GEOLOGICAL CLASSIFICATION OF SOILS 63 



spar, mica, hornblende, augite, calcite and other minerals 

 are found. 



A few typical analyses are given below which show the 

 variability that may be expected, especially in the nitrogen, 

 phosphoric acid, potash, and lime. 



Table X 



ANALYSES OF AMERICAN LOESS SURFACE SOILS 1 



Whenever moisture relations are favorable, loess is an 

 exceedingly fertile soil. Under heavy cropping, especially 

 when little in the way of organic or mineral matter is re- 

 turned, this soil shows a need of phosphoric acid and lime, 

 the application of which is becoming part of good farm prac- 

 tice in the Central West. Considering the wide extension of 



1 1. Marshall silt loam, Pottawattamie Co., la. 



Bennett, H. H., Soils and Agriculture of the Southern States, 

 p. 332; New York, 1921. 



2. Memphis silt loam, Grenada Co., Miss. 



Eobinson, W. O., et al., Variation in the Chemical Composition 

 of Soils; U. S. Dept. Agr., Bui. 551, June, 1917. 



3. Cherokee silt loam, Cherokee Co., Kan. 



Bennett, H. H., Soils and Agriculture of the Southern States, 

 p. 332; New York, 1921. 



4. Silt loam, Weeping Water, Neb. 



Alway, F. J., and Rost, C. O., The Loess Soils of the Nebraska 

 Portion of the Transition Begion, Part IV; Soil Sci., Vol. I, 

 No. 5, p. 431, May 1916. 



