MANAGEMENT OF SPECIAL SOILS 265 



killed by -having their roots exposed, or by being covered 

 by the drifting particles, or by abrasions resulting 

 from the long continued impingement of the drifting 

 particles against the tender tissues of the plant. The 

 soil itself is injured by the removal of much of the sur- 

 face or more productive part. Aside from these more 

 or less general effects of soil drifting there are other 

 objectionable features such as the possible serious injury 

 to adjoining crops or fields, the spread of weeds and the 

 interference with traffic as a result of the accumulation 

 of drifting soil in road allowances. 



218. The Chief Factors Favoring Soil Drifting are a fine 

 textured soil, low precipitation and frequent high winds 

 in early summer before the land is protected by the 

 growing crop. When to these are added too much or 

 unsuitable surface tillage, and a system of farming 

 which is wasteful of soil humus and returns little or no 

 organic matter to the soil, we have a combination of 

 conditions that is responsible, not only for the large 

 losses from soil drifting that have already occurred, but 

 also for preparing the way for still more serious losses 

 in the future if some radical changes are not made in the 

 methods of tillage and cropping heretofore practised in 

 the affected areas. The greatest damage from this cause 

 is to be observed in southern Alberta, portions of west- 

 ern and southern Saskatchewan and in southwestern 

 Manitoba. 



. 219. The Chief Causes of Soil Drifting are a high wind 

 velocity and the low cohesion or binding force of the ex- 

 posed soil particles. The wind velocity as well as the 

 frequency of high winds and their general direction is a 

 climatic condition which cannot be controlled; hence 

 man's only recourse is, (1) to increase the cohesion of the 



