viii PREFACE 
The book now offered is the first attempt to 
assemble and organize the known facts of science 
in their relation to the profitable production of 
plants, without irrigation, in regions of limited 
rainfall. The needs of the actual farmer, who 
must understand the principles before his- practices 
can be wholly satisfactory, have been kept in view 
primarily ; but it is hoped that the enlarging group 
of dry-farm investigators will also be helped by 
this presentation of the principles of dry-farming. 
The subject is now growing so rapidly that there 
will soon be room for two classes of treatment: 
one for the farmer, and one for the technical 
student. 
This book has been written far from large 
libraries, and the material has been drawn from 
the available sources. Specific references are not 
given in the text, but the names of investigators 
or institutions are found with nearly all state- 
ments of fact. The files of the Experiment Station 
Record and Der Jahresbericht der Agrikultur 
Chemie have taken the place of the more desirable 
original publications. Free use has been made 
of the publications of the experiment stations and 
the United States Department of Agriculture. 
Inspiration and suggestions have been sought and 
found constantly in the works of the princes of 
American soil investigation, Hilgard of California 
