and wheat after the removal of the clover, also without 

 manure; in order to gauge, and as far as possible 

 equalise, the condition of the different plots. Experi- 

 ments might then be re-commenced with mangels, or 

 with some other root-crop. 



It is undesirable to reduce the number of samples 

 taken of mangel roots, and mangel leaves, as long as tin- 

 present arrangement of plots and manuring is continued, 

 as it is very important to keep up the chemical statistics 

 of the crops, and especially the nitrogen statistics. But, 

 if it were considered necessary to reduce the sampling, 

 the most important to continue are Nos. 4, 5, and 6, <>f 

 each of the five series ; and of these the leaves, as well 

 as the roots, should be sampled as at present. Although 

 the leaves of the crop are left on the land, they are 

 always weighed, and it is very important to have the 

 means of estimating the amount of constituents 

 accumulated in the leaves, and how much, therefore, of 

 the constituents of the manure and of the crop, remains 

 as only manure again, under the different conditions as 

 to manuring, and the coincident different conditions of 

 development and maturation. 



With a view to the elucidation of the points here 

 referred to, as well as of others, complete analyses of 

 mangel-root-ash, and of mangel-leaf-ash, are specially 

 needed in "mixed-year" samples, for the 5 years 

 1876-80 (or for the 6 years 1878-83 see "Root-crop" 

 Lecture, No. 76, p. 25), and also for the 5 years 

 1886-90, or at least for one of these periods, for the 

 plots as under : 



Series " 0," Plot 4, Plot 5, Plot 6. 

 Series " N," 



Series "A," 

 Series "AC," 

 Series C," 



2. The Soils of the Root-crop Plots. 



Samples of the soil of the root-crop land were col- 

 lected in 1870, from 35 of the plots, at 4 places on 



