100 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



The line of separation between these two types (which may 

 consist of a narrow strip of intermediate soil) is then outlined on 

 the map. Other areas are outlined in the same manner. 



The identification of the types is aided by physical analysis. 

 It is, of course, not possible to make a great number of types in a 

 given area, and a certain latitude must be allowed, between which 

 limits the soil may vary. As a rule the different types of soil and 

 their properties are very well known to the farmers in the area 

 surveyed. So far the types have been largely based upon physical 

 differences as observed by the surveyor, with no great emphasis 

 on the physical analysis. 



Value of Soil Survey. A soil survey outlines the various types 

 of soil in the area surveyed, shows their extent and relative 

 importance, and exhibits, to some extent, the soil problems of the 

 locality. It also indicates the adaptation of the various types of 

 soil to different crops. 



A soil survey should not be considered as an end in itself, but 

 as a means of ascertaining the various types of soil in the area, 

 as a basis for further study. Thorough chemical, physical, 

 bacteriological, and other studies should then be made of the 

 various types of soils. The results of these studies can then be 

 applied to definite areas. 



Soil surveys also show what crops may possibly be grown upon 

 the various types of soil in question. Information secured upon 

 the same types in other districts, may be made available. Results 

 of fertilizer experiments made upon definite types of soil can be 

 applied to similar types of soils elsewhere, but not indis- 

 criminately, as has been too often done. Other experimental 

 work can also be definitely applied to the kind of soil on which it 

 is carried out. Relations between the various types should be 

 traced so that work on one type may be applied to other types. 



