34 



BULLETIN 1170, U. S. DEPARTMENT OF AGRICULTURE. 



weeds in the biennial units were coarser and because of the accumu- 

 lated growth of 1920, which made the hay " dusty." Ea,ch of 

 these factors reduces the feeding value of the hay. There is also 

 more waste in feeding the hay from the biennial units, but perhaps 

 not enough to overcome the difference in vield. 



Table 11. — Yields of native hay for the years 1919 to 1921, inclusive. 

 [Series I is mowed in odd years, Series II each year, and Series III in the even years.] 





Acre 

 units. 



Yield of hay per acre (pounds). 



Year mowed. 



Series. 



Average. 





I. 



II. 



III. 



1919 



22 

 33 



726 



855 



519 

 697 

 592 



700 





560 492 

 426 413 



583 



477 



Average 



570. 7 586. 7 



602.7 



586.7 





1 

 2 

 3 





1920 





287 

 229 

 199 



210 

 210 

 242 



























238.3 



220.7 







1 

 2 

 3 







1 921 



548 258 

 628 330 

 655 335 



























610. 3 307. 7 



















1 Not mowed since 1915. 



2 Part mowed in 1916 and 1917. 



3 Mowed in 1918. 



The mowed units bear a direct relation to the grazing experiment, 

 as they at once supply data upon which to base an estimate of the 

 extent of the feed annually available for grazing. The units also 

 bear a direct relation to the clipped quadrats. The quantity of 

 feed the cattle obtain by grazing is between that of the yields of the 

 mowed units and the clipped quadrats. The cattle get feed by 

 grazing that is not recovered by a mowing machine, but they do 

 not graze as closely as the vegetation is removed in the clipped 

 quadrats. 



Blue grama grass and the two species of Carex enter but slightly 

 into the hay, as during most seasons they are too short to be cut with 

 a mowing machine. 



FIELD GERMINATION TESTS. 



Field germination tests have been made with more than 30 

 species of native grasses. The seeds were collected during 1916 and 

 1917 and were planted in the grass nursery in the spring of 1918. 

 Seeds of some of the more common species have been collected and 

 planted since that time. In no case has any one of the highly im- 

 j)ortant grazing grasses shown a high degree of germination. Boute- 

 loua gracilis is very low in vitality and produced only two or three 

 j)lants from several hundred seeds sown. The same is true for 

 Stipa comata. However, another species of Stipa (S. viridula), 

 which is not common on the prairie, has a germination equal to that 

 of the ordinary field crops. Koeleria cristata also has shown a very 

 low germination. Seasons more favorable to the growth and ma- 



