on
of a good corn-crop. However, when calculated to the acre, we find that
six inches of surface soil in an acre of land, actually contain over two
tons of phosphoric acid. An average crop of wheat, assumed to be 25
bushels of grain, at 60 lbs. per bushel, and 3,000 lbs. of straw,
removes from the land on which it is grown, 20 lbs. of phosphoric acid.
The clover-soil analyzed by me, consequently contains an amount of
phosphoric acid in a depth of only six inches, which is equal to that
present in 247-1/2 average crops of wheat; or supposing that, by good
cultivation and in favorable seasons, the average yield of wheat could
be doubled, and 50 bushels of grain, at 60 lbs. a bushel, and 6,000 lbs.
of straw could be raised, 124 of such heavy wheat-crops would contain no
more phosphoric acid than actually occurred in six inches of this
clover-soil per acre.

"The mere presence of such an amount of phosphoric acid in a soil,
however, by no means proves its sufficiency for the production of so
many crops of wheat; for, in the first place, it can not be shown that
the whole of the phosphoric acid found by analysis, occurs in the soil
in a readily available combination; and, in the second place, it is
quite certain that the root-fibres of the wheat-plant can not reach and
pick up, so to speak, every particle of phosphoric acid, even supposing
it to occur in the soil in a form most conducive to 'ready assimilation
by the plant.'

"The calculation is not given in proof of a conclusion which would be
manifestly absurd, but simply as an illustration of the enormous
quantity in an acre of soil six inches deep, of a constituent forming
the smaller proportions of the whole weight of an acre of soil of that
limited depth. It shows the existence of a practically unlimited amount
of the most important mineral constituents of plants, and clearly points
out the propriety of rendering available to plants, the natural
resources of the soil in plant-food; to draw, in fact, up the mineral
wealth of the soil, by thoroughly working the land, and not leaving it
unutilized as so much dead capital."

"Good," said the Deacon, "that is the right doctrine."

"The roots," continues Dr. Voelcker, "from one square foot of soil were
cleaned as much as possible, dried completely at 212deg., and in that
state weighed 240 grains. An acre consequently contained 1,493-1/2 lbs.
of dried clover-roots.

"The clover-roots contained, dried at 212deg. Fahr.,