PREFACE 



Nearly six tenths of the earth's land surface 

 receive an annual rainfall of less than twenty 

 inches, and can be reclaimed for agricultural pur- 

 poses only by irrigation and dry-farming. A per- 

 fected world-system of irrigation will convert about 

 one tenth of this A^ast area into an incomparably 

 fruitful garden, leaving about one half of the 

 earth's land surface to be reclaimed, if at all, by 

 the methods of dry-farming. The noble system 

 of modem agriculture has been constructed almost 

 wholly in countries of abundant rainfall, and its 

 applications are those demanded for the agricul- 

 tural development of humid regions. Until re- 

 cently, irrigation was given scant attention, and 

 dry-farming, Avith its woi-ld problem of conquering 

 one half of the earth, Avas not considered. These 

 facts furnish the apology for the writing of this 

 book. 



One volume, only, in this Avorld of many books, 

 and that less than a year old, is devoted to the 

 exposition of the accepted dry-farm practices of 

 to-day. 



