20.5% Boron


B 20.5% minimum

Solubor is manufactured to achieve the highest level of soluble boron in water.

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Solubor DF

B 17.2% minimum

Solubor DF sodium borate is a free-flowing, white, micro-granular product manufactured in France by Borax Français S.A.S.

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Solubor Flow

B 9.6% minimum

Solubor Flow is the first and only aqueous suspension of sodium borate microcrystals, readily dissolves when added to water, and therefore more effective for agriculture.

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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:
  • To coat finished solid fertilizers
  • As part of solution or suspension fertilizers
  • In the formulation of high-performance liquids for fertigation (fertilization through irrigation systems)
  • In multi-element soluble powder formulations for spraying
  • 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.

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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—up to 68.6% B2O3, compared to 56.8% maximum.



  • 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.

Solubor Flow Technical Details

Solubor Flow has a chemical composition that allows for rapid dissolution in water, allowing for a pumpable means of delivering boron into agriculture processes.


Boron (B) 9.6%
Material required for 1 lb (.45 kg) of B 10.33 lb (4.69 kg)
Derived from sodium borates and boric acid
  • Solubor Flow is available in a 1300 kg polypropylene container (100 X 120 + 116cm)
(boric acid)
Solubor Solubor DF Solubor Flow
%B 17.5% 20.5% 17.2% 9.6%
Max. concentration at 10°C 3.5 (0.6 %B) 4.5 (0.9 %B) 6.7% wt (theoretical) 11.6% wt (theoretical, expected based on overall chemistry composition)
pH of max. solution at 10°C at 10% is 4.2
Solutions start acidic and increase in acidity as concentration increases
at 10% is 8.0
Solutions start alkaline and increase in acidity as concentration increases
at 23°C for a 1% solution is 8.3, and for a 15% solution is 7.1 pH of maximum solution between 20°C and 25°C: 6. 4 -7
Sodium borate No Yes Yes Yes
Particle size Granular Powder Granular N/A
Dissolution Quick dissolution under most conditions Rapid dissolution under all conditions Rapid dissolution under all conditions Rapid dissolution under all conditions
OMRI registration Yes Yes No No
A 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. Watch the video
Discover the characteristics, benefits, and uses of Solubor, the most concentrated form of refined boron available on the market and the perfect prod... Watch the video
A 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. Watch the video

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 500 customers with more than 1,700 delivery locations globally. We supply 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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