Solubor Liquid Organic Fertilizer

B 20.5%

The best choice for foliar applications, Solubor is formulated to disperse quickly in liquid, leave minimal residue, and provide an economical source of boron.


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.


Highly Concentrated Boron Powder Product Overview

Discover the primary characteristics, benefits, and uses of Solubor, the most concentrated form of refined boron product available on the market and ... Watch the video

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.

Learn more about OMRI Listed® Products >

“Our refined sodium borate is able to deliver that steady, constant release of boron over the entire growing season.”

Damien Slowik | Technical Development Specialist
Damien Slowik | Technical Development Specialist


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.


  Optibor (boric acid) Solubor
%B 17.5% 20.5%
Max. concentration at 10°C 3.5 (0.6 %B) 4.5 (0.9 %B)
pH of max. solution at 10°C 4.2
Solutions start acidic and increase in acidity as concentration increases
Solutions start alkaline and increase in acidity as concentration increases
Sodium borate No Yes
Particle size Granular Powder
Dissolution Quick dissolution under most conditions Rapid dissolution under all conditions
OMRI registration Yes Yes

Rio Tinto Borates is a global leader in the supply and science of borates - naturally-occurring minerals containing boron and other elements. Refined borates are essential nutrients for crops. We are 1,000 people serving 500 customers with over 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 east of Los Angeles.  Learn more about Rio Tinto

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