A Comprehensive Overview of Boron Products: From Borax Pentahydrate to DOT – Exploring Agriculture and Industry

I. Introduction: The Overlooked “Micro Hero”

In agricultural production, people often focus first on the three major nutrients—nitrogen, phosphorus, and potassium. Calcium, magnesium, and sulfur, as secondary nutrients, follow thereafter. Micronutrients such as boron, zinc, iron, and manganese are often regarded as “supporting roles.” Yet it is precisely these seemingly negligible nutrients that frequently determine whether a crop can flower and fruit successfully, and whether it can produce full, high-quality yields.

Boron is such an “invisible hero.” Although present at extremely low levels in plants, it directly determines whether pollen tubes can grow properly, whether fruits can expand normally, and even a crop’s resistance to stress and overall quality. In boron-deficient fields, one often sees “flowers without fruit”: blossoms open in abundance, but because pollination fails, fruit set is sparse or absent. For fruit trees, tea, vegetables, and other cash crops, such deficiency may mean the loss of an entire season’s income.

If agriculture is one of boron’s “stages,” then industry is its larger “backstage.” Borax and boric acid are key raw materials for modern glass, ceramics, detergents, flame retardants, and wood preservatives. For example: laboratory beakers, household heat-resistant glass cookware, and fiberglass insulation for construction all depend on boron. Without boron, many of today’s fundamental industrial materials would not achieve their current level of performance.

Within the “boron family,” four products are the most common:

• Borax Pentahydrate (Na₂B₄O₇·5H₂O)

• Borax Decahydrate (Na₂B₄O₇·10H₂O)

• Boric Acid (H₃BO₃)

• Disodium Octaborate Tetrahydrate (DOT, Na₂B₈O₁₃·4H₂O)

They are “siblings” of the same origin but assume different roles in application. This article systematically reviews their chemical properties, agricultural and industrial uses, differences in NPK+TE fertilizer formulations, global market perspectives, and some illustrative case stories—helping readers truly understand the “world of boron.”

II. The Chemistry and Geology of Boron: From Minerals to Products

1. Boron in Nature

Boron (B) is a relatively rare element in the Earth’s crust, with an average abundance of only 10 ppm, far lower than common elements like iron, aluminum, or calcium. However, boron does not exist in isolation in nature—it prefers to form borate minerals with sodium, calcium, or magnesium, appearing in various hydrated crystalline forms.

The most important boron ores include:

• Borax (Na₂B₄O₇·10H₂O) – decahydrate borax, the most common borate mineral.

• Kernite (Na₂B₄O₇·4H₂O) – abundant in California and Turkey.

• Colemanite (CaB₃O₄(OH)₃·H₂O) – a major industrial borate ore.

• Ulexite (“TV rock”) – famous for its natural fiber-optic effect.

Globally, Turkey, the USA (California), and South America (Chile) are the main boron-mining regions. According to USGS data, Turkey holds over 70% of the world’s boron reserves, making the state-owned Eti Maden the global market leader.

2. Chemical Characteristics of Boron

Boron is notable for several chemical features:

1. Variety of valence and structures – boron forms B(OH)₃, B₄O₇²⁻, B₈O₁₃²⁻ and other species, giving rise to different borate products such as pentahydrate, decahydrate, and DOT.

2. Good solubility – most borates are soluble in water, and solubility increases significantly with temperature.

3. Glass-forming agent – under high temperature, boron-oxygen units readily form triangular or tetrahedral networks, making boron indispensable in the glass industry.

3. Transformation from Ore to Product

Industrial borate production generally follows these steps:

1. Mining and beneficiation – extracting boron ores such as borax or colemanite.

2. Leaching and crystallization – hot-water leaching yields a solution that, upon crystallization, separates borax hydrates of different water content.

3. Further processing – borax solutions, when acidified, yield boric acid; under controlled conditions, concentrated salts such as DOT can be synthesized.

This explains why the market simultaneously offers borax pentahydrate, borax decahydrate, boric acid, and DOT—they are essentially different hydration states or salts derived from the same mineral source, produced under different conditions.

.

III. Four Boron Products in Detail

3.1 Borax Pentahydrate (Na₂B₄O₇·5H₂O)

Borax pentahydrate is formed by heating and partially dehydrating decahydrate borax. It appears as white crystals or powder. The product contains about 14.8% boron (as B) and nearly 48% B₂O₃, making it one of the most widely used borates in both industry and agriculture.

Industrial Applications

• Glass industry: A star raw material. It lowers the melting point of glass, increases thermal stability and transparency, and is a key ingredient for heat-resistant glass (such as laboratory beakers, cookware, and solar panel glass).

• Ceramics and enamels: Used as a flux, giving ceramics a glossy and chemically resistant surface.

• Metallurgy: Applied as a flux or protective layer in metal refining.

Agricultural Applications

• Frequently used as a boron fertilizer for field crops such as cotton, rapeseed, and maize, typically via soil application or irrigation.

• Advantages: low cost, medium boron concentration, suitable for large-scale use.

• Disadvantages: dissolves more slowly than boric acid; introduces sodium, which can be problematic in saline soils or for sodium-sensitive crops.

Market PositionBorax pentahydrate is a general-purpose industrial-agricultural product with stable demand and large global trade volumes.

3.2 Borax Decahydrate (Na₂B₄O₇·10H₂O)

Borax decahydrate is the most common natural form of borax and the “ancestor” of boron products. It contains about 11.3% boron (as B) and about 36% B₂O₃. It appears as white crystalline granules and, due to its high water content, is physically stable.

Industrial Applications

• Primarily used in detergents, cleaners, and chemical buffers. In washing powders and soaps, it acts as an alkaline buffer, enhancing cleaning power and preventing metal ions from interfering with washing performance.

• Also used as a preservative, flame retardant, and in glass and ceramics, but in these fields it is often replaced by pentahydrate borax or boric acid because of their higher boron content.

Agricultural Applications

• Its role is minimal. Due to low boron content, high water content, and higher transport costs, it is rarely recommended as a boron source for agriculture. Occasionally it appears in low-cost formulations but is almost eliminated from high-end water-soluble fertilizers.

Market PositionBorax decahydrate is essentially a traditional industrial product with declining presence in modern agriculture.

3.3 Boric Acid (H₃BO₃)

Boric acid is one of the best-known boron products, appearing as a white crystalline powder or flakes. It is highly soluble in water, with a boron content of about 17.5% (as B) and about 56% B₂O₃. It is produced by acidifying borax or directly extracting from ores.

Agricultural Applications

• Boric acid plays an extremely important role. With fast solubility and flexible application, it can be used for foliar spray, fertigation, or drip irrigation.

• Particularly effective for fruit trees (citrus, apple), vegetables (tomato, cauliflower), tea, grapes, and other cash crops.

• Compared to borax pentahydrate, its greatest advantage is sodium-free, making it very suitable for saline soils and controlled-environment agriculture.

Industrial Applications

• Widely used in fiberglass production, preservatives, flame retardants, and pharmaceuticals.

• For example, in fiberglass, boric acid improves strength and heat resistance; in flame retardants, it acts as an inorganic additive; in medicine, it has historically been used as an eye wash and antiseptic (though its use has narrowed today).

Market PositionBoric acid is a dual-role “star” across agriculture and industry, with irreplaceable status in high-end applications.

3.4 Disodium Octaborate Tetrahydrate (DOT, Na₂B₈O₁₃·4H₂O)

DOT is a relatively new “high-concentration” boron product, containing about 20.5% boron (as B) and as much as 67% B₂O₃. It appears as a white powder or crystalline substance, highly soluble in water, forming clear and stable solutions.

Agricultural Applications

• DOT is considered a representative of “high-end boron fertilizers” because of its high boron concentration and excellent solubility.

• Particularly suitable for drip irrigation and fertigation, especially in controlled-environment agriculture and high-value crops such as grapes, flowers, and greenhouse vegetables.

• In formulations, DOT can meet the same boron demand with smaller additions, reducing transportation and storage costs.

Industrial Applications

• DOT’s main industrial use is as a wood preservative. Applied by soaking or spraying, DOT effectively prevents fungi and insects (such as termites) from damaging wood, greatly extending its service life. This is especially important in construction industries in North America and Europe.

Comparison to Boric Acid

• Advantages: higher boron concentration, lower transport costs.

• Disadvantages: introduces sodium, requiring caution for sodium-sensitive agricultural systems.

Market PositionDOT is a high-concentration, dual-purpose modern product, representing the developmental direction of boron fertilizers.

Summary

• Borax Pentahydrate → Low cost, dual-use, common in glass and field crops.

• Borax Decahydrate → Lower boron content, mainly for detergents, marginal in agriculture.

• Boric Acid → High-purity, sodium-free, dual-use star for high-end agriculture and industry.

• DOT → High concentration, efficient, rising star in fertigation and wood preservation.

Together, these four form the “all-star lineup” of boron products, each with distinct roles yet overlapping in some applications.

IV. Boron in Agriculture: The Plant’s “Invisible Nutritionist”

If nitrogen, phosphorus, and potassium are the “main food” of crops, then boron is like a subtle but indispensable “seasoning.” Though its required amount is extremely small, even a minor deficiency can disrupt the whole balance. The importance of boron in plants has been repeatedly confirmed in research and practice.

4.1 Physiological Functions of Boron

1. Cell wall formation and stability

   
   

   Boron participates in the synthesis of pectin and lignin, making it indispensable for cell wall structure. When boron is deficient, cell walls are weak, stems are brittle, and shoot tips die.

2. Pollen germination and pollen tube elongation

   
   

   Boron promotes pollen germination and ensures pollen tubes elongate rapidly to reach ovules, completing fertilization. Without boron, flowers may open normally but fruit set will fail.

3. Sugar transport and metabolism

   
   

   Boron binds with sugars, promoting carbohydrate transport through the phloem. This increases fruit sugar content, improves coloration, and enhances flavor.

4. Root development and stress resistance

   
   

   Boron stimulates root elongation and branching, improving tolerance to drought and diseases. This is especially critical during the seedling stage—boron deficiency causes poor root growth and later stunting.

📌 In short, boron acts simultaneously as the “architect” (cell walls), matchmaker (pollination), transporter (sugars), and bodyguard (stress resistance)” of plants.

4.2 Symptoms of Boron Deficiency

Typical boron deficiency symptoms appear in fast-growing tissues such as shoot tips, flowers, and young fruits, because boron is immobile in plants:

• Cotton: shoot tip necrosis (“terminal dieback”), malformed or shed bolls.

• Rapeseed: flowers do not set pods, siliques sparse or empty, yields drop sharply.

• Maize: hollow stems, poor pollen viability, barren ear tips.

• Fruit trees (apple, citrus): rough and cracked peel, more deformed fruits, lower market value.

• Tea: new leaves thicken and harden, buds stop growing.

• Vegetables (cauliflower, tomato): heart tissue necrosis, cauliflower fails to form curds, tomato fruit set rate is low.

These symptoms often strike at critical growth points, making boron deficiency especially harmful to reproductive growth and marketable yield.

4.3 Differences in Crop Boron Requirements

Not all crops require the same level of boron. Some are “boron-loving,” while others are relatively tolerant.

• High-demand crops: cotton, rapeseed, sugar beet, tea, sunflower, grape.

• Moderate demand: wheat, rice, maize.

• Relatively tolerant: legumes, potatoes.

Soil type also matters:

• Sandy soils, acidic soils, or high-rainfall leached soils → more prone to boron deficiency.

• Soils near boron-rich deposits → may suffer from boron excess, which is also toxic (leaf necrosis, growth inhibition).

4.4 Methods of Boron Fertilization

• Base/soil application

  Common products: borax pentahydrate, boron-magnesium fertilizers.

  Pros: provides long-term boron supply.

  Cons: slow effect, prone to fixation.

  
  

• Fertigation / drip irrigation

  Common products: boric acid, DOT.

  Pros: fast dissolution, high utilization efficiency, ideal for greenhouse farming.

  Cons: requires periodic reapplication.

  
  

• Foliar spraying

  Common products: boric acid, DOT.

  Pros: fast-acting, efficient absorption, quickly alleviates deficiency.

  Cons: must control concentration carefully (boric acid typically 0.1–0.3%) to avoid leaf burn.

  
  

• Seed treatment

  Common product: boric acid.

  Pros: promotes germination and seedling vigor.

  Cons: narrow dosage window, high risk of overdose.

4.5 Market Trends in Agriculture

Modern agriculture shows several clear trends for boron demand:

1. Precision fertilization → shifting from broad application to targeted supplementation; boric acid and DOT increasingly replace decahydrate.

2. Greenhouse and fertigation rise → highly soluble boron sources gain share, with DOT especially favored.

3. Crop structure changes → more fruit, vegetable, and tea acreage, which are all high-boron-demand crops.

4. Low-sodium demand → boric acid stands out for salt-sensitive crops and controlled-environment farming.

Industry forecasts suggest global agricultural boron fertilizer demand will grow 3–5% annually over the next 5–10 years, with boric acid and DOT leading the growth.

V. Boron in Industry: The “Invisible Backbone”

If boron is the “nutritionist” of plants in agriculture, then in industry it acts as the silent foundation supporting modern civilization. From glass and ceramics to detergents, flame retardants, wood protection, and medicine, boron compounds appear everywhere—even though consumers rarely notice them.

5.1 Glass Industry: The Secret of Transparency and Heat Resistance

The glass industry is the single largest consumer of boron, accounting for more than 40% of global demand.

• Borax pentahydrate and boric acid are the two core raw materials.

• Their role: lower melting temperature, increase chemical durability and thermal stability, and improve transparency.

Applications include:

• Borosilicate glass: laboratory glassware, kitchenware, and scientific instruments that withstand rapid heating and cooling.

• Fiberglass: used in construction insulation and automobile parts—lightweight yet strong.

• Solar glass: used in photovoltaic panels, requiring high transparency and weather resistance.

Without boron, modern glass could not achieve the balance of strength, transparency, and heat resistance.

5.2 Ceramics and Enamels: Gloss and Hardness

In ceramics and enamel manufacturing, borates act as fluxes and stabilizers:

• Borax pentahydrate reduces firing temperature, saving energy and improving workability.

• Boric acid improves chemical resistance, durability, and gloss.

Examples: high-grade ceramic tiles and sanitary ware, which become more wear-resistant and aesthetically appealing thanks to boron additives.

5.3 Detergents and Cleaning Products: The Hidden Household Ingredient

Borax decahydrate plays a significant role in cleaning and detergent formulations:

• Acts as a pH buffer, maintaining alkalinity during washing.

• Binds calcium and magnesium ions, preventing water hardness from reducing cleaning power.

• Works in synergy with surfactants, improving foam quality and stain removal.

Although environmental regulations have restricted boron use in detergents in regions like the EU, borax decahydrate remains widely used in markets such as Latin America and the Middle East.

5.4 Flame Retardants and Corrosion Protection: Enhancing Safety

Boron compounds are widely applied in flame-retardant and anti-corrosion systems:

• Boric acid forms a glassy protective layer when heated, blocking oxygen and heat transfer. It is used in paper, textiles, and wood treatments.

• Borax serves as a corrosion inhibitor in metal systems, extending equipment service life.

Example: adding boron-based flame retardants to cable sheathing materials significantly reduces fire hazards.

5.5 Wood Preservation: The Exclusive Domain of DOT

In wood protection, Disodium Octaborate Tetrahydrate (DOT) is the undisputed mainstay:

• DOT penetrates deeply into timber, effectively protecting against fungi, termites, and insects.

• It is widely used in construction industries in the US and Europe, where wooden structures such as fences, decks, bridges, and pergolas need long-term protection.

• Compared to older preservatives, DOT offers high efficacy, low toxicity, and environmental sustainability.

5.6 Medicine and Special Applications: Small but Significant

Boron also has roles in the medical and specialty fields:

• Boric acid was historically used in eye drops and as a mild antiseptic (though restricted today, it still survives in niche uses).

• BNCT (Boron Neutron Capture Therapy) is an innovative cancer treatment under research, which relies on boron-10’s ability to capture neutrons and release targeted radiation.

Other uses include:

• Borates in electronic ceramics and advanced materials.

• As fluxes and additives in metallurgy.

• As components in pesticide formulations.

Summary

In industry, boron can be summed up as the “invisible backbone” that strengthens multiple sectors:

• Glass (borosilicate, fiberglass, solar glass)

• Ceramics and enamel

• Detergents and cleaners

• Flame retardants and corrosion inhibitors

• Wood preservation (DOT as the core product)

• Medical and high-tech applications

Though hidden from public awareness, boron is indispensable to modern industry and daily life.

VI. Boron in NPK+TE Water-Soluble Fertilizers: How to Choose the Right Source

With the rapid rise of water-soluble fertilizers (WSF) and precision agriculture, the choice of boron source has become a key technical issue for fertilizer formulators. Although boron is a micronutrient, the selection of raw material directly affects product performance, safety, and cost-effectiveness.

6.1 Selection Logic

• Sodium Control

  In greenhouses and for sodium-sensitive crops (e.g., grapes, tomatoes, flowers), sodium levels must be strictly limited.

• Boric acid is the best option as it is sodium-free.

• Boron Concentration and Transport Efficiency

  For large-scale fertilizer production and exports, a higher boron concentration means smaller dosage and lower freight cost.

• DOT has a clear advantage: 20.5% B content, the highest among common products.

• Cost Sensitivity

  For standard solid WSF formulations, price matters most. Borax pentahydrate offers the best cost-performance ratio.

• The Decline of Borax Decahydrate

  With its low boron content and high water of crystallization, it has nearly disappeared from modern WSF production.

  
  

6.2 Formulation Adaptability

• 20-20-20+TE (universal formulation)

  
  

  → DOT or borax pentahydrate: stable, cost-efficient.

• 13-40-13, 10-52-10 (high-phosphorus types for fertigation/foliar spray)

  
  

  → Boric acid: fast dissolving, pH-lowering, foliar-safe.

• Formulas containing calcium (NPK+Ca+TE)

  
  

  → DOT: better compatibility with Ca and Mg, lower crystallization risk.

• Greenhouse fertigation systems

  
  

  → DOT or boric acid: both dissolve completely and prevent clogging of drip lines.

  
  

6.3 Calculation Example

Suppose a 25 kg bag of water-soluble fertilizer needs to contain 0.1% B. Required raw material per bag is:

Raw Material	B content	Required amount (g/25 kg)
Boric acid	~17.5%	142.9 g
Borax pentahydrate	~14.8%	168.9 g
Borax decahydrate	~11.3%	221.2 g
DOT	~20.5%	122.0 g

Conclusion: DOT requires the smallest amount, boric acid ensures safety and solubility, pentahydrate is a cost-effective compromise, and decahydrate is impractical.

6.4 Engineering Notes

1. Compatibility

2. Boric acid is stable in acidic environments but may crystallize with alkaline components.

3. DOT is broadly compatible but adds sodium.

4. Anti-caking Measures

5. Boric acid is hygroscopic → needs anti-caking agents and moisture-proof packaging.

6. Pentahydrate and DOT granules flow better, more suitable for large-scale mixing.

7. Foliar Spray Safety

8. Boric acid typical concentration: 0.1–0.3%. Exceeding this may cause leaf burn.

9. DOT also requires careful dosage to avoid phytotoxicity.

10. Labeling and Compliance

11. Fertilizer labels must specify “B content (as element B)”.

12. Compliance must follow local standards such as China’s NY/T, EU’s Fertilizing Products Regulation (FPR), or the US AAPFCO rules.

6.5 Market Trends

Global demand for NPK+TE water-soluble fertilizers is rising rapidly, especially in China, India, the Middle East, and Latin America. With the spread of fertigation and greenhouse production, DOT and boric acid are gaining larger market shares.

• Boric acid → high-end greenhouses, foliar applications.

• DOT → concentrated mother solutions, fertigation, premium WSF formulations.

• Borax pentahydrate → remains widely used in cost-sensitive, mass-market fertilizers.

• Borax decahydrate → gradually exits the stage.

Future pattern: A “dual-core” model led by boric acid and DOT:

• Boric acid = sodium-free, safe for sensitive crops.

• DOT = concentrated, cost-efficient, excellent for high-end fertigation.

VII. Illustrative Extension: The “Multiple Identities” of Boron

In the scientific world, boron is a chemical element; but if viewed differently, it resembles an actor with multiple identities, playing different roles on different stages.

• In agriculture, boron is the “nutritionist.” It guides crops to grow stronger, sweeter, and more attractive—just like a nutritionist designing balanced diets. Without boron, plants quickly show “malnutrition”: dead shoot tips, weak pollen, malformed fruits.

• In the glass industry, boron is the “invisible engineer.” It strengthens glass, improves heat resistance and transparency, and silently optimizes material performance.

• In detergents and cleaning products, boron is the “cleaning expert.” Borax decahydrate enhances detergent effectiveness and stabilizes foaming.

• In wood preservation, boron is the “guardian.” DOT protects timber from fungi and termites like a loyal guard watching over houses.

• In medicine and research, boron is the “doctor and scientist.” From early antiseptics to modern boron neutron capture therapy (BNCT), boron plays its role in human health.

If we personify the four products:

• Borax pentahydrate → the “diligent worker”, affordable, practical, widely used.

• Borax decahydrate → the “backstage assistant”, once important in detergents, now fading.

• Boric acid → the “gentle doctor”, sodium-free, precise, safe for sensitive crops and high-tech applications.

• DOT → the “high-performing athlete”, concentrated and efficient, excelling in fertigation and wood preservation.

Boron’s fascination lies in this contrast: invisible in quantity, yet transformative in function.

VIII. Future Outlook: Boron in Green Agriculture and Emerging Industries

Boron products are not only continuing in their traditional roles but also opening new frontiers in future industries.

8.1 Agriculture: Precision and Sustainability

• Precision agriculture: With fertigation and smart nutrient delivery systems, DOT and boric acid will play increasingly important roles.

• Crop restructuring: More fruit, tea, and vegetable acreage leads to steadily rising boron demand.

• Low-sodium and eco-friendly trends: Sodium-sensitive formulations will favor boric acid, avoiding soil salinization.

• Water-soluble compound fertilizers: DOT is expected to dominate as a boron source in high-end formulations.

8.2 Industry: New Energy and Materials

• Glass and renewable energy: Expanding photovoltaic (PV) industries will require more boron-rich solar glass.

• Electronics and ceramics: Borates in batteries, capacitors, and sensors will expand boron’s role in advanced materials.

• Medicine: BNCT (boron neutron capture therapy) offers a potential breakthrough for targeted cancer treatment.

8.3 Global Resources and Trade

• Turkey: over 70% of global reserves, with Eti Maden dominating supply.

• USA (Rio Tinto Borax): remains a major player.

• China: partially self-sufficient but still dependent on imports for high-grade boron products.

• South America (Chile, Argentina): emerging sources of boron.

The future boron market will be driven not only by price and volume, but also by product specialization, sustainability, and technological applications.

IX. Conclusion: Boron—Small in Quantity, Big in Significance

From borax pentahydrate to borax decahydrate, from boric acid to DOT, the “boron family” forms a complete portfolio with distinct features:

• Borax Pentahydrate: low-cost, versatile, indispensable in glass and field crops.

• Borax Decahydrate: traditional, now limited to detergents and cleaning products.

• Boric Acid: sodium-free, highly soluble, premium choice for sensitive crops and advanced industries.

• DOT: high concentration, efficient, rising star in fertigation and wood preservation.

In agriculture, boron is the invisible nutritionist—a small amount determines whether crops bloom, fruit, and yield.In industry, boron is the silent backbone—without it, glass, ceramics, detergents, and wood preservation would not be the same.In the future, boron will also shape renewable energy, advanced materials, and medical frontiers.

Final takeaway: Boron may be a micronutrient, but its influence is far from microscopic.Choosing the right boron source means not only securing harvests, but also enabling the sustainable industries of tomorrow.