40 FARM ARITHMETIC. 



pound, phosphoric acid 5 cents a pound, and potash 4 

 cents a pound ? What is the total value of the plant food 

 contained in a ton of manure? 



3. If a farmer puts five loads of manure on an acre, 

 how many pounds of plant food is he returning to the 

 land? How many pounds of each of the elements ? How 

 do the amounts correspond with the number of pounds 

 of plant food taken from the soil by an acre of corn? 

 (See the answers to questions on page 29.) Can corn 

 get nitrogen from any other source than the manure or 

 fertilizer that has been added to the soil? 



ANSWERS TO ABOVE QUESTIONS. 



1. A ton of average barnyard manure contains of 

 nitrogen 10 pounds, of phosphoric acid 6 pounds, of 

 potash 8 pounds ; total 24 pounds. 



2. Nitrogen $2, phosphoric acid 30 cents, potash 32 

 cents; total, $2.62. 



3. Five loads of manure, weighing a ton each and of 

 average quality, contain 120 pounds of available plant 

 food, consisting of nitrogen 50 pounds, of phosphoric 

 acid 30 pounds, of potash 40 pounds. This is about the 

 same amount of phosphoric acid and potash that is taken 

 from the soil by the grain and stalks of a crop of corn 

 yielding 25 bushels and two tons of stalks per acre. 



