294 GRAZING INDICATORS. 



and for sheep by Jardine and Anderson (1919: 48). The essential features 

 are fencing or proper herding, adequate water development, deferred or rota- 

 tion grazing, winter and drought feeding, and improvement of the herd. Fenc- 

 ing is first of all important in enabling the stockman to control his own range, 

 but it is also necessary in order to minimize bunching and trampling, as well 

 as to permit rotation. In the case of sheep in the national forests, the carry- 

 ing capacity of the range is greatly Conserved by the open or "blanket" 

 method of herding. Proper water development insures fairly uniform 

 utilization by reducing the distance to water, and hence decreasing the ten- 

 dency of cattle to overgraze the areas about wells or tanks and to undergraze 

 distant ones. Rotation grazing permits the utilization of types or areas under 

 conditions which maintain the yield, and affords an opportunity for the de- 

 velopment of reserve pastures against periods of drought. It likewise en- 

 courages the grazing of cattle by classes, such as breeding-cows, steers, etc. 

 Feeding during winter or drought has an obvious effect upon carrying capacity. 

 It not only conserves the actual supply of natural forage, but it also reduces 

 the intensity of grazing in early spring, owing to the fact that the stock come 

 out of the winter in good condition. This is especially important, as the 

 rapid growth of the leaves in spring determines not merely the amount of 

 summer forage, but is even more important in deciding the amount of storage 

 in rootstock and seed, and hence the yield of the following year. In its re- 

 lation to carrying capacity, the improvement of the herd depends chiefly 

 upon eflSciency in transforming grass into flesh, but partly also upon the 

 abiUty to "rustle." It is evident, moreover, that carrying capacity will 

 vary with the breed as well as the animal, and that certain breeds will be more 

 eflScient in one grazing type than in another. 



Measurement of carrying capacity. Spillman (Griffiths, 1904: 5) has 

 emphasized the importance of carrying capacity as a basis for the grazing 

 industry: 



" A knowledge of the canying capacity of the ranges is of the most import- 

 ance, for it must form the basis of any intelligent legislation relating to the 

 range question. This knowledge determines the rental and sale value of 

 range lands, and should also determine the size of the minimum lease or home- 

 stead for range purposes in case laws are passed providing for such disposal 

 of the public ranges. " 



It is evident that definite knowledge of carrying capacity can be obtained 

 only through its measurement, and hence methods of measuring it come to 

 be of the first importance. The best measure of carrying capacity is that 

 furnished by actual grazing test, and all other methods find their warrant in 

 the use of this as a final criterion. However, so many factors enter into 

 practical grazing that experience alone is not a reUable guide to actual carrying 

 capacity, and still less to potential carrying capacity. It must be refined and 

 supplemented by experimental tests under controlled conditions which per- 

 mit varying one factor, such as grazing type or kind of animal, while the other 

 factors remain esssentially the same. Such grazing experiments may be in- 

 tensive or extensive in scope, though it is desirable to make use of both kinds 

 in connection with putting experimental results into practical commission. 

 Extensive experimentation has been carried on for several years on the Jor- 

 nada and Santa Rita Range Reserves by the Forest Service (Jardine and 



