DRY FARMING 325 



Fill one can full of moist soil and the other to within 

 about one inch of the top with a portion of the same soil. 

 Pour dry dust over the surface of the soil in the second 

 can to the depth of about an inch. Adjust the amount 

 of soil in the two cans so that the system exactly bal- 

 ances. Allow the apparatus to stand over night. The 

 amount of water that must be added to one can to restore 

 a balance represents the water that has been saved by 

 the protective covering of dust the dry earth mulch. 

 Hold the bar horizontally while adding the water. 



The effect of mulches of cut straw, leaves, or other 

 material may be studied in the same way. 



