Evaluating In-Season Boron Applications
Boron plays a role in reproductive development, including flowering and pod set, leading some growers to adopt in-season applications in hopes of boosting yield. However, boron responses can be inconsistent, and unnecessary applications add cost without guaranteed return.
Micronutrient management has become an increasing focus in soybean production systems as growers aim to maximize yield potential. Among these nutrients, boron has received particular attention due to its role in reproductive processes such as flowering, pollination, and pod development.
Despite its importance in plant physiology, boron deficiencies are relatively uncommon in many South Carolina soils, and the benefits of in-season boron applications are not always clear. As a result, many applications are made without confirmed deficiency, raising questions about their economic value.
This project was designed to evaluate the effectiveness of in-season boron applications in soybean and determine whether these treatments contribute to increased yield under South Carolina growing conditions.
Treatments included foliar boron applications at key reproductive growth stages, alongside untreated control plots. These applications were timed to coincide with periods when boron demand is typically highest, allowing for evaluation of potential benefits during pod development.
In addition to yield measurements, tissue samples were collected before and following application to assess boron uptake and determine whether foliar treatments effectively increased plant nutrient levels. This provided a direct comparison between plant response and final yield outcomes.
Results
Key findings from the study include:
Foliar boron applications consistently increased tissue boron concentrations
Increased boron levels in plant tissue did not consistently result in higher yields
Yield response varied by environment and was often negligible under non-deficient conditions
No clear economic benefit was observed from routine boron applications
Across all locations, the lack of consistent yield response suggests that boron is not a limiting factor in most soybean production systems where soil fertility is already adequate. These results reinforce the importance of verifying nutrient deficiencies before making in-season applications.
As a result of this project, researchers have demonstrated that routine boron applications are unlikely to improve soybean yield in the absence of a confirmed deficiency. While boron remains an essential nutrient, its management should be based on soil and tissue testing rather than preventative application.
The key takeaway for growers is that boron applications should be used strategically, not routinely. Tissue testing can confirm whether boron is limiting, and in most cases, applying boron without evidence of deficiency is unlikely to provide a return on investment.
This information is from the 2025 research project, In-Season Boron Applications. The lead was University of Clemson researcher Kyle Smith. Project sponsored by the South Carolina Soybean Board.
