48 



CONSERVATION OF THE SOIL 



EXERCISE 



1. What is the loss in plant food to a farmer who burns 

 a straw stack weighing 20 tons ? 



2. How much plant food does a farmer lose when selling 

 the fodder from a 10-acre field averaging 50 bu. per acre ? 



3. What is the value of the plant food returned to the 

 soil when 25 A. of clover, averaging 1 ton per acre, are 

 plowed under ? 



4. How does the value of 1 ton of fresh farm manure 

 compare with that of 1 ton of cowpeas plowed under for fer- 

 tilizer ? (A ton of fresh manure shrinks one half in weight 

 during the first six months when exposed to the weather.) 



5. How does 1 ton of barnyard manure compare in soil 

 fertility with 1 ton of wheat straw ? 



6. What is the loss on 10 tons of piled manure exposed 

 6 or more months ? (Make an estimate based on the com- 

 mercial value of plant food given in the table.") 



