image21H. W. FairbanksThese jagged rocks are formed of once molten lava. By and by they will crumble and be covered with a layer of soil.
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 supportthem 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.
image22A field of wheat on one of the Western prairies.
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 andfishing, 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.
image23H. W. FairbanksAt the top of the bank we see a layer of dark, rich soil.
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.
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 ispeat, 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 isnitrogen, 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 callhumus. 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 setaside 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 arequartz. Some of them are clear like glass, others are reddish. In this quartz sand are a few grains ofironwhich the magnet picks out, and a number of scales of yellowmica.
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 callclay. 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 aheavy soil. In the West it is calledadobeand 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 aslightorsandy. A soil composed of sand and clay is sometimes calledloam. If it is nearly all clay it is aclay loam; if there is much sand it is asandy loam.
Soils found in low, swampy places are sometimes formed almost wholly of decaying vegetable matter. Such soils are known aspeat 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 frombeing 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 mass of little bubbles. Such behavior teaches us that the white substance is probably a mixture oflimeandsoda. Besides these there are tiny particles ofpotashandphosphorus, 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 calledlimestone soils. Plants need a little soda, but when there is much in the soil it will kill them. Soils rich in soda are known asalkali 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 thembacteria.
Plants cannot make use of most of the substances in the soil without the aid of these organisms. The bacteria liveupon 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.
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 washedaway, she raises up new ones somewhere else so that the tearing-down work begins again.
image24H. W. FairbanksLittle by little the great rocks break in pieces and crumble finally to form soil.
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.
When it rains, water creeps into the tiny crevices. The water carries with it a little carbonic acid which the raindrops took from the air. This substance aids in dissolving some of the rock materials. If the nights are very cold, the water in the crevices freezes and opens them a little wider, for ice, as you know, takes up a little more room than it did when it was water.
Plants also aid in breaking the rock. Often seeds are dropped by the wind, and the rootlets of some of these seeds, when they sprout, may find a crevice large enough and deep enough for them to push their way into the rock. In these crevices they find a little food and slowly grow larger and stronger. By and by some of the roots are strong enough to push apart large pieces of rock.
If the rock which we are studying is granite, we shall after a time be able to pick out the different minerals of which it is composed. We can tell the grains of quartz, because they look glassy and remain very hard. Other grains, which we callfeldspar, soften and change into clay, which makes the water muddy as it runs over the rocks. We see also little scales of yellow mica, sometimes called "fool's gold," and a few grains of iron. There are tiny quantities of other things which we shall not be able to see, for the rainwater dissolves them and carries them away.
As the rock slowly crumbles to sand and clay, the bacteria begin to make their home in it. Hardy plants, that are not particular about what they grow in, get a foothold, and when they die their stems and leaves decay and mix with the rock particles until at last this material begins to look like soil. It has become dark in color and rich in plant food. Then, many other plants that require a good soil take root there. The rock has at last completely disappeared under the layer of soil and its carpet of vegetation.
Suppose, now, that we dig down and find how deep the soil is and what lies below it. When we have gone down two feet the soil is harder and of a lighter color, for there arefewer plant remains in it. This poorer, lighter-colored soil we callsubsoil. If we dig a little deeper, we shall find pieces of rock in the subsoil. Below these we come to soft, crumbling rock and last of all the solid rock.
The soil that is found resting on the rocks from which it was formed is known asresidual soil. This name is given to such soil, because it is what remains after long years of rock decay during which the rains have washed away a part of the finer material.
What has become of the soft earth that the water washed away? The muddy rivulet has already told us its interesting story. We have learned that a part of this earth (or soil) is borne to the distant ocean. There it is forever lost unless the sea bottom should some day become dry land. Stranger things than that have happened on this ancient earth of ours. The part of the soil which the water carried away to form the rich valley lands and deltas is known asalluvial soil.
image25U. S. Department of AgricultureA flood plain, where alluvial soil has been deposited by the river.
U. S. Department of Agriculture
A flood plain, where alluvial soil has been deposited by the river.
Long ago the northern part of our country was coveredwith a sheet of ice. This ice crept slowly southward, and as it moved along it tore off all the soil and loose rocks on the surface of the earth over which it passed. When it melted it left them spread roughly over the country. Such material formsglacial soil. It is often deep but not very rich.
image26U. S. Geological SurveySoil brought by a glacier and deposited as the ice melted.
U. S. Geological Survey
Soil brought by a glacier and deposited as the ice melted.
There is another kind of soil, formed by the wind. If you have ever been in a dust storm you have seen the fine, powdery substance that settles over everything and creeps into the smallest cracks. In some countries where there are strong winds and not much rain there is little vegetation on the surface to hold the soil. Year after year the winds pick up particles of the dusty soil, whirl them high in the air, and do not let them down again until they have been carried many miles. In some far-off land where the winds go down the dust particles settle again to the earth. After a long, long time, enough dust collects to form a thicklayer of the richest soil. This is called æolian soil, from the wordÆolus, meaning the "wind."
There is one more kind of soil which we ought to know about; that ispeat soil. It is found in marshy or swampy lowlands and is formed largely of plant remains. When lands with such soil are drained, they prove very rich.
image27H. W. FairbanksWhat the rivulets did to the hillside pastures where the grass was destroyed.
H. W. Fairbanks
What the rivulets did to the hillside pastures where the grass was destroyed.
A walk up the mountains on a rainy day is not a pleasant one. There are mud and water under our feet, and overhead are the dripping branches which, if touched, send down a shower of drops. But if we keep our eyes open we shall learn something which will be of great value to us. We shall learn how it is that Nature holds the soil on the slopes—the wonderful soil which it takes her so long a time to make and which is the source of all our wealth.
Our way up the mountains is by a winding road. We first pass the foothills upon which there are scattered oaks. The rain is steadily pouring down and rivulets loaded with mud are eating little gullies all over the slopes. Along the roadside, where they have united, the rivulets form a torrent which is making a deep ditch that threatens to render the road impassable.
These slopes were once covered with grass and the rivulets ran down them without doing any harm. But so many sheep were pastured here that the grass was killed. The roots, which once formed a thick protecting sod, are now decaying. How quickly the rivulets have taken advantage of the unprotected slopes!
The road leads still upward until it brings us to where there were once pine forests. The lumbermen cut off all the trees, and then fire came and burned the decaying vegetation which once lay spread over the ground. Now all that remains is bare earth and blackened stumps.
What are the raindrops doing here? They gather in rivulets just as they do on the once grassy hillside; but because there are so many roots still remaining in the ground they have not done much work. They are not loitering, however, and by and by, when the roots have rotted, they will seize their chance and begin tearing away the soil from the mountain side.
But this is not the end of the road. Farther up we come to the primeval forests, where the giant trees stand just as they did before men came. Here we can see how the slopes are protected, for in making the road the workmen cut deep into the hillside. They first removed a layer of pine needles and decaying branches. Then they cut through a layer of soil about two feet thick which was completely filled with little roots of trees and bushes. Below this they came to the soft subsoil, which contained only a few roots, and at the bottom they reached the solid rock.
The layer of roots and soil at the top of the bank, you can see from the picture, now overhangs the road, because the raindrops which beat against the bank have washed awayall that they could reach of the unprotected earth at the bottom. How plainly we can see the network of roots. What a hard task it must be for the water to get at the soil in which these roots are growing.
image28H. W. FairbanksThe layer of roots holds the soil on the mountain side.
H. W. Fairbanks
The layer of roots holds the soil on the mountain side.
We will now leave the road and, although it is still raining hard, we will walk a distance through the forest and see if there is anything more that we can learn. We are soon in the deep woods where, perhaps, no one has ever been before. Around us are trees of all ages and sizes, from little seedlings to great giants six feet through. Among them are the crumbling stumps of trees long dead. Their trunks lie on the ground, and many are so soft and rotten that we can kick them to pieces with our feet.
As we walk our feet never touch the real earth. It is always on the soft, yielding leaves and crumbling branches that we step. These leaves and branches form a thick layer completely hiding the soil. But the strangest thingis that, although the rain is still falling, we can discover no rivulets. What, then, becomes of the water? The soft, decaying vegetation on which we are walking and the rotting stumps and logs act like a great sponge. As long as this sponge can take up the falling drops, none have a chance to run away. If it rains a very long time and the sponge becomes saturated, the drops that creep away and finally unite in rivulets in the hollows do no harm to the soil, for they cannot get at it.
image29H. W. FairbanksThe roots of the tree grip the soil like the fingers of a great hand.
H. W. Fairbanks
The roots of the tree grip the soil like the fingers of a great hand.
Long after the storm has passed, the earth underneath the trees remains wet, while the ground out in the open has become dry. A part of the water held by the decaying vegetation evaporates. Another part creeps down through the earth to the crevices in the rocks and feeds the springs.
Let us now put aside our storm clothes and journey, in imagination, far away to where it seldom rains—to that land which we call the desert. Here the bare rocks of the mountain slopes are burned brown by the hot sun. Here there is little soil and only a few little bushes that somehow manage to live. Why does not the soil gather over the rocks as it does in other places? The rocks are surely crumbling, for we can crush some of the pieces in our hands.
Once in a long time it rains in this desert. Then the drops descend furiously. The water gathers in rivulets and these turn to torrents which sweep down the slopes.They carry away the particles of sand and clay which would in time, if there were plant roots to hold them, turn to soil.
The winds also help keep the desert rocks bare and free of soil. Have you ever been in a dust storm or have you read of caravans caught in such storms in the Sahara Desert? The fierce wind picks up the particles of sand and clay from the bare earth and sweeps them along as it does the snow in winter, or it whirls them in clouds high in the air. The dust clouds are often so dense that they hide the sun and all landmarks by which the traveler can guide his way. But have any of us ever seen the winds pick up much dust from the green fields where the vegetation protects the surface?
image30H. W. FairbanksThe vegetation prevents the wind from blowing the sand away, so that wherever the roots obtain a hold there a little mound is formed.
H. W. Fairbanks
The vegetation prevents the wind from blowing the sand away, so that wherever the roots obtain a hold there a little mound is formed.
If we turn now to a very wet country, such as that upon our northwest coast, where often nearly eight feet of rain falls in a year, we shall find the vegetation so dense that it hides both soil and rocks. Here water can do little inwearing away the soil, even upon the steepest slopes, while the wind cannot get a peep at the earth.
Does it not seem strange that where little rain falls the earth washes a great deal faster than where it rains very heavily? The reason is that the more it rains the more dense becomes the carpet of vegetation. If we wish to preserve the soil, we must preserve the natural growth on the hillsides.
Not all of the muddy streams are due to the carelessness of men. It is the business of some of the servants of Nature, as we have already learned, to tear down the mountains and fill up the hollows in the earth. It is the business of others to spread a carpet of vegetation over the surface, and wherever they have already succeeded in their work the waters run clear most of the time.
Where it is dry so much of the time that few plants can live, the destructive servants have their own way when the occasional rains come. Where there is a warm sun and frequent rains, a green carpet is spread over all the slopes. But when men destroy the carpet and take no care of the soil underneath, the raindrops are able to do as much damage as they do during the cloudbursts in the deserts.
The Colorado is one of those rivers in the basin of which few people live. Much of its journey is through a land in which there is little vegetation. Here, the waters from the melting snows upon the lofty mountains about the basin and those of the occasional heavy rains have things their own way. They are always yellow with mud. The amount of mud which this river carries has been measured. You will hardly believe me when I tell you that it amounts to sixty-one million tons every year. This is enough to cover 164 square miles one foot deep. We might call this the cream of the soil from all the slopes of the great basin of the Colorado River.
In other parts of our land, where abundant rains fall,the streams tell a different story. Before men came the water of these streams was clear throughout the greater part of the year. It was only when the rains were very heavy that the soil washed away, for the vegetation held it well. Now the gullies on the hillsides and along the roads tell us as plainly as though they could speak that our country is losing wealth here.
image31H. W. FairbanksThe roots of the tree form a wonderful network underground from which the water cannot tear the soil.
H. W. Fairbanks
The roots of the tree form a wonderful network underground from which the water cannot tear the soil.
The soil is our most valuable possession. The people of many lands are suffering from poverty today because their forefathers did not take care of the soil as they should. In such lands the people who live on the mountain sides are poor, because the best of their soil has been washed away. Those who live in the valleys are often poor because of the sands and gravels which floods have spread over their fertile fields.
While it is raining, let us fill a bottle from some muddystream and allow it to stand until the water settles. In the bottom will then appear a layer of fine mud, orsiltas it is usually called. How much soil do you suppose the rivulets washed from my garden and from yours during the last severe storm? How much do you suppose all the rivulets which make up the rivers of your state washed from all the gardens and fields during the same storm? Make a guess and then multiply your answer by the number of storms in one year and that by fifty years, and you will get a quantity greater than you would believe possible.
This is the way Nature takes her toll for our carelessness. So quietly does she do it that often the farmer does not have any idea of what is happening. She is like a thief that comes and steals his goods while he is sleeping.
image32Bailey WillisThe soil on the hillsides of China is being washed away because of the thoughtlessness of the people.
Bailey Willis
The soil on the hillsides of China is being washed away because of the thoughtlessness of the people.
When the farmer finally awakes and begins to wonder why his crops grow smaller each year, he has already lostthe cream of his soil. He must at once stop plowing the steep hillsides and leaving the ground bare for the winter rains to wash it away. To save the slopes he can either terrace them or he can sow grass or clover, which will form a sod and hold the soil. If the farmer can get peas, beans, alfalfa, or clover to grow upon his wasted lands, they will make it fertile again, for these plants have the wonderful power of taking nitrogen from the air and storing it in the soil.
image33American Forestry AssociationThe farmer who owns this land will soon be made poor because of his carelessness in destroying the covering of the soil.
American Forestry Association
The farmer who owns this land will soon be made poor because of his carelessness in destroying the covering of the soil.
More earth has been washed from the hillsides of our country during the last fifty years than during thousands of years before white people came. The farm lands have been injured, the bays have been made shallower, and many river channels have been so filled up that it is more difficult to navigate them now than it was in the early days.
The farmer, the stockman, the lumberman, and the miner has each been selfishly doing his share in the destruction of the soil. Each one has thought only of how he could make the most money in the shortest time. It has not occurred to them that they are making it difficult for their children and grandchildren to live.
In the Southern states thousands of acres are being gullied by the rains, and the soil destroyed. The floods of spring have become worse in late years, because of the destruction of the forest cover in the Appalachian Mountains. Buildings and bridges are frequently carried away, and gravel and boulders are washed over the rich bottom lands.
In the mountains of far-away Italy the soil is poor, and so are the people. They have cut down nearly all the trees and for hundreds of years the brush and grass have been eaten so closely by the sheep and goats that few rootsremain to hold the soil. It does not need to rain heavily there to cause the rivers to become muddy and swollen. The soil which once covered the slopes has been carried to the bays, and now there is land where ships floated two thousand years ago.
image34U. S. Forest ServiceTerraces of rock built by natives of China to aid in holding the soil.
U. S. Forest Service
Terraces of rock built by natives of China to aid in holding the soil.
In Spain so much of the best soil has been lost that the people now do not raise enough food to support themselves, and much has to be imported from other lands.
France is a rich country still, in spite of the cutting of so much of the forest and the careless pasturing of the mountain slopes. The people are industrious and hard working and thus make a living in spite of the loss which they are suffering.
The Montenegrins are among the bravest people of Europe, but their land is barren and they enjoy few luxuries. Their country consists largely of limestone mountains, from which they have been cutting the trees for hundreds of years. There is but little soil and that is to be found in the hollows of the rocks. This soil is so precious that every bit, be it ever so small, is carefully cultivated.
In the mountains of Palestine and Syria the people have so completely destroyed the trees and grasses which Nature once planted there that it is difficult for them to raise enough to live upon. The rivers are muddy after every rain, and even the water from the melting snows picks up some of the soil and flows away with a dirty, yellow color.
When we reach China and Korea, we find that there the people have been most severely punished for their carelessness. The mountain sides have been torn by the rains and deeply gullied. The once smooth slopes upon which grew trees and grasses are now a mass of sharp ridges anddeep hollows of bare earth. The water falling upon these mountains runs off in torrents, carrying even large boulders as it does in our Western deserts. Here and there the natives have built terraces of rock to aid in holding the soil, but many parts of the country are almost wholly deserted. The waters run off the mountains so quickly that they often form vast floods which spread over the lower valleys and plains. The floods destroy the crops and drown the people.
Eastward of China there is an arm of the Pacific Ocean known as the Yellow Sea. Why do you suppose this name was given to the sea? One of the great rivers of China, the Yangste-kiang, empties into it. The river rises in the barren mountains of which we have just been speaking, and it is continually bringing so much mud and sand that a whole sea is being filled. Long before a ship comes within sight of the land the waters are seen to be of a muddy, yellow color.
In the smaller valleys of Korea the natives build dikes along the rivers to keep the mountain floods from spreading sand and gravel over their rice fields. Every year they have to make the dikes higher as the river beds fill up.
Thus we see that all over the world people are suffering because they have not obeyed the laws which Nature has made for the protection of the soil.
The ocean is the home of the water. The water would always remain in the ocean if it could, but the sun and air are continually at work stealing little particles away and sending them on long journeys.
The water particles are so small as they rise from the ocean that we cannot see them. By and by they crowd together and make the clouds that float across the sky. As soon as the clouds meet colder air, the little water particles rush together and thus become larger and larger until they grow so heavy that they can no longer float in the air, but must fall. Some of them fall into the ocean again, but others drop upon the land.
The raindrops that reach the land have many sorts of stories to tell before they again get back to the ocean. Some of them are at once snatched up again and are started upon another journey. The thirsty air, whether over the ocean or over the land, is ever in search of water particles.
If the air is very cold, the clouds turn to snow instead of rain. The feathery flakes fall slowly through the air and form a soft white mantle over the earth. Those that fall on lofty mountains form great banks which may not entirely melt and turn to water until late in the summer.
The raindrops that fall where the slopes are steep, where Nature has grown little vegetation, or where men have destroyed the earth cover, have little to detain them and are soon on their way back to their home. In their hasty journey they do much damage to the unprotected soil.
image35George J. YoungThe cool and shady stream before men came and cut the trees away so that the hot sun could get at it.
George J. Young
The cool and shady stream before men came and cut the trees away so that the hot sun could get at it.
If the drops fall upon gentle slopes, or where there aremarshes and lakes, or upon the forest with its decaying vegetation, or upon deep beds of gravel and sand, they are a long time getting back to the ocean.
We can in no way change the amount of rain that falls upon any part of the earth. We cannot call up a storm when we wish it, nor can we send it away when there has been rain enough. But there are many ways in which we can hasten or delay the return of the water to the ocean. Nature shows us some of these. The spongelike carpet underneath the forest holds the water until it has had time to soak into the earth from which it later emerges as springs. Nature forms basins on the heads of the rivers where a part of the water, instead of immediately flowing away, collects in the form of lakes. From these lakes the water runs away slowly instead of in torrential floods.
image36H. W. FairbanksThe rotting tree trunks take up the rainwater like a sponge.
H. W. Fairbanks
The rotting tree trunks take up the rainwater like a sponge.
Only a few places in our country have more rain than is really needed. One of these is the region about the mouthof the Mississippi River upon the Gulf of Mexico. Another is upon the Northwest coast. Throughout the central part of the country the summer rains are sometimes too light to afford a full harvest. The rainfall upon the plains and valleys of the Southwest is so small that the only plants that can live there are those strange and curious forms that have become used to desert conditions. The only way in which these lands can be made useful to the farmer is by means of irrigation. To obtain water for irrigation we have either to go to the distant mountains and build reservoirs to collect the rains which fall there and then dig canals to carry the water to the desert valleys, or to make use of some river flowing through them, if they are fortunate enough to have such a river. Can you think of any rivers that are used in this way?
image37Brown BrothersThe great Roosevelt Dam, in the Salt River irrigation project, Arizona.
Brown Brothers
The great Roosevelt Dam, in the Salt River irrigation project, Arizona.
Although water sometimes seems the greatest blessing that we have, yet it may prove a curse if it is not looked after. If you give the water a chance to make gullies in your fields, you lose not only the water but the best of the soil also. If you cultivate your fields with care, most of the water will soak into the ground. If you are a wise farmer you know also that cultivation of the soil helps to hold the water, for it cannot escape through loose soil as it can through compact soil. Thus if you know how to handle both the water and the soil, you can, with only a little rain, accomplish a great deal.