I30 



Journal of Agricultural Research 



Vol. X, No. 3 



the moisture in the upper 2 feet and prevent its rapid descent into the 

 lower soil layers. This allows much of the moisture to be lost by evapo- 

 ration; hence, the lower layers remain drier than the corresponding layers 

 of spring-plowed soil. 



EFFECT OF PRECIPITATION ' 



The data presented in figure 13, showing the effect of the season on the 

 distribution of soil moisture, were obtained from the experiment on the 



Percentage ' of mo isfure at d ifferent dates 



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Fig. 12.— Diagram showing the effect of spring and fall plowing under dry-farming conditions on the dis- 

 tribution of moisture in the spring, summer, and fall to a depth of 6 feet. Average of eight years. 



effect of mulches under dry-farming conditions at Nephi presented in 

 figures lo and ii. 



Each column in the figure is the average of the moisture in the 24 plots 

 receiving the 1 2 treatments described in the above experiment . 



The rainfall throughout this period is in Table II. 



Table II. — Rainfall {in inches) at Nephi Substation from May ig to August 16, IQ16, 



inclusive'* 



o There was no precipitation in June. 



