Agriculture for Beginners | Page 6

is carried away by
drying winds and warmth, the water deeper in the soil rises through the
soil spaces. In this way water is brought from its soil storehouse as
plants need it.
[Illustration: FIG. 7. APPARATUS FOR TESTING THE HOLDING
OF WATER BY DIFFERENT SOILS]
Of course when the underground water reaches the surface it
evaporates. If we want to keep it for our crops, we must prepare a trap
to hold it. Nature has shown us how this can be done. Pick up a plank
as it lies on the ground. Under the plank the soil is wet, while the soil
not covered by the plank is dry. Why? Capillarity brought the water to
the surface, and the plank, by keeping away wind and warmth, acted as
a trap to hold the moisture. Now of course a farmer cannot set a trap of
planks over his fields, but he can make a trap of dry earth, and that will
do just as well.
When a crop like corn or cotton or potatoes is cultivated, the fine, loose

dirt stirred by the cultivating-plow will make a mulch that serves to
keep water in the soil in the same way that the plank kept moisture
under it. The mulch also helps to absorb the rains and prevents the
water from running off the surface. Frequent cultivation, then, is one of
the best possible ways of saving moisture. Hence the farmer who most
frequently stirs his soil in the growing season, and especially in seasons
of drought, reaps, other things being equal, a more abundant harvest
than if tillage were neglected.
=EXERCISE=
1. Why is the soil wet under a board or under straw?
2. Will a soil that is fine and compact produce better crops than one
that is loose and cloddy? Why?
3. Since the water which a plant uses comes through the roots, can the
morning dew afford any assistance?
4. Why are weeds objectionable in a growing crop?
5. Why does the farmer cultivate growing corn and cotton?
SECTION IV. HOW THE WATER RISES IN THE SOIL
[Illustration: FIG. 8. USING LAMP-CHIMNEYS TO SHOW THE
RISE OF WATER IN SOIL]
When the hot, dry days of summer come, the soil depends upon the
subsoil, or undersoil, for the moisture that it must furnish its growing
plants. The water was stored in the soil during the fall, winter, and
spring months when there was plenty of rain. If you dig down into the
soil when everything is dry and hot, you will soon reach a cool, moist
undersoil. The moisture increases as you dig deeper into the soil.
Now the roots of plants go down into the soil for this moisture, because
they need the water to carry the plant food up into the stems and leaves.
You can see how the water rises in the soil by performing a simple

experiment.
=EXPERIMENT=
Take a lamp-chimney and fill it with fine, dry dirt. The dirt from a road
or a field will do. Tie over the smaller end of the lamp-chimney a piece
of cloth or a pocket handkerchief, and place this end in a shallow pan of
water. If the soil in the lamp-chimney is clay and well packed, the
water will quickly rise to the top.
By filling three or four lamp-chimneys with as many different soils, the
pupil will see that the water rises more slowly in some than in others.
Now take the water pan away, and the water in the lamp-chimneys will
gradually evaporate. Study for a few days the effect of evaporation on
the several soils.
SECTION V. DRAINING THE SOIL
A wise man was once asked, "What is the most valuable improvement
ever made in agriculture?" He answered, "Drainage." Often soils unfit
for crop-production because they contain too much water are by
drainage rendered the most valuable of farming lands.
Drainage benefits land in the following ways:
1. It deepens the subsoil by removing unnecessary water from the
spaces between the soil particles. This admits air. Then the oxygen
which is in the air, by aiding decay, prepares plant food for vegetation.
2. It makes the surface soil, or topsoil, deeper. It stands to reason that
the deeper the soil the more plant food becomes available for plant use.
3. It improves the texture of the soil. Wet soil is sticky. Drainage makes
this sticky soil crumble and fall apart.
4. It prevents washing.
5. It increases the porosity of soils and permits roots to go deeper into

the soil for food and moisture.
6. It increases the warmth of the soil.
7. It permits earlier working in spring and after rains.
[Illustration: FIG. 9. LAYING A TILE DRAIN]
8. It favors the growth of germs which change the unavailable nitrogen
of the soil