210 NITROGENOUS FERTILIZERS 



quartz down through which water trickles. Nitric acid is 

 formed according to the following equation: 



3N0 2 + H2O = 2HNOs + NO. 



This nitric acid is neutralized by limestone and milk of 

 lime. The resulting solution of calcium nitrate is evaporated 

 to the proper concentration, then cooled, and the resulting 

 product placed on the market as lime nitrate, Ca(N0 3 )2, 

 containing about 13 per cent, nitrogen. There is also made 

 another product called basic calcium nitrate by adding lime 

 to a hot solution of calcium nitrate. This product has a 

 formula (CaO) 2 N 2 05, or expressed graphically: 



Ca— O— Nf 

 I % 



O 



Ca— O— Nf 

 ^O 



It contains about 10 per cent, nitrogen and does not absorb 

 moisture to such an extent as the normal nitrate, although 

 the special process employed in manufacturing the lime 

 nitrate fertilizer is successful in making a product which 

 is fairly satisfactory to handle. Pure, crystallized calcium 

 nitrate is deliquescent and not easily handled. 



(6) Availability. — Like nitrate of soda, nitrate of lime, 

 both normal and basic, is readily soluble in water and hence 

 immediately available to plants, it being in the form best 

 adapted to plant use and in every way similar to nitrate of 

 soda in effectiveness on crops. It is not readily retained in 

 the soil and hence can be lost by leaching. 



(c) Effect on the Soil. — Although there is little choice 

 between sodium nitrate and calcium nitrate as far as avail- 

 ability and direct effect on the plant is concerned, there is 

 a decided choice in favor of the latter fertilizer on account 

 of its action in the soil. It was seen that sodium nitrate, 

 although serving to release insoluble stores of potassium and 

 to neutralize acidity, has a tendency to deflocculate heavy 

 soils and render them difficult to handle. Calcium nitrate 



