vi PREFACE 



periods to the consideration of experimental results in gen- 

 eral, to the making of local applications and the applying of 

 the principles of plant physiology and plant-breeding to field 

 crops. 



Many students in field crop courses, both in agricultural 

 schools and colleges, have come from town or city homes, 

 and have had little or no farm experience. While it is not 

 possible to acquire farm experience from a textbook, it is 

 possible to gain from such a source much of the general 

 information which is lacking. 



In the writing of this book there has been included but 

 little statistical matter and but little experimental data, 

 which can be presented in a more up-to-date form by 

 means of lectures. As the book was originally written, it 

 contained some discussion of all of the North American 

 field crops, but in order to keep it within a reasonable size, 

 it has been necessary to omit some of them, the most im- 

 portant of which are sugar cane and tobacco. 



The author has observed, first as a student and later as 

 an instructor, that the interest which the student feels in 

 any subject depends largely upon whether or not the sub- 

 ject matter is presented in an attractive manner. For that 

 reason he has included in this book somewhat in detail 

 some facts which are of interest but not generally con- 

 sidered of vital importance. 



It is hoped that this book will prove useful as a general 

 textbook of field crops in elementary courses, and as a sup- 

 plementary textbook in other courses, for students with 

 little or no elementary knowledge of the subject. 



I am indebted to C. G-. Williams and F. A. Welton of the 

 Ohio Experiment Station, to Professor E. G. Montgomery 

 and Dr. H. H. Love, of Cornell University, to C. E. Ball 

 and Dr. C. E. Leighty, of the U. S. Department of Agri- 

 culture, and to Professor H. D. Hughes, of Iowa State 



