34 RURAL CALIFORNIA 



of Hilgard's work, soil surveying and mapping was 

 begun in California by the Division of Soils of the 

 United States Department of Agriculture under the 

 direction of Milton Whitney,, which in 1913 was 

 merged into cooperative soil investigation with the 

 California Experiment Station. Thus, California has 

 had continuous field and laboratory soil study for 

 forty-five years and the greater part of the agricul- 

 tural area of the State has been covered. 1 In ad- 

 dition, the area of the National Forests in California, 

 comprising about nineteen million acres in 1918, has 

 been covered by the forest land classification of the 

 Division of Forestry of the United States Department 

 of Agriculture. These National Forests and their 

 agricultural significance will be considered more spe- 

 cifically in a later connection. The regions for 

 which soil surveys have been made are indicated in 

 Plate IV. 



By reason of their uniqueness and diversity and 

 their adaptation to such varied production; because 

 of the association of rainfall and irrigated agricul- 

 ture; and because the latter presented demonstra- 

 tions of great suggestiveness in the reclamation of 

 arid interior states, California has presented a very 

 attractive field for soil research from the points of 

 view of actual crop production and of soil science. 

 The results of such research by a score of investiga- 

 tors are succinctly presented by C. F. Shaw, who 

 has had charge of the government and state coopera- 



1 A list of the areas covered by the Division of Soils of the 

 U. S. Dept. of Agr. and of which soil maps and descriptions 

 are available, is given in Appendix C. 



