16 



should not be limited by the exigencies or possibilities 

 of existing lines of investigation or discussion. 



I have referred to these points here, as they naturally 

 arise in connection with the question of the wheat field 

 soils and subsoils ; but, as has been intimated above, 

 they will probably prove of greater interest and im- 

 portance in connection with the soils of other crops, 

 and having indicated the points here, I may refer to 

 them more briefly when considering the history of other 

 fields and crops. I have also gone into more detail in 

 regard to other points in connection with the wheat 

 experiments, which, mutatis mutandis, will apply to the 

 other fields and crops, and which therefore may be 

 treated more briefly so far as they are concerned. 



In conclusion in regard to the wheat experiments, as 

 has been indicated, most of the results relating to the 

 total nitrogen of the surface soils, and most of those 

 relating to the nitrogen as nitric acid, in both surface 

 and subsoils, have already been published ; but from 

 what has been said it will be readily understood why 

 the results relating to the total nitrogen of the subsoils 

 have not been recorded, but have only been used as a 

 means of forming approximate estimates of the total 

 amount of combined nitrogen existing to given depths, 

 on a given area. 



It should be added that a rdsumt, both of the Field 

 and the Laboratory results relating to wheat, is given in 

 No. 68, published in 1884 



II. THE CONTINUOUS GROWTH OF BARLEY, IN 



HOOSFIELD. 



1. The Field Eesults. 



The fortieth crop of barley in succession on the same 

 land, without manure, with farmyard manure, and with 

 different chemical manures, is now growing (April 

 1891). A summary of the results is annually given 

 in the " Memoranda" It will there be seen that 



