12 CULTIVATED FORAGE CROPS OF THE NORTHWEST. 



whose cultivation should be extended. Among these may be men- 

 tioned the Canada field pea, rape, and awnless brome grass. 



Great Basin. 



This reo-ion extends from the Sierra Nevada Mountains to the Rockv 

 Mountains, and from Arizona north into southeastern Oregon and 

 southern Idaho. It is an arid region, having an annual rainfall of 

 less than 15 inches over the greater part, and in central Nevada of 

 less than o inches. The altitude of this great plateau is about 5,000 

 or 6,000 feet, with numerous mountain chains rising :2,000 or 3,000 

 feet higher. There are several lakes or depressions having no outlet, 

 the largest of which is the Great Salt Lake of Utah. 



In such localities there is usually an excessive accumulation of min- 

 eral salts, known as alkali. The water of the streams flowing into 

 these depressions holds these salts in solution. l)ut deposits them upon 

 the surface of the soil when the water evaporates. These alkali soils 

 modify the vegetation. Each species of plant is able to withstand a 

 certain amount of alkali in the soil upon which it grows. If the amount 

 is in excess of this limit, the plant can not exist. Consequently, the 

 native vegetation gives a fair index of the alkaline condition of the 

 soil. The presence of saltbushes {Atriplex spp.), salt grass {Distlchlls 

 Kpicata)^ and grease wood {Sa/'cohatus vermiculatus) indicates a strongly 

 alkaline soil. A still larger amount of soluble mineral matter prevents 

 the growth of even the salt plants, and in such cases the soil is devoid 

 of vegetation. 



The prevailing vegetation over the whole region, except in the 

 mountains and upon the abov'e-mentioned alkali soils, is the sagebrush 

 {Artemisia tridentata). Hence such localities are called sagebrush 

 plains. As in the case of the two preceding areas the chief agricul- 

 tural industrv is the raising of stock — cattle, sheep, and horses. The 

 latter class of stock is of importance in certain localities, but is rela- 

 tively unimportant over the whole area. The sheep are herded in the 

 mountains in summer, where there is water, and upon the deserts in 

 winter, where there is snow. There are vast areas where stock can 

 not graze on account of the insufficiency of food or water, or both. 



Alfalfa is grown in large quantities under irrigation in the valleys 

 and is practically the only supplemental forage for all kinds of stock. 

 In some of the larger valleys other crops are raised, such as grain and 

 sugar beets. As an example, the highly cultivated Cache Valley, in 

 northern Utah, mav be mentioned. In a few favored localities drj- 

 farming may be carried on successfully. This, however, is where 

 there is seepage and conservation of water from the winter snow on 

 the mountains. In the Cache Valley there are numerous instances of 

 grain and alfalfa fields on the hillsides above the canals. 



