Draining for Profit, and Draining for Health | Page 8

and often even in
midsummer, the water-table,--the top of the water of saturation,--is
within a few inches of the surface, preventing the natural descent of
roots, and, by reason of the small space to receive fresh rains, causing
an interruption of work for some days after each storm.
If such land is properly furnished with tile-drains, (having a clear and
sufficient outfall, offering sufficient means of entrance to the water
which reaches them, and carrying it, by a uniform or increasing descent,
to the outlet,) its water will be removed to nearly, or quite, the level of
the floor of the drains, and its water-table will be at the distance of
some feet from the surface, leaving the spaces between the particles of

all of the soil above it filled with air instead of water. The water below
the drains stands at a level, like any other water that is dammed up.
Rain water falling on the soil will descend by its own weight to this
level, and the water will rise into the drains, as it would flow over a
dam, until the proper level is again attained. Spring water entering from
below, and water oozing from the adjoining land, will be removed in
like manner, and the usual condition of the soil, above the water-table,
will be that represented in Fig. 3, the condition which is best adapted to
the growth of useful plants.
In the heaviest storms, some water will flow over the surface of even
the dryest beach-sand; but, in a well drained soil the water of ordinary
rains will be at once absorbed, will slowly descend toward the
water-table, and will be removed by the drains, so rapidly, even in
heavy clays, as to leave the ground fit for cultivation, and in a condition
for steady growth, within a short time after the rain ceases. It has been
estimated that a drained soil has room between its particles for about
one quarter of its bulk of water;--that is, four inches of drained soil
contains free space enough to receive a rain-fall one inch in depth, and,
by the same token, four feet of drained soil can receive twelve inches of
rain,---more than is known to have ever fallen in twenty-four hours,
since the deluge, and more than one quarter of the annual rain-fall in
the United States.
As was stated in the previous chapter, the water which reaches the soil
may be considered under two heads:
1st--That which reaches its surface, whether directly by rain, or by the
surface flow of adjoining land.
2d--That which reaches it below the surface, by springs and by soakage
from the lower portions of adjoining land.
The first of these is beneficial, because it contains fresh air, carbonic
acid, ammonia, nitric acid, and heat, obtained from the atmosphere; and
the flowage water contains, in addition, some of the finer or more
soluble parts of the land over which it has passed. The second, is only
so much dead water, which has already given up, to other soil, all that

ours could absorb from it, and its effect is chilling and hurtful. This
being the case, the only interest we can have in it, is to keep it down
from the surface, and remove it as rapidly as possible.
The water of the first sort, on the other hand, should be arrested by
every device within our reach. If the land is steep, the furrows in
plowing should be run horizontally along the hill, to prevent the escape
of the water over the surface, and to allow it to descend readily into the
ground. Steep grass lands may have frequent, small, horizontal ditches
for the same purpose. If the soil is at all heavy, it should not, when wet,
be trampled by animals, lest it be puddled, and thus made less
absorptive. If in cultivation, the surface should be kept loose and open,
ready to receive all of the rain and irrigation water that reaches it.
In descending through the soil, this water, in summer, gives up heat
which it received from the air and from the heated surface of the
ground, and thus raises the temperature of the lower soil. The fertilizing
matters which it has obtained from the air,--carbonic acid, ammonia
and nitric acid,--are extracted from it, and held for the use of growing
plants. Its fresh air, and the air which follows the descent of the
water-table, carries oxygen to the organic and mineral parts of the soil,
and hastens the rust and decay by which these are prepared for the uses
of vegetation. The water itself supplies, by means of their power of
absorption, the moisture which is needed by the particles of the soil;
and, having performed its work, it goes down to the level of the