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 statements 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 and King of Wisconsin.  I am under deep obligation, for assistance rendered, to numerous friends in all parts of the country, especially to Professor L. A. Merrill, with whom I have collaborated for many years in the study of the possibilities of dry-farming in Western America.

The possibilities of dry-farming are stupendous.  In the strength of youth we may have felt envious of the great ones of old; of Columbus looking upon the shadow of the greatest continent; of Balboa shouting greetings to the resting Pacific; of Father Escalante, pondering upon the mystery of the world, alone, near the shores of America’s Dead Sea.  We need harbor no such envyings, for in the conquest of the nonirrigated and nonirrigable desert are offered as fine opportunities as the world has known to the makers and shakers of empires.  We stand before an undiscovered land; through the restless, ascending currents of heated desert air the vision comes and goes.  With striving eyes the desert is seen covered with blossoming fields, with churches and homes and schools, and, in the distance, with the vision is heard the laughter of happy children.

The desert will be conquered.

John A. Widtsoe.

June 1, 1910.

CHAPTER I

INTRODUCTION

DRY-FARMING DEFINED

Dry-farming, as at present understood, is the profitable production of useful crops, without irrigation, on lands that receive annually a rainfall of 20 inches or less.  In districts of torrential rains, high winds, unfavorable distribution of the rainfall, or other water-dissipating factors, the term “dry-farming” is also properly applied to farming without irrigation under an annual precipitation of 25 or even 30 inches.  There is no sharp demarcation between dry-and humid-farming.

When the annual precipitation is under 20 inches, the methods of dry-farming are usually indispensable.  When it is over 30 inches, the methods of humid-farming are employed; in places where the annual precipitation is between 20 and 30 inches, the methods to be used depend chiefly on local conditions affecting the conservation of soil moisture.  Dry-farming, however, always implies farming under a comparatively small annual rainfall.