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Boron Deficiency in Soybeans

Boron is essential for all plant growth. Soybeans, like all legumes, have a high boron requirement. Boron is necessary for:

  • Stimulation of root growth
  • Increased soybean root nodulation development for nitrogen fixation
  • Increased branching and flowering
  • Increased bloom retention
  • Increased number of pods
  • Better seed development and grain yield

Soybeans are considered non-responsive to boron. And, soybeans appear to be sensitive to boron toxicity, especially when the boron is applied to the leaves. However, yield reductions do not necessarily accompany leaf spotting and marginal necrosis caused by excessive boron accumulation.

What does boron deficiency in soybeans look like?

As with many plants, the earliest sign of boron deficiency in soybeans occurs in the roots. The root tips die and new roots are initiated giving a rosette appearance.

Likewise, the death of the shoot growing point is followed by prolific development of lateral shoots with brittle petioles.

Spotting Boron Deficiency in

What fertilizer to use for soybeans

Boron fertilization of soybeans has been shown to increase grain yield at many locations in several states. University researchers have found yield increases ranging from 5 to 18 bushels per acre.

Field studies conducted by the MS Foundation (Dr. Douglas Gitti) in Maracaju, Mato Grosso do Sul, Brazil, during the 2016-17 crop, demonstrated that Granubor® provided a higher yield gain in the soybean crop when compared to granulated ulexite applied equivalently in-furrow.

The same research group found that during the 2017-18 harvest Granubor provided a gain of 6.4 sacks/ha of soybeans in comparison to the control when applied in a pre-sowing dose of 7 kg/ha (1 kg/ha of boron). There were better climatic conditions for soybean cultivation during the 2017-18 crop compared to the 2016-17 crop.

Correcting boron deficiency in soybeans: How much is enough?

Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue tests. Never apply boron in direct contact with the seed.

When to fertilize soybeans

  • Boron may be applied in dry or fluid blends. With dry bulk blend fertilizer, broadcasting before planting is recommended, using Granubor.
  • Boron in liquid suspensions may be applied broadcast before planting, banded at planting, or sidedressed, using Fertibor® in suspensions.
  • Boron in liquid fertilizers may be broadcast before planting, banded at planting, sidedressed, or fertigated using Solubor®. This material may also be mixed with pesticides or applied to foliage in aqueous spray.* A cost-effective solution, Solubor is one of the best foliar fertilizers for soybeans available.
*Foliar sprays should not exceed 0.5 lbs/acre boron per application.
*Fertigation allows timely split applications of boron when it is needed by the crop and minimizes leaching. Drip-trickle fertigation allows incremental applications of 0.1 to 0.25 lbs/acre boron through the drip system.
*The total amount of boron added in foliar sprays or split applications should not exceed the total broadcast recommendations.

U.S. Borax Products

15% Boron |  | OMRI Certified
Optimum product for suspensions

A fine crystalline borate ideal for NPK compound fertilizers and suspensions. Manufactured as free-flowing granules, Fertibor is easily handled and offers superior flow and consistency.

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15% Boron |  | OMRI Certified
Made especially for bulk blenders

A pure, 100% water-soluble micronutrient that meets boron demand during the growing season. Made especially for bulk blenders, Granubor helps to ensure uniform distribution in nutritional blends and in the field.

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20.5% Boron |  | OMRI Certified
Product of choice for foliar applications

A concentrated, highly soluble, and fast dissolving powder that is ideal for foliar and other sprays. With the highest concentration of boron in any approved product, Solubor is an economical choice for nutritional formulations.

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20.8% Boron
Boron for fertilizer manufacturing

This refined U.S. Borax product is made from the dehydration and fusion of borax. Depending on the grade, Anhybor can be used to produce boron-enriched compound fertilizers or to coat different fertilizer products, such as NPK blends with the aid of a binder.

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10% Boron
Solubor Flow
For fertigation or hydroponic growing

First and only aqueous suspension of sodium borate microcrystals.

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14.5% Boron | 29% Zinc
Perfect combination of zinc and boron

Because zinc and boron deficiency are widespread around the world, a product with both nutrients is a good fit in many regions. Zincubor brings these two important micronutrients together in one product.

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Calculate Your ROI

Soil Application (Suggested rates of application)

  Granubor Fertibor
LBS/ACRE 4.46 - 9.0 4.46 - 9.0
KG/HA 5.0 - 10.0 5.0 - 10.0

Foliar Application (Suggested rates of application)

KG/HA 2.0
Value in Use
Current Yield (Per Acre)
Expected Sale Price

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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