68 FARM FORESTRY 



on the poorer sites a closer spacing should be used. Cultiva- 

 tion of the soil is necessary during the first few years. 



The Southern Plains. On the uplands the southern and 

 western sides of each quarter section should be protected by 

 shelterbelts from the dry southwestern winds with belts run- 

 ning east and west every 30 to 40 rods. In the more humid 

 eastern region cottonwood, green ash, Russian mulberry, 

 osage orange and white elm will thrive, and black locust where 

 it is not subject to the locust borer. In the very dry western 

 portion of the region there are no trees that are sure of success. 

 The following are recommended as being likely to succeed : 

 Green ash, white elm, osage orange, red cedar, black locust, 

 honey locust and Russian mulberry for fence posts and west- 

 ern yellow pine and cottonwood for lumber. 



On the lowlands better conditions of soil moisture are 

 found. The most valuable species for planting are osage 

 orange, black locust, Russian mulberry and cottonwood for fuel 

 and lumber. As in the other parts of this region, thorough 

 cultivation of the soil is essential for success in starting 

 plantings. Mixtures of a few of the species will often do 

 better than where a single species is planted. This is because 

 of the denser shade that is formed. Under planting the plan- 

 tations with the more tolerant species will prove of value. 



Planting for Windbreaks. Windbreaks are grown for the 

 purpose of protecting homes, cattle, orchards and fields from 

 the wind. In many regions this is essential. There is scarcely 

 a portion of the country that is not subject to severe winds. 

 Windbreaks planted about fields diminish soil erosion, me- 

 chanical injury to the soil and crops and evaporation from the 

 soil and plants. 



Trees form one of the most effective means of protection 

 against winds. Where the protecting trees are in one or two 

 rows the term windbreak is applied. A shelter belt consists 

 of three or more rows but not wider than twice the ultimate 



