Nitrate of Soda 



necessary to buy it in a really assimilable form and 

 to use it only in such a way that there will be no 

 fear of loss in the drains. 



All these products should be bought on analysis 

 or origin. Often the nitrogen in organic compound 

 manures will be questionable because it may be 

 present in a form either slowly or partially assimil- 

 able or even almost entirely inassimilable. 



Care should be taken, however, not to abuse the 

 use of nitrogenous manures, specially on cereals, be- 

 cause in this case it will cause a tendency to lay the 

 com. It is also necessary to take care not to mix 

 nitrogenous manures which are susceptible to loss, 

 with others which will promote it, because such 

 losses are at times very considerable. 



Nitrate of Soda. 



Nitrate of soda or Chili saltpetre comes from Chili, 

 as its name indicates. It is still the most abundant 

 source of nitrogen for agricultural purposes among 

 the commercial manures. About 2,000,000 tons are 

 exported per annum, but in spite of that there is still 

 enough to last nearly another hundred years. It is 

 extracted from beds of salts formed on a high plateau 

 at an elevation of nearly 3300 feet, situated between 

 the Andes and the coastal range on the Pacific 

 border, in a hot climate, where it rains on an average 

 only about once in six or seven years. Iquique and 

 Antofagasta are the chief ports of exportation. 



In this hot, rainless climate, the nitrate is formed 

 by nitrification of the organic matter which is formed 

 in the soil of the higher part of the plain. The 

 rain water rushing down from the mountains has 



33 D 



