CANADA 7 



in which the soluble salt content of the soil is not at present 

 sufficient to interfere with crop growth, but there is suffi- 

 cient of the salts present if concentrated by unwise methods 

 of irrigation, by drouth, or by other means to bring the 

 soil to the danger point, especially should drainage be poor. 



The looth meridian may be taken roughly as the line 

 separating the humid from the arid part of the continent. 

 This line is not absolute; it varies somewhat with latitude, 

 altitude, and several other factors. There are a number 

 of places west of this line where the rainfall is high. This 

 is particularly true along the northwest coast and along 

 some of the mountain ranges. 



Canada. In western Canada, especially in the prov- 

 inces of Saskatchewan, Alberta, and British Columbia, 

 there are several rather large tracts where the soluble- 

 salt content of the soil is sufficiently high to render crop 

 production difficult. In southeastern Alberta the soil of 

 one of these regions originated from the glaciation of shale 

 that was high in soluble salts, particularly the sulphates. 

 Therefore, sulphates are the predominating salt of the 

 region. The soil is heavy and impervious; consequently, 

 there has been very little movement of salts from its original 

 place in the soils. 



Under irrigation these salts may be either leached down- 

 ward or brought to the surface. When appearing as a 

 white inflorescence they are very conspicuous and would 

 lead the casual observer to believe the condition to be 

 much worse than it really is. A large quantity of gypsum 

 is present in these soils and, when dissolved and brought 

 to the surface, it, together with sodium sulphate, forms 

 a conspicuous white soil covering. Fortunately, the 

 percentage of the more harmful chlorides and carbonates 

 is very low. 



