SUMMARY ON DRY-FARM SOILS 73 
leaching by downward drainage is very small in 
countries of limited rainfall. 
Further, arid soils show no real difference between 
soil and subsoil; they are deeper and more perme- 
able; they are more uniform in structure; they 
have hardpans instead of clay subsoil, which, how- 
ever, disappear under the influence of cultivation; 
their subsoils to a depth of ten feet or more are as 
fertile as the topsoil, and the availability ‘of the 
fertility is greater. The failure to recognize these 
characteristic differences between arid and humid 
soils has been the chief cause for many crop failures 
in the more or less rainless regions of the world. 
This brief review shows that, everything considered, 
arid soils are superior to humid soils. In ease of 
handling, productivity, certainty of crop-lasting 
quality, they far surpass the soils of the countries 
in which scientific agriculture was founded. As 
Hilgard has suggested, the historical datum that the 
majority of the most populous and powerful histor- 
ical peoples of the world have been located. on soils 
that thirst for water, may find its explanation in the 
intrinsic value of arid soils. From Babylon to the 
United States is a far cry; but it is one that shouts 
to the world the superlative merits of the soil that 
begs for water. To learn how to use the ‘‘desert” 
is to make it ‘‘blossom like the rose.” 
