THE SO-CALLED ALKALI SPOTS OF THE YOUNGER 

 DRIFT-SHEETS 



O. W. WILLCOX 

 Fort Hancock. N. J. 



The surface of cultivated fields on the younger sheets of glacial 

 drift in Iowa, Wisconsin, Illinois, and Indiana is frequently marked 

 by patches of a white efflorescence which is distinctly hostile to many 

 cultivated plants, particularly corn. These patches have received 

 the name of "alkali spots" from the farmers of the region, to whom 

 they are a source of perplexity and loss. 



Genetically, these "alkali spots" are invariably connected with 

 the small sloughs or lakelets which characterize the extreme topo- 

 graphic youth of drift-sheets. As is well known, the surface of 

 the Wisconsin drift is pitted with countless thousands of these small 

 bodies of water; the Iowan drift bears them in notably smaller 

 proportion, a circumstance in harmony with the more advanced 

 development of the natural drainage of this drift-sheet. In their 

 undrained condition these basins are a hindrance to agricultural 

 operations, although in general the water may readily be removed 

 by drainage; this is being done on an enormous scale in the states 

 mentioned. In a very large number of cases, however, the farmer, 

 after doing away with the standing water, finds the reclaimed land 

 affected by the harmful efflorescence mentioned above. 



Analysis shows the efflorescence to consist of small amounts of 

 sodium chloride and much larger amounts of the carbonates and 

 sulphates of magnesium and calcium; magnesium sulphate is a 

 leading constituent. Sodium carbonate is absent; the efflorescence 

 lacks therefore the character of a true alkali, and the soil infested 

 with it is not an alkali soil, as this term is understood in the semi- 

 arid West. The hostility of the soil of the "alkali spots" to corn 

 is due to the presence of excessive amounts of magnesium salts in 

 the soil moisture. 



The ralson d'etre of the efflorescence is not far to seek. It will be 



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