174 
INVESTIGATIONS ON ROTHAMSTED SOILS. 
conserve, the " fed" plats show throughout a very decided superiority 
in nitrogen to the "carted " plats. This also accords with the relative 
fertility of the plats as evidenced by their crops. 
In the case of the very liberally manured series ("mixed manure"), 
the plats on which the roots have been fed show in every case more 
nitrogen than those from which the roots have been carted, this being- 
more especially the case again in the plats on which leguminous 
vegetation takes part in the rotation. 
The data, however, to which I am more especially desirous of direct- 
ing your attention are those relating to the comparison (whether on 
the " carted " or on the " fed " plats) of the fallow portions with those 
portions on which leguminous plants have taken a place in the rota- 
tion. These are best studied b} r the arrangement of figures to be 
found in the right-hand half of each of the Tables 89 and 90. 
Taking first the unmanured land, it will be seen that both in 1874, 
in the seventh rotation, and in 1883-84, after the ninth rotation, the 
leguminous land was found to be decidedly richer in nitrogen than 
the fallow land. In five out of the six cases in which the soils were 
comparatively analyzed there was found on the average, in the sur- 
face soils of these unmanured leguminous plats, about 126 pou'nds 
more of nitrogen per acre than on the plats on which neither beans 
nor clover were grown. 
On the superphosphate series there is also throughout a great advan- 
tage in favor of the leguminous plats. On the plats from which the 
turnips are annually carted we find that the portions on which beans 
or clover have been grown show on the average 194 pounds more of 
organic nitrogen per acre in the surface soil than do the fallow por- 
tions, while if we regard the plats which have been kept in higher 
condition by the consumption of the roots on the land, the superiority 
in the soils under the leguminous rotations, as compared with those 
under rotations which included. a bare fallow, is represented by an 
average of no less than 322 pounds of nitrogen per acre. 
So in the mixed manure series the advantage on the whole lies dis- 
tinctly with the bean or clover land, the average excess of nitrogen 
found in it as compared with the fallowed portions of the plats being 
111 pounds per acre where the roots are carted, and as much as 257 
pounds per acre where the roots are fed. 
Thus we have from these plats further interesting analytical testi- 
mony, if such were needed, to the effect of leguminous crops in 
increasing or maintaining the nitrogenous contents of the soil, and 
also analytical evidence of the effect on the soil of the alternative 
met hods of carl ing or consuming the root crop. 
So far we have been referring only to the organic or total nitrogen 
found in the soils. The soils ol* some of the plats, however, have 
been subjected to a much more complete examination as regards their 
contents of nitric nitrogen, which on four of the plats has been deter- 
