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.
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