Irrigation and Climate 



PROP. A. C. HcADIE, U. S. Weather Bureau 



MONG the cardinal principles laid 

 down in standard works upon 

 agriculture is this, that though 

 all plant life is largely water, 

 and plant nourishment is ob- 

 tained from air and soil, the 

 chief function of ordinary 

 earthy soil is to afford standing 

 room for the plant. In California 

 there is no dearth of soil. In other words, there is 

 a large amount of excellent standing room and 

 the chief object of irrigation from the good citi- 

 zen's standpoint is to decrease this standing room 

 by filling up vacant places with living plants and 

 after these, homes and habitations. California 

 has soil, water and climate. Climate must be 

 taken as it is. But water can be stored and used 

 when needed and even the soil modified and to 

 some degree controlled. 



If the rainfall of California could be distrib- 

 uted equally over the State, there would be 

 enough to satisfy all. But the rainfall is not 

 equally distributed and some portions of the 

 State have too little and other portions too much. 

 It is in that portion of the State where the rain- 

 fall is scant that the greatest gain in population 

 and home building has been made, and the ex- 

 planation is given by the words Climate, Soil, 

 Irrigation. 



The rainfall map herewith shows that there is 

 a large water supply in California. It is neces- 

 sary in the southern portion of the State to get 

 a maximum efficiency from the water; whereas 

 in some portions of the north and at certain 

 times, especially from January to March, under 

 existing conditions, an excess of water works 

 positive injury. In the same section much fertile 

 land could be cultivated if properly irrigated. 

 But all years are not alike, and even in the north 

 with a plethora of water, there have been sea- 

 sons when the rainfall did not exceed five inches, 

 where the average seasonal, for a period exceed- 

 ing fifty years, is about twenty inches. And 

 conversely, in the far south there have been 

 seasons of fifteen inches (in one year twenty-six 

 inches) where the normal seasonal rainfall based 

 on fifty-five years' record, gives about ten inches. 

 In a single month, January, 1884, nine inches of 

 rain fell at San Diego and at Los Angeles thirteen 

 inches. Such seasons are generally associated 

 with enormous crop yields. 



California, then, both north and south, is a 

 land where water plays an important role. It is 



