In the soil 

Boron is a naturally occurring element in soil, where it originates from minerals in the earth’s crust. Large deposits formed over many years, with high concentrations of borates encapsulated in nonpermeable layers of clay. As a water-soluble element, boron’s availability and boron levels in soil depend on several factors: 
  • The solubility of boron in the parent rock 
  • The physical and chemical characteristics of the soil 
  • The availability of water moving through the soil 

The total boron level in soil can be categorized as low boron (less than 10 mg B/kg of soil) or high boron (around 100 mg/kg). The average overall concentration of boron in all soil ranges from 10 to 20 mg/kg; extremely high-boron soils are rare.   


In the atmosphere 

Boron has been detected in measurable (albeit minimal) quantities in: 

  • Evaporation from seawater 
  • Evaporation of rain, snow, and hot springs 
  • Industrial airborne dust 
In rain and snow, boron has been reported in concentrations of between 0.002 and 0.1 mg B/L. 

In the water 

When you surf in the ocean or kayak in a freshwater lake, you’re swimming in boron—5 mg B/L for seawater and <1 mg B/L for freshwater, on average. 

Boron for crops

In your food 

People didn’t know about mineral nutrients when they first started growing crops more than 10,000 years ago. Only during the past century or so have scientists and farmers discovered the seven essential micronutrients—boron among them—that plants need to grow.   

At the cellular level, boron is integral to a plant’s reproductive cycle. Boron controls flowering, pollen production, germination, and seed and fruit development. Plants get the boron they need from soil and water. In fact, they can’t live without it. For humans, experts agree that boron is nutritionally important, and mounting evidence suggests that boron may be an essential element in our diet as well. 

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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