Vlll PREFACE. 



sible. Fifty years ago the practice may be said to 

 have been unknown ; yet so widespread lias it now 

 become, that at the present time the capital invested 

 in the manure trade in this country alone amounts to 

 millions sterling. It need scarcely be pointed out, there- 

 fore, that a practice in which such vast monetary 

 interests are involved is worthy of the most careful 

 consideration by all students of agricultural science, 

 as well as, it may be added, by political economists. 



The aim of the present work is to supply in a 

 concise and popular form the chief results of recent 

 agricultural research on the question of soil fertility, 

 and the nature and action of various manures. It 

 makes no pretence to be an exhaustive treatise 

 on the subject, and only contains those facts which 

 seem to the author to have an important bearing 

 on agricultural practice. In the treatment of its 

 subject it may be said to stand midway between 

 Professor Storer's recently published elaborate and 

 excellent treatise on ' Agriculture in some of ' its Re- 

 lations to Chemistry ' a work which is to be warmly 

 recommended to all students of agricultural science, 

 and to which the author would take this opportunity 

 of acknowledging his indebtedness and Dr J. M. 

 H. Munro's admirable little work on ' Soils and 

 Manures.' 



In order to render the work as intelligible to the 

 ordinary agricultural reader as possible, all tabular 

 matter and matter of a more or less technical nature 



