THE IRRIGATION AGE. 



361 



planned to suit . the source from which water is ob- 

 tained and the regulations governing its delivery. 



Climate has a still greater influence. It is the 

 cloudless sky, the high summer temperature, the ex- 

 cessive evaporation, and the lack of rainfall that com- 

 pel Western farmers to irrigate. It is none the less true 

 that the elements which go to make up the general 

 term "climate" differ in every locality. Over the vast 

 area of 1,433,830 square miles which lie west of the 

 one hundredth meridian there is the widest diversity. 

 No two States or river basins have the same climate. 

 On the border land between. the wet and dry regions 

 irrigation is not an absolute necessity. It is- resorted 

 to only in years of scanty rainfall. At the other ex- 

 treme is the irrigated section of southern California, 

 where irrigation not only is a necessity, but must be 

 practiced the greater part of the year. The average 

 annual rainfall at San Diego, Cal., for example, for 

 the past -fifty-two years has been only 9.43 inches. 

 What is true of rainfall applies with equal force to 



A good example of steep grades may be seen in 

 going from Sacramento, Cal., to Eeno, Nev. The or- 

 chards on the western slope of the Sierras seem to be 

 on edge. Here, as elsewhere throughout the West, 

 costly trials and patient effort have finally overcome 

 the difficulty, and these orchards are now irrigated with 

 much the same ease as orchards on gentle slopes. 



And, finally, the variety of crops raised is a cause 

 of differences in irrigation methods. There is a won- 

 derful diversity in the cultivated plants of the irrigated 

 farm, from the native blue joint of the North to the 

 date palm of the South, and from the corn fields of 

 the East to the citrus groves of the West. For each of 

 these scores of plants some particular kind of soil, cli- 

 mate, and locality will suit best. There is also for 

 each the proper time to sow and to reap, to cultivate 

 and to irrigate. 



"Everything grows in California," said a Francis- 

 can monk of Santa Barbara last April. This growth, 

 however, is seldom due to natural conditions. The 





Sau-cbrush Plain, Yakiniu Valley, Washington. 



evaporation, and temperature. 1'he evaporation from 

 an irrigated field in Arizona in midsummer is quite 

 different from what it is in Wyoming. 



There is a wide diversity in the soils and subsoils 

 of the arid region. This diversity calls for modifica- 

 tions in the methods employed in preparing the sur- 

 face and applying the water. The farmer in one lo- 

 cality can not use the furrow system on account of 

 the porous nature of the soil and subsoil. A stream 

 might run for days and days in a furrow and not ad- 

 vance beyond a sandy "sump." In other localities 

 nothing but furrows can be used for the reason that 

 the fine particles of basaltic soil bake so readily when 

 the surface, is flooded as to damage the crops. 



The nature -of the surface, as well as the steepness 

 of the slope, is likewise to be considered. The hog 

 wallows of California are first cousins to the buffalo 

 wallows of Montana. In every locality, wherever found, 

 this unfavorable formation of alternate height and hol- 

 low must receive special treatment. The methods suit- 

 ed to an even, uniform slope do not apply to such land. 



highest intelligence is required to sow the seed in the 

 right place and to properly care for the plant. Fre- 

 quently other soils and other climates produce the seeds 

 which are made to flourish in a western desert. 



Many reasons might be given for publishing de- 

 scriptions of different methods of preparing land and 

 supplying water. It is thought advisable, for instance, 

 that the farmers of one arid State shall be made fa- 

 miliar with the practices of those of their calling in 

 other arid States. Again, since there are so many 

 different ways of performing the same task, it is con- 

 sidered wise to bring together in one publication such 

 information regarding different methods as will enable* 

 the reader to make an intelligent comparison. There 

 is also a desire to place in the hands of the new settlers 

 on irrigated farms some of the lessons of costly experi- 

 ence of the past fifty years. 



In the reports given herein no effort has been made 

 to cover the entire arid region or to describe all of 

 the different methods adopted. Notwithstanding this 

 nccessarv limitation, the information contained in this 



