Calcium Nitrate Tetrahydrate (CNT): A High-Purity Calcium and Nitrate Source for Agriculture and Industry

Calcium Nitrate Tetrahydrate (CNT), with the chemical formula Ca(NO₃)₂·4H₂O, is a high-purity, fully water-soluble, chloride-free inorganic salt. It appears as white to transparent crystals or granules, with excellent solubility in water and moderate hygroscopicity.

CNT provides a dual nutrient supply of nitrate nitrogen and available calcium, making it highly suitable for precision fertilization in modern agriculture. Owing to its neutral and mild nature, low corrosiveness and high purity, it is also widely used in construction, environmental protection, oilfield drilling, fine chemicals and latex products. It is a versatile basic raw material serving both agricultural and industrial applications.

1. Key Physicochemical Properties

Item	Specification
CAS No.	13477-34-4
Molecular Formula	Ca(NO₃)₂·4H₂O
Molecular Weight	236.15 g/mol
Appearance	White to transparent crystalline granules, hygroscopic
Solubility	Highly soluble in water
Aqueous Solution	Neutral to slightly acidic
pH, 1% Solution	5.5–6.5
Density	1.82 g/cm³

2. Production Process and Quality Control

Main Raw Materials

CNT is mainly produced from high-purity limestone or hydrated lime, concentrated nitric acid and purified water. Through controlled acid-base neutralization and purification, the process ensures stable product purity and low impurity levels.

Reaction Principle

Using calcium carbonate:

CaCO₃ + 2HNO₃ → Ca(NO₃)₂ + CO₂↑ + H₂O

Using calcium hydroxide:

Ca(OH)₂ + 2HNO₃ → Ca(NO₃)₂ + 2H₂O

The reaction solution is then concentrated and crystallized under controlled temperature conditions to form stable calcium nitrate tetrahydrate crystals.

Process Flow

Raw material feeding and neutralization → impurity removal and purification → concentration → controlled-temperature crystallization → centrifugal dehydration → screening and grading → finished product packaging

Key Quality Control Points

• Reaction temperature is controlled at ≤60°C to prevent the formation of unwanted salts and ensure product purity.

• Crystallization temperature is maintained at 15-25°C to produce uniform and stable crystals.

• Finished product moisture is controlled at 12-18% to reduce caking and secondary crystallization.

• Food-grade anti-caking agents or surface coating treatment can be applied where required to improve storage and transportation stability.

3. Core Agricultural Applications

Calcium Nitrate Tetrahydrate is a premium fully water-soluble calcium and nitrate nitrogen source. It dissolves completely, leaves no residue, and does not harden the soil. Nitrate nitrogen is rapidly absorbed by crops, while available calcium helps correct calcium deficiency efficiently. CNT is especially suitable for fruit expansion stages, vegetable production and crop calcium-deficiency correction.

Nutritional Benefits

Nitrate Nitrogen

Nitrate nitrogen can be directly absorbed by crops without conversion. It provides fast-acting nitrogen nutrition, supports photosynthesis, strengthens seedlings and promotes balanced vegetative growth without excessive elongation.

Available Calcium

Calcium strengthens cell walls, improves fruit firmness and resilience, and helps prevent physiological disorders caused by calcium deficiency, such as fruit cracking, blossom-end rot and tip burn. It can significantly improve fruit quality, storage performance and market value.

Suitable Crops

CNT is widely suitable for:

• Fruit crops: citrus, grapes, apples, bananas and other fruit trees

• Vegetables: tomatoes, peppers, cabbage, celery and leafy vegetables

• Root and tuber crops: potatoes, carrots and similar crops

• Field crops: corn, wheat, rapeseed and other broad-acre crops

Recommended Application Methods and Dosage

Application Method	Recommended Dosage / Concentration	Suitable Stage	Key Benefits
Soil flushing / fertigation	5–10 kg/mu, equivalent to 75–150 kg/ha	Before flowering and during fruit expansion	Fast absorption and quick correction of nutrient deficiency
Drip irrigation	2–5 kg/mu, equivalent to 30–75 kg/ha	From young fruit stage to harvest	Fully water-soluble, pipe-friendly and suitable for integrated water-fertilizer systems
Foliar spray	0.3–0.5% solution	Early calcium deficiency and fruit expansion stage	Rapid calcium correction and emergency nutrient supply
Basal application / furrow application	10–20 kg/mu, equivalent to 150–300 kg/ha	Before sowing or transplanting	Longer nutrient supply, simultaneous calcium and nitrogen supplementation, stronger roots and seedlings

Soil Compatibility

CNT solution is slightly acidic and does not significantly increase soil pH. It is suitable for acidic, neutral and slightly alkaline soils. It can also be used for long-term calcium supplementation in greenhouses and continuous cropping systems, helping reduce calcium deficiency while avoiding excessive soil alkalization.

4. Industrial Applications

4.1 Construction Industry: Chloride-Free Early Strength Agent and Antifreeze Additive

CNT is widely used in winter construction, bridge and road projects, underground engineering and precast concrete production. Its calcium ions can accelerate cement hydration, shorten initial setting time and improve early strength development.

Compared with traditional calcium chloride-based antifreeze agents, CNT is chloride-free and does not corrode steel reinforcement. It is therefore more suitable for high-performance concrete, prefabricated building materials and environmentally friendly construction systems.

4.2 Environmental Water Treatment: Biological Denitrification Regulator

CNT can be used in municipal sewage and industrial wastewater denitrification systems. It provides nitrate nitrogen as a reaction substrate, while calcium ions assist sludge flocculation and sedimentation. This helps improve denitrification efficiency and stabilize total nitrogen and ammonia nitrogen indicators in treated water.

CNT has no ammonia volatilization issue, has a mild pH profile, and can be used together with carbon sources such as sodium acetate and glucose.

4.3 Oilfield Drilling: Drilling Fluid Stabilizer

In deep wells, horizontal wells and high-salinity formations, CNT can be used to adjust calcium ion concentration in drilling fluids. It helps inhibit clay dispersion, stabilize wellbore walls and reduce the risk of collapse.

With low corrosiveness and no chloride ion damage, CNT can also function as a corrosion-inhibition auxiliary to help protect downhole equipment and pipe strings.

4.4 Fine Chemicals and Laboratory Use: High-Purity Calcium Source

Thanks to its high purity and excellent water solubility, CNT is suitable for the preparation of high-grade calcium salts, EDTA calcium, catalyst carriers, fluorescent materials and molecular sieves.

It can also be used to prepare standard calcium solutions for laboratory analysis, conductivity calibration and high-precision fine chemical applications.

4.5 Latex Industry: Coagulant for Rubber Gloves

CNT is a mainstream coagulant for nitrile gloves, natural latex gloves and medical protective latex products. After molds are dipped in a calcium nitrate solution, calcium ions quickly induce uniform latex coagulation and film formation, resulting in smooth surfaces, fewer bubbles and fewer defects.

Compared with calcium chloride, CNT offers lower corrosiveness, better finished product appearance and reduced mold wear, making it a preferred raw material for high-end latex products.

Typical concentration: 8-15% aqueous solution, adjustable according to temperature and humidity conditions.

Typical process flow:

Mold cleaning → coagulant dipping → drying → latex dipping → film formation and vulcanization → washing and drying → demolding and finished product

5. CNT vs. CAN: Product Differentiation

Item	Calcium Nitrate Tetrahydrate (CNT)	Calcium Ammonium Nitrate (CAN)
Composition	Pure calcium nitrate tetrahydrate, Ca(NO₃)₂·4H₂O	Mixed system of calcium nitrate and ammonium nitrate
Nitrogen Form	Pure nitrate nitrogen, faster and safer uptake	Combination of nitrate nitrogen and ammonium nitrogen
Calcium Content	High-calcium product, mainly used for calcium supplementation	Medium-calcium product, mainly used for nitrogen supplementation
Solubility	Fully water-soluble, suitable for drip irrigation and sprinkler irrigation	More commonly used as granular fertilizer for broadcasting, basal application and topdressing
Main Application	High-value fruits and vegetables, cash crops, precision calcium supplementation and fertigation	Field crops, broad nitrogen supplementation and cost-effective fertilization

6. Product Summary

Calcium Nitrate Tetrahydrate (CNT) combines the key advantages of high calcium availability, pure nitrate nitrogen, full water solubility, chloride-free formulation, low corrosiveness and high purity.

It is not only an essential raw material for high-efficiency calcium supplementation in modern agriculture, but also a versatile industrial material for construction, environmental protection, oilfield drilling, latex products and fine chemical applications.

With strong cost performance and broad compatibility, CNT is a reliable basic chemical product for both agricultural and industrial markets.

Calcium Nitrate Tetrahydrate (CNT): A High-Purity Calcium and Nitrate Source for Agriculture and Industry