{Oryza sativa}

Boron and Rice

Boron is essential to rice growth. Without sufficient levels of this essential micronutrient, boron deficiency occurs in rice, negatively impacting both crop health and yield. However, sufficient boron in the soil has the following benefits for rice:

  • Increased pollination and seed set
  • Increased grain filling
  • Reduced chaffiness
  • Reduced bursting when cooking
  • Increased uptake of macronutrients which leads to greater vigor and better use of the fertilizer for rice
  • Speeds maturity
  • Increased yield, quality, and income from the crop

When there is not enough boron in the soil, boron deficiency results in reduced pollen viability.

What causes boron deficiency in rice?

Boron deficiency in rice can be caused by one or more of the following:

  • Very little available boron in soil
  • Boron adsorption on organic matter, clay minerals, and sequioxides
  • Reduction in boron mobility due to drought
  • Excessive liming
The critical soil level for occurrence of boron deficiency is 0.5 mg B kg-1.

How common is boron deficiency in rice?

Boron deficiency is not very common in rice, but can occur in the following soils:
  • Highly weathered, acid red soils and sandy rice soils in China
  • Acid soils derived from igneous rocks (as opposed to soils formed from marine sediments)
  • High organic matter status soils in Japan

What are the symptoms of boron deficiency in rice?

In rice plants, boron is relatively immobile—it does not move throughout the plant. Because it does not move to new growth, boron deficiency symptoms usually appear first on young leaves. These leaves don’t grow properly, remaining short and narrow with faint white or yellow, rolled leaf tips.
The next emerging leaves are folded, bent, and almost white. If such leaves open, a large part of the blade will quickly dry up. Boron deficiency also leads to shorter plant height. When the deficiency is severe, growth stops completely, but new tillers continue to be produced. These tillers will quickly show the same symptoms and remain stunted.
The panicles in rice are also severely affected by boron deficiency. Rice plants may fail to produce panicles if they are boron deficient at the panicle formation stage. Roots of severely affected plants are stubby, tough, and light brown in color.

Prevent and cure nutrient deficiencies in rice

With the right fertilizer and appropriate application of boron in rice, you can prevent or correct any deficiencies. Below, you'll see our options for borate fertilizers for rice and application recommendations: 
  • Granubor® is an ideal material for dry blends that are applied broadcast preplant or sidedressed.
  • Fertibor® works best in fertilizer suspensions for preplant broadcasts, sidedressing, or band sprayed over the pre-emergent seed row.
  • Solubor® allows the most flexibility for applying boron. It can be dissolved alone in water or in liquid fertilizers and/or pesticides and then applied to the soil or directly onto the foliage.
  • Apply 20 Mule Team® borate fertilizers in soluble forms for rapid treatment of boron deficiency broadcast and incorporated before planting, topdressed, using Fertibor or Granubor or as foliar spray using Solubor during vegetative rice growth.
  • For foliar application, 10g of Solubor in 15L of water is a recommended concentration of the spray solution. Solubor can be mixed with common insecticides or fungicides used in the nursery. Split the boron foliar spray into three or four applications along with the insecticidal or fungicidal spraying rounds.
  • For soil application, broadcast or topdress 4-6kg of Fertibor or Granubor per hectare in one time application before planting or split on twice application half dosage before planting and half dosage at vegetative growth stage.

U.S. Borax Products for Rice

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 3-6 3-6
KG/HA 3.38 - 6.75 3.38 - 6.75

Foliar Application (Suggested rates of application)

KG/HA 2.25 - 4.5
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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