12 Nebraska Experiment Station Research Bulletin 19 
in soil fertility are found with the exception perhaps of the 
great Sand Hills Area of north and west central Nebraska, as 
compared with the balance of the State. Special adaptations to 
these soil differences are rather obscure. Some communities 
have certain favorite corns for the very fertile bottom land and 
others for the poorer hills and uplands. The writers have not 
undertaken in these investigations to substantiate these local 
preferences. 
These investigations are especially concerned with the crop 
growing conditions in twelve counties in different parts of the 
State, namely : Richardson, Lancaster, Washington, Thurston. 
Holt, Nuckolls, Kearney, Lincoln, Cherry, Grant, Kimball and 
Dawes. It is for corn grown in these counties that the com- 
parative type studies were made. 
CLIMATE 
The climatic considerations of primary importance in a 
study of the environment as related to the regional adaptation 
of corn are: (1) Temperature, (2) precipitation, and (3) at- 
mospheric power for evaporation. The accompanying climatic 
data are based largely upon observations made by the United 
States Weather Bureau.* The normal climate of any region is 
best represented by the average for a large number of years. 
Thirty or more years have been averaged in the following data. 
Fig. 3 — Normal isotherms for the corn growing season of May, June, July, and 
August. (Degrees F.) 
*The writers are indebted to Director G. A. Loveland of the Nebraska Section of 
the Weather Bureau for access to the records and for help in compilation. 
