July i6, 1917 Movement and Distribution of Moisture in Soil 125 



The difference between the moisture in the beet and the potato soil was 

 not great except in the plots receiving no water and 2% inches. Beets 

 drew heavily on the water of the fourth, fifth, and sixth feet, while 

 potatoes took more from the lower depths of the unirrigated soil. In 

 nearly all depths for the 2X-inch irrigation the potatoes used more water 

 than did the beets. 



Distribution Before and After Irrigation 



Figure 8, showing the distribution of moisture immediately before 

 and 24 hours after irrigation of i, 2K. 5. and 7X inches, was taken from 

 plots 41 F to 45 F and 61 F to 65 F, described in the above experiment. 

 The results are averages of several tests in 1912 and 191 3. 



This graph strikingly indicates the rapidity of moisture movements. 

 With a slight exception in the case of the 2>^-inch watering, there was an 

 appreciable increase in the soil moisture to a considerable depth within 

 24 hours after the application of from i to 7>^ inches of water. Most of 

 the moisture, however, was retained in the first 4 feet, below which 

 there was an irregular decrease with depth. 



Before and after irrigation the water in the soil tended to accumulate 

 in the first 3 and the last 3 feet. This distribution is most evident where 

 small irrigations were given, for with the larger applications the moisture 

 tended to decrease irregularly with depth. 



EFFECT OF MULCHES 

 Under Irrigation 



This was a study on the Greenville Farm in 191 3 of a fallow plot receiv- 

 ing different cultural treatments. On June 12 and on August 7 and 27, 

 5-inch applications of irrigation water were given the soil. The plot 

 was divided into three equal parts; one part was left unmulched with 

 the weeds pulled, another received a 2-inch straw mulch, and the third 

 was cultivated 2 inches deep. 



Samples of the soil were taken on July 16, August 8, 15, 22, 28, and 

 September 10, 191 3. Figure 9 shows the distribution of moisture under 

 the different mulches as found by averaging all these samplings. It 

 will be noticed that the moisture under all treatments increased from 

 the surface dov/n to the third foot, after which there was a decrease to 

 the ninth foot. 



The 2-inch straw mulch showed the highest percentage of water for 

 all depths except the tenth foot, while the unmulched soil with weeds 

 pulled had the least moisture, except in the eighth foot. There was 

 about the same difference between the 2-inch straw mulch and the 2-inch 

 cultivation as there was between the latter and unmulched soil, at 

 least in the upper soil layers. The lower depths showed less difference. 



