4 COLORADO AGRICULTURAL EXPERIMENT STATION 
this was not a simple problem because Colorado presents all possible 
conditions of altitude variation, between an altitude of approximately 
3,500 feet and over 14,400 feet. These variations in altitude alone 
bring forth conditions varying from a temperate to an arctic climate. 
The climatic variations due to altitude are not the sole climatic varia¬ 
tions to be met in a study of this kind. The rainfall varies from a 
minimum of less than ten inches to a maximum of over 30 inches in 
some localities. We have dry land agriculture and irrigated agricul¬ 
ture represented in practically every section under these various con¬ 
ditions of altitude and rainfall. 
Plate No. 3. 
