6J2 
Rotation of Crops. 
first line shows the amounts obtained under rotation, the second 
those in the crop grown continuously, and the third the differ- 
ence between the two : — 
The Dry Matter in the Turnip Crops . — Referring first to the 
upper division of the Table, relating to the Swedish turnips, it 
should be stated that results for the crops grown continuously 
are not available for the same eight years as those grown in ro- 
tation ; but for each of the three conditions as to manuring, the 
average for 19 years of growth is taken. So far as manuring is 
concerned, the unmanured and the superphosphate conditions 
were the same for the rotation and for the continuous crops. 
But, in the case of the mixed manure, the rotation plots received 
a larger amount of nitrogen for the roots ; in fact, enough to carry 
the four crops of the course. The continuous plot, on the other 
hand, received a less amount each year ; but, unlike the rotation 
plots, with no intermediate crops to use up any available residue 
from the previous application. 
The figures show that — without manure — the difference in 
the amounts of dry matter produced in rotation and in continu- 
ous growth are immaterial. The utter failure in both cases 
without manure is confirmatory of the absolute dependence of 
this valuable rotation crop on supplies within the soil itself, 
either from accumulations, or from direct manuring. 
The less produce of the continuous than of the rotation crops 
with superphosphate is also quite consistent with the supposi- 
tion that, under such conditions, the crop greatly exhausts the 
available nitrogen of the soil, and especially of the surface soil. 
With the mixed mineral and nitrogenous manure, again, there 
is also considerably less production of dry substance when the 
crop is grown continuously than when it is grown in rotation. 
The result is, however, due partly to the larger amount of nitro- 
gen directly supplied by manure to the rotation crops as above 
referred to, but partly to the fact that when the same description 
of root-crop, with the same character and range of roots, is 
grown year after year on the same land, the surface-soil be- 
comes close, and a somewhat impervious pan is formed below ; 
conditions which are very unfavourable for a crop which pre- 
eminently requires a good tilth for great development of fibrous 
root within the soil. The results with the mixed manure are, of 
course, the most comparable with those of ordinary practice ; 
and it is clear that, however explained, much more produce 
is obtained under rotation than with continuous growth. It 
need only further be remarked that, of the total dry matter 
produced, there are many times as much in the edible root as in 
the leaf which almost wholly remains only for manure again. 
