The effectiveness of a windbreak depends in large measure 

 upon its height, density, width, and shape. Height is a key 

 characteristic. A windbreak that reduces wind acceptably for 

 25 times its height will bring an additional 25 feet of ground 

 under protection for each added foot of height. 



As a result of their fundamental influences on weather 

 factors, field crops have been found to be benefited by wind- 

 break shelter in many parts of the world. All the reasons for 

 the benefits are not apparent. But the amount of benefit depends 

 in part on the crop, the amount of windbreak protection, the lati- 

 tude, and seasonal moisture. The benefits are greater during dry, 

 hot, and windy seasons; less during wet, cool seasons. The best 

 density of windbreaks for sheltering crops is not known. 



Although much has been written on the effect of shelterbelts 

 upon wind, soil moisture and crop yields, most of the research 

 that has been done has been accomplished in areas other than Montana. 



A crop yield study in the Great Plains of North Dakota, 

 South Dakota, Nebraska, Kansas, Oklahoma and Texas was completed 

 during the years 193$ to 1951 ■ Results of that study showed that 

 yields of small grains were favored by the presence of shelter- 

 belts upon field crops. Montana shelterbelts are located in areas 

 where shelterbelt research has been conducted , 



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