16 



Under the longer growing seasons, it is probable that when 160 pounds of 

 nitrogen are applied per acre, the two-cut system produces more hay than 

 the single-cut system. 



Changing the Composition of the Sward 



The proportion of legumes in the sward is important as far as yield and 

 quality of hay are concerned. The legumes normally found in Colorado 

 mountain meadows are alsike and redtop clover. These legumes are adapted 

 to different areas. One area may utilize redtop clover successfully while 

 alsike clover may be almost impossible to establish. In an adjacent area, 

 the opposite might be true. 



High yields of mountain meadow hay are usually associated with con- 

 siderable clover in the sward when little or no commercial nitrogen fer- 

 tilizer is used. The clover adds to the yield directly, and it is believed that 

 the clover's fixation of nitrogen increases the yield of the grasses in the 

 sward. Intermittent irrigation, reasonably good drainage and, when needed, 

 phosphate fertilizer, are essential to establish and maintain stands of clover. 



The term, "clover year, " is heard frequently in the mountain meadow 

 areas. It indicates that in that particular year an unusually large part of the 

 hay was clover. The factors that are responsible for good and poor clover 

 years are presently unknown, 



A limited amount of research has been done on the seeding of clovers into 

 the sward in Colorado mountain areas. From 1950 to 1953, inclusive, a few 

 trials were made as part of the Blackstock experiments near Gunnison, Colo. 

 A summary of the results of this phase of the experiment is presented in 

 table 5. 



The data used for the basis of table 5 were tested by Willhite and Rouse 

 for statistical significance and none was found at the 5-percent level. This 

 is despite the fact that, in each instance, the sods seeded with clover outpro- 

 duced the native sods. In their test for significance, Willhite and Rouse used 

 all 4 years and all 6 treatments. If the 2 years following seeding are con- 

 sidered alone, then sod seeding by itself under either harvest system, or in 

 conjunction with phosphate fertilizer under the two-cut harvest system, shows 

 a statistically significant increase in production (see appendix table 19), The 

 2 years following the year of sod seeding are perhaps the only years in which 

 any appreciable increase in production can be expected. Tests for statis- 

 tical significance show that this was the case in the Blackstock experiments. 

 Sod seeding also increased the crude protein content of the hay slightly. 



