18 



DRY-FARMING 



Crop-producing power of rainfall 



If this conclusion, that not more than 750 pounds 

 of water are required under ordinary dry-farm 



conditions for the 

 production of one 

 poimd of dr}' matter, 

 be accepted, certain 

 interesting calcula- 

 tions can be made 

 respecting the pos- 

 sibilities of dry-farm- 

 ing. For example, 

 the production of one 

 bushel of wheat will 

 require 60 times 750, 

 or 45,000 pounds of 

 water. The wheat 

 kernels, however, 

 cannot be produced 

 without a certain 

 amount of straw, 

 which under con- 

 ditions of dr}'-farm- 

 ing seldom forms 

 ciuite one half of the 

 weight of the whole 

 plant. Let us say, however, that the weights of 

 straw and kernels are eciual. Then, to produce one 



Fig. 7. The water in the hirpe Vjottle 

 would be required to produee the 

 grain in the small bottle. 



