PREFACE TO THE THIRD EDITION 



Considerable revision has been made in this third edition. The 

 first two editions of the book have had a very wide use in the colleges 

 and agricultural schools. However, in the second edition in 1918 

 it was not possible to bring much statistical data up-to-date, as 

 the war had disturbed the collection of crop statistics in many 

 foreign countries and conditions were generally abnormal. It is 

 possible now to bring the world statistics in most cases up to date. 

 In addition, the Fourteenth Census of the United States has been 

 completed and a new, complete set of charts prepared by the 

 Department of Agriculture, on the distribution of crops, which 

 I am fortunate in being able to include in this new edition. Also 

 the proposed Federal standards for rice, sorghum, and rye have 

 been included, bringing the book up-to-date in practically all its 

 essential details. 



E. G. MONTGOMERY. 

 WASHINGTON, D. C. 



September 14, 1922. 



