228 Bulletin 37. 



rapidly than it could percolate downward. From the 16th to the 

 25th foot the percentage of moisture gradually decreased. The 

 fact that the 25th foot contained the least water of any foot of the 

 clay soil indicates that the soil down to just above that region 

 had been reached by the irrigating water, the latter having per- 

 colated through the gravel into the first eight feet of clay. 



Below the 25th foot the moisture content was apparently af- 

 fected by the ground water nine feet below. It will be observed 

 that the increase in the degree of saturation is quite gradual, 

 however, and that in passing downward wet soil is not .en- 

 countered suddenly, as is commonly supposed. The increase in 

 wetness is, to be sure, more marked in the last three feet above 

 ground water. The degree of saturation of the 34th foot is given 

 as 88 per cent. This, it will be understood, applies to the mixed 

 sample of soil taken from between a plane lying 33 feet below the 

 surface, and a plane lying 34 feet below. At 34 feet from the sur- 

 face the soil was saturated with water, and the degree of satura- 

 tion would be expressed by 100 per cent. The regularity of the 

 changes in the degree of saturation compared with the changes 

 in the actual moisture content, in passing downward, is quite no- 

 ticeable, illustrating the importance of determining the former, in 

 making soil investigations. 



Table of Losses and Gains. 



For the purpose of showing the loss or gain in the moisture 

 content of the respective feet, and the total loss from the orchard, 

 Table II was computed from Table I. As it seemed evident that 

 only or principally the upper 25 feet were affected by surface 

 operations and conditions, the computations are given for only 

 that depth. The percentages given in Table II are the differ- 

 ences between corresponding percentages of moisture for the two 

 dates being compared ; and the pounds are the products of the 

 respective weights per cubic foot and the above differences. 



