THE SOIL AND THE CROP 43 



Problems. 



1. Suppose a load of barnyard manure weighs a 

 ton. How many pounds of nitrogen in it? Of phos- 

 phoric acid ? Of potash ? 



2. How much of each of the above m 15 loads? 

 20 loads ? 50 loads ? 



3. How many loads of manure were hauled onto 

 your land last year? How much of each fertilizing 

 substance was supplied ? 



4. If you put 15 loads on an acre, how much of 

 each fertilizing substance per acre? 



5. Suppose you harvested 50 bu. of corn per acre. 

 How much of each fertilizing substance did you take 

 off with the crop ? 



6. Was your soil richer or poorer after the corn 

 was harvested? Did you take off more than you put 

 on? How much of each kind? 



7. How much of each of these fertilizing sub- 

 stances is taken off with a 25 bu. crop per acre of 

 wheat ? A 40 bu. crop of barley ? 



8. How many loads of manure per acre are neces- 

 sary to restore the fertility lost when a 25 bu. per acre 

 wheat crop is harvested? 



9. Pupils will furnish data for similar problems. 



