Liquid Boron: A Modern Approach to Efficient Boron Nutrition

We have previously provided a detailed introduction to boron as an element and its related products. Please refer back to the following article:https://www.kelewell.de/en/post/a-comprehensive-overview-of-boron-products-from-borax-pentahydrate-to-dot-exploring-agriculture-a

In addition to the boron fertilizers we have already discussed—such as boric acid and disodium octaborate tetrahydrate—there is another emerging form of boron fertilizer: liquid boron, which can serve as an efficient boron supplementation solution.

I. What Is Liquid Boron?

Liquid boron refers to a category of liquid boron fertilizers formulated using boric acid or borate salts as base materials, processed through thickening or stabilization technologies. Compared with traditional solid boron fertilizers (such as borax or granular boric acid), liquid boron shows clear differences in formulation type, solubility, and crop uptake pathways.

From a formulation perspective, liquid boron keeps boron in a stable and controllable liquid form within an aqueous system. At normal application concentrations, it can fully dissolve, is less prone to precipitation, and is well suited for modern agricultural practices such as foliar spraying, drip irrigation, and fertigation systems.

Depending on the production process, liquid boron can be classified into:

• Chelated liquid boron: Organic ligands are used to reduce boron reactivity and improve formulation stability.

• Sugar-alcohol-based liquid boron: Polyols (such as sorbitol, mannitol, ethanolamine, etc.) form reversible complexes with boron, enhancing its transport and redistribution within plants.

II. Differences Between Liquid Boron and Traditional Boron Fertilizers

Traditional boron fertilizers mainly exist in inorganic forms and rely largely on soil dissolution and root uptake. Their utilization efficiency is strongly influenced by soil type, pH, rainfall, and leaching conditions.

In contrast, the core advantage of liquid boron does not lie in a “different boron element,” but rather in the following aspects:

1. Formulation differences

   The liquid form allows boron to be absorbed directly through leaves, bypassing part of the soil fixation and leaching processes.

   
   

2. Differences in uptake pathways

   Under foliar application, boron can enter directly through the leaf cuticle and stomata, resulting in faster absorption and more immediate physiological responses.

   
   

3. Differences in internal transport behavior

   With sugar-alcohol carriers or specific chelation systems, boron redistribution within the plant is improved and is no longer strictly limited to xylem transport.

III. The Role of Boron in Crop Growth

Boron is an essential micronutrient for crops. Although required in small quantities, it is involved in highly critical physiological processes, mainly including the following:

1. Cell Structure and Meristem Development

Boron is an important component of pectin structures in the cell wall and plays a key role in maintaining cell wall stability. Under boron deficiency:

• Growth points may undergo necrosis

• Leaves may become wrinkled or deformed

• Abnormal development of root tips and shoot meristems may occur

Therefore, boron plays a fundamental role in root elongation, meristem vitality, and overall plant structural integrity.

2. Reproductive Growth and Pollination

Boron is particularly important during the reproductive stage, mainly by:

• Promoting pollen germination

• Enhancing pollen tube elongation

• Improving pollination and fertilization success rates

When boron supply is insufficient, crops often show symptoms such as “many flowers but few fruits” or poor fruit set. Proper boron supplementation helps increase fruit set and reduce flower and fruit drop.

3. Nutrient and Assimilate Transport

Boron contributes to maintaining the structure and function of phloem tissues and regulates the transport of assimilates (such as sugars and amino acids) within plants. With adequate boron supply:

• Assimilate transport efficiency improves

• Sink organs such as fruits and grains receive more nutrients

• Yield formation and quality development are enhanced

4. Stress Resistance and Metabolic Stability

By influencing cell membrane structure and antioxidant systems, boron helps to:

• Reduce abnormal increases in membrane permeability

• Minimize water and nutrient loss under stress conditions

• Maintain metabolic stability under drought, high-temperature, or low-temperature stress

IV. Functions of Liquid Boron

From a mechanistic perspective, the advantages of liquid boron are mainly reflected in the following aspects:

1. Improved internal mobility of boron

   Sugar-alcohol–complexed boron shows better mobility within plants and, under certain conditions, can participate in phloem transport, alleviating the issue of boron being difficult to redistribute.

   
   

2. Regulation of auxin metabolism

   Boron can influence the metabolism of indole-3-acetic acid (IAA) by affecting IAA oxidase activity, thereby indirectly regulating root and meristem development.

   
   

3. Stabilization of antioxidant systems

   Boron is involved in ascorbic acid metabolism and helps maintain antioxidant capacity in root tips and young tissues, supporting continuous root elongation.

   
   

4. Synergy with calcium ion dynamics

   During pollen germination and pollen tube elongation, boron participates in regulating pollen tube growth direction and speed by influencing calcium ion concentration gradients.

V. Applications of Liquid Boron in Major Crops

1. Cereal Crops (Wheat, Rice, etc.)

• Key stages: Booting stage, flowering stage

• Main effects: Improved seed set, increased thousand-kernel weight

2. Cash Crops (Cotton, Rapeseed, Peanut)

• Cotton: Reduced flower and boll shedding, increased boll number

• Rapeseed: Enhanced floral bud differentiation, higher seed set and oil content

• Peanut: Improved peg penetration and pod filling

3. Fruit Trees (Apple, Citrus, Pear, Winter Jujube, etc.)

• Boron application during flowering, early fruit development, and fruit enlargement stages

• Improved fruit set and reduced physiological fruit drop

• Better fruit size, uniformity, and marketability

4. Vegetable Crops

• Reduced fruit deformities

• Higher flowering and fruit set rates

• More stable yields and improved appearance quality

VI. Suitable Application Scenarios

• Liquid boron

  More suitable for rapid boron supplementation, precision fertilization, and foliar nutrient management, especially for boron-sensitive crops with high economic value.

  
  

• Traditional boron fertilizers

  More suitable as a long-term soil-based boron supplementation strategy to improve overall soil boron availability through sustained application.