110 



THE PRINCIPLES OF SOIL MANAGEMENT 



Fio. 33. Effect of freezing on the granulation of clay soil. The lower pan 

 of soil on the left was not frozen. That on the right was frozen and thawed 

 once. The upper pan of soil on the left was frozen and thawed three times, 

 the one on the right five times. Notice the increased number of checks on the 

 more frequently frozen soil. 



table, which represents the effect of repeated freezing 

 of a uniform sample of wet puddled clay, after which 

 all were permitted to dry out. The figures are for the 

 weight necessary to force a knife-edge a uniform dis- 

 tance into the soil, in each case reduced to basis of 100. 



1. Check, unfrozen 100.00 



2. Frozen once 30.31 



3. Frozen three times ...... 27.33 



4. Frozen five times 21.88 



