5 8o 



VARIOUS FERTILITY FACTORS 



crops are grown every year; but the fact remains that at least 75 

 per cent of the talk of " dry farming " is falacious. It is to be cred- 

 ited largely to land agents, farmers of short experience, and to 

 one-sided enthusiasts. When it is found impossible to win con- 

 fidence in the " dry farming " theory, the advocate insists that 

 the seasons in the semiarid region have changed, that more abun- 

 dant rainfall follows the plow, and that the semiarid region has 

 become humid. 



It is true, as stated above, that a series of wet years may follow 

 a dry series, but it is not true that seasons change measurably in 

 any permanent way during human experience. 



The accompanying chart showing the total annual rainfall at 

 North Platte, Nebraska, for the 34 years, 1875 to 1908, presents 

 some interesting, instructive, and valuable data. 



sggg 



20 



18.86 

 18 

 17 

 16 

 15 

 II 

 13 

 12 

 11 

 10 



30 



29 



28 



27 



26 



26 



21 



23 



22 



21 



20 



18.86 



18 



17 



18 



15 



11 



13 



12 



11 



10 







8 



7 



PRECIPITATION (.inches) AT NORTH PLATTE, NEBRASKA, FOR THIRTY-FOUR 

 YEARS 1875 TO 1908 



It will be observed that the average rainfall for the seven years, 

 1902 to 1908, is 23.17 inches, and it will also be noted that every 

 year has been above normal, with the exception of 1903, which was 

 slightly below. Previous to 1902 was a remarkable period of nine 

 years when every year was distinctly below normal, the rainfall 



