BULLETIX 307, U. S. DEPAETMEXT OF AGEICULTUEE. 
influences vary in amount from only slight injury to total crop failure 
and in extent from restricted localities to extended areas. A year 
seldom occurs in which as a result of these influences there is not 
some restriction to the growth and development of the corn plant. 
In favorable seasons and localities good yields are frequently ob- 
tained, but efforts to 
grow corn for grain 
with the natural rain- 
fall of this area have 
often resulted in par- 
tial or total crop fail- 
ures. It is to be ex- 
pected that the same 
conditions and results 
will in a large measure 
continue to occur. 
In those locahties 
where it has been pos- 
sible to supplement 
the natural rainfall 
with irrigation, corn 
is raised with consid- 
erable success. Fail- 
ures which at first oc- 
curred on account of 
carelessness and the 
unintelligent use of 
water and from at- 
tempting to grow va- 
rieties not adapted to 
the locality are being 
corrected as knowl- 
edge is gained from 
experience. 
The part of the 
Great Plains area 
best adapted to corn 
production is the 
north-central section. 
(Fig. 1.) In this sec- 
tion, notwithstanding the frequent failures of corn to produce grain, 
the area devoted to its production has increased until corn is one of 
the most generaUy and widely grown crops. Corn is less successful in 
the southern Plains area, as drought injury is more severe, on account 
of the higher evaporation rate. Corn does not successfully compete 
in production with the grain sorghums under these conditions, and 
Fig. 1.— Sketch map of the Great Plains area, showing the annual 
rainfall (heavy black lines) and the region (dotted section) to 
which the varietal adaptations of corn discussed in this bulletin 
apply. 
