"Science for Success\" initiative conducted 46 trials across 16 states. These trials rigorously assessed the impact of six distinct macro and micronutrient packages applied to soybeans during the R3 growth stage. The expansive geographical scope, ranging from North Dakota to Ohio and North Carolina, provided a robust dataset to evaluate the efficacy of foliar applications. The conclusive findings were unambiguous: when no visible symptoms of nutrient deficiencies were present, foliar fertilization offered no discernable yield or economic benefit to the soybean crops. Consequently, many agricultural specialists now caution against indiscriminate foliar fertilizer use.
Despite these findings, the conversation around foliar applications continues to evolve. Prominent experts, including Shawn Conley, an Extension soybean specialist at the University of Wisconsin; Laura Lindsey, an Extension soybean specialist at Ohio State University; and Seth Naeve, an Extension agronomist at the University of Minnesota, consistently uphold the initial conclusions of the Science for Success study. They assert that the study's title, \"Foliar Fertilizers Rarely Increase Yields in U.S. Soybeans,\" remains highly accurate. Lindsey highlights a specific instance in Ohio where foliar manganese increased yield in one of four environments, notably where interveinal chlorosis, a clear symptom of manganese deficiency, was present, indicating that targeted applications for confirmed deficiencies can be beneficial.
Conley concurs, emphasizing that their micronutrient trials, designed as prophylactic additions without existing deficiencies, did not show positive results. He argues that even if applied once at a 'wrong' time, the rates were sufficient to elicit a response if true deficiencies existed, and applications were timed with peak nutrient uptake. Both Lindsey and Conley acknowledge that while some farmers report yield increases from nitrogen application at R4 to R5 stages, such benefits are often marginal and rarely economically viable given fluctuating crop prices. Naeve further elaborates that visible nutrient deficiencies do not invariably lead to yield loss, as other limiting factors like pests, water availability, or temperature often cap yields. Therefore, adding nutrients in such scenarios might not be effective, and early-season fertilization showing initial 'greening' may not translate to improved yields during critical seed filling periods.
An alternative perspective comes from Steve Gauck, a farmer and regional agronomy manager for Beck’s, based near Greensburg in south-central Indiana. Initially aligned with the Science for Success findings, Gauck's views shifted after observing consistent positive trends in Beck’s Practical Farm Research (PFR) program. His family farm now routinely incorporates foliar fertilizers, focusing on applying specific nutrients at times when agronomic knowledge suggests they are most critically needed by the plant. Gauck clarifies that their approach deviates from a single, blanket application at R3, emphasizing instead a more nuanced, trend-based strategy that has proven effective for their operations.
The Continuing Dialogue: Balancing Science with Practical Experience
The ongoing discussion surrounding foliar applications in soybean farming underscores a critical tension between rigorous scientific findings and practical, on-the-ground farmer experiences. While academic research provides invaluable data, individual farm conditions, specific nutrient profiles, and adaptive management strategies can sometimes yield different outcomes. This highlights the importance of integrating scientific recommendations with personalized farm research and observation, advocating for a data-driven yet flexible approach to crop management. For farmers, it implies a need for precise diagnostic tools and a deep understanding of their specific field's needs to make economically sound decisions, moving beyond generalized applications to more strategic interventions.
