HOW PLANTS INDICATE THE SOIL 



61 



cultural plants without reclamation methods first being 

 applied. 



These characteristic plants are generally recognized by 

 the farmers of the district in which they occur, but the exact 

 qualities of the soil and the possibilities of its reclamation 

 are not so often known. The kind of plant also varies 

 considerably even within relatively short distances be- 



FIG. 8. ALKALI CRUSTS AT THE SURFACE PREVENTING THE 

 GROWTH OF PRACTICALLY ALL VEGETATION. 



cause of difference in soil or drainage. Changes in climate 

 or altitude also influence the type of plant that indicates a 

 particular type of soil. 



A number of studies of the characteristic plants of alkali 

 lands have been made together with the kind and amounts 

 of alkali present in soils on which they grew. From these 

 studies fairly intelligent conclusions may be drawn as to 

 the kind and quantity of alkali in the soil without making 

 a chemical analysis. 



In using native vegetation to indicate the alkalinity of 

 a soil, however, it is essential that judgment should not be 



