

' 



%' PREFACE 



These practices are the result of ten years' experience in 

 teaching soil physics, and are designed for one semester's work, 

 during which it is hoped to give the student a knowledge of the 

 principles that underlie many common agricultural operations. 



In a number of practices students may work together in 

 groups, not so large, however, but that each one may have a 

 distinct problem to work out in each practice. This plan will 

 enable the class to complete the work in one semester, which 

 otherwise might not be possible. 



Questions are asked and references given to enable the stu- 

 dent to get the greatest amount of information possible out of 

 each practice. 



An appendix of additional practices is added for students who 

 wish to pursue the subject further. 



THE AUTHORS 



UNIVERSITY OF ILLINOIS, COLLEGE OF AGRICULTURE 

 URBANA, ILLINOIS 



COPYRIGHT, 1912, BY GINN AND COMPANY 

 212.9 



