34 DRY-FARMING 
per cent more receives from 20 to 30 inches under 
conditions that make dry-farming methods necessary. 
A total of about 65 per cent of the earth’s land sur- 
face is, therefore, directly interested in dry-farming. 
With the future perfected development of irrigation 
systems and practices, not more than 10 per cent 
will be reclaimed by irrigation. Dry-farming is 
truly a problem to challenge the attention of the 
race, 
