1916I 



SHULL— SOILS 



more uniform behavior might be obtained under experimental con- 

 ditions. The other seeds used were obtained from local seedsmen 

 under the names given. 



The soils used in the major portion of the work will be charac- 

 terized briefly. As a representative of heavy clay soil, the subsoil 

 of the Oswego silt loam was chosen. Specimens of this subsoil were 

 obtained from Riley County, Kansas, on an area about 2 miles 

 west of Manhattan. The Oswego silt loam is a residual soil derived 

 by weathering from underlying unbedded shales and sandstone, 

 with the shales predominating. Its subsoil forms a hard, compact, 

 brittle soil, with a gray to dark brown color. The average com- 

 position as determined by mechanical analysis is given in table I. 



The moisture equivalent is 35.2 per cent, and the wilting 

 coefficient is 19. 1 per cent. The general details in regard to the 

 Oswego silt loam and its subsoil may be obtained from the Eighth 

 Report, Field Operations of the Bureau of Soils (11). 



As a contrast to the heavy silt clay, a fine quartz sand, the 

 no. 2/0, which is manufactured by the Wausau Quartz Company 

 from quartz rock, was chosen. This grade passes through a 124- 

 mesh screen, and over a 147-mesh screen. The average, diameter 

 of the particles is very close to 0.10 mm. The chemical analysis 

 given below shows it to be a very pure quartz sand. 



Silicon dioxide 99- 07 per cent 



Iron oxide o. 17 



Aluminum oxide o. 52 



Hygroscopic moisture o. 06 



Undetermined 0.18 



The moisture equivalent is 2.41 per cent and the wilting co- 

 efficient 1.3 per cent. 



