Drainage benefits land in the following ways:
1. It deepens the subsoil by removing unnecessary water from the s.p.a.ces 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.
[Ill.u.s.tration: FIG. 9. LAYING A TILE DRAIN]
8. It favors the growth of germs which change the unavailable nitrogen of the soil into nitrates; that is, into the form of nitrogen most useful to plants.
9. It enables plants to resist drought better because the roots go into the ground deeper early in the season.
A soil that is hard and wet will not grow good crops. The nitrogen-gathering crops will store the greatest quant.i.ty of nitrogen in the soil when the soil is open to the free circulation of the air.
These valuable crops cannot do this when the soil is wet and cold.
Sandy soils with sandy subsoils do not often need drainage; such soils are naturally drained. With clay soils it is different. It is very important to remove the stagnant water in them and to let the air in.
When land has been properly drained the other steps in improvement are easily taken. After soil has been dried and mellowed by proper drainage, then commercial fertilizers, barnyard manure, cowpeas, and clover can most readily do their great work of improving the texture of the soil and of making it fitter for plant growth.
[Ill.u.s.tration: FIG. 10. A TILE IN POSITION]
=Tile Drains.= Tile drains are the best and cheapest that can be used.
It would not be too strong to say that draining by tiles is the most perfect drainage. Thousands of practical tests in this country have proved the superiority of tile draining for the following reasons:
1. Good tile drains properly laid last for years and do not fill up.
2. They furnish the cheapest possible means of removing too much water from the soil.
3. They are out of reach of all cultivating tools.
4. Surface water in filtering through the tiles leaves its nutritious elements for plant growth.
=EXPERIMENTS=
=To show the Effect of Drainage.= Take two tomato cans and fill both with the same kind of soil. Punch several holes in the bottom of one to drain the soil above and to admit air circulation. Leave the other unpunctured. Plant seeds of any kind in both cans and keep in a warm place. Add every third day equal quant.i.ties of water. Let seeds grow in both cans and observe the difference in growth for two or three weeks.
=To show the Effect of Air in Soils.= Take two tomato cans; fill one with soil that is loose and warm, and the other with wet clay or muck from a swampy field. Plant a few seeds of the same kind in each and observe how much better the dry, warm, open soil is for growing farm crops.
SECTION VI. IMPROVING THE SOIL
We hear a great deal about the exhaustion or wearing out of the soil.
Many uncomfortable people are always declaring that our lands will no longer produce profitable crops, and hence that farming will no longer pay.
Now it is true, unfortunately, that much land has been robbed of its fertility, and, because this is true, we should be most deeply interested in everything that leads to the improvement of our soils.
When our country was first discovered and trees were growing everywhere, we had virgin soils, or new soils that were rich and productive because they were filled with vegetable matter and plant food. There are not many virgin soils now because the trees have been cut from the best lands, and these lands have been farmed so carelessly that the vegetable matter and available plant food have been largely used up. Now that fresh land is scarce it is very necessary to restore fertility to these exhausted lands. What are some of the ways in which this can be done?
[Ill.u.s.tration: FIG. 11. CLOVER IS A SOIL-IMPROVER]
There are several things to be done in trying to reclaim worn-out land.
One of the first of these is to till the land well. Many of you may have heard the story of the dying father who called his sons about him and whispered feebly, "There is great treasure hidden in the garden." The sons could hardly wait to bury their dead father before, thud, thud, thud, their picks were going in the garden. Day after day they dug; they dug deep; they dug wide. Not a foot of the crop-worn garden escaped the probing of the pick as the sons feverishly searched for the expected treasure. But no treasure was found. Their work seemed entirely useless.
[Ill.u.s.tration: FIG. 12. INCREASING THE PRODUCTIVE POWER OF THE SOIL Second crop of cowpeas on old, abandoned land]
"Let us not lose every whit of our labor; let us plant this pick-scarred garden," said the eldest. So the garden was planted. In the fall the hitherto neglected garden yielded a harvest so bountiful, so unexpected, that the meaning of their father"s words dawned upon them. "Truly," they said, "a treasure was hidden there. Let us seek it in all our fields."
The story applies as well to-day as it did when it was first told.
Thorough culture of the soil, frequent and intelligent tillage--these are the foundations of soil-restoration.
Along with good tillage must go crop-rotation and good drainage. A supply of organic matter will prevent heavy rains from washing the soil and carrying away plant food. Drainage will aid good tillage in allowing air to circulate between the soil particles and in arranging plant food so that plants can use it.
But we must add humus, or vegetable matter, to the soil. You remember that the virgin soils contained a great deal of vegetable matter and plant food, but by the continuous growing of crops like wheat, corn, and cotton, and by constant shallow tillage, both humus and plant food have been used up. Consequently much of our cultivated soil to-day is hard and dead.
There are three ways of adding humus and plant food to this lifeless land: the first way is to apply barnyard manure (to adopt this method means that livestock raising must be a part of all farming); the second way is to adopt rotation of crops, and frequently to plow under crops like clover and cowpeas; the third way is to apply commercial fertilizers.
To summarize: if we want to make our soil better year by year, we must cultivate well, drain well, and in the most economical way add humus and plant food.
=EXPERIMENT=
Select a small area of ground at your home and divide it into four sections, as shown in the following sketch:
On Section _A_ apply barnyard manure; on Section _B_ apply commercial fertilizers; on Section _C_ apply nothing, but till well; on Section _D_ apply nothing, and till very poorly.
_A_, _B_, and _C_ should all be thoroughly plowed and harrowed.
Then add barnyard manure to _A_, commercial fertilizers to _B_, and harrow _A_, _B_, and _C_ at least four times until the soil is mellow and fine. _D_ will most likely be cloddy, like many fields that we often see. Now plant on each plat some crop like cotton, corn, or wheat. When the plats are ready to harvest, measure the yield of each and determine whether the increased yield of the best plats has paid for the outlay for tillage and manure. The pupil will be much interested in the results obtained from the first crop.
[Ill.u.s.tration: FIG. 13]
Now follow a system of crop-rotation on the plats. Clover can follow corn or cotton or wheat; and cowpeas, wheat. Then determine the yield of each plat for the second crop. By following these plats for several years, and increasing the number, the pupils will learn many things of greatest value.
SECTION VII. MANURING THE SOIL
In the early days of our history, when the soil was new and rich, we were not compelled to use large amounts of manures and fertilizers. Yet our histories speak of an Indian named Squanto who came into one of the New England colonies and showed the first settlers how, by putting a fish in each hill of corn, they could obtain larger yields.