Disodium Manganese EDTA (EDTA-MnNa₂) - A Stable, High-Efficiency Source of Manganese for Sustainable Agriculture

Overview

Disodium Manganese EDTA (EDTA-MnNa₂) is a chelated form of manganese with broad application value across agriculture, chemical industries, pharmaceuticals, and food processing.

• In agriculture, it serves as a micronutrient fertilizer that supplies essential manganese to crops, supporting plant growth and development.

• In chemical production, it functions as an additive for catalysts.

• In pharmaceuticals, it can be used in drug synthesis, medical devices, and diagnostic reagents.

• In the food industry, it is used as a preservative to extend shelf life and maintain freshness and quality.

Basic Information

• Molecular Formula: C₁₀H₁₂N₂O₈MnNa₂·2H₂O

• Molecular Weight: 425.16 g/mol

• Appearance: Light pink crystalline powder

• Solubility: Easily soluble in water

• Purity: >99%

• Manganese Content: 12.5% – 13.5%

• Water-Insoluble Matter: <0.1%

• pH (10 g/L, 25 °C): 6.0 – 7.0

• Melting Point: 80 – 82 °C

• Boiling Point: 154 – 155 °C (20 mm Hg, lit.)

• CAS No.: 15375-84-5

• EINECS No.: 239-407-5

• Storage: Store in a cool, dry place. Exposure to light can deactivate the product.

Elemental Composition

Element	Symbol	Atomic Weight	Atoms	Mass Percent
Carbon	C	12.011	10	28.250%
Hydrogen	H	1.0079	16	3.793%
Nitrogen	N	14.007	2	6.589%
Oxygen	O	15.999	10	37.632%
Manganese	Mn	54.938	1	12.922%
Sodium	Na	22.990	2	10.815%

Importance of Manganese in Plants

Manganese is one of the essential micronutrients for crops. It serves either as a structural component or an activator of many enzymes, playing a catalytic role in chlorophyll synthesis. Application of manganese fertilizers:

• Improves photosynthetic efficiency

• Enhances transport of photosynthates

• Improves nitrogen metabolism

• Promotes nitrate reduction inside plants, which aids in protein synthesis and increases nitrogen use efficiency

Manganese deficiency symptoms include:

• Stunted plant growth

• Chlorosis and whitening of leaves

• Malformed or poorly developed fruits

• Shortened internodes

• Arrested root growth

For a detailed article on manganese in agriculture and deficiency symptoms, see:🔗 Manganese Fertilizers in Agriculture

Mechanism of Action of EDTA-MnNa₂

As a chelated manganese fertilizer, the action of EDTA-MnNa₂ is based on “stabilizing manganese ions and improving bioavailability.” It addresses the problem of manganese fixation in soils, ensuring efficient plant uptake. The mechanism includes four key stages:

1. Chelation Protection by EDTA

   • In alkaline or calcareous soils, free Mn²⁺ is easily transformed into insoluble MnO₂ or Mn(OH)₂.

   • In high-calcium/high-phosphorus soils, manganese precipitates as manganese phosphate or manganese–calcium carbonate complexes.

   • These forms are unavailable to plants.

   • EDTA, with four carboxyl (-COOH) groups and two amine (-NH₂) groups, forms a strong chelate with Mn²⁺, preventing precipitation or oxidation. This keeps manganese soluble and available.

     
     

2. Targeted Transport and Absorption

   • Soil application: Chelated Mn moves with soil water to the rhizosphere. Plants may directly absorb the EDTA-Mn complex, or root exudates partially release Mn²⁺ for uptake.

   • Foliar application: EDTA-MnNa₂ adheres to leaves and enters through stomata or cuticular pores, bypassing soil fixation. This method offers particularly high efficiency in alkaline soils or for emergency manganese supplementation.

     
     

3. Physiological Role in Plants

   • Photosynthesis: Manganese is essential in Photosystem II, enabling water splitting and oxygen evolution, and supporting ATP synthesis.

   • Enzyme Activation: Mn activates key enzymes like superoxide dismutase (antioxidant defense), isocitrate dehydrogenase (carbohydrate metabolism), and phosphoenolpyruvate carboxykinase (nitrogen metabolism).

   • Structural Role: It stabilizes pectin in cell walls and maintains ionic balance, improving stress resistance (drought, salinity) and disease resistance.

     
     

Production and Preparation

Key Raw Materials

1. Chelating agent: Disodium EDTA (EDTA-2Na)

2. Manganese source: Manganese sulfate (MnSO₄)

3. Auxiliary reagents: Sodium hydroxide (for pH adjustment), deionized water

Typical Industrial Process

• Dissolve EDTA-2Na in deionized water at 50–60 °C.

• Dissolve MnSO₄ separately and filter impurities.

• Slowly add MnSO₄ solution to EDTA-2Na under stirring, adjusting pH to 6.5–7.5 with NaOH.

• Stir for 1.5–2 hours until the solution turns light pink (indicating complete reaction).

• Purify with activated carbon, filter, concentrate, and obtain product via spray drying (powder) or dilution (liquid).

Quality Control Considerations

• Purity of raw materials (avoid Ca/Mg impurities).

• pH and temperature control.

• Storage conditions (powder: moisture-proof; liquid: preservative addition).

Product Forms

• Powder: Convenient for transport and mixing with solid fertilizers or feed.

• Liquid: Ready-to-use, ideal for foliar and fertigation applications.

Application Fields

• Agriculture: Foliar sprays, soil application, fertigation; prevents manganese deficiency, enhances plant vigor.

• Pharmaceuticals: Used in formulations of dietary supplements and drugs requiring manganese.

• Industry: Applied in textiles, ceramics, and wastewater treatment as catalyst or additive.

• Food industry: Acts as a preservative to extend shelf life and maintain product quality.

Advantages Over Conventional Inorganic Manganese Fertilizers

1. Overcomes Soil Fixation Problems

• Traditional Mn fertilizers (MnSO₄, MnCl₂) are quickly fixed in alkaline or calcareous soils, becoming unavailable.

• EDTA-MnNa₂ maintains solubility across a wide range of soils (>90% of farmland), ensuring availability.

2. Higher Uptake Efficiency and Faster Response

• Traditional fertilizers: absorption efficiency only 10–20%; visible effects take 1–2 weeks.

• EDTA-MnNa₂: uptake efficiency >80%; foliar sprays correct chlorosis within 3–5 days; soil application shows improved growth within a week.

3. Flexible Application

• Suitable for crops with high Mn demand (soybeans, fruit trees, tomatoes).

• Can be applied through foliar spraying, fertigation, or drip irrigation.

• Highly effective in emergency correction of deficiencies.

4. Greater Stability and Compatibility

• Storage: Retains effectiveness for up to 2 years (powder form) or longer with preservatives (liquid form).

• Compatibility: Mixes safely with NPK fertilizers and most pesticides without precipitation problems, saving labor and application costs.

Conclusion

As a representative of high-efficiency chelated manganese fertilizers, EDTA-MnNa₂ breaks through the limitations of conventional manganese salts with its resistance to soil fixation and superior absorption efficiency. It not only ensures manganese nutrition for crops—especially high-value crops sensitive to deficiency—but also extends its applications in water treatment, pharmaceuticals, and food industries.

With the growing emphasis on sustainable agriculture, efficient fertilization practices, and global demand for advanced micronutrient fertilizers, EDTA-MnNa₂ is expected to play an increasingly important role in supporting agricultural productivity and cross-industry needs.