potatoes, must be considered as of substantially equal 

 importance ; that is if, as hitherto, questions of funda- 

 mental, permanent, and general, as distinguished from 

 those which are of passing, or local, interest, are to be 

 kept in view. It was further considered that, under 

 the same assumption, the laboratory investigations con- 

 nected with the field results, are not susceptible of any 

 great or material change, or reduction ; as the plan and 

 objects supposed, involve the keeping up of the 

 chemical history, both of the experimental crops, and 

 of the soils on which they are grown ; and that all that 

 can be done is, to consider what modifications or 

 reductions in the detailed conduct of the different 

 experiments are admissible, or may be desirable, within 

 the comparatively near future, without sacrificing the 

 main objects of enquiry. 



In a letter received from Sir J. B. Lawes since the 

 above was written, he says " * * * looking forward 

 to the great questions which are being raised in regard 

 to exhaustion of soil, and restoration of fertility, I 

 certainly think that our soil samples, and their history, 

 take the first place in importance." 



I will now briefly indicate the scope of the investiga- 

 tions, and what has been published, in connection with 

 each of the above enumerated subjects of experiment. 



I. THE CONTINUOUS GROWTH OF WHEAT, IN 

 BROADBALK FIELD. 



1. The Field Results. 



The first experimental crop was harvested in 1844, so 

 that the crop of the present year, 1891, will be the 

 48th. But as the arrangement of the manuring of the 

 different plots was not thoroughly systematised until 

 1851-52, this is only the 40th year under substantially 

 the same plan as to manuring as now followed. 



In the "Memoranda " is annually given a statement of 

 the manuring, and of the produce, of each plot, in the 



