98 DRY-FARMING 
the somewhat hard, sun-baked soils, and the numer- 
ous drainage channels, formed by successive tor- 
rents, combine to furnish the rains with an easy 
escape into the torrential rivers. Persons familiar 
with arid conditions know how quickly the narrow 
box cafions, which often drain thousands of square 
miles, are filled with roaring water after a compara- 
tively light rainfall. 
The run-off 
The proper cultivation of the soil diminishes very 
greatly the loss due to run-off, but even on such soils 
the proportion may often be very great. Farrel 
observed at one of the Utah stations that during a 
torrential rain — 2.6 inches in 4 hours — the surface 
of the summer fallowed plats was packed so solid. 
that only one fourth inch, or less than one tenth of 
the whole amount, soaked into the soil, while on a 
neighboring stubble field, which offered greater 
hindrance to the run-off, 14 inches or about 60 per 
cent were absorbed. 
It is not possible under any condition to prevent 
the run-off altogether, although it can usually be 
reduced exceedingly. It is a common dry-farm 
custom to plow along the slopes of the farm instead 
of plowing up and down them. When this is done, 
the water which runs down the slopes is caught by 
the succession of furrows and in that way the run- 
off is diminished. During the fallow season the disk 
