EXPERIMENTS ON THE MIXED HERBAGE OF PERMANENT MEADOW. 327 
There was, too, an average of about 8 lbs. more silica annually taken up on the straw 
plot, but less over the second period than the first. Of lime, magnesia, and phosphoric 
acid, the straw applied would contain considerably more, and of silica about eight times 
more, than the increased amount of them taken up where it was used. But of potass 
the amount contained in the straw would be much less than the increased amount of it 
taken up. There is evidence here, again, that owing to the increased activity of growth 
from whatever cause, the growing herbage had availed itself of more of the other 
supplies within the soil than those actually contributed by the straw itself. 
Something may be due to the “ mulching ” effect, or protection given by the straw 
to the young shoots, and something (though the effects obtained by sawdust would 
not lead us to expect much) to a slightly increased supply of carbonic acid to the young 
plants, and to the soil. At any rate the herbage shows a somewhat better colour in the 
early spring. 
Upon the whole, there can be little doubt that some of the increased luxuriance 
under the influence of the straw-manuring is to be attributed to an increased supply 
of manurial constituents, and some may be due to its mechanical effects. But the 
question suggests itself—whether something may not be also due to the position of the 
plot as above referred to, and something possibly also to an unknown difference in the 
character of the soil and subsoil ? Finally, it must not be overlooked that if the 
combination of the conditions of manure, soil, and local circumstances, was more favour¬ 
able to certain freer-growing species, these, as a coincident of the character of freer 
growth, would necessarily be able to avail themselves more than others could do, of the 
same supplies within the soil. In fact, something is to be attributed to the greater 
powers of food-collection of the species favoured, as well as to the somewhat increased 
supplies by manure. With an increased faculty to take up food, more of it is taken 
up than would result from the mere increase of supply ; that is, more than would be the 
case were one and the same species, with one and the same habit and functional capacity, 
growing on the two differently manured plots. 
9. 800 lbs. Ammonia-Salts, and Mixed Mineral Manure containing Potass; 
Plots 11-1 and 11-2. 
The next illustrations show the effects of a considerably increased supply of ammonia- 
salts, used in conjunction with the same mixed mineral manure, including potass, as on 
plot 9. During the first three years double the amount, or 800 lbs. per acre, of 
ammonia-salts, containing about 200 lbs. of ammonia, equivalent to about 164 lbs. of 
nitrogen, was annually applied. This quantity, from its effects, appearing excessive, was 
then reduced to one-half, or to the same as on plot 9, for three years. But, as it then 
appeared that the maximum growth possible was not attained, the quantity was again 
doubled, and so has remained up to the present time. At the period of this change, 
too, that is, after the first six years, the plot (11) was divided, and to one-half, in 
