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Yearbook of Agriculture 1949 



golden willow, silver poplar, and the 

 native cottonwoods do well. 



In the Corn Belt region of north- 

 central United States, the trees that 

 have proved adaptable are green ash, 

 American elm, black locust, honey- 

 locust, hardy catalpa, black walnut, 

 the Russian-olive, redbud, honeysuckle, 

 Norway spruce, white spruce, Black 

 Hills spruce, red pine, and white pine. 

 In areas with considerable moisture, 

 the golden willow, green willow, and 

 native cottonwoods are recommended. 



In southwestern United States, the 

 citrus-growing sections of Arizona, 

 New Mexico, and California, eucalyp- 

 tus (sometimes known as bluegum) 

 has been used most satisfactorily to pro- 

 tect citrus groves. In California, Mon- 

 terey cypress has been used to some 

 extent, while in Arizona and New 

 Mexico, the Arizona cypress is planted 

 occasionally with success. 



In the New England States, New 

 York, and Pennsylvania, the planting 

 is usually confined to the farmstead 

 windbreaks, and conifers are favored, 

 including Norway and white spruce, 

 white pine, and red pine. 



In the southeastern part of the 

 United States from Georgia westward 

 to eastern Texas, there is occasionally 

 an area of sandy soil that requires pro- 

 tection from wind erosion. Under such 

 conditions the native pine species, 

 especially loblolly pine, makes a satis- 

 factory quick-growing shelterbelt. 



Good composition in a shelterbelt, 

 like good structural engineering in a 

 bridge or barn, improves its appear- 

 ance and increases its effectiveness. 



For an all-purpose principal shelter- 

 belt in the drier parts of the United 

 States, one of the most important re- 

 quirements for good composition is a 

 tight row of shrubs on the windward 

 side. 



Shrubs should be combined with 

 conifers, low, medium, and tall trees 

 to produce a compact barrier. Five 

 rows represent the minimum that 

 should be used when maximum pro- 

 tection is needed; seven rows are 

 better. 



The protection afforded by the prin- 

 cipal shelterbelt may be carried entirely 

 across the farm with one-, two-, and 

 three-row supplemental belts at in- 

 tervals of 10 rods to 20 rods or more, 

 depending upon the protection that is 

 needed. 



In the citrus-growing sections of 

 California and the Southwest, one- or 

 two-row plantings of eucalyptus or 

 cedar give good results. In areas of 

 better rainfall or where experience has 

 shown that narrow belts will survive 

 (for example, on muck soils of In- 

 diana) single-row plantings of willow 

 are satisfactory. 



On the sandy soils of central Wis- 

 consin, three-row belts, preferably of 

 red and jack pine, are recommended. 



THOROUGH CULTIVATION is necessary 

 during the first 3 to 5 years of the life 

 of the plantation. No amount of care- 

 ful site preparation and good planting 

 will compensate for neglect. In most 

 cases, the regular farm equipment can 

 be used in caring for the belts. If the 

 equipment is too wide, some modifica- 

 tion can be made by the farmer or his 

 local blacksmith. Usually a spacing of 

 12 feet between rows will require a 

 cultivation period of 5 years or more, 

 depending on how fast the trees grow. 

 A closer spacing will considerably 

 shorten this period. As soon as the 



