SOIIv DEFICIENCIES 



259 



Other salts than those mentioned above may be present in 

 alkali. Calcium chloride, for example, may give the soil a black 

 color, and have the appearance of black alkali, but it is not as 

 injurious as carbonate of soda. Nitrate of soda has been found 

 in Colorado soils. 1 



Origin of Alkali. Alkali conies originally from the decompo- 



Fig. 63. Alkali spot remaining in reclaimed field, Utah. Bureau of Soils. 



sition of rocks. In climates where there is an abundance of rain, 

 and much water passes through the soil, the alkali salts are 

 1 Headden, Bulletin 178, Colorado Station. 



