over, corn.

CHAPTER XXV

FARM DRAINAGE

Some farm lands contain so much water that the conditions of fertility
are interfered with and therefore the crop producing power of these
lands is lowered.

HOW SURPLUS WATER AFFECTS FERTILITY

This surplus water diminishes fertility by reducing the area of film
water in the soil.

It checks soil ventilation.

It tends to keep the soil cold.

It dilutes plant food in the soil.

It interferes with proper tillage.

INDICATIONS OF A NEED OF DRAINAGE

The above-mentioned state of affairs occurs sometimes in fields at the
foot of hills, or on sloping uplands which receive spring water or
seepage water from higher lands. Some fields are underlaid by a close,
compact subsoil which so checks percolation that the surface soil is
too wet for tillage operations the greater part of the year. In such
cases:

A need of drainage is generally indicated by the presence of more or
less free water standing on the surface.

In some lands the surface water does not appear as free water standing
on the surface. In such cases:

A need of drainage is indicated by the curling and wilting of the
leaves of corn and other crops during dry, hot weather. This curling
and wilting is due to the fact that during the early growth of the
crop free water stands so high in the soil that the crop roots are
confined to a shallow layer of soil. When dry, hot weather comes, the
free water recedes, the upper soil dries out, and the roots cannot get
sufficient water to supply the demands of transpiration, hence the
curling and wilting of the leaves.

If drains are placed in this soil, the free water will be kept at a
lower level in the spring and the plant roots will develop deeper in
the soil, where there will be constant supply of film water during the
dryer and warmer summer weather.

The wiry and spindling growth of grass and grain crops may indicate
too much water.

The growth of moss on the surface of the ground and the cracking of
the soil in dry weather are also indications of too much water.

DRAINS

How can we get rid of this surplus free water?

We can make passageways through the soil to a lower level and then
let gravity pull the water through them to lower ground below. These
passageways are called drains.

Drains may be classed as:

Surface drains which are shallow, open channels made in the soil with
a plow, hoe or other tool, to carry off surface water. They