EFFECTS OF DIFFERENT SYSTEMS OF GRAZING. 41 



loss in weight toward the close of the season. The vegetation has 

 not been severely damaged by the heavy grazing to date, but it 

 would require a period of rest or a different system of grazing to 

 bring it back to a state of maximum production. In order for a 

 pasture of this size to produce enough feed to graze cattle for five 

 months and produce normal gains, it would be necessary for it to 

 yield a maximum crop of forage each year. 



THE 30-ACRE PASTURE. 



The 30-acre pasture is grazed at the rate of one 2-year-old steer 

 to 3 acres. It has not produced feed enough to carry the cattle and 

 produce normal gains for more than an average of two months each 

 season. The seasonal gain per head has been less than for any other 

 pasture, but the gain per acre has been the highest produced, because 

 of the reduced acreage. Early in the season, or during the time 

 when the vegetation is making its maximum growth, the cattle make 

 gains equal to those in the other pastures. This pasture has been 

 overgrazed, which is best shown by the increase of Artemisia frigida; 

 it is not large enough to produce sufficient feed to graze the cattle 

 for five months even during a season of maximum crop production. 



The increase in the number of plants of A. frigida on overgrazed 

 pastures is not confined to the area included in the grazing experi- 

 ment. Many native pastures in the vicinity of Mandan are so badly 

 infested with a heavy growth of this sage that they have been prac- 

 tically abandoned. The results obtained in the 30-acre pasture indi- 

 cate that it does not take a pasture many years to reach this condi- 

 tion under continuous severe grazing. Plate IX shows an abundance 

 of this plant in a pasture adjoining the station, which had been 

 heavily grazed for a number of years. 



While the 30-acre pasture has been severely injured by overgrazing, 

 no effort as yet has been made to restore it to higher production. It 

 is probable that when this is done it will be by a system of deferred 

 and rotation grazing, which may be aided by some mechanical means. 



The results obtained on this small pasture are remarkable in show- 

 ing that the cattle are able to maintain themselves and make some 

 gain as long as they do. They also clearly bring out a point not 

 generally recognized, that cattle on a short pasture may appear to 

 be doing well when, in fact, they are only maintaining their weight. 



THE 70-ACRE DEFERRED AND ROTATION PASTURE. 



For the first two years the deferred and rotation pasture was 

 grazed at the rate of one 2-year-old steer to 7 acres. During 1921 

 the rate was one steer to 4.12 acres. At the higher rate of grazing 

 it produced feed enough to make gains per head greater than the 

 small pastures but less than the larger pastures and at the same time 

 showed the greatest total gain per acre. The utilization of the vege- 

 tation has been greater for the gains made than in any other pasture, 

 with a minimum injury to the vegetation. This system of grazing 

 is to be preferred to that of continuous grazing, since a greater total 

 gain can be produced on less acres. 



The cost of fencing a deferred and rotation pasture will be more 

 than to inclose one of the same size for continuous grazing, but 50 



