CALCIUM NITRATE

A white deliquescent compound, Ca(NO3)2, that is very soluble in water; cubic; r.d. 2.50; m.p. 561°C.

 

It can be prepared by neutralizing nitric acid with calcium carbonate and crystallizing it from solution as the tetrahydrate Ca(NO3)2.4H2O, which exists in two monoclinic crystalline forms (α, r.d. 1.9; β, r.d. 1.82).

 

There is also a trihydrate, Ca(NO3)2.3H2O. The anhydrous salt can be obtained from the hydrate by heating but it decomposes on strong heating to give the oxide, nitrogen dioxide, and oxygen. Calcium nitrate is sometimes used as a nitrogenous fertilizer.

 

Calcium nitrate, also called Norgessalpeter (Norwegian saltpeter) is the inorganic compound with the formula Ca(NO3)

 

2. This colourless salt absorbs moisture from the air and is commonly found as a tetrahydrate.

 

It is mainly used as a component in fertilizers. Nitrocalcite is the name for a mineral which is a hydrated calcium nitrate that forms as an efflorescence where manure contacts concrete or limestone in a dry environment as in stables or caverns.

 

[1]

Production and reactivity

Norgessalpeter was the first synthetic nitrogen fertilizer compound to be manufactured. Production began at Notodden, Norway in 1905. Most of the world's calcium nitrate is now made in Porsgrunn. It is produced by treating limestone with nitric acid, followed by neutralization with ammonia:

CaCO3 + 2 HNO3 → Ca(NO3)2 + CO2 + H2O

It is also a byproduct of the Odda Process for the extraction of calcium phosphate:

Ca3(PO4)2 + 6 HNO3 + 12 H2O → 2 H3PO4 + 3 Ca(NO3)2 + 12 H2O

Like related alkaline earth metal nitrates (as well as LiNO3), calcium nitrate decomposes upon heating to release nitrogen dioxide:[1]

2 Ca(NO3)2 → 2 CaO + 4 NO2 + O2 ΔH = 369 kJ/mol

 

Use in fertilizer

 

The fertilizer grade (15.5-0-0 + 19% Ca) is popular in the greenhouse and hydroponics trades; it contains ammonium nitrate and water, as the "double salt" 5Ca(NO3)2.NH4NO3.10H2O. Formulations lacking ammonia are also known: Ca(NO3)2.4H2O (12.8-0-0 + 18.3%Ca). A liquid formulation (9-0-0 + 11% Ca) is also offered. An anhydrous, air-stable derivative is the urea complex Ca(NO3)2.4[OC(NH2)2], which has been sold as Cal-Urea.

 

 

Features:

           Removing calcium deficiency

           Root development

           Growth of plants

           Preventing bitter pit in apples and flower dropping in flowers

           Suitable for fertigation and foliar application

Calcium Nitrate (I) Fertilizer are known for the following unique features:

          

Calcium Nitrate enhances uptake of potassium, magnesium and calcium from soil as these are positively charged and fixed in soil. Negative charge of nitrate releases them from soil and thus promotes their uptake as solution of calcium nitrate sprayed on leaves to roots also.

          

Nitrate increases soil pH a combined effect of increased pH and strengthening of cell walls by calcium controls cluck root disease in brassica crops.

          

Foliar spray of Calcium Nitrate during critical growth stages prevents bitter pit in apple, prevent flowering and fruit dropping and improves quality form fruit setting onwards.

          

A 4-9 gms/liters water solution can be sprayed on both sides of leaves at 10-15 days interval in the afternoon (4-6 pm.), 2-4 sprays may be sufficient from flowering to fruit setting onwards.