204 THE LURE OF THE LAND 



line of change of color, or below the minimum depth 

 of six inches. But should the change of color occur 

 at a greater depth than 12 inches, the soil specimen 

 should nevertheless be removed to the depth of 12 

 inches only, which is the limit of ordinary tillage ; then 

 another specimen from that depth down to the line of 

 change, and then the subsoil specimens beneath that 

 line. The depth to which the last should extend will 

 depend upon circumstances. It is always desirable to 

 know what constitutes the foundation of a soil to the 

 depth of three feet at least, since the question of drain- 

 age, resistance to drought, etc., will depend essentially 

 upon the nature of the substratum. 



It is evident that no rigid definition of the differ- 

 ence between soil and subsoil can be made as the one 

 gradually merges into the other. In general it may be 

 said from the practical point of view that the soil is 

 that part of the surface of the field extending to a depth 

 of nine inches or to the depth turned by good plowing 

 and the subsoil the layer of nine inches in depth im- 

 mediately underneath the soil. 



The Bureau of Soils, of the Department of Agricul- 

 ture, has undertaken a re-classification and naming of 

 types of soils on a vast scale. The number of such dif- 

 ferent types which have already been described is prob- 

 ably more than a thousand. This detail of classifica- 

 tion is wholly unwarranted from a scientific stand- 

 point, since it gives certain geographic names of locali- 

 ties in great numbers to a soil of practically a single 

 type. Only the utmost confusion can result from an 

 attempt to make permanent such finely drawn differ- 

 ences as are found to exist among soils of this kind. 

 The classification which has been given in the preced- 

 ing descriptions is entirely sufficient for both practical 



