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, (8) Arizona, (4) the 
Northern Rocky Mountain and Eastern Foothills, 
and (5) the Plains Type: — 
