268 CLARENCE F. KORSTIAN 



capabilities of crop production, the type of land that is charac- 

 terized by the wire-grass association is classed as the most valu- 

 able agricultural land in eastern Colorado. That type of short- 

 grass land which bears a considerable growth of wire-grass or 

 Psoralea is classed with or very close to the wire-grass associa- 

 tion land, since the presence of these plants indicate conditions 

 intermediate between those of the typical wire-grass association 

 and those indicated by the typical grama — buffalo-grass asso- 

 ciation. On new land where crops have not yet been produced, 

 the character, growth, and condition of the native vegetation are 

 the best possible indicators of crop production, either positive 

 or negative, since plant growth is the ultimate criterion of the 

 suitability of the physical environment. 



Kearney and others' have gone still farther in the scientific 

 study of native vegetation from the indicator point of view in 

 suggesting the possibility of correlating the distribution of the 

 vegetation with the physical and chemical properties of the 

 soil and the utilization of such a correlation in the classification 

 of the agricultural potentialities of the land. The investigations 

 in the Great Basin of central Utah were directed toward the 

 solution of the problems of what types of vegetation indicate 

 conditions of soil moisture favorable or unfavorable to dry 

 farming and what types indicate the presence or absence of 

 alkaline salts in sufficient quantities to injure cultivated crops. 

 The results of the studies in Tooele Valley show that the dif- 

 ferent types of native vegetation indicate the conditions of soil 

 moisture and alkalinity of the land on which they are found 

 and consequently provide a basis for estimating its potentiali- 

 ties for crop production. A good stand and growth of sagebrush 

 (Artemisia tridentata) indicates land .that is well adapted to 

 both dry and irrigation farming. Where the stand of sage- 

 brush is open and the growth poor the good soil is usually too 

 shallow for profitable crop production, at least without irrigation. 

 Dry farming is precarious on land covered by the Kochia (Kochia 



^ Kearney, T. H., Briggs, L. J., Shantz, H. L., McLane, J. W. and Piemeisel, 

 R. L. Indicator Significance of Vegetation in Tooele Valley, Utah. Journal of 

 Agricultural Research 1 : 365-417. 1914. 



