20 



BULLETIN 157, U. S. DEPARTMENT OF AGRICULTURE. 



either plat, but whatever growth appeared on the cultivated plat 

 was destroyed, while on the uncultivated plat it was allowed to remain 

 but not to mature. Both plats were seeded uniformly in the fall 

 of 1912 and they were treated alike during 1913. Two alternate 

 plats were added to the test in 1912. 



Soil samples were taken from the fallow plats, and moisture deter- 

 minations were made. These showed no appreciable difference in the 

 moisture content of the plats in either the individual foot sections 

 or the 6-foot averages. There was a uniform decline in the moisture 

 content of the plats from spring to seeding time in the fall. The 



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Fig. 10.— Graphs comparing the average percentage of moisture in each of the upper 6 feet of soil at 

 the beginning, in the middle, and at the end of the fallow season, as found in the summer-cultivation 

 tests of fall-plowed fallow at the Nephi substation, 1909 to 1912, inclusive. 



yield of the plats in 1913, 11.9 and 9.5 bushels per acre, slightly 

 favored the noncultivated plat, but there was so much winterkilling 

 on both that the yields are not significant. 



The value of these tests was increased in 1912 by the addition of 

 nine other plats, treated as follows: Two plats, light cultivation; two 

 plats, medium cultivation; two plats, heavy cultivation; and three 

 plats, no cultivation. 



These nine plats will be kept free from all vegetative growth. The 

 noncultivated plats will be weeded with the least possible disturbance 

 of the soil, thus affording an opportunity to study the- value of cul- 

 tivation methods for moisture conservation alone and not in connec- 

 tion with weed eradication. 



