PREFACE 



In many of the high schools and other secondary schools 

 into which instruction in agriculture was introduced a few 

 years ago there has been such a development of the subject 

 that one general text is no longer adequate. In these schools 

 some of the more important phases of the subject now re- 

 ceive a degree of attention that calls for specialized texts. 

 This is particularly true of the secondary agricultural schools 

 and the normal schools. It was with the hope of meeting 

 this need, and also of contributing to the demands of short 

 courses in agriculture and of summer courses for teachers, 

 that this book was written. 



The attempt has been made so to present the subject that 

 the pupil who has no knowledge of chemistry or other natural 

 science will be able to understand it. No chemical symbols 

 or formulae have been used. Use has been freely made of a 

 limited number of names of chemical substances contained 

 in commercial fertilizers which contribute to the nutrition 

 of plants. These, however, are terms with which the pupil 

 can familiarize himself as readily as with the geographical 

 and other names that he has already mastered. 



Following each chapter are field and laboratory exercises, 

 designed to illustrate in a concrete manner the teachings of 

 the text. There are more of these than any one teacher will 

 probably find it expedient to have his class perform, but the 

 considerable number and variety of exercises will make it 

 possible for any school to afford the necessary facilities for 

 performing some of the demonstrations. 



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