32 



each, and in each case to the depth of 3 times 9 inches, 

 or in all 27 inches. The nitrogen has been determined 

 in the mixed sample from the 4 holes, for each depth, 

 for each of the 35 plots. 



The results relating to some of the surface soils only, 

 have as yet been published (No. 67) ; and they are of 

 much interest as showing that, under the influence of 

 the growth without nitrogenous manure, of these 

 reputed restorative crops, the surface soil is to a greater 

 extent exhausted of its available nitrogen than by the 

 growth of any of the other experimental crops, even 

 than by the continuous growth of the cereals. 



The results relating to the subsoils are subject to 

 the same observations as those obtained with other sub- 

 soils, and have not been published. 



The soils of the root-crop plots should be again 

 sampled, both for total nitrogen and for nitric acid 

 determinations, whenever the growth of mangel-wurzel 

 is discontinued, and again after the 5 years of the 

 gauge-cropping, as above proposed. 



V. THE CONTINUOUS GROWTH OF POTATOES IN Hoos- 

 FIELD. 



1. The Field Eesults. 



These experiments were commenced in 1876, and are 

 still in progress, so that the crop of the present season, 

 1891, is the sixteenth in succession on the same land. 

 The series comprises 10 plots. The description and 

 amounts of the manures used (if any), and the amounts 

 of produce, each year, are given in the " Memoranda" 



2. The Composition of the Crops. 



Hitherto, samples have been taken of the " good," of 

 the " small," and of the diseased potatoes, of each plot, 



