14 



DRY FARMING 



duce one pound of threshed grain, or over one ton to 

 produce 1^2 pounds of wheat. At this rate if it were 

 all conserved and utilized, one acre inch of water Would 

 produce over 2 l / 2 bushels of wheat and 8 inches would 

 produce at least 20 bushels per acre. 



Our precipitation is about twice 8 inches, or more, 

 and we crop our land only three times in four years, or 



Fig. 5. Precipitation Zones in Canada. 



Approximate boundaries based on Meteorological Service data. 

 Figure 110 for more recent detailed map). 



(See 



twice in three years, yet our average yield equals less 

 than the amount eight inches of moisture might produce. 

 The loss through "run-off", seepage, evaporation and 

 transpiration through weeds accounts for this poor 

 showing. 



From these figures it will be apparent that the pre- 

 cipitation in Western Canada is one of the chief limiting 

 factors in crop yields ; it suggests the desirability of more 

 efficient control of the limited amount of moisture that 

 falls. 



