EXPERIMENTS ON THE MIXED HERBAGE OF PERMANENT MEADOW. 335 
of stones) 18,000,000 lbs., it would result that, down to that depth, the soil of plot 9 
(with the ammonia-salts) contained 200 tons, and that of plot 14 (with the nitrate) 
325 tons, less water per acre, than that of the unmanured plot to the same depth— 
quantities which correspond respectively, to about two, and three-and-a-quarter, inches 
of rain. And, from the great difference in the percentage of moisture at the lower 
depths, it may be concluded that the difference extended deeper still. 
It would thus seem that the subsoil had contributed more water to the growing 
vegetation on the manured than on the unmanured land, and much more where the 
nitrate was applied than where the ammonia-salts were used. But the questions 
arise—if the unmanured subsoil retained so much more water, why did the crop suffer 
from the drought ? and why did the crop manured with the ammonia-salts suffer so 
much more than that with the nitrate ? The answer, briefly stated, is that different 
plants, of different habits of growth, prevailed on the respective plots, according to the 
conditions of manuring. 
On the unmanured plot there was the greatest number of species, but those which 
prevailed had finer and less vigorous roots, which penetrated comparatively little below 
the surface soil; the raw clay of the subsoil was consequently much less changed, and 
it had yielded up very much less moisture to the growing crop. 
On the plot manured with the mineral manure and ammonia-salts free-growing 
grasses predominated, but chiefly those whose underground habit rendered them 
dependent for their food and moisture in a great measure on the stores to be found 
in the surface soil, and in the upper layers of the subsoil. Still, owing to the increased 
vigour of growth under the influence of the manure, more moisture was obtained from the 
lower layers ; probably, in part directly by the roots, and in part by the aid of capillary 
action induced by the pumping out of the upper layers ; and the results indicated that 
the action extended beyond the depth to which the samples were taken. 
On the plot manured with mineral manure and nitrate of soda, in that year one 
species, the Bromus mollis, contributed nearly half the produce ; its wiry roots have a 
very characteristically downward tendency, and they were found to penetrate deeper 
than those of any other of the grasses, and, therefore, to have acquired command of 
lower layers than any associated with them ; and this was especiahy so compared 
with the herbage on plot 9, with the ammonia-salts. The result was that the lower 
layers were pumped drier, and, under these circumstances, the drought affected the 
amount of crop but little. 
In accordance with these facts as to the difference in the character of growth, and 
the amount of water found at different depths, great differences were observed in the 
characters of the soil and subsoil of the several plots. 
The first nine inches of soil of the unmanured plot possessed the character of mould 
in nearly the same degree as that of the manured plots. The second nine inches was 
also very much altered from the character of the clay subsoil. Below this point very 
slight difference was observable, though the next, the third from the surface, perhaps 
