The Florida agriculturist. [volume] (DeLand, Fla.) 1878-1911, 1879-03-12
Moisture Retaining Power of the
Soil.
STIRRING THE SOIL IN A DRY TIME
IS IT AN ADVANTAGE?

PROFESSOR G. G. CALDWELL, CORNELL UNI.
VERSITY.
The editor of the Rural Neac
Yorker has given us in " Notes from
the Rural Grounds an account of
some experiments of his own on the
influence of loosening the surface of
the soil on the rapidity with which
it dries. Three flower pots with the
drain-holes loosely covered were
filed with sifted loan; in one
case the loan was pressed down
compactly quite to the top; in anoth-
er it was compactly filled up to
within an inch and half of the top
and the remaining space was loosely
filled; in the third case the whole
pot was loosely filled. Each pot was
then set into pail of water, and the
excess of watei was allowed to flow
over the sides of the pail; all the
pots and buckets being of the same
size, the same quantity Of water re-
manned in all three cases. The wa
ter disappeared soonest in the buck
ct with the pot containing the loose
soil, then in the pot with the loosened
surface soil, and last i'll the compact
soil; the difference in time between
the first and last was about four days.
Hence the editor concludes that the
teaching now so generally given by
the masters to the effect that stirring
the soil serves to retard its driving,
may be erroneous.
can hardly regard these results as
leading to this conclusion, because
they do not actually represent the
ordinary condition OF the soil, where
the level OF the bottom or standing
water is usually a few feet instead OF
a few inches below the surface. In
the soil we have two kinds of spaces
between the solid particles-those
that are too large to be capillary, and
which therefore cannot hold the wa
ter above the level of the bottom
water, and secondly, the capillary
spaces that can hold the water above
that level, the wider spaces only for
a short distance, the narrower ones
holding it up to higher point. But
even the narrowest do not appear to
have the power to raise the water
more than about six feet; and many
VIII teAifs theas subjects assert that
if the level of the bottom water is
even not more than two or three
feet down, no capillary spaces will
take it to the surface under ordinary
circumstances. Furthermore, in
soil in it's usual condition as to moist
ure, not only are the non capillary
spaces empty, but even the capillary
spaces are, to great extent, dry;
soils in such condition do not con.
tain more than one-tenth to one third
of all the water that they can hold
in their capillary spaces, and still
plants show no evidence of suffering
from drought.
In these experiments of the RetrdCs
editor, the level of the bottom water
was, / infer, no further from the sur
face than the depth of an ordinary
pail; all the capillary spaces were
probably, therefore, filled with water
quite up to the surface during the
whole duration of the experiment,
even in the pot with loose soil; it
was simply question of pumping
up the water through these capillary
spaces by series of continuous col
umns reaching from top to bottom !;
as fast as the water was evaporated
from the upper surfaces of the col
umns it was replaced from below,
and the evaporation would be most
rapid in that pot with the freest Cir
culation of water. Some recent ex-
periments by Won Klenze have
shown that capillary spaces of GER
tain size conduct water more rapidly
than those that are either larger or
smaller In the Rauops experiments
the pot with the loosest soil appears
to have allowed the treest circula.
ton; at least we can in this way,
without doing any violence to the
facts, account for the more rapid
evaporation IN that case.
In an ordinary soil, on the other
hand, the desiccation is not a pump
ing up of bottom water through a
multitude of minute pipes reaching
down to it, but rather drying out
of that comparatively small proper
ton that remains nearer the surface
and within the reach of plants, after
the water of the last rain has fallen
to it's level in or far below the sub
soil; we have instead of full capil-
larry spaces throughout, only scat
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