An ancient story tells us that men were made from the dust of the earth.

This dust under our feet, which soils our shoes, this dust which the wind sometimes sweeps along in blinding clouds, is indeed precious. The delicate tissues of our bodies are made from the food we eat. If it be plant food, it comes directly from the soil. If it be meat or eggs or milk, it comes from animals which live upon the plants, that in turn got their nourishment from the soil.

This soft, dark substance which covers the rocky skeleton of the earth we call the _soil_. How common and cheap it looks when it is placed by the side of a piece of gold! But how much more wonderful it would seem if we could know all about it. The soil is far more necessary to our comfort and prosperity than gold. Gold, silver, or precious stones cannot keep us alive. They are of little worth to us compared with food and clothing. The soil, then, is the real wealth of the world. The farmer, who tills the soil, is the one worker we could not possibly do without. All the wealth of the world, all the comforts which we have, all the luxuries brought from far corners of the earth, come in the first place from the soil.

We do not have to journey far over the earth to learn that there are many lands where the fields are not fruitful, and yet such lands are often rich and prosperous. How can this be if the soil is so necessary?

Let us go to New England and ask the people living there if they can tell us why rich people sometimes inhabit lands which do not raise enough for them to eat.

[Ill.u.s.tration: _H. W. Fairbanks_ These jagged rocks are formed of once molten lava. By and by they will crumble and be covered with a layer of soil.]

Much of New England is hilly and has a poor, rocky soil. The farmers who first settled there toiled hard, working early and late, and yet got few of the comforts of life. Most of the farmers did not know how to improve the soil or even to keep it in as good condition as it was when they first cleared away the forests and began cultivating it; so many left their farms to seek a living elsewhere. There are now many abandoned farms that are growing up to forests again.

In spite of this poor land, the New England states form one of the most wealthy and prosperous parts of our country. There are many great cities containing hundreds of thousands of people in this territory. The inhabitants enjoy luxuries of every kind sent from all parts of the world. The farmers of New England certainly do not produce this wealth from their rocky soil. Where, then, does it come from?

Industries of almost every sort except farming are carried on in the cities of New England. All these people have to be fed and the farms of this region would hardly support them even if the soil were very productive. So much food is needed every day that if the supply were cut off for only a short time, there would be great suffering.

Somewhere there must be farmers at work raising food supplies for the people of the great cities. The many beautiful and wonderful things made by the workers in the cities must be exchanged with the farmers for the real necessities of life.

Somewhere there must be vast fertile fields which produce much more than their owners require. We will journey westward to the prairies of the Mississippi Valley. Here for hundreds of miles we can see hardly anything but fields of waving wheat and corn. Here are hundreds of granaries and flour mills. Upon the rivers and lakes there are many boats, and upon the land railroads, all carrying flour and other farm products to feed the people of New England. Here are great stock ranches with thousands of cattle and hogs, which, when fattened upon the grain, are also shipped to New England to help feed the people there.

[Ill.u.s.tration: A field of wheat on one of the Western prairies.]

We must conclude, then, that if it were not for the vast fields with their deep, rich soil, where the farmers are able to grow much more than they need for themselves, it would not be possible for the people of New England to become wealthy by working at other things than farming. The articles which they are making add to their own comfort and pleasure as well as to that of the farmers, but they have to have the products of the soil to keep alive.

If the farmers of the Mississippi Valley and of all the other valleys that help support the city people are careful of their soil and keep up its fertility, our country will remain prosperous. But we are sorry to say that the farmers have not always been careful. Many have wanted to make more than they should from their lands. The plant food with which Nature has filled the soil has been taken away year after year faster than she has been able to renew it. Many fields do not produce the crops they once did. The smaller the yield becomes, the higher the prices the produce brings. This makes it more difficult for the workers in the cities to live comfortably. The less abundant the supply of food becomes, the less prosperous is the country.

There are countries, such as England, that have neglected agriculture but have, in spite of this, become rich and powerful through devoting their time to manufacturing articles to sell to other people. But those who work in the factories of England have to be fed, and so they must depend upon other countries to supply much of their food. If, for any reason, they were cut off from trade with these countries, not only would their manufacturing be ruined, but they would be in danger of starvation.

To the first men, who lived entirely upon hunting and fishing, the soil was of little consequence. Now things are different. The wild game has mostly gone and we have to depend upon the products of the soil.

[Ill.u.s.tration: _H. W. Fairbanks_ At the top of the bank we see a layer of dark, rich soil.]

The people of those lands where the climate is unfavorable and the soil poor and rocky lack most of the comforts of life, unless they are able to obtain them through trade. It does not follow, however, that people living in lands favored by Nature are always happy and prosperous.

You must remember that when the first men increased in numbers over the earth, the soil was fresh from the hand of Nature. Although they had everything about them that could be asked for, yet they were poor. There are men living today on the rich deltas that we have learned about who have few of the comforts that we have. This is because they are lazy and ignorant, and do not make proper use of this valuable gift, the rich soil.

We conclude, then, that the soil forms the real wealth of the world. All our comforts and luxuries come in the first place, as we have seen, from the soil. The more crowded people become upon the earth, and the greater the number that engage in manufacturing and trade, the more important becomes the care and cultivation of the soil. If we do not take the best of care of the soil, there may come a time when there will not be food enough for us all.

CHAPTER NINE

THINGS OF WHICH SOIL IS MADE

Let us take a spadeful of soft, dark earth from the garden and see if we can find of what it is made.

We will first put the earth in a dish of water and stir it thoroughly.

We notice that the water at once becomes muddy and that little particles of a dark substance rise to the surface. These particles appear to be pieces of stems and leaves.

This crumbling vegetation is _peat_, a substance which fills many swamps and, when cut into blocks and dried, is used for fuel. When scattered through the earth peat has a very different use. As the leaves and stems of plants die and slowly mingle with the earth, they give it the dark color, which usually extends down for two or three feet. As this vegetation changes, or decays, as we usually say, it furnishes a number of substances which supply food to the roots of growing plants. One of the most important of these is _nitrogen_, an invisible gas.

The decaying vegetation which we find mixed with the soil has other uses. It holds water and so helps to keep the soil moist. It makes the soil loose and more easy to cultivate. It absorbs heat from the sun and so helps to warm the soil. This vegetable matter, when it is completely decayed, we call _humus_. Soils that are rich in humus are usually very fertile.

We will now turn the muddy water into another dish, pour more clear water upon the material that remains in the bottom of the dish, and wash it again, repeating the work until the water is no longer muddied. We will set aside the dish containing the muddy water and examine what remains in the bottom of the dish that once contained the earth or soil.

This is mostly sand, but with it are rough fragments of rock which can be crumbled in the hand. The greater number of the little sand grains are _quartz_. Some of them are clear like gla.s.s, others are reddish. In this quartz sand are a few grains of _iron_ which the magnet picks out, and a number of scales of yellow _mica_.

After standing a few hours the muddy water has become clear, and a deposit of a yellowish substance has collected in the bottom of the dish. We will carefully pour off the water and examine what remains.

This fine soft mud we call _clay_. As it dries and becomes hard it shrinks and cracks, and thus breaks up into little pieces. Clay forms a greater or lesser part of all soil. Clay soil is very sticky when it is wet, as you will be sure to remember if you have tried to walk over it.

When soil is formed largely of clay we speak of it as a _heavy soil_. In the West it is called _adobe_ and is sometimes used in making houses.

When adobe soil dries, great cracks form in it. These cracks are sometimes large enough for small animals to fall into. When there is a large amount of sand, we speak of the soil as _light_ or _sandy_. A soil composed of sand and clay is sometimes called _loam_. If it is nearly all clay it is a _clay loam_; if there is much sand it is a _sandy loam_.

Soils found in low, swampy places are sometimes formed almost wholly of decaying vegetable matter. Such soils are known as _peat soils_. They are usually very fertile.

We have now learned about three things that the soil contains that are bulky and easy to discover: decaying vegetation, sand, and clay. These are, however, far from being all that compose the soil. There are still many other things, some of which are invisible to the unaided eye and difficult to find.

We will next take the clear water that remained after the mud settled.

We will pour it into a dish, place the dish over a fire, and let the water boil slowly until it has all evaporated. There will remain in the bottom of the dish a thin white coating. Moisten this with a drop of vinegar or other weak acid and it will disappear in a ma.s.s of little bubbles. Such behavior teaches us that the white substance is probably a mixture of _lime_ and _soda_. Besides these there are tiny particles of _potash_ and _phosphorus_, which we cannot distinguish by the means we have used.

Some soils contain a great deal of lime, and because they have been formed from limestone, are called _limestone soils_. Plants need a little soda, but when there is much in the soil it will kill them. Soils rich in soda are known as _alkali soils_. They were formed in the bottom of lakes the waters of which contained soda. Salt is another harmful thing found in the soil. You can sometimes see faint whitish deposits of soda and other salts on the soil in flower pots.

There is one more thing that the soil contains that we must not forget, for it is one of the most important of them all. This is a living organism so small that we cannot see it with the unaided eye. Many thousands of these organisms are contained in a bit of earth such as you could take up on the point of a small knife blade. We have named them _bacteria_.

Plants cannot make use of most of the substances in the soil without the aid of these organisms. The bacteria live upon the materials of the soil and change them into such form that plants can digest them.

Soil may be supplied with all kinds of plant food in just the right amount and yet, if it is packed hard and is not watered, no living thing can take root in it and grow. Plants drink their food and so we must supply water. They also require oxygen, as do other living things. For this reason we must leave the soil loose, so that the air can enter it and the roots get the oxygen which it contains.

Thus we learn how wonderfully the soil is made. We learn that it contains many things required by plants. In order that the plants may be thrifty, there must be enough but not too much of these different things.

CHAPTER TEN

HOW THE SOIL IS MADE

The substances which we found in the soil teach us that it was formed from the rocks. If we could take the sand, clay, potash, soda, lime, and iron that we found in the soil and put them together as Nature knows how to do, we should have rock again.

But if we should take a piece of rock and crush it to a fine sand, that would not be soil, because soil cannot be made in that way. It takes Nature many, many years, as the rocks slowly crumble and decay, to change the materials of which they are composed into true soil with its swarms of bacteria and its plant food.

If we should dig down through the soft earth under our feet, we would at last come to solid rock. This is the rough and jagged crust of the earth on which rests the carpet of soil. In the mountains where the slopes are steep the rocks stick up through the soil. The outer parts of this solid rock are, however, always crumbling. Little particles, as soon as they become loosened, either fall by their own weight or are washed away.

Some of the rock fragments collect upon the gentler slopes and finally turn to soil. This soil is not rich and it dries out quickly, because it is shallow. The soil in the valleys, as we have already learned from the muddy rivulet, is deep and rich.

Nature is slowly spreading her mantle of soil over the earth. In some parts of the earth one can travel for hundreds of miles and see no rocks. One might think that in time Nature's work would be finished. But before the mountains in one place have crumbled and been washed away, she raises up new ones somewhere else so that the tearing-down work begins again.

[Ill.u.s.tration: _H. W. Fairbanks_ Little by little the great rocks break in pieces and crumble finally to form soil.]

Let us, in imagination, sit down by the side of a rock, prepared to stay there many years, that we may learn just how Nature makes the soil. It will be a long, long time before we can see any change in the rock. Each bright day the sun warms the cold rock and makes it expand a very little. At night the rock grows cold and shrinks. In this way minute crevices are finally formed between the grains of the different minerals that make up the rock.