28 BULLETIN 1405, U. S. DEPARTMENT OF AGRICULTURE 



season and at varying frequency, chemical analyses were made (by 

 the Bureau of Chemistry) of representative forage samples taken 

 from typical plots. Special examinations and numerous physical 

 and chemical analyses were also made of the root systems of vari- 

 ously treated plants, the object being to determine their depth, 

 spread, and weight, and also to ascertain the amount of food stored 

 in the roots, especially at the time of inception of growth in the 

 spring. 



SPECIES OBSERVED 



The following plants were included in the tests: 



Violet wheat grass (Agropyron vio 

 laceum). 



Common brome (Bromus inermis). 



Mountain brome (Bromus polyan- 

 thus). 



Nevada blue grass (Poa nevaden- 

 sis). 



Letterman needle grass (Stipa let 

 termani). 



RESULTS 



Yarrow {Achillea lanulosa). 

 Mountain dandelion (Agoseris pu- 



mila ) . 

 Wild geranium (Geranium viscosis- 



simum). 

 Snowberry (Symphoricarpos oreophi- 



lus). 



Athough conditions within the experiment were made as compar- 

 able for each cropping method studied as was possible, considerable 

 variation occurred in individual species. These variations were 

 attributed to fluctuations in climatic conditions within a season and 

 from year to year, unusual wind movement, the variation in soil, 

 soil moisture, slope and exposure, competition from adjacent vegeta- 

 tion, injury by rodents, and possibly other factors. Highly favor- 

 able growing seasons render obscure or practically offset the effects 

 of a given cropping method which otherwise would show a cumula- 

 tive physiological response by a diminution of yield. 



Though the results presented can not yet be considered as conclu- 

 sive in all cases, they do give indications of what may be expected 

 from different methods of grazing and clearly show the undesir- 

 ability of adopting or continuing certain grazing practices and the 

 good results to be obtained from others. 



PLOTS HARVESTED FREQUENTLY 



The data in Table 5 typify the results obtained from cropping 

 the herbage in the plots five times in a season to 1 inch above the 

 ground. The first harvesting was made two weeks after growth 

 began, the following three at monthly intervals, and the last, which 

 provided for the removal of the aftermath, at the end of the grow- 

 ing season. . 



