B. P. I.—39. G. F. P. I.—97. 
CULTIVATED FORAGE CROPS OF THE NORTH- 
WESTERN STATES. 
DESCRIPTION OF THE REGIONS. 
The present bulletin discusses briefly the forage resources of that 
portion of the United States extending from Colorado and central 
California north to Montana and Washington. The whole area may 
be divided into several well-marked regions, each of which will be 
discussed separately. Each region has its characteristic climate, 
topography, and physiognomy. The climate depends chiefly upon 
the latitude, altitude, and the amount and distribution of the rainfall. 
The latter factor is greatly influenced by the presence and trend of the 
mountain chains and the direction of the prevailing winds. In gen- 
eral the winters are longer and more severe as the latitude increases. 
The climate is cooler at higher altitudes. The Coast Range, Sierra 
Nevada, and Cascade Mountains rob the winds of their moisture as 
they blow from the Pacific Ocean eastward, thus producing an arid 
region in the interior. The physiognomy, or general appearance, 
depends very largely upon the character of the vegetation, which in 
turn varies according to the climate and soil. The low and scattered 
vegetation of the sagebrush plains of the Great Basin region, the 
forests of the Pacific slope, and the buffalo-grass sod of the Great 
Plains are examples of the characteristic physiognomy. It is not the 
intention to discuss minutely the physical geography of the region, 
but these preliminary remarks will call attention to the basis of the 
regional classification. The relation of these physical factors to the 
agriculture of the individual regions will be referred to later. 
The soil conditions are more local in their effect than the above-men- 
tioned factors, but in some cases may profoundly modify the growth 
of plants. The soil factors may be physical, such as its ability to hold 
or transport water, the size of the particles, and character of the sub- 
soil; or chemical, depending upon the chemical constituents, such as 
the presence of excessive amounts of carbonate of soda, salt, or other 
substances, producing alkali soils. One other factor should be men- 
tioned, which, though not included among those determining the clas- 
sification into areas, is nevertheless of vast importance in its relation 
to agriculture. This is artificial water supply or irrigation. 
