THE EARTH'S BOUNTY 



Commercial nitrogen is valued at 15 cents, 

 phosphoric acid at 6 cents, and potash at 4 1 /2 

 cents per pound; and it has been estimated 

 that the amount and value of manure pro- 

 duced per 1,000 pounds of live weight of dif- 

 ferent animals is: 



These estimates are based on droppings 

 from animals of all ages. The fertilizing 

 value would be much greater if manure from 

 full-grown animals, in normal condition, had 

 been considered, for they do not require any 

 of the nitrogen, phosphoric acid, or potash; 

 therefore, nearly all these ingredients pres- 

 ent in the material fed pass through the body 

 without deduction. On the other hand, grow- 

 ing animals and milch cows retain from 25 to 



114 



