Table 5.14 — Non-range grazing, 1976-78 average and projected grazing capacity in ttie United States 



for 2000 and 2030 





1976-78 average 



2000 



2030 



Percent change 





Million 



Million 



Animal 



Million 



Animal 



Million 



Animal 



in yield 



Non-range 



acres 



animal 

 unit 



unit 

 months 



animal 

 unit 



unit 

 months 



animal 

 unit 



unit 

 months 



per acre 



grazing 



1976-8 



1976-8 







months 



per 



months 



per 



months 



per 



to 



to 







1 



acre 





acre 





acre 



2000 



2030 



Pasture 



112 



302 



2.7 



423 



3.8 



454 



4.0 



40 



50 



Cropland 





















pasture 



84 



385 



4.6 



655 



7.8 



687 



8.2 



70 



79 



Aftermath 



— 



14 



— 



33 



— 



60 



— 



— 



— 



Total 



196 



701 



— 



1,111 



— 



1,201 



— 



— 



— 



'An animal unit month (AUM) Is the amount of forage required by a 1,000-pound cow or equivalent in 1 month. 



Table 5.^5 — Present and expected production of herbage and browse and range grazing on the two 



largest grassland and shrubland ecosystems 





Area 

 grazed 



Present production 



Potential production' 



Ecosystem 



Herbage 

 & browse 



Range 

 grazing 



Herbage 

 & browse 



Range 

 grazing^ 



Plains grasslands 

 Prairie 

 Sagebrush 

 Desert shrub 



Million 

 Acres 



172.4 

 39.1 



116.8 

 57.1 



Million 

 Tons 



66.4 



50.6 



46.2 



5.7 



Million 

 AUM's^ 



54.3 



45.4 



24.6 



2.8 



Million 

 Tons 



87.6 

 64.9 

 60.0 



7.1 



Million 

 AUM's 



98.6 

 73.0 



67.5 

 8.0 



Total 



385.4 



168.9 



127.1 



219.6 



247.1 



' Production expected if all lands grazed were in "good" condition. 



'Assumes that 45 percent of the herbage and browse would be available as 

 forage if the range were in good condition and that 1 ton of forage equals 2.5 

 AUM's. 



^An animal unit month (AUM) is the amount of forage required by a 1,000 

 pound cow or equivalent in one month. 



Thus, the plains grasslands, prairie, sagebrush, and 

 desert shrub ecosystems could provide a total of 219.6 

 million tons of herbage if all lands grazed in those 

 ecosystems were improved to good condition. Assum- 

 ing 45 percent of the herbage and browse is available, 

 this production is the equivalent of 247 million 

 AUM's of grazing, 120 million more than the eco- 

 systems now produce. In other words, these four 

 ecosystems, which now supply about 60 percent of 

 the Nation's range grazing, could in themselves pro- 

 vide almost as many AUM's of range grazing as are 

 projected to be needed in year 2000 without increas- 

 ing area grazed in the ecosystems if all of their 

 acreage were improved to good condition, a prob- 

 ability highly unlikely because of economic con- 

 siderations. 



The biological potential indicates only the physical 

 capacity of the ecosystem for producing forage. Addi- 

 tional grazing above the current level is possible only 

 at increasing costs because more intense manage- 

 ment, technology, and improvements are needed. The 

 physical limits of range grazing supply do not restrict 



the demand, but the question remains how much 

 range grazing can be increased and at what cost. The 

 per unit costs of range grazing at biological potential 

 are likely to be more than double the current costs. 

 Such cost levels would exceed the amounts that could 

 be recovered and would probably result in the use of 

 nonrange sources of feed for livestock. 



Institutional constraints such as maintenance of 

 undisturbed ecosystems, perpetuation of all plant and 

 animal species, and multiple use constraints may 

 often prevent reaching the biological potential on 

 range ecosystem. Constraints against application of 

 certain technology may further limit achievement of 

 the biological potential, primarily by increasing the 

 cost of range management. 



It is possible that production per acre on range will 

 increase at a slower rate than that shown for cropland 

 pasture and other pasture (table 5.14). Much of the 

 range is in the semiarid areas of the United States. In 

 the drier areas, range yields can be very low with very 

 limited opportunities to increase output to any signifi- 

 cant extent. However, the yields and responses of the 



185 



