Draining for Profit, and Draining for Health | Page 9

water
below, and, swelling the tide above the brink of the dam, sets the drains
running, until it is all removed. In its descent through the ground, this
water clears the passages through which it flows, leaving a better
channel for the water of future rains, so that, in time, the heaviest clays,
which will drain but imperfectly during the first one or two years, will
pass water, to a depth of four or five feet, almost as readily as the
lighter loams.
Now, imagine the drains to be closed up, leaving no outlet for the water,
save at the surface. This amounts to a raising of the dam to that height,
and additions to the water will bring the water-table even with the top
of the soil. No provision being made for the removal of spring and

soakage water, this causes serious inconvenience, and even the rain-fall,
finding no room in the soil for its reception, can only lie upon, or flow
over, the surface,--not yielding to the soil the fertilizing matters which
it contains, but, on the contrary, washing away some of its finer and
looser parts. The particles of the soil, instead of being furnished, by
absorption, with a healthful amount of moisture, are made unduly wet;
and the spaces between them, being filled with water, no air can enter,
whereby the chemical processes by which the inert minerals, and the
roots and manure, in the soil are prepared for the use of vegetation, are
greatly retarded.
Instead of carrying the heat of the air, and of the surface of the ground,
to the subsoil, the rain only adds so much to the amount of water to be
evaporated, and increases, by so much, the chilling effect of
evaporation.
Instead of opening the spaces of the soil for the more free passage of
water and air, as is done by descending water, that which ascends by
evaporation at the surface brings up soluble matters, which it leaves at
the point where it becomes a vapor, forming a crust that prevents the
free entrance of air at those times when the soil is dry enough to afford
it space for circulation.
Instead of crumbling to the fine condition of a loam, as it does, when
well drained, by the descent of water through it, heavy clay soil, being
rapidly dried by evaporation, shrinks into hard masses, separated by
wide cracks.
In short, in wet seasons, on such land, the crops will be greatly lessened,
or entirely destroyed, and in dry seasons, cultivation will always be
much more laborious, more hurried, and less complete, than if it were
well drained.
The foregoing general statements, concerning the action of water in
drained, and in undrained land, and of the effects of its removal, by
gravitation, and by evaporation, are based on facts which have been
developed by long practice, and on a rational application of well know
principles of science. These facts and principles are worthy of

examination, and they are set forth below, somewhat at length,
especially with reference to Absorption and Filtration; Evaporation;
Temperature; Drought; Porosity or Mellowness; and Chemical Action.
ABSORPTION AND FILTRATION.--The process of under-draining is
a process of absorption and filtration, as distinguished from
surface-flow and evaporation. The completeness with which the latter
are prevented, and the former promoted, is the measure of the
completeness of the improvement. If water lie on the surface of the
ground until evaporated, or if it flow off over the surface, it will do
harm; if it soak away through the soil, it will do good. The rapidity and
ease with which it is absorbed, and, therefore, the extent to which
under-draining is successful, depend on the physical condition of the
soil, and on the manner in which its texture is affected by the drying
action of sun and wind, and by the downward passage of water through
it.
In drying, all soils, except pure sands, shrink, and occupy less space
than when they are saturated with water. They shrink more or less,
according to their composition, as will be seen by the following table of
results obtained in the experiments of Schuebler:
1,000 Parts of Will Contract 1,000 Parts of Will Contract Parts. Parts.
Strong Limey 50. Pure Clay 183. Soil Heavy Loam 60. Peat 200. Brick
Maker's 85. Clay
Professor Johnson estimates that peat and heavy clay shrink one-fifth of
their bulk.
If soil be dried suddenly, from a condition of extreme wetness, it will
be divided into large masses, or clods, separated by wide cracks. A
subsequent wetting of the clods, which is not sufficient to expand it to
its former condition, will not entirely obliterate the cracks, and the next
drying will be followed by new fissures within the clods themselves;
and a frequent repetition of this