STOCKING NORTHERN GREAT PLAINS SHEEP RANGE 



35 



mended minimum that should be allowed to meet the ever present 

 risk of unfavorable weather. 



On this basis, 0.56 surface acre per yearling ewe per month, the 

 average allowance under conservative stocking during 1941, plus the 

 20 percent margin, amounts to 0.67 acre per yearling ewe month. 

 Thus about 5.4 acres is considered the minimum acreage for a dry 

 yearling ewe on good northern plains range similar to the experi- 

 mental range dining a relatively favorable season of 8 months begin- 

 ning in March. 



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1937 



1938 



1939 



1940 



1941 



1936 



Figure 13. — Total annual precipitation was increasingly favorable each year after 

 1936, except in 1939, and stocking was increased accordingly in all pastures. 



SUMMARY 



The northern Great Plains constitute one of the most important 

 range areas in the United States for the production of wool, feeder 

 lambs, and replacement breeding ewes. In this region, the major 

 range problem confronting sheep ranchers is how to stock their range 

 (1) to get the greatest possible production year after year without 

 deteriorating the forage and soil and (2) to permit recovery from 

 drought within a reasonable time. 



To obtain guides to proper stocking of northern Great Plains range, 

 the Northern Rocky Mountain Forest and Range Experiment Station. 

 in cooperation with the Bureau of Animal Industry and the Montana 

 State Agricultural Experiment Station conducted a study of sheep 

 grazing near Miles City, Mont., from 1936 to 1941. Three range 

 pastures, having areas of 332, 476, and 847 acres, were established and 

 stocked each year with equal numbers of yearling Rambonillet ewes 

 to maintain three relative 1 intensities of grazing. Studies of density, 

 composition, and herbage production of tin 4 vegetation, pins surveys 



