The morning news. [volume] (Savannah, Ga.) 1887-1900, 1893-07-31
The Preservation of Soil-moisture by
Shallow TiIlage.

In a recent issue we spoke of the neces-
sity of surface tillage for checking the
waste of saltwater by evaporation, says
Garden and Forest Referring to this
advice, a correspondent asks whether the
stirring of the soil in hot weather does
not help to hasten the drying-out process
rather than retard it, Some of the most
difficult problems in physics are involved
in the movement of water in soil, and no
doubt there are many things yet to be
learned. However, we can accept some
facts as established. Some six or eight
years ago there was a very general dis
cussion by agricultural writers as to the
value of summer tillage, and there were
many experiments conducted in the state
stations of New York. Missouri and else
where. From these and from data al
ready gathered by European experiment
ers, it came to be accepted as generally
true that ground covered with
sod lost water more rapidly
by evaporation than ground from
which all vegetation was removed, and
that ground which was stirred lightly at
the surface lost less water than ground
which was simply kept free from vegeta-
ton. OF course, results vary much in
different kinds of soil, and there are
many conditions of drainage, porosity,
percentage of water to the soil, etc, to be
taken into account, but the theory that
most students accepted was, that water
rises readily by capillary attraction
through a compacted soil and it passes
off in vapor when it reaches the surface
On the other hand, when the surface is
stirred so that an inch or two of soil is
loosened the particles are so separated
that capillary attraction does not take
place, and this covering laid as a mulch
on the compacted earth below prevents,
to certain extent, the escape into vapor
of the moisture which arises to the point
where the compacted earth has been
broken.
In a recent number of the Pacific Rural
Press is stated by Gen. Chapman, of
Red Bluff, Cal. that he once left off cul-
tivating his vineyard at a critical time,
having been advised that since the wea-
Their was hot the earth which he turned
up would soon lose its moisture, and that
each cultivation would turn up a new
layer to dry out. He was told that the
crust which had formed on the top of his
land would check the water from passing
off in Vapor, but his vines began to lam
guish as cultivation ceased and he was
compelled to rig up a portable tank and
haul water a mile to asSuage their thirst.
In his dilemma he wrote to Prof Hill
gard, who reminded him, in reply, that
if a dry brick was laid on a wet
sponge the brick would soon absorb
all the water; if a dry sponge was laid
on wet brick, however, the sponge
would not absorb the water. Professor
Hilgard compared the crust on top of the
ground to a brick on sponge and sUg-
geSted that the lmpacted surface was
rapidly taking up the moisture and let
ting it OFF in vapor, that, therefore, the
true course was to keep the ground titled
on the surface In General Chipman's
language the surface pulverizatiou acted
like wooden blanket thrown over ice, its
non-conductive quality helping it to retain
the moisture in the soil where it could be
taken up by the roots
OF course, weeds must not be left in
the ground for they pump up the moisture
night and day, But besides the value of
surface culture in destroying weeds, sue
cessful fruit-growers find that the prac-
tiCe of pulveriZing the surface proves to
be useful in preserving moisture. Market
gardeners assert that light summer snow
erS, in comparatively dry time, are
often injurious rather than otherwise, for
the ground at once hardens into a crust
and the soil soon gives out more water to
the air than has fallen in the shower.
They, therefore, at once break up this
crust and arrest the evaporation Of
able, even if it did not break the roots of
the growing crops. All the ground that
is turned up loosely or in clods loses it's
moisture in the hot air. The true plan is
to stir the soil to a sufficient depth to
make light mulch. In California vine
yards fine slant-toOthed harrows are used
for this purpose. Any implement which
gives a light and shallow stirring
to the soil is effective.
The Importance of this matter viii be
understood when it is remembered that
in most of our agricultural lands the
evaporation throughout the whole season
nearly equals the rainfall, which directly
enters the soil and that it is probable
that during the growing season of most
crops evaporation largely exceeds the
rainfall. Inasmuch as plants take all
their nourishment dissolved in water, it
is necessary for full crop to husband the
soil-moisture with the greatest care.
Hellriegel's well-6nown experiments show
that the water exhaled by an average
barley crop, together with that evapora-
ted from soil. is fully equal to all the rain |
which falls during the growth of the crop, |
and that during several of the years !
in which the experiments at Dahme were |
made the rainfall was wholly insufficient |
for the needs of such crop, not TO speak |
of the large crops which can be raised in |
some favored regions Many European |
investigators, in studying the question, |
have found that the rain which falls on |
their agricultural fields does not suffice to /
produce large crops, and for most temper
ate regions it may be considered as estab- ]