RECLAIMING THE EARTH 



year. After the alkali lands of the arid region 

 were proven to be unusually fertile, the further 

 demonstration was made that they were ren- 

 dered unproductive solely by the excess of 

 various salts, that the total depth of these salts 

 was usually not more than four or five feet 

 from the surface, and that not only could these 

 salts be removed to large degree by drainage, 

 but that their re-ascent could be prevented 

 simply by preventing surface evaporation — and 

 this prevention was effected by means of deeper 

 irrigation, called deep-furrow irrigation, the 

 surface being kept dry while the earth around 

 the roots is moist. Then, again, extensive 

 chemical analyses of the waters in different 

 portions of the arid regions were made so that 

 the orchards should not be irrigated with water 

 which, of itself, would work harm to the land. 

 Certain portions of the desert had what is 

 called black alkali, or carbonate of soda, which 

 has been very difficult to combat. It was found 

 that gypsum spread upon such soil neutralized 

 the alkali. Investigation was at once set on 

 foot, and a deposit of the gypsum was found 

 by the station within the borders of the state 

 itself, a never-failing supply. 



245 



