EXPERIMENTS OX THE MIXED HERBAGE OF PERMANENT MEADOW. 375 
In comparing these results with one another, and with those obtained on the mixed 
herbage of permanent meadow land, it must be borne in mind that, in the case of 
the wheat, the farmyard manure had been applied, and the crop grown, for eight 
years preceding the period for which the calculations are made, and there was doubt¬ 
less, therefore, already a considerable accumulated residue within the soil; and that, 
for both the wheat and the barley, the manure was applied in each of the 20 years, 
instead of only for eight years as for the grass. Further, in the case of the wheat 
and the barley the increase is reckoned over the produce by purely mineral manure, 
whereas in that of the grass it is taken over that without manure, since the elfect of 
the mineral manure on the mixed herbage is to develop so much more of the highly 
nitrogenous leguminous plants. 
The general result is that, according to the estimates, a higher proportion of the 
supplied nitrogen was annually recovered over the 20 years in the autumn-manured 
and autumn-sown (and longer so grown) wheat, than in the spring-manured and 
spring-sown barley ; and that, about the same proportion was recovered in the barley, as 
over the eight years in the grass. But it will be obvious that the estimate of the 
nitrogen in the increase is likely to be nearer the truth in the case of the two cereal 
crops than in that of the mixed herbage, the character of which, and consequently the 
capability of collection from normal sources, is so changed by manure. The comparison 
of the results with the cereal crops may indeed be taken to indicate that the pro¬ 
portion of the nitrogen of the farmyard-manured hay crops estimated to be derived 
from the manure is too low; and it would seem to be a further reason for this suppo¬ 
sition, that, with the much greater variety of root-distribution, and of root-capacity, and 
a much longer season of greater or less activity of growth, in the case of the mixed 
herbage, there would also be a greater power of gathering up the supplies by manure. 
However this may be, the evidence as it stands points to the conclusion that, neither 
with the wheat, the barley, nor the mixed herbage, was there more than from 10 to 
15 per cent, of the nitrogen supplied in the farmyard manure recovered in the 
increase of crop during the years of the application. 
In the case of the barley experiments, after the farmyard manure had been applied 
for 20 years in succession, the plot was divided ; to one-half, the dung was still 
annually applied, but the other was now left without any further manure. The 
following table shows the result as to the recovery of the nitrogen of the manure in 
the two cases. In the upper division, are given the particulars for the 20 years (as 
already quoted), for the next six years, and for the 26 years, where the application was 
continued; and in the lower division, for the 20 years of the application, for the six years 
after the discontinuance, and for the 2 6 years, 20 with, and six without, the manure. 
