PKEFATOEY XOTE 



The student practices described in this laboratory manual are the 

 result of ten years' experience by the authors in conducting classes 

 in a course of study in soil fertility. With some modifications the 

 usual chemical methods are employed, specific chemical directions 

 being commonly based upon those adopted by the Association of 

 Official Agricultural Chemists. Otherwise these practices were origi- 

 nated in this University. 



The increasing number of students in this institution, and the 

 fact that some other institutions also use our manual, induced us 

 to put it in printed form. 



Suggestions from other teachers of soil fertility regarding pos- 

 sible improvements in the manual will be gladly received. 



THE AUTHORS 



UNIVERSITY OF ILLINOIS, URBAXA 



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