32 



BULLETIN 157, U. S. DEPARTMENT OF AGRICULTURE. 



expected to create a mulch which would prevent the evaporation of 

 soil moisture and allow the plant greater freedom for growth. These 

 factors constitute the basis of a great deal of argument in favor of 

 the spring cultivation of winter wheat, a practice which is rather gen- 

 eral in the Great Basin area. The results obtained are quite contrary 

 to those which were expected. 



YIELD OF GRAIN. 



The annual and average yields of the plats for 1909 to 1913, inclu- 

 sive, are given in Table XIII and are shown graphically in figure 16. 



Table XIII. — Annual and average yields of winter wheat obtained from cultivated and 

 uncultivated plats at the Nephi substation, for the years 1909 to 1913, inclusive. 1 



Treatment. 



Yield per acre of grain (bushels). 



1909 



1910 



1911 



1912 



1913 



Average. 





8.33 

 12.66 



19.00 

 19.50 



27.90 

 27.70 



14.90 

 14.90 



9.83 

 10.50 



15.99 





17.05 







1 The Koffoid variety was used in 1909, while the Turkey was used in 1910 to 1913, inclusive. 



It is of peculiar interest to note that in four of the five years there 

 has been practically no difference in the yields obtained in this test. 

 The yield of the noncultivated plat has been higher in three of the 

 five years, while in 1911 the difference of 0.2 of a bushel per acre 

 favored the cultivated plat. The yields of 1912 were identical. The 

 difference in the average yield of 1.06 bushels in favor of the noncul- 

 tivated plat is largely due to the greater yield of this plat in 1909. 



EFFECT ON SOIL MOISTURE. 



Soil samples were taken each year from each of the plats, usually 

 at the beginning, in the middle, and at the end of the season. Six- 

 foot samples were taken, and the moisture content of each foot section 

 was determined in the manner previously described in this bulletin. 

 The results are presented in Table XIV, which shows the annual and 

 average percentage of moisture in each foot and for the entire 6 feet 

 in the spring, in the summer, and in the fall. 



Table XIV shows a marked uniformity in the moisture content of 

 the two plats at the beginning, in the middle, and at the end of the 

 season, the seasonal loss from both plats being about the same. The 

 greatest difference was shown in 1909, when the cultivated plat with 

 a thin stand of grain lost moisture less rapidly than the noncultivated 

 plat, on which the stand was thicker. In all other years the stands 

 were more nearly alike. Figures 17, 18, and 19 illustrate graphically 

 the results shown in Table XIV. It is apparent that spring cultiva- 

 tion of whiter wheat did not conserve any appreciable amount of 



