Rotation of Crops. 
599 
assumed restorative crop— the roots — gave practically no pro- 
duce at all without manure, the barley gave, on land un- 
manured for so many years, an average of rather over 30 bushels 
per acre. The truth is that the cultivation for the preceding 
roots kept the land clean, and as there was practically no pro- 
duce of roots, the soil was, in point of fact, left almost fallow 
for the barley during the winter preceding the roots, during the 
root-crop period itself, and during the succeeding winter, before 
the sowing of the barley. There was, therefore, very good 
preparation for the barley. It will be seen further on that, 
when grown continuously without manure, both wheat and 
barley yield more in proportion to their respective averages 
under ordinary cultivation than do either of the fallow crops — 
the roots or the leguminous crops. Yet, the produce of barley 
in rotation without manure was much in excess of that when it 
is grown continuously; the explanation doubtless being, as 
above referred to, that the crop had been grown after well-cul- 
tivated bare fallow. 
Next, it is to be observed that, there having been practically 
no crop of roots without manure, there was no material differ- 
ence between the yield of the succeeding barley where the roots 
were carted off or where they were fed on the land. 
Turning now to the produce on the four plots with super- 
phosphate alone, it is seen that whilst the average yield of 
barley on the two portions from which the roots had been carted 
off was under 98 bushels, that on the portions where they had 
been fed on the land was, in one case more than 35^, and in the 
other 38 bushels. The effect, on the one hand of the removal 
of the larger crop of roots, and on the other of the retention on 
the land of the greater part of its constituents, is thus very evi- 
dent. It is further to be remarked, that the produce of barley 
where the roots grown by superphosphate had been removed 
from the land, was even less than on the two corresponding 
portions of the unmanured plot. Thus, there is confirmation of 
the supposition that the higher crop of barley without maniu’e 
was due to the previous preparation, and conservation of con- 
stituents, by fallow ; and that the lower produce on the super- 
phosphate plot where the roots had been removed was largely 
due to so much greater exhaustion, especially of the available 
nitrogen, of the surface soil. 
Next it is seen that, on the plots where the mixed manure 
containing nitrogen had been applied for the preceding turnips, 
the produce of barley was on a much higher level ; and it was 
much higher on the portions where the turnips had been fed on 
the land than on those from which they had been removed. 
