July i6, 1917 Movement and Distribution of Moisture in Soil 



123 



plots receiving 5 inches of water this increase began after the sixth foot, 

 while in those receiving 20 and 40 inches there was an increase in moisture 

 from the surface to the third foot, then a decrease until the sixth foot, 

 before the rise. 



The fallow plots showed no marked variation in the percentage of 

 moisture of the first 7 feet, but there was a sudden decrease from the 

 seventh to the eighth, ninth, and tenth feet for all quantities of irrigation 

 water. 



The third and sixth feet in the fallow plots were highest in moisture 

 for all irrigations. 



Percentage of moisfLAre 



ralLovv 



Cropped 



Fig. 6.— Diagram shovsdng the effect of diflferent fiuantities of irrigation water on the average final -water 

 content in lo feet of soil in the fall in cropped and fallow plots. Average of three years. 



The great variation in the moisture of the cropped soils receiving 

 small applications of water was, of course, due to the withdrawal of 

 moisture from the upper few feet by the crop. This loss is much less 

 noticeable in the heavily irrigated soils. 



Figure 6, derived from the same data as figure 5, shows the variation 

 in the moisture content of the first 10 feet of cropped and fallow plots 

 receiving different quantities of water. 



That the first 5 inches of irrigation produced the greatest increase of 

 moisture, and that each successive increase of 10 inches of water pro- 

 duced smaller increases in the moisture content of both cropped and 



