12 WINDBREAKS. 



are considered more serious. Even in this latitude the protective 

 value of windbreaks properly placed would warrant their more exten- 

 sive use. 



In that portion of the plains region where the rainfall exceeds 20 

 inches tree culture has been most developed, and results show that a 

 fair profit may be expected from the timber yield of the best adapted 

 species. Here, therefore, the windbreak serves a double purpose 

 protection and production. Since the production is not comparable 

 to that of field crops, however, and since the protection may be 

 unnecessary in certain years, both must be considered. 



(3) Where there is less than 20 inches of rainfall per annum, 

 especially in the southern portion of the plains, every drop of 

 moisture is of value to crops, and its conservation becomes of the 

 utmost importance. In this region "dry farming" and irrigation are 

 being widely developed, and the checking of evaporation can not fail 

 to be of great benefit. Little has been done in windbreak planting, 

 but it is certain that the benefits obtained in more humid regions can 

 be had here in even greater degree. In such regions as eastern Colo- 

 rado, western Oklahoma, Texas, and New Mexico, even though the 

 difficulty of establishing windbreaks is great and their timber value 

 small, they will prove profitable through their effect on the con- 

 servation of moisture. In New Mexico, low, shrubby species like 

 sage-brush have been used with thorough success. 



THE UTILITY OF WINDBREAKS. 



The term " windbreak" may be applied to any object which serves 

 as an obstacle to surface winds. For the purposes of this study, how- 

 ever, it must be limited to bodies or rows of trees. Windbreaks may 

 be divided according to their general arrangement into three classes : 

 (1) Rows and hedgerows; (2) belts or shelter belts; (3) groves, or, in the 

 most extensive case, forests. A belt usually consists of three rows or 

 more, but its width is less than twice the ultimate height of the trees. 



In European countries the windbreak perhaps serves its greatest 

 utility as a check upon drifting sands along the coast, especially in 

 France. In the interior steppes of Russia, which correspond to our 

 middle western plains, windbreaks have been planted more or less 

 extensively to protect fields from the desiccating winds of the region. 

 In Schleswig-Holstein earth walls are thrown up and shrubbery is 

 planted upon them, since forest trees can not be made to grow there. 



Although windbreaks are of very real benefit to the famer and fruit 

 grower everywhere, it is in the treeless, wind-swept plains that they 

 find their greatest utility. In addition to the esthetic benefits and 

 the general " improvement " value to the farm, it would in many 

 instances be almost impossible to raise crops without protection from 

 the hot, dry winds of summer and the cold, dry winter winds. 



