38 SUCCESSFUL FARMING 



Such a classification should meet the needs of an enlightened agriculture. 

 The first classification of the soils of the United States and Canada to be 

 put into extensive use was that devised by the Bureau of Soils of the 

 United States Department of Agriculture, and used extensively in the 

 soil survey of the United States during the past sixteen years. This 

 classification is based upon factors that can be recognized in the field, and 

 has for its ultimate aim the crop adaptation and management of the soil. 



Soil Surveys^ — "A soil survey exists for the purpose of defining, 

 mapping, classifying, correlating and describing soils. The results ob- 

 tained are valuable in many ways and to men of many kinds of occupation 

 and interests. To the farmer it gives an interpretation of the appearance 

 and behavior of his soils, and enables him to compare his farm with ether 

 farms of the same and of different soils. The soil survey report shows 

 him the meaning of the comparison and furnishes a basis for working out 

 a system of management that will be profitable and at the same time 

 conserve the fertility of his soil. To the investor, banker, real estate 

 dealer or railway official it furnishes a basis for the determination of land 

 values. To the scientific investigator it furnishes a foundation knowledge 

 of the soil on which can be based plans for its improvement and further 

 investigation by experiment. To the colonist it furnishes a reliable 

 description of the soil." 



Soils of the United States. — "For the purposes of soil classification 

 the United States has been divided into thirteen subdivisions, seven of 

 which, lying east of the Great Plains, are called soil provinces, and six, 

 including the Great Plains and the country west of them, are known as 

 regions. 



"A soil province is an area having the same general physiographic 

 expression, in which the soils have been produced by the same forces or 

 groups of forces and throughout which each rock or soil material yields 

 to equal forces equal results. 



"A soil region differs from a soil province in being more inclusive. 

 It embraces an area, the several parts of which may on further study 

 resolve themselves into soil provinces. 



"Soil provinces and soil regions are essentially geographic features."* 

 The soils in a province are separated into groups. Each group constitutes 

 a series. A soil series is divided finally into types. The type is deter- 

 mined by texture. The texture may range from loose sands down to the 

 heaviest of clays. All types in a soil region or province that are closely 

 related in reference to color, drainage, character of subsoil and topog- 

 raphy and are of a common origin, constitute a group or series of soils. 

 A soil type is, therefore, the unit in soil classification. "It is limited to a 

 single class, a single series and a single province."* 



Classification by Texture. — The soil type of a particular series is 



* That which is enclosed in quotation marks is quoted from U. S. Bureau of Soils Bulletin No. 96, 



"Snils ..f the United States." 



