62 DRY-FARMING 
developing the principles upon which successful dry- 
farming rests. Further, it may be said that while 
in the humid East the farmer must be extremely 
careful not to turn up with his plow too much of 
the inert subsoil, no such fear need possess the 
western farmer. On the contrary, he should use 
his utmost endeavor to plow as deeply as possible 
in order to prepare the very best reservoir for the 
falling waters and a place for the development of 
plant roots. Figure 18 shows graphically the dif- 
ference existing between the soils of the arid and 
humid regions. 
Gravel seams.—It need be said, however, that 
in a number of localities in the dry-farm territory 
the soils have been deposited by the action of running 
water in such a way that the otherwise uniform 
structure of the soil is broken by occasional layers 
of loose gravel. While this is not a very serious 
obstacle to the downward penetration of roots, it 
is very serious in dry-farming, since any break in 
the continuity of the soil mass prevents the upward 
movement of water stored in the lower soil depths. 
The dry-farmer should investigate the soil which he 
intends to use to a depth of at least 8 to 10 feet to 
make sure, first of all, that he has a continuous soil 
mass, not too clayey in the lower depths, nor broken 
by deposits of gravel. 
Hardpan. — Instead of the heavy clay subsoil of 
humid regions, the so-called hardpan occurs in 
