PREFACE TO THIRD EDITION 



THIS work is the outgrowth of instruction given at 

 the University of Minnesota to young men who intend 

 to become farmers and who desire information that will 

 be of assistance to them in their profession. At first 

 mimeographed notes were prepared, which were later 

 published under the title " The Chemistry of Soils and 

 Fertilizers." This was revised, enlarged, and published 

 as " Soils and Fertilizers." With the extension of 

 various lines of investigation relating to soils, a sec- 

 ond revision and enlargement of the book has become 

 necessary. It is the aim to present in condensed form 

 the principles of the various sciences, particularly chem- 

 istry, which have a bearing upon the economic produc- 

 tion of crops and the conservation of the soil's fertility. 

 The work as now presented includes all the topics 

 and the laboratory experiments relating to soils, as out- 

 lined by the Committee on Methods of Teaching Agri- 

 culture, of the Association of Agricultural Colleges and 

 Experiment Stations. 



HARRY SNYDER. 



UNIVERSITY OF MINNESOTA, 

 COLLEGE OF AGRICULTURE, 



ST. ANTHONY PARK, MINNESOTA, 



March i, 1908. 



