10 



BULLETIN 1170, U. S. DEPARTMENT OF AGRICULTURE. 



been in operation there have been little heading and seeding of blue 

 grama grass (Boateloua gracilis) in the fall division. There have 

 been heading and seeding of this grass in the spring-grazed division, 

 however. Grazing or mowing seems to stimulate its production of 

 flower stalks and heads. The vitality of the seeds is very low, and 

 only a few ever germinate. This fact is further evidence that the 

 value of this grazing system lies largely in the effects of normal 

 development upon the plants. 



PERIOD OF GRAZING AND CATTLE USED. 



The period of grazing has been five months during the warm 

 season. Grazing has started in the spring from May 15 to June 1 

 and continued to October 15 or November 1. Three years out of the 



Fig. 3. — Two-year-old steers used in the grazing experiment. These steers are of the 

 type used at the Northern Great Plains Field Station, near .Mandan, N. Dak., dur- 

 ing 1921. 



six the seasonal grazing has started in May, and three years on June 

 1. This experiment does not take into consideration winter grazing, 

 which should not be depended upon in this section of the Plains. 

 The severe conditions of the winter of 1921-22 emphasize this fact. 



The cattle used for the grazing work have been 2-year-old grade 

 steers of the standard beef breeds. Figures 3 and 4 illustrate the 

 type of steers that have been used. 



The 2-year-old beef steer was decided upon as the unit, as (a) he seemed to 

 be the unit most used by ranchmen figuring on this question; (&) he has 

 about the average capacity for consumption between yearlings, cows, and large 

 steers; (c) he is not disturbed, like the heifer, by periods of cestrum or by 

 calving during the trial. 10 



10 Shepperd, J. H. Carrying capacity of native range grasses in North Dakota. In 

 Jour. Amer. Soc. Agron., v. 11, pp. 129-142, figs. 10, pis. 3-5. 1919. 



