PRINCIPLES OF MANURING. 



51 



Below are given the names of most of the principal manures sold 

 in our markets, arranged in classes as indicated above. 



Sources and Character of the Various Fertilizers. 



Perhaps a brief description of the source and character of the com- 

 mercial fertilizers in most common use may not be out of place. 



Nitrate of soda, or Chili saltpetre, is obtained from the immense- 

 beds of that substance found in vSouth America. The nitrogen exists 

 in it as nitric acid (the aqua fortis of commerce,) and is united to 

 soda. In the saltpetre used medicinally, the nitric acid is united to 

 potash instead. Nitrate of soda should contain 15 to 16 per cent, of 

 nitrogen, unless largely diluted with some other substance. It is 

 veiy eas}' to do this with common salt, and the fraud escape detec- 

 tion by any ordinary method of examination. As common salt is 

 much the cheaper material there is a strong temptation to such dis- 

 honesty. The nitrogen purchased in nitrates costs more per pound : 

 than when bought in any other form. In such combinations it is in 

 a condition to be immediately' used b}- plants. It should be remem- 

 'bered, however, that the soil has but little power of retaining nitric 

 acid, and therefore when nitrogen is used in this form it should not 

 be applied to the land very long before it will be needed b}" the 

 growing crop, else it ma^' be leached out and carried off in the drain- 

 age water. 



Sulphate of ammonia is obtained from the waste products of gas 

 manufacture. The nitrogen in the form of ammonia is combined 

 with sulphuric acid (oil of vitriol), and costs less than when bought 

 in Chili ; saltpetre being valued by the Connecticut Experiment Sta- 

 tion at 3| cts. less per pound. A good sample of sulphate of ammo- 

 nia should contain 20 p3r cent, of nitrogen, but like nitrate of soda., 

 can be easily diluted with sevei'al cheaper substances. Ammonia is: 

 not leached from the soil like nitric acid, only to the extent that it is 

 oxidized and converted into the latter ; therefore its application 

 some time previous to the time of planting or sowing is not so dan- 



