Rotation of Crops. 
621 
amounts of nitrogen removed in the leguminous crops of the rota- 
tion are to be attributed ; and it is these amounts that have to 
be taken into consideration in comparing the effects on the 
yield of the other crops of the rotation, and of the rotation as a 
whole, on the one hand of growing a leguminous crop, and on 
the other of fallowing, which of course neither yields nor 
removes nitrogen — unless by loss in drainage. 
Further, the figures show that there was generally three or 
even more times as much of the total nitrogen of the bean crops 
accumulated in the corn as remained in the straw. Lastly, not 
only does the leguminous crop of the rotation yield the most 
nitrogen, but, unless in the case of some of the corn of the 
beans, the whole of it is supposed to be retained on the farm ; 
and there is, in addition, more or less, and sometimes a con- 
siderable amount, of nitrogenous crop-residue left within the 
soil for succeeding crops. 
The Nitrogen in the Wheat Crops . — The results on this head 
are recorded in the bottom division of Table VI. 
Referring first to the amounts of nitrogen in the total produce 
(grain and straw together), it is seen that, both without manure 
and with superphosphate alone, that is with the greatest ex- 
haustion, especially of nitrogen, there was generally about, or 
even more than, twice as much in the rotation as in the con- 
tinuous crops. With the full manure, both mineral and nitro- 
genous, applied for the rotation crops only at the beginning of 
the course, but for the continuous ones each year for the wheat 
crop to be grown, the relative deficiency in the continuous 
crops was, however, very much less. Thus, the figures show 
that the average amounts of nitrogen in the total wheat crops 
were — without manure nearly 35 lb. per acre per annum in 
the rotation crops, and only 17 lb. in the continuous ones ; with 
the superphosphate alone nearly 40 lb. under rotation, but in 
the continuous crops not 20 lb. ; and lastly, with the full 
manure there was an average of more than 42 lb. in the rota- 
tion crops, and of 34 lb. in those grown continuously. There is 
direct evidence, therefore, that there was, under all conditions, 
more nitrogen available to the crops grown in rotation, than 
to those growing year after year on the same land ; and 
the advantage is relatively much the greater where no nitrogen 
had been supplied in manure. The beneficial effect of the 
interpolation of other crops with the cereals is, therefore, very 
obvious. 
In the case of the second crop of the course — the barley — it 
was shown that without manure the increased produce in 
rotation was due to scarcely any roots having been grown, so 
VOL. V. T. S. — 20 T T 
