282 



Canadian Forestry Joitrnal. June. V^20. 



Trees on the prairie make all the difference between a "house" and a "home." View taken at Indian 



Head, Sask. 



of a crop on the damaged area. On 

 the protected portion the total saving 

 was 260 bushels, or the full crop of 

 6 acres, whereas the windbreak oc- 

 cupied only 2 acres. 



Movement of the topsoil also may 

 be checked and dust storms prevented 

 by breaking the force of the wind. 

 For this reason windbreaks are of im- 

 mense benefit in sandy regions or re- 

 gions where the soil is very fine. 



Added to the crop and soil protec- 

 tion there is the personal comfort to 

 be derived from protection from wind 

 about the farm and home and along 

 public roads. Futhermore, a protect- 

 ed home is heated in winter more 

 readily, and hence more cheaply, than 

 one exposed to the wind. 



REDUCING EVAPORATION 



There is no part of the United Sta- 

 tes, except small areas in the Appala- 

 chian and Cascade Mountains, which 

 normally obtains more precipitation 

 than is needed for growing the best 

 crops. The farmer usually plows, cul- 

 tivates, and mulches with the object 

 of conserving every drop of water that 

 may reach the soil during the year. 

 In the "dry-farming" regions of the 

 West these conservation measures are 

 carried farthest. Here it may be neces- 

 sary to save the moisture of two sea- 

 sons to grow a single crop. 



Anything which helps to conserve 

 the moisture of the soil is of direct 

 benefit to the farmer. The windbreak 

 has this effect in a marked degree. 

 The drying power of the wind is re- 

 duced by the windbreak very nearly 

 in the same proportion as its velocity. 

 In the immediate lee of the most ef- 

 fective windbreaks evaporation is re- 

 duced as much as 65 per cent. Farther 

 from the trees the reduction is less. 

 The amount of reduction depends not 

 only upon the density and proximity 

 of the windbreak, but upon whether 

 the field is fallow or in crops. The 

 saving in moisture is least when the 

 field is fallow, so that the only reduc- 

 tion is in the direct evaporation from 

 the soil ; it is greatest when the field 

 is in crops, so that there is a reduc- 

 tion not only in the direct evapora- 

 tion from the soil but also in the evap- 

 oration from the leaves of the crops. 



The more frequently winds occur 

 in any locality during the growing 

 season, and the greater their velocity 

 and drying power, the more import- 

 ant it is to use every means of pre- 

 venting evaporation. Windbreaks are 

 especially valuable, therefore, in the 

 Middle West, where hot, dry winds, 

 often of high velocity, are of frequent 

 occurrence during the summer months 

 and in Montana and the Dakotas, 



