The Importance of Boron in Plant Nutrition

While the quantity of boron absorbed by plants is significantly lower compared to macronutrients like nitrogen or potassium, its importance cannot be understated. Since the 1840s, when Carl Sprenger and Justus von Liebig introduced the now well-known Law of the Minimum, it has been recognized that even nutrients required in minimal amounts can be limiting factors in plant growth.

Boron is a vital micronutrient, typically required in concentrations ranging from 0.5 to 2.0 mg/kg of soil. Although this is considerably less than the amount needed for macronutrients such as nitrogen, boron’s role in plant physiology is crucial. It is involved in several key processes.

Boron helps plants form cell walls. Cell wall formation is a prerequisite of any growth. If the ability to form cell walls is impaired, plants stop developing normally. It has detrimental effects on many processes within the plant. New shoots and roots are stunted, leaf tips are yellow to brown. Sugars are not transported well and there is lack of energy for the growing plant parts. Pollen tube does not grow properly which means the pollination is often incomplete and there is no fruit/seed set. It all results in reduced yields and poor harvest quality.

Boron deficiency in a Conilon coffee plant, Brazil (Photo courtesy of ICL)

Symptoms of boron deficiency on Arabica coffee plants in Brazil (Photo courtesy of ICL)

How to Identify Boron Deficiency in Crops

Boron is an immobile nutrient in plants. Once boron is incorporated into plant tissues, it cannot be easily redistributed to other parts of the plant. As a result, symptoms of boron deficiency typically appear first in the newer, growing tissues.

Distinguishing boron deficiency from other nutrient deficiencies can be challenging as many symptoms are similar.

Common symptoms of boron deficiency in plants include:

Stunted and distorted growth: The growing tips of roots and shoots may become stunted and distorted, which can lead to the death of these tips.
Brittle foliage: Leaves may become thickened, brittle, and may curl or wrinkle.
Yellowing of leaf tips: The tips of leaves may turn yellow, and in severe cases, necrotic spots can develop.
Poor flowering and fruiting: Flowering and fruiting are often reduced, and developing fruits may be distorted.
Hollow or rough stems: Stems may become hollow or rough, particularly in crops like broccoli and cauliflower.

Symptoms of boron deficiency in a citrus plant, China (Photo courtesy of ICL)

How to Prevent Boron Deficiency

Preventing boron deficiency in plants involves several key practices:

To prevent boron deficiency, it is essential to regularly assess soil nutrient levels. Regular soil testing can detect potential deficiencies early, allowing for timely intervention. For effective crop management, you can always take following steps:

Balanced fertilization: use fertilizers containing boron, for example in a mix with other micronutrients.
Add organic matter into the soil: it improves boron availability
Manage pH level: maintain optimal pH levels (pH 6.0 to 7.0) as boron availability is reduced in alkaline soils with pH above 7.5
Ensure consistent and adequate irrigation: boron is most available in moist soils where organic matter decomposes efficiently. Too wet or too dry conditions slow down the breakdown of organic matter and release of complexed boron.
Monitor plant symptoms: regularly inspect your crop for any signs of boron deficiency. Act promptly if any symptoms are detected.

Stunted growth on soya leaves caused by boron deficiency, Brazil (Photo courtesy of ICL)

How to Address Boron Deficiency

Early interventions can prevent more severe problems. As soon as you detect boron deficiency in your crops, it is advisable to act quickly to mitigate the symptoms and restore healthy growth:

Foliar fertilization: application of a boron-containing spray allows a quicker uptake by the plant than from soil. Foliar application can be particularly effective for addressing acute deficiencies.
Soil fertilization: it is recommended to apply dry granular NPK fertilizers containing boron to ensure even distribution across the field. For best results, incorporate the fertilizer in the upper soil profile to make it more accessible to plant roots.
Fertigation: boron can be supplied to plants also through irrigation by using a soluble boron fertilizer which can easily dissolve in water.

Be careful with dosing as excessive level of boron can interfere with calcium absorption and utilization and may disrupt calcium metabolism and signaling.

Boron deficiency in citrus in Brazil (Photos courtesy of ICL)

Which ICL Fertilizers Supply Boron?

Fertilizers containing boron are essential for preventing boron deficiency in crops, ensuring optimal plant growth and enhancing overall agricultural productivity. Some of the ICL fertilizers that supply boron include:

Foliar Fertilizers:

Agroleaf® Liquid B10: A liquid premium fertilizer packed with 10% soluble boron. It prevents or corrects deficiencies or imbalances in the uptake of this micronutrient. It features ICL’s advanced F3 SurfActive technology for improved spreading, adhesiveness, and retention.
Agroleaf® Foliar Line: Fully water-soluble NPK formulations with micronutrients, including boron.
Nutrivant Foliar Line: Some of these fully soluble foliar NPK formulations are enriched with boron. This line features Fertivant technology to improve penetration and retention, thus enhancing crop yield and quality.

Water Soluble Fertilizers for Fertigation:

Most of ICL’s water soluble fertilizers contain boron and micronutrients for full nutrition of crops through fertigation systems. Some examples are:

Agrolution® Liquid ME-6: This liquid specially-designed formula is rich in EDTA-chelated manganese, iron, zinc, and copper, along with added mineral-form molybdenum and boron. Ideal for fertigation of all crop types to prevent or correct nutrient deficiencies.
Solinure®: A water-soluble NPK fertilizer line with micronutrients, including boron, designed for fertigation of field or greenhouse fruit and vegetable crops.
Agrolution® Special: NPK water-soluble fertilizers enriched with micronutrients package, including boron. The acidifying effects of these formulations make more nutrients available to crops.

Granular Fertilizers for Soil Application:

Agroblen® with V-Factor 8-20-7+3MgO+0.1B: an innovative, fully coated controlled release fertilizer, providing full nutrition to young seedlings for 8-9 months. It supplies NPK in the perfect ratio for long-term establishment, plus magnesium and boron. It is ideal for new plantations in forestry, vineyards, and orchards. On top of the nutrients, it also contains V-Factor organic growth enhancer to help form stronger roots.

ICL PKpluS®: A line of PK (phosphorus and potassium) granulated fertilizers based on Polysulphate, containing five nutrients in a single granule: phosphorus, potassium, sulfur, magnesium, and calcium. Tailor-made formulae with additional micronutrients, including boron, are available upon request.