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Best bets for boron in bulk blending

:: Wednesday, September 3, 2025 :: Posted By Roger Gunning

Determining the correct blend of nutrients for your crops is vital. Just as important is ensuring the best application of those nutrients to your field. Several options exist for applying fertilizer to correct a boron deficiency. One of the most common methods is broadcast or banded application of a bulk blended nitrogen, phosphorous, and potassium (NPK) fertilizer to the soil.

If you’re applying a bulk blend directly to soil, it’s important to follow a few best practices—and know that the boron product you’re using is formulated for your specific application method.

For bulk blending applications, borate fertilizers are typically added into a mix of nutrients that can be custom formulated for the needs of the crop. Why?

  1. Boron is a micronutrient so only needed in small amounts. A refined product such as Granubor®, which contains 15% boron, is difficult to apply by hand in the limited recommended rates.
  2. For each application, you can save costs by preparing only the required amount of a bulk blend.
  3. Combining boron with other fertilizers also reduces overall application costs. You can perform a fertilizer application once rather than repeating the process multiple times for multiple products.

Refined boron: Uniformity matters

When applying a bulk blend, it’s important that the ratio of nutrients remain consistent across the entire field. If nutrients aren’t mixed properly—or if they contain granules that tend to settle, clump, or segregate during handling—the blend application won’t be uniform.

For example, unrefined borates tend to be crushed or ground, resulting in a variety of particle sizes, from substantial chunks to powder. The product will not distribute evenly in a bulk blend; chunks may settle to the bottom of a hopper or bin, and particles can clump together.

When deciding on a boron supplement, look for a high-quality boron source with uniform particle size that closely matches the particle size and density of other NPK components.

Granubor is specially formulated and ideally suited for use in bulk blends. Granubor’s unique refinement process ensures that the boron granules are uniform in both size and density. In addition, the granules are coated to prevent crushing, crumbling, or clumping, so particles flow freely, and distribute evenly and remain balanced throughout a mixture.

Learn more about Granubor distribution field tests

Contact us

Consult with your local agronomist or soil specialist to test for boron deficiency. If your fields are deficient in boron, contact our regional experts. We can talk you through what application method is best for your farm based on your crops, soil, and season to ensure you are giving your crops the best chance to thrive.

 

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U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles. Learn more about Rio Tinto.

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