20.5% Boron

Quick liquid dispersal

The best choice for foliar applications

Maximize the dispersion of plant micronutrients

The best choice for foliar applications, Solubor is formulated to disperse quickly in liquid, leaves minimal residue, and provides an economical source of boron. Solubor combines the highest boron concentration with the maximum possible dispersion and solubility in water, making it ideal for use in agro-industrial markets and farm sprays.

Application and benefits

Solubor is often used in the manufacture of or in combination with other fertilizers. Use Solubor:
  • In multi-element soluble powder formulations for foliar spraying
  • In the formulation of high-performance liquids for fertigation (fertilization through irrigation systems)
  • 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. The product is 100% water soluble and features optimized dissolution in water or more viscous liquids, even 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 equipment.

Thanks to its formulation, Solubor cleans up easily with water and doesn’t leave behind the sticky, difficult-to-clean residue that less refined products do. 

And, because Solubor provides the highest approved concentration of boron (typically 20.9%), only relatively small quantities are needed to correct boron deficiencies, making Solubor an economical choice—less than half the cost of solvent-based liquid products per pound of boron.

OMRI Listed
SOLUBOR may be used in certified organic production and in food processing and handling according to the USDA National Organic Program Rule.

Learn more about OMRI Listed® Products >
Research has shown that not all boron sources are equal in their ability to provide plants with soluble boron throughout the season.

Solubor Resources
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Solubor Technical Details

Solubor has a minute particle size of <75 microns, which contributes to its inherent high solubility. The product’s slight buffering action helps it to maintain pH in solutions. And, Solubor provides a higher concentration of boron than boric acid in solution does—0.9% B (w/w) versus 0.6% B (w/w) at room temperature.



  • Boron (B) 20.5%
    Material required for 1 lb (.45 kg) of B 4.9 lb (2.22 kg)
  • Derived from sodium borates
+200     8
-200     92
Bulk Density
Loose pack 25 lb/ft3 (400.46 kg/m3)
Tight pack 35 lb/ft3 (560.6 kg/m3)

  • Solubor is available in 1700 lb (771 kg) super bags, and in 50 lb (22.7 kg) multiwall paper bags with a polyethylene moisture resistant barrier.

Solubor DF Technical Details

Solubor DF is a mixture of disodium tetraborate, boric acid, and sodium pentaborate. The chemical composition and physical size of Solubor DF promote rapid dissolution in water.



Boron (B) 17.2%
Material required for 1 lb (.45 kg) of B 5.77 lb (2.62 kg)
Derived from boric acid and sodium borates
Bulk Density
  • 700-720 kg/m3

  • Solubor DF is available in 2.20 lb (1000 kg) IBCs, and in multiwall paper bags with a polyethylene moisture resistant barrier for the 11 lb (5 kg) size, and in polyethylene bags for the 26.4 lb (12 kg) and 55.1 lb (25 kg) sizes.
Minute in the Field: Solubor's Cost-Effectiveness
Dan Luepkes from Corn Warriors talks to U.S. Borax about how Solubor is more cost effective than other boron delivery products. Learn More
Amounts of Solubor to mix into spray tanks to supply desired boron rates
Solubor is highly water soluble, and is commonly applied in foliar sprays. Because the season for the most effective foliar application of boron... Learn More
Minute in the Field: Solubor's Solubility
Dan Luepkes from Corn Warriors talks to U.S. Borax about how easy it is to mix Solubor in solutions. Learn More

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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