Rotation of Crops. 
619 
grown without any manure. The results relating to the rota- 
tion barley crops show, however, that the average annual removal 
in them was without manure nearly 30 lb. ; the conditions of 
growth being substantially equivalent to fallow, as practically no 
root-crop had been removed. 
Consistently with other evidence on the point, the amounts 
of nitrogen removed in the barley crops grown on the super- 
phosphate plots is seen to be even considerably less than with- 
out manure, where the increased crop of roots grown under the 
influence of the superphosphate had been removed from the 
land ; but where the superphosphate turnips had been fed on 
the land, the amounts of nitrogen removed in the barley crops 
are more than under the parallel conditions without manure. In 
other words, an increased amount of nitrogen having been taken 
up from the soil by the turnips under the influence of the super- 
phosphate, the land was left poorer in available nitrogen for the 
barley where the increased turnip crop had been removed from 
the land, but richer where it, or its manurial residue, was left 
upon it. 
Again, under the influence of the mixed manure, supplying 
a liberal amount of nitrogen for the roots, which took up a con- 
siderable quantity of it, there was much less nitrogen in the 
succeeding barley, where the roots so grown had been removed, 
than where they or their manurial residue had been left on the 
land. 
The actual quantities of nitrogen removed in the barley crops, 
where the roots had previously been removed, were — without 
manure nearly 30 lb., with superphosphate about 23^ lb., and 
with the mixed manure about 40 lb. ; but where the roots had 
been fed or left on the land, they were, without manure about 
28 lb., with superphosphate more than 30 lb., and with the 
mixed manure containing nitrogen about 47 lb. 
Comparing the amounts of nitrogen taken up by the rotation, 
with those by the continuously grown barley, it is seen, as might 
be expected under the conditions described, that both without 
manure and with superphosphate, the rotation barley took up 
much more than the continuously grown. Where, however, 
nitrogenous manure had been applied for the roots, and they had 
been removed, the succeeding barley took up less nitrogen than 
the continuous crops which annually received nitrogenous 
manure; but where the roots had not been removed from 
the land, the nitrogen in the rotation and in the continuously 
grown barley were nearly the same — about 47 lb. per acre per 
annum. 
The influence of the manuring, and of the amount and 
