238 
Repoi't of Experiments with different Manures 
Graminaceous crops appear to be the most strikingly independent 
of anj artificial carbonaceous suppl3^ 
2. Tlie Mineral Matter per Acre. 
The average annual yield per acre of mineral matter (Table V.) 
was, in the unmanured hay-crop, Vb%\ lbs. This, it may be 
observed, is about \\ times as much as was contained in the 
annual unmanured produce of either wheat or barley. 
By the use of ammoniacal salts alone, an average of 223i lbs., 
or about 2 cwts. of mineral matter, was annually taken from the 
land in the hay-crop. This, again, is from 1^ to 1^ times as 
much as was removed in either wheat or barley when similarly 
manured ; that is, by ammoniacal salts alone. By the addition 
of mineral manures to the same amount of ammoniacal salts, the 
quantity of mineral matter annually taken off the land in the 
hay-crop was increased to nearly 4 cwts. per acre. Against this 
amount, farm-yard manure gave an average of only 306f lbs. of 
mineral matter in its annual yield of hay, notwithstanding that it 
itself contained not only a very large amount of mineral con- 
stituents, but of nitrogen also, which is so essential to bring them 
into pla}-. Tiiis comparatively defeciive action of the consti- 
tuents of farm-yard manure is, doubtless, owing in great measure 
to the slow liberation of both the nitrogen and the mineral 
matter supplied in that form. When ammoniacal salts were used 
in addition to the farm-yard manure, still only 374^ lbs. of 
mineral matter were annually taken from the land ; that is to say, 
still considerably less than when the whole of both the nitrogen 
and the mineral matter were provided in a more readily available 
condition. 
It is more particularly' in potash* that the hay-crop is more 
exhausting than what might be called a corresponding produce of 
either wheat or barley. In relation to this point, attention should 
be called to the fact, that, as practice goes, almost as a matter of 
course, a notable proportion of the phosphoric acid, and of tlie 
magnesia, almost the whole of the silica, and by far the larger 
proportion of both the lime and the potash, taken from the land in 
the ichcat and the barley crops, will, at some period of the rota- 
tion, be returned to it, in the home-manures to which the straw 
of these cr()j)s has contributed. Ikit, in the case of meadow-land 
associated with land under tillage, it is by no means so probable, 
* Independently of the fact that an ordinary hay-crop will contain more mineral 
matter tlian tlie corn and tlie straw of an ordinary 'wheat or barley crop, tlie ash 
of the luiij contains alioiit twice as high a pcr-cintage of potash, as that of the 
gross produce (corn and straw) of wlieui or Ixtrlcij. ]}ut further particulars will be 
given regarding the indicidual mineral constituents of the hay-crop, iu Part IV. of 
our Paper. 
