BASIS FOR ESTIMATING GRAZING CAPACITY 329 



in Arizona and New Mexico. In one series of tests, employing 

 what may be termed the indirect method, the investigation 

 provided for the harvesting of all the herbage that was produced 

 on specially selected plots about 5 by 10 feet in size. Some of 

 the plots were fully protected from stock; others were located 

 in special pastures. The herbage was usually harvested in the 

 summer, but from some plots it was removed in the spring. 

 From the weights of dry material obtained, the total productiv- 

 ity in terms of pounds of forage per acre was calculated. From 

 each year's calculations an average for the year was figured, 

 and from the yearly averages an average of all the records was 

 obtained. 



In addition to this clear-cutting method of determining the 

 forage per acre, hay was cut on the better parts of the range 

 reserve, and the production of hay per acre was compared with 

 the total amount produced as determined by the collections. 

 With a knowledge of the forage requirements in terms of air- 

 dry roughage, the grazing capacity of the area was calculated. 



Another plan, which may be termed the direct method, 

 employed by the same bureau in determining grazing-capacity 

 estimates, was to keep a record of the animal-days' feed con- 

 sumed within the individual pastures. Such records were kept 

 for a period of five successive years under the management 

 which is in common practice in that particular grazing region. 

 In order to derive reliable grazing-capacity estimates by the 

 direct method, notably where the animals cannot be under the 

 observation of the investigator at all times, the type should be 

 uniform and relatively pure; the area should be securely fenced 

 if possible; the exact acreage of the area must be known; the 

 departures from the normal in forage production and the close- 

 ness of the grazing should be carefully recorded at the end of 

 each grazing season; the dates at which the stock is admitted 

 and removed from the pasture should be noted; and the num- 

 ber, class, and age of the stock used each year in the test should 

 be registered. The test should be continued long enough to in- 

 clude the more striking departures in the annual forage pro- 

 duction. 



