226 THE PRINCIPLES OF SOIL MANAGEMENT 



Table XXXIX 



Northern India 



Italy 



Idaho 



Utah 



San Joaquin Valley, California 

 Santa Clara Valley, California 



In Sefi, on the lower Nile canals in Egypt, one second- 

 foot is said to be sufficient for 350 acres, as managed. 

 In the humid regions much less water need be added 

 by irrigation, and is necessary only to supplement the 

 rainfall in the drought periods to fill in the gaps. Ordi- 

 narily only a few inches per season are needed, usually 

 toward the latter part. Dr. Yoorhees has compiled the 

 following figures, which show the percentage of years 

 in which there was a deficiency of one inch or more per 

 month in the rainfall, as compared with the average. 



Table XL 



New York, 1836-1895 . . 

 Philadelphia, 1868-1895 



One month 



Per cent 

 75 



88 



Two months 



Per cent 

 42 

 56 



Three months 



Per cent 

 21 

 30 



In this region, the deficiency is most likely to occur 

 in the summer season. The records show that during 

 one-fourth of the term there is a deficiency of rainfall 

 covering three months. Considering the monthly rain- 



