Calcium nitrate (Norwegian saltpeter)

Properties

Calcium nitrate forms white, crystalline solids that are highly soluble in water and are hygroscopic or deliquescent under humid conditions. It is an oxidizing salt: it does not burn on its own but can accelerate the combustion of organic materials. When heated strongly, it releases nitrogen oxides and leaves calcium oxide as a residue. Typical handling requires dry storage and segregation from combustible substances.

Production and historical notes

Industrial production commonly involves neutralizing nitric acid with calcium carbonate, limestone, or lime to produce calcium nitrate and water. The traditional name "Norwegian saltpeter" reflects historical associations with nitrate resources in northern Europe, but modern manufacture is chemical and continuous. For more on industrial methods see production and processing.

Uses

• Fertilizer: supplies readily available nitrate nitrogen and soluble calcium, useful for horticultural crops and to reduce disorders such as blossom-end rot in tomatoes.
• Construction: used as a concrete admixture to accelerate setting and to help control reinforcement corrosion in cold or damp conditions.
• Water treatment and industry: used to promote aerobic microbial processes and to prevent sulfide formation in wastewater systems; also a precursor in some chemical syntheses.

Safety, environment and distinctions

As a nitrate salt, calcium nitrate can contribute to eutrophication if runoff reaches surface waters. It is an oxidizer and should be stored away from organic materials and reducing agents. Compared with ammonium nitrate, it supplies calcium as the cation and is less prone to explosive decomposition, but both require careful management. Proper personal protective equipment and spill controls are advised in industrial and agricultural settings.

Notable facts: its dual role supplying both nitrogen and calcium makes it particularly valuable where crop calcium nutrition is important, and its high solubility makes it suitable for foliar and fertigation applications.