PREFACE 



The author wishes to express his in- 

 debtedness for much valuable aid to the 

 following: Messrs. E. C. Chilcott, L. J. 

 Briggs, and William M. Jardine of the 

 National Department of Agriculture; 

 Dr. John A. Widtsoe, Professor Lewis 

 A. Merrill, and Professor J. C. Hogen- 

 son of Utah; Professor F. B. Linfield 

 and Professor A. Atkinson of Montana; 

 Mr. H. W. Campbell of Lincoln, Ne- 

 braska; Dr. V. T. Cooke of Wyoming; 

 Mr. Gifford Pinchot, Chief Forester, 

 Washington, D. C; and Professor E. 

 W. Hilgard of California. Nor must he 

 fail to thank Mr. John T. Burns of 

 Colorado, Secretary to the Dry-Farming 

 Congress, for much kind assistance. 



College of Agriculture 

 University of Minnesota 

 Minneapolis, June 1, 1909. 



XIV 



