Press Bulletin No. 23.
Protection Against Drought.
(BY HI. E. STroK amDGi),
The "lay drouth" is o'f such regular reoccurrence that
it has becnme a recognized factor in tlhe arrangement of
crops and methods on Florida farms. Not only is there
a period in the late spring when protracted dry weather
must be expected, but at all seasons of the year absence
of rain-fall may be so persistent as to threaten serious
damage to growing crops.
Any practical means by which this danger may )be
reduced or eliminated becomes of the greatest impor-
Although Florida soils are usually considered as thirsty
and as specially dependent on regularity of rainfall, it is
not true that they suffer more during times of drouth
May 1st, 1902.
than soils commonly supposed to be more fertile and less
liable to danger from continued dry weather.
It is a fact tt at the ,average sandy loan soils of mid-
dle Florida have as the result of careful investigation by
the Division of Soils of the United States Department of
Agriculture been found to be nearly identical in w ater-
holding power with the far fainmed tobacco soils of the
Connecticut valley. It is also a fact of common obser-
vation that our soils are affected less during dry seasons
than are the heavier soils farther north.
The importance of a regular water supply to grow-
ing crops is due to two facts. First, Plants secure little
moisture directly from the air, and yet water is the life,
the blood of the plant. Practically the entire supply
must be obtained from the soil through the action of the
roots. Second, All soil food enters the plant in solution,
thle plant always drinks, never eats, and water is the in-
Most of the water thus entering the plant is evapor-
ated from the leaves, the quantity being enormous. A
crop of corn requires about 86 times its weight" in water
during its growing period and a crop of cabbage will
evaporate 5 million pounds in the same time. So indis-
pensable is the sufficient supply of water to the plant that
slight deficiency is denoted by wilting and if the de-
mand is not made good or the wilting continues wither-
ing and death follow.
Not only do crops exhale enormous quantities of
water, but evaporation from the surface of the soil goes
on constantly wherever the air is dryer than soil, which
is practically at all times except during rains.
In all soils there is at some depth a permanent and
inexhaustible supply of water. This water constantly
rises to the surface by capillary action and is then not
only adequate but available.
To protect the crop from drouth all that is necessary is
to prevent the waste of this water supply by stopping
its escape into the air. Mulching effectively does this,
but is not practical over large areas.
The principle or law controlling the movement of soil
waters, however, furnishes the means for accomplishing
the desired end, namely, checking evaporation.
The upward movement of water depends on the com-
pactness of the soil-the closeness together of its parti-
cles. The closer the particles the more easily and quick-
ly water moves from one to the other upward till the sur-
face of the soil is reached. The greater the distance be-
tween soil particles the greater the difficulty of the move-
ment andl tie smaller thie quantity of water moving.
Therefore in times of drouth when water is needed
and the supply in the soil should be husbanded, the plow
and all implements stirring the lower enable soil, or
bringing it to the surface where it dries, should be sedu-
ously kept from the field.
Not only this, but since thorough pulverization of
the surface soil renders the same more porous and the
particles farther apart so that the movement of water is
checked, frequent shallow surface cultivation with the weed
or, cultivator or sweep should be practiced, and the result
will be to stop evaporation of soil water and the holding
of the same beneath the fine "dust blanket" produced on
the surface, through which the water cannot pass and
escape into the air and be lost to the crop.
The amount of water thus shown to be daily saved to
an nere of soil by shallow cultivation has in careful experi-
ments approximated 130 barrels. Was there ever a drouth
so severe that this amount, of water given to the crop
daily would not have roudered a good Ilrivest certain?
The method requires no noew tools, lnt simply the rever-
sal of a common practice. It is universally- followed by
thousands of successful farmers, Inlt is too frequently
neglected where the idea of the use of the plow has de-
scended from generations of cotton growers to whom it
was chiefly a weapon for fighting grass.
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