U.S. Borax in American agriculture

:: Friday, February 24, 2023 :: Posted By Roger Gunning
Boron sourced from an American mine

Product origin is a hot topic. Whether you’re curious about where the cotton fibers in your bed sheets came from, or where the berries in your morning yogurt grew, sourcing is top of mind lately.

For U.S. Borax, the answer is right there in our name. Our borate fertilizers are mined and manufactured in the United States, before being distributed to agricultural regions around the world.

We operate California’s largest open pit mine in Boron, California—one of the richest borate deposits on the planet. While boron is everywhere in the environment, substantial deposits of borates are relatively rare. Through a 150-year history of innovation, U.S. Borax has been a source for top-quality refined boron, meeting around 30% of global demand.

High quality products for high quality crops

U.S. Borax Solubor®—which you probably know by name—is our easily dissolvable borate fertilizer that leaves very little to no residue. Solubor is best used:

  • In multi-element soluble powder formulations for foliar spraying
  • In the formulation of high-performance liquids for fertigation
  • As part of liquid nitrogen fertilizer applications, such urea ammonium nitrate (UAN) solutions or liquid fertilizer starters
  • In hydroponics

Solubor’s unique properties make it particularly well suited for these applications. It’s 100% water soluble and can dissolve in water or more viscous liquids at low ambient temperatures. Many liquid boron formulations become increasingly viscous or crystallize as temperatures drop. But up to 2.7% Solubor can be added to liquid fertilizer while maintaining crystallization temperatures below 1.7°C (35°F), putting less stress on your equipment.

If liquid fertilizer is not part of your operation, Granubor® is another U.S. Borax product that might be a better fit. The granulated form of our refined boron has been formulated to distribute evenly in a bulk fertilizer blend. The boron in Granubor will not peak in the middle of an application like some other micronutrient additives.

  • With an average particle size of 2.8 mm, Granubor is perfect for blending, providing a minimum of segregation in bagging, transport, and application
  • Granubor’s physical form makes it an excellent choice for direct application, such as large acre cropland, under or around trees and plantation crops
  • Granubor provides gradual release or boron, for more consistent, long-lasting benefits
  • The product is highly crush resistant, limiting dust during transport, hauling, and spreading
  • Granubor contains no fillers, coatings, or added ingredients

Our research speaks for itself

U.S. Borax isn’t just an excellent source for your boron needs, we also have years of research into boron fertilizer’s affects on soil and crops. With continuous innovation and the farmer in mind, we are constantly running field trials, conducting research, and optimizing best practices for you. Take a look at some of our recent research.

Local expertise for local markets

When you are purchasing fertilizer from U.S. Borax, you can trust you’re buying a high-quality product. Ask for it by name at your local retailer.

As a Certified Crop Advisor for nearly 30 years, I am well-versed in agricultural practices and how best to fit boron into your fertilization program. If you’re in North America, contact me to speak about your needs. For those in other regions, contact your local U.S. Borax agriculture expert to help you find a distributor in your area.


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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