vi INTRODUCTION 



productivity of the land : agriculture is the oldest and 

 most widespread art the world has known, the applica- 

 tion of scientific method to it is very much an affair 

 of the day before yesterday. Nor can we see our way 

 to any radical acceleration of the turnover of agricultural 

 operations that shall be economical ; the seasons and the 

 vital processes of the living organism are stubborn facts, 

 unshapable as yet by man with all his novel powers. 

 But even if the best farming practice is still a step 

 beyond its complete explanation by science, yet the 

 most practical man will find his perception stimulated 

 and his power of dealing with an emergency quickened 

 by an appreciation of the reasons underlying the 

 tradition in which he has been trained ; and such an 

 introduction to the knowledge of the soil it is the aim 

 of this little book to supply. The book is primarily 

 intended for the students of our agricultural colleges 

 and schools, and for the farmer who wishes to know 

 something about the materials he is handling day by 

 day. While a certain knowledge of chemistry is 

 assumed, it is hoped that the subject is so treated as 

 to be intelligible to the non-technical reader who is 

 without this preliminary grounding. Though the book 

 is in no sense an exhaustive treatise, it has been my 

 desire to give the reader an outline of all the recent 

 investigations which have opened up so many soil 

 problems and thrown new light on difficulties that 

 are experienced in practice. The scope of the book 

 precludes the giving of references and authorities for 

 all the statements which are made; but, for the sake 

 of the more advanced student, a bibliography has 

 been appended, which will take him to the original 

 sources and give him the means of learning both 

 sides of the more controversial questions. 



The same reason — want of space — has prevented me 



