You have seen how the air helps to

You have seen how the air helps to

You have seen how the air helps to crumble the stone and brick in old buildings. It does the same with soil if permitted to circulate freely through it. The agent of the air that chiefly performs this work is called carbonic acid gas, and this gas is one of the greatest helpers the farmer has in carrying on his work. We must not forget that in soil preparation the air is just as important as any of the tools and implements used in cultivation.

Fig. 3. Slope to Water shows Soil weathered from Face of Cliff

If the soil is fertile and if deep plowing has always been done, good crops will result, other conditions being favorable. If, however, the tillage is poor, scanty harvests will always result. For most soils a two-horse plow is 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.

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.

Fonte: Agriculture for Beginners