he leaves to the air and some of it is condensed on the
side of the glass.

By experiments at the Cornell University Agricultural Experiment
Station, Ithaca, N.Y., it has been found that during the growth of a
sixty bushel crop of corn the plants pump from the soil by means of
their roots, and send into the air through their leaves over nine
hundred tons of water. A twenty-five bushel crop of wheat uses over
five hundred tons of water in the same way. This gives us some idea of
the importance of water to the plant and the necessity of knowing
something of the power of the soil to absorb and hold moisture for the
use of the plant. Also the importance of knowing if we can in any way
control or influence the water-holding power of the soil for the good
of the plant.

SOURCES OF SOIL WATER

From what sources does the soil receive water? From the air above, in
the form of rain, dew, hail and snow, falling on the surface, and from
the lower soil. This water enters the soil more or less rapidly.

ATTITUDE OF THE SOILS TOWARDS WATER

Which soils have the greater power to take in the rain which falls on
their surface?

[Illustration: FIG. 21.
To show what becomes of the water taken from the soil by roots.
Moisture, sent up from the roots, has been given off by the leaves and
has condensed on the glass.]

[Illustration: FIG. 22.--PERCOLATION EXPERIMENT.
To show the relative powers of soils to take in water falling on the
surface. _A_, sand; _B_, clay; _C_, humus; _D_, garden soil.]

=Experiment.=--Take four student-lamp chimneys. (In case the chimneys
cannot be found get some slender bottles like salad oil bottles or
wine bottles and cut the bottoms off with a hot rod. While the rod
is heating make a shallow notch in the glass with the wet corner of a
file in the direction you wish to make the cut. When the rod is hot
lay the end of it lengthwise on the notch. Very soon a little crack
will be seen to start from the notch. Lead this crack around the
bottle with the hot rod and the bottom of the bottle will drop off.)
(Fig. 23.) Make a rack to hold them. Tie a piece of cheese cloth or
other thin cloth over the small ends of the chimneys. Then fill them
nearly full respectively, of dry, sifted, coarse sand, clay, humus
soil, and garden soil. Place them in the rack; place under them a pan
or dish. Pour water in the upper ends of the tubes until it soaks
through and drips from the lower end (Fig. 22). Ordinary sunburner