732 SOILS: PROPERTIES AND MANAGEMENT 



the soil and the other the subsoil. If there is a marked 

 change in appearance or texture in the subsoil, other divi- 

 sions of the sample may be made. Usually a composite 

 of a number of borings over an area of several square 

 rods, or even of several acres, may be necessary in order 

 to secure an accurate sample and to obtain enough ma- 

 terial. A composite of several representative borings 

 made over a considerable area gives a more nearly accu- 

 rate sample than is possible in a single boring. The 

 possibility of local variations is very great, and their 

 effect is reduced when composite sampling is done. 



Each bag should bear a tag which is given a number 

 and on w^hich is placed the name of the type, the location 

 of the sample in the section, and a brief description of the 

 material. The same data are recorded in the field note- 

 book, which is finally preserved as a part of the permanent 

 office record of the survey. The description in the note- 

 book may be amplified more than is possible on the tag. 

 The location where each sample was taken should be 

 accurately marked on the field map by a number corre- 

 sponding to the number of the sample. Usually^ each 

 sample is given a number^ and the parts are indicated by 

 a letter, proceeding from the surface downward. Where 

 the material is very wet and likely to become lumpy 

 when dry, it may be dried in a thin layer before being 

 finally bagged for shipping or preservation. Care should 

 be bestowed on every part of the operation of collection, 

 describing, numbering, tagging, tying, and shipping, in 

 order to insure accuracy and permanency of the record. 



The soil auger is generally used in taking the sample 

 and in examining the soil section. The worm of the 

 auger is bored into the soil until it is filled. It is then 

 withdrawn and the soil is removed. The soil may be 



