xii PREFACE 



investigations with the material in which the Station is 

 so rich. 



In this book little has been said of the work now in progress ; 

 speaking generally, the old plots as described are being continued 

 without essential change, but the current investigations deal 

 chiefly with the composition of the crops produced and with the 

 soil. The bacterial life of the soil forms indeed the unknown 

 territory which promises the greatest reward to the explorations 

 of the agricultural chemist of to-day. 



In the preparation of the book, I have to thank Dr N. H. J. 

 Miller for most of Chapter II., and both him and Mr J. J. 

 Willis for much detailed information and many facts that have 

 never been recorded. Dr H. T. Brown, F.R.S., and Dr J. A. 

 Voelcker have been good enough to read the proof-sheets and 

 make many suggestions. Particularly I have to thank Mr G. 

 T. Dunkley for the great trouble and care he has taken over 

 the preparation of the tables and diagrams ; without the help 

 of his knowledge of the past history and his familiarity with the 

 records, I should have found it impossible to prepare this account 

 of the Kothamsted Experiments. 



A. D. HALL. 



THE ROTHAMSTED EXPERIMENTAL STATION, 

 HARPENDEN, March 1905. 



