x PKEFACE 



they never can have any bearing upon the business of farming. 

 There are, however, many matters in which the actual farmer 

 will always have to rely upon the advice of scientific experts, 

 and as a rule the unpractical- looking experiments are devised 

 to settle this or that point on which the scientific man must 

 have information in order to form a correct judgment for the 

 guidance of the practical man. 



Agricultural science involves some of the most complex 

 and difficult problems the world is ever likely to have to solve, 

 and if it is to continue to be of benefit to the working farmer, 

 the investigations, as far as their actual conduct goes, must 

 very quickly pass into regions where only the professional 

 scientific man can hope to follow them. However, it is not 

 with such research that the present volume deals ; here, I 

 trust, there is nothing that the farmer with an intelligent 

 interest in his profession cannot appreciate and find useful. 

 The book is intended, firstly, for any man concerned with the 

 management of land, whether farmer or market gardener, land- 

 owner or agent, who wants to learn something of the processes 

 going on in the growing crop and in the soil, as they have been 

 elucidated by the most complete set of field experiments the 

 world has yet seen. Secondly, the book is intended for the 

 agricultural student ; it will furnish a running commentary on 

 a very large portion of the information he finds in his text- 

 books on agriculture and agricultural chemistry. It is of great 

 importance to the student that he should from time to time get 

 in touch with the sources of the statements and conclusions he 

 reads in his text-books or hears in lecture, since he obtains 

 thereby some idea of the extent to which these statements can. 

 be trusted to apply to working conditions. Lastly, the book is 

 intended for the agricultural teacher and expert, for whom it 

 will provide a certain amount of unpublished matter con- 

 cerning Kothamsted, and will also serve as a guide to the 

 very extensive series of reports issued by Lawes and Gilbert. 

 To this end references have been added at the close of each 

 chapter to the original papers dealing with the subject. 



