34 TOBACCO CULTURE. 



Notwithstanding the material differences in the com 

 position of tobacco grown in different places, particularly 

 as to the total quantities of the different plant-food constitu- 

 ents removed from an acre of land; all practical planters 

 now agree that the crop requires large amounts of potash 

 as compared with phosphoric acid. 



The conclusions of accepted authorities may be thus 

 stated: The demands of the crop for phosphoric acid are small, 

 for nitrogen they are large, but the greatest demand is for potash 

 in fact, greater than that of any other cultivated plant. 



The general rule of practice for cigar cobacco planters 

 to follow may be stated thus: Nitrogen, 4 to 6 parts, pot- 

 ash, 8 to 15 parts, and phosphoric acid, i to 3 parts. 



This may be more concisely expressed as follows: 



Ammonia 4 to 5 per cent. 



Potash 8 to 9 per cent. 



Available Phosphoric Acid 2 to 4 per cent. 



Commercial fertilizers are valuable as plant food only 

 to the extent that they contain nitrogen, potash and availa- 

 ble phosphoric acid, provided always that proper proportions 

 of these ingredients are used. An excessive amount of any 

 one of these three plant foods in a fertilizer will not make 

 up for the loss caused by the lack of either of the other. 

 The old saying that "a chain is no stronger than its weakest 

 link" applies here, for, the value of any fertilizer will de- 

 pend on the proportions of all three nitrogen, phosphoric 

 acid and potash which it contains, 



