CEREAL EXPERIMENTS AT DICKINSON, N. DAK. 3 
from the open range to small farms and ranches. In 1893 it sup- 
ported 3 banks; in 1908, 5 banks; and in 1913, 98 banks. This 
rapid growth is largely due to the great influx of settlers who have 
practiced general farming instead of exclusive grazing. Although 
there are still large tracts where, because of the roughness of the 
land and its consequent lack of adaptability to diversified farming, 
stock raising is still a dominant industry, this section now pro- 
duces 8,000,000 to 10,000,000 bushels of wheat annually. 
GENERAL PHYSICAL FACTORS. 
A study of the crop yields for the series of years here presented 
necessitates some knowledge of the factors which have influenced the 
growth of the crop. The most important physical factors are (1) 
the soil; (2) the annual rainfall and its distribution; (8) the evap- 
oration, especially that during the crop season; (4) the wind, with 
special reference to that which passes directly over the ground 
surface during the growth of the crop; and (5) the temperature, 
especially the spring and fall frosts which limit the growing season. 
These data regarding the factors recorded at the Dickinson substa- 
tion are summarized herewith. 
SOIL. 
The soil of the Dickinson substation is reasonably typical of a 
_ large portion of the soils of the northern Great Plains region lying 
west and south of the Missouri River, which are mostly residual. 
That at Dickinson is classed in the Morton series. It varies from 
a clay loam to a fine sandy loam. Mechanical analyses of several 
samples taken from the substation show the proportion of clay to 
vary from 9 to 25 per cent; silt, 15 to 47 per cent; very fine sand, 
13 to 29 per cent; fine sand, 10 to 31 per cent; medium sand, 1 to 11 
per cent; and coarse sand, 0.5 to 3 per cent. The soils are seen to 
contain a considerable proportion of clay and silt, but not so much 
that they are difficult to work; and they would ordinarily be called 
light. The soil varies in depth from 8 inches to about 10 feet. 
The color is usually black, but in places it is quite brown and in 
others gray. The subsoil varies from a clay to a fine sand. Chemi- 
cal analyses which have been made show the soil to be fairly fertile. 
The percentage of lime is considerably greater than that found in 
soils of more humid regions, but both it and the potash content 
are less than those generally found in arid and semiarid soils. The 
soils are deficient in humus, owing to the scanty growth of native 
vegetation. : 
NATIVE VEGETATION. 
- The native vegetation on this soil was principally blue grama 
(Bouteloua oligostachya), prairie June-grass (Aoeleria cristata) , 
Buckley’s spear-grass (Poa buckleyana), and needle grass (Stipa 
