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 
Fic. 7. The water in the large bottle 
would be required to produce the 
grain in the small bottle. 
plant. Let us say, however, 
straw and kernels are equal. 
conditions for the 
production of one 
pound of dry 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 dry-farm- 
ing seldom forms 
quite one half of the 
weight of the whole 
that the weights of 
Then, to produce one 
