664 STATE BOARD OF AGRICULTURE. 



The Lenawee county soils showed no appreciable increase in the con- 

 centration of the soil solution after 10 days in five instjinces. In two 

 cases there was a slight decrease in the concentration of the soil solutioii. 

 In five soils the virgin samples showed, a decidedly greater increase in 

 the soluble salt content than the cropped samples. 



At the end of the thirty-day period these soils exhibited n decided 

 difference in behavior from the Ingham county soils under the same 

 conditions. In every case but one there was a marked increase in the 

 soluble salt content above that present after ten days. This is a very 

 interesting point and further reference will be made to it. 



At the end of the second period four soils showed a greater increase 

 in the concentration of the solution of the virgiu sample than in that 

 of the cropped. In one soil there was no difference and in two cases the 

 cropped samples were lost so comparisons could not be made. 



A summary of the results with the Lenawee county soils brings out 

 that there is a tendency for virgin soils to go into solution to a greater 

 extent than the cropped. This agrees with xhe results from the Ingham 

 county soils at high water content but is somewhat at variance with the 

 results obtained when a medium water content was used. 



Optimum Water Content. In order to simiilate field conditions more 

 nearly it was considered advisable to carry on a series of experiments 

 in which the soils were maintained at a moisture content similar to that 

 found under natural conditions. 



For this investigation samples of soil from Lenawee county were used. 

 They were brought to a laboratory as quickly as possible, screened 

 through a coarse screen and thoroughly mixed. When not sufficiently 

 moist distilled water was added to bring them to optimum moisture 

 content. Two hundred gram samples were weighed into sterile tumblers 

 and incubated at 25° C. To determine the freezing point depression 

 sufficient distilled water was added to make a thick cream and the soil 

 stirred thoroughly to insure uniformit3^ Samples were removed with a 

 spoon to a freezing point tube and the determinations made witli the 

 Beckmann thermometer, as usual. 



In the table below are found the freezing point depressions and Ihe 

 calculated parts per million of soluble salts present at the beginning of 

 the experiment and after 10 and 42-day periods. 



