ANALYSIS OF THE SOIL 243 



be considered to be comparatively free from alkali. Certain 

 other plants such as salt grass (Distichlis spicatd) are sel- 

 dom found except on land highly charged with salt, and 

 where found the soil should be thoroughly investigated 

 before an attempt is made to use it for agriculture. Since 

 this question has already been so fully discussed, no de- 

 tails will be given here. Chapter VI should be consulted 

 for further information. 



The Water-table. Alkali lands are often wet. Sur- 

 face accumulations of salt usually result from a rapid 

 evaporation of water which rises from a water- table that 

 is comparatively near the surface. There are soils high 

 in alkali with a water-table hundreds of feet below the 

 surface. In these soils the ground water has nothing to 

 do with the alkali accumulation. Soils are frequently 

 found containing a medium quantity of salt distributed 

 through considerable depth. With the introduction of 

 irrigation and a consequent raising of the water-table to 

 within a few feet of the surface, an ideal condition is pro- 

 vided for a concentration of these diffused salts at the 

 surface. This may render entirely unproductive a soil 

 that previously raised good crops. A thorough knowledge 

 of ground-water conditions is, therefore, important be- 

 fore a person is able to make an intelligent judgment re- 

 garding alkali land. 



Analysis of the Soil. It is impossible to get an adequate 

 idea of alkali land without having a chemical analysis of 

 its water-soluble material. As has already been explained, 

 a superficial examination may be somewhat deceiving, 

 and it is necessary to know the nature and concentration 

 of the salts to considerable depth before being able to tell 

 definitely how the soil will act and whether or not the alkali 

 is likely to cause trouble. The depth to which the soil 



