s necessary to break up and pulverize the land.

A shallow soil can always be improved by properly deepening it. The
principle of greatest importance in soil-preparation is the gradual
deepening of the soil in order that plant-roots may have more
comfortable homes. If the farmer has been accustomed to plow but four
inches deep, he should adjust the plow so as to turn five inches at the
next plowing, then six, and so on until the seed-bed is nine or ten
inches deep. This gradual deepening will not injure the soil but will
put it quickly in good condition. If to good tillage rotation of crops
be added, the soil will become more fertile with each succeeding year.

[Illustration: FIG. 4. MIXED GRASSES GROWN FOR FORAGE]

The plow, harrow, and roller are all necessary to good tillage and to a
proper preparation of the seed-bed. The soil must be made compact and
clods of all sizes must be crushed. Then the air circulates freely, and
paying crops are the rule and not the exception.

Tillage does these things: it increases the plant-food supply, destroys
weeds, and influences the moisture content of the soil.

=EXERCISE=

1. What tools are used in tillage?

2. How should a poor and shallow soil be treated?

3. Why should a poor and shallow soil be well compacted before
sowing the crop?

4. Explain the value of a circulation of air in the soil.

5. What causes iron to rust?

6. Why is a two-horse turning-plow better than a one-horse plow?

7. Where will clods do the least harm--on top of the soil or below
the surface?

8. Do plant roots penetrate clods?

9. Are earthworms a benefit or an injury to the soil?

10. Name three things that tillage does.

SECTION III. THE MOISTURE OF THE SOIL

Did any one ever explain to you how important water is to the soil, or
tell you why it is so important? Often, as you know, crops entirely fail
because there is not enough water in the soil for the plants to drink.
How necessary is it, then, that the soil be kept in the best possible
condition to catch and hold enough water to carry the plant through dry,
hot spells! Perhaps you are ready to ask, "How does the mouthless plant
drink its stored-up water?"

The plant gets all its water through its roots. You have seen the tiny
threadlike roots of a plant spreading all about in fine soil; they are
down in the ground taking up plant food and water for the stalk a