AUTHORS' PREFACE 



In teaching introductory courses in soil technology 

 to agricultural students, the authors feel that the use of 

 a text book enables the student to get a more thorough 

 mental discipline and a better grasp of the details of the 

 subject than can result from a course of lectures. The 

 present book is the outgrowth of their experience in 

 teaching soil technology through a period of several 

 years. It has been their endeavor to present the appli- 

 cation of science to soil problems from the standpoint 

 of crop-production rather than that of any one of the 

 underlying sciences of geology, chemistry, physics or 

 bacteriology. This has necessitated drawing from a wide 

 range of literature, and arranging the material in a form 

 which it is thought adequately represents all phases of 

 the subject. The sources of such data have been freely 

 drawn upon, and the authors take this opportunity to 

 express their obligations for the aid they have received 

 from a very large number of papers and books dealing 

 with soils, and which it has not been found practicable to 

 credit specifically in the text, as has been done in many 

 instances. 



It may happen that some teachers will not wish to 



(ix) 



