4 BULLETIN 1293, U. S. DEPARTMENT OF AGRICULTURE 
TEMPERATURE 
Temperatures at the three stations do not vary greatly. The mean 
annual temperature at Williston is 39.2° F., at Dickinson 40.3 : . and 
at Hettinger 41.5°. The low average at Williston results from low 
winter temperatures, the summer temperatures being about equal. 
The factors which affect crops most are the relatively cool summers 
and the low temperatures of winter. Low winter temperatures, 
frequently coupled with a dry soil, make the growing of winter 
grains except rye uncertain, whereas the cool summers are favorable 
to spring-grain production. 
Killing frosts seldom affect grain crops at these stations, but 
corn, fruits, or other tender plants sometimes are injured by late- 
spring or early-fall frosts. The average period between the last 
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Fig. 1. — Diagram of the dry-land rotation field at the suhstation at Dickinson. N. Dak. 
The lettering shows the cropping in 1923. The following abbreviations are used to in- 
dicate the preparation : SP=Spring plowed, FP=fall plowed, DC=disked cornland. 
F=fallowed, and GM=green manured 
frost of spring and the first frost of fall is 112 days both at Dick- 
inson and Hettinger and 126 days at Williston. This does not 
mean, however, that plant growth is limited to these periods, as all 
but the most tender vegetation may survive temperatures several 
degrees below freezing. The longer frost-free period at Williston 
is accounted for by the fact that the altitude of this station is only 
1,875 feet, whereas that of Hettinger is 2,675 feet and Dickinson 
2.543 feet. 
SOILS 
The soils of the stations are typical of the good farm lands of the 
area. They are described as dark-brown loams, varying in texture 
from fine sand to clay. Like other soils of the area, they are high in 
fertility and characterized by a definite lime-carbonate accumulation 
at a depth of from 14 to 16 inches. The soil at Williston is compara- 
tively light, that at Dickinson is intermediate, and that at Hettinger 
heavy. In a reconnaissance soil survey of western North Dakota 2 the 
2 Lapbam. M. IF. and others. Soil survey of western Xortli Dakota. F. S. Dept. Agr., 
Bur. Soil., ii, 1,1 Oper., 1908. Adv. Sheets. 80 p.. illus. 1910. 
