78 DRY-FARMING 



of aridity increase. Tiie}^ are less marked as we go 

 eastward or westward toward the regions of more 

 abundant rainfall; that is to say, the most highly 

 developed arid soils are found in the Great Basin 

 and Colorado River districts. The least developed 

 are on the eastern edge of the Great Plains. 



The fudging of soils 



A chemical analysis of a soil, unless accompanied 

 by a large amount of other information, is of little 

 value to the farmer. The main points in judging a 

 prospective dry-farm are: the depth of the soil, the 

 uniformity of the soil to a depth (>f at least 10 feet, 

 the native vegetation, the climatic conditions as 

 relating to early and late frosts, the total annual rain- 

 fall and its distribution, and the kinds and yields of 

 crops that have been grown in the neighborhood. 



The depth of the soil is best determined li}'' the use 

 of an auger (Fig. 21). A simple soil auger is made 

 from the ordinar}' carpenter's auger, 1^ to 2 inches 

 in diameter, by lengthening its shaft to 3 feet or 

 more. Where it is not desirable to carry sectional 

 augers, it is often advisable to have three augers 

 made : one 3 feet, the other 6, and the third 9 or 10 

 feet in length. The short auger is used first and the 

 others afterwards as the depth of the boring in- 

 creases. The boring should l)e made in a large 

 number of average places — preferably one boring or 



