38 DRY-FARMING 



and down to the seacoast, semiarid to sub-humid 

 conditions are again found. 



Seasonal distribution of rainfall 



It is doubtless true that the total annual precipi- 

 tation is the chief factor in determining the success 

 of dry-farming. However, the distribution of the 

 rainfall throughout the year is also of great impor- 

 tance, and should be known by the farmer. A small 

 rainfall, coming at the most desirable season, will 

 have greater crop-producing power than a very 

 much larger rainfall poorly distributed. Moreover, 

 the methods of tillage to be employed where most of 

 the precipitation comes in winter must be consider- 

 ably different from those used where the bulk of 

 the precipitation comes in the summer. The suc- 

 cessful dry-farmer must know the average annual 

 precipitation, and also the average seasonal dis- 

 tribution of the rainfall, over the land which he 

 intends to dry-farm before he can safely choose his 

 cultural methods. 



With reference to the monthly distribution of the 

 precipitation over the dry-farm territory of the 

 United States, Henry of the United States Weather 

 Bureau recognizes five distinct types ; namely : 

 (1) Pacific, (2) Sub-Pacific, (3) Arizona, (4) the 

 Northern Rocky Mountain and Eastern Foothills, 

 and (5) the Plains Type : — 



