STOCKING NORTHERN GREAT PLAINS SHEEP RANGE 29 



Not all herbage, even of the mosl palatable species, can bo con- 

 sidered as usable forage. Of the many factors involved, the necessity 

 of leaving considerable herbage to protect the soil and insure regrowth 

 of the range vegetation is most important. Since grazing capacity is 

 based only on herbage that should properly be used instead of total 

 herbage produced, a conversion is necessary. To make this conver- 

 sion, total pounds of air-dry herbage for each key species were weighted 

 by the average percentage grazing use obtained during 3 years (table 4, 

 p. 13) in the sheep pastures under each intensity of stocking. For 

 other species or groups of species for which average use percentages 

 were not available, weighting was done by applying estimated factors 

 for all areas regardless of degree of stocking. These data (table 9) 

 indicate the proportionate part of total herbage that was considered 

 to be usable forage on the differently stocked areas. 



In 1942, when the pastures were not grazed, the pasture that had 

 been heavily stocked for 6 years produced less perennial-type herbage 

 per acre, based on samples hand-clipped to a 1-centimeter stubble, 

 than either of the other pastures (table 9). Even when the yields of 

 blue grama, bluestem, and threadleaf sedge were mathematically 

 converted into usable forage, the advantage was still with the con- 

 servative and light stocking rates. With the addition of annual-type 

 herbage, however, the area that was heavily stocked showed greater 

 production in total herbage than the conservative and in usable forage 

 than all but the ungrazed area. The fact that the annual type forage 

 is nutritious only when lush and green and that it dries and weather- 

 away quickly, offsets any advantage the greater quantity might 

 appear to have. Year-long sheep operations in the northern Great 



*?+* 



$&*»*" 



Figure 11. — Six years of conservative sheep grazing did not materially cl 

 this typical northern Greal Plait:- range. Palatable perennial grass es are 

 abundant but low-value annual- very inconspicuous. 



