SOIL PHYSICS 

 LABORATORY MANUAL 



STOCK SOILS AND THEIR PREPARATION 



The soils commonly used are (1) a sand or sandy loam, 

 (2) a gray silt or gray silt loam, (3) a brown silt loam, (4) a 

 clay or clay loam, and (5) peat. Any other soils may be used. 

 The selection of soils for class use should depend largely on the 

 locality. The prevailing types in the vicinity should be used. 



These soils should be thoroughly air-dried, and ground suffi- 

 ciently fine to pass through a 2-mm. sieve. 



COLLECTING SOIL SAMPLES 



In collecting samples of soil a one and one-half or a two-inch 

 auger with an extension, making it 40 inches long, should be 

 used. Select the place for sampling and remove any vegetation. 

 Collect the surface soil to -a depth of approximately 6| inches, 

 -or to the plow line. Enlarge the hole by reaming out with the 

 auger so that the subsurface soil may be removed without 

 coming in contact with the surface soil. Take the subsurface 

 sample to the depth of 20 inches. This gives the subsurface 

 131 inches, or twice that of the surface. It may be desirable in 

 some cases to take the subsurface to the natural subsoil line, as 

 indicated by the change in color and physical composition, usu- 

 ally from 15 to 20 inches in depth. Enlarge and clean out the 

 hole as before and collect the subsoil to a depth of 40 inches. 

 It may be convenient to divide the subsoil into two equal parts 

 of 10 inches each. In collecting samples for moisture determi- 

 nations, expose the soil to the air as little as possible before 

 putting in jars. 



