CHAPTER III 

 THE DOMAIN FOR DRY FARMING 



This chapter will consider more particularly the do- 

 main for dry farming in the United States and Canada. 

 The domain for the same, including all the continents, 

 is very wide. Taking into consideration only the tillable 

 portions of the earth's surface, it would seem safe to say 

 that more than half the area, if farmed at all, must be 

 farmed on the principles that underlie successful dry land 

 farming. In the United States and Canada, it is not 

 possible to determine with absolute precision at the pres- 

 ent time the relative or even the absolute proportion of 

 the tillable area that must be farmed, if farmed at all, on 

 the methods that lead to success as practised in what are 

 usually termed dry land areas. It would be safe to say, 

 however, that nearly one-half of the tillable, area in the 

 United States must be thus farmed, if farmed at all, and 

 the same is true of certain areas in western Canada. 

 But in portions of western Canada in which trees grow in 

 clumps in the depressions, it may be taken for granted 

 that the annual precipitation is higher than in areas far- 

 ther south, or the trees would not be in evidence. Where- 

 ever nature sustains such a vegetation, even in the de- 

 pressions, the ability of the soil and climate to grow good 

 crops need not be questioned. 



Influences that bear upon dry farming. In chap- 

 ter I these influences are discussed to some extent when 

 explaining the causes of aridity (see p. 14). They are 

 enlarged upon here. The influences that bear upon dry 

 farming include: (1) the amount. of the precipitation; (2) 

 the time at which the precipitation falls ; (3) the character 

 of the evaporation ; (4) the temperature that is normally 

 present, and (5) the character of the soil. The fact should 

 never be overlooked when sitting in judgment on areas 



