h it
occurred, and from which it could not be separated; but unfortunately,
I neglected to weigh the soil from a square yard, and am, therefore,
unable to state how much nitrogen per acre was present in the shape of
small root-fibres and other organic matters.

"Before mentioning the details of the experiments made in the next
season, I will here give the composition of the ash of the partially
cleaned clover-roots:

Composition Of Ash Of Clover-Roots, (Partially Cleaned).

Oxide of iron and alumina 11.73
Lime 18.49
Magnesia 3.03
Potash 6.88
Soda 1.93
Phosphoric acid 3.61
Sulphuric acid 2.24
Soluble silica 19.01
Insoluble silicious matter 24.83
Carbonic acid, chlorine, and loss 8.25
------
100.00
======

"This ash was obtained from clover-roots, which yielded, when perfectly
dry, in round numbers, eight per cent of ash. Clover-roots, washed quite
clean, and separated from all soil, yield about five per cent of ash;
but it is extremely difficult to clean a large quantity of fibrous roots
from all dirt, and the preceding analysis distinctly shows, that the ash
of the clover-roots, analyzed by me, was mechanically mixed with a good
deal of fine soil, for oxide of iron, and alumina, and insoluble
silicious matter in any quantity, are not normal constituents of
plant-ashes. Making allowance for soil contamination, the ash of
clover-roots, it will be noticed, contains much lime and potash, as well
as an appreciable amount of phosphoric and sulphuric acid. On the decay
of the clover-roots, these and other mineral fertilizing matters are
left in the surface-soil in a readily available condition, and in
considerable proportions, when the clover stands well. Although a crop
of clover removes much mineral matter from the soil, it must be borne in
mind, that its roots extract from the land, soluble mineral fertilizing
matters, which, on the decay of the roots, remain in the land in a
prepared and more readily available form, than that in which they
originally occur. The benefits arising to wheat, from the growth of
clover, may thus be due partly to thi