Название | Checking the Waste: A Study in Conservation |
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Автор произведения | Mary Huston Gregory |
Жанр | Языкознание |
Серия | |
Издательство | Языкознание |
Год выпуска | 0 |
isbn | 4064066211769 |
If the soil has become worn-out and the farmer is trying to improve its general condition, he can gain better results by keeping the field in clover a second year, when a profitable crop of clover seed may be had from the land. This system of changing each year, and alternating cereal crops, which take the nitrogen from the soil, with leguminous plants, which restore it to the soil again, is called "rotation of crops," and if regularly followed will preserve a proper balance of nitrogen in the soil.
In some parts of the West there is a lack of decaying vegetable matter in the soil, because the few plants which naturally grow there have small roots, and leave little vegetable material behind when they decay. For this condition one of the best crops to employ in rotation is sugar-beets, because they strike many small roots deep into the earth. As these decay, each leaves behind a tiny load of vegetable mold deep in the earth, and also makes the soil more porous. As the principal elements of the soil needed by sugar-beets are carbon and oxygen, which are absorbed from the air and sunshine, and as the beets can be sold at a good profit, it is an excellent crop to employ in rotation. In the United States records in various states show that where sugar-beets are used in rotation, the wheat and corn yield is increased from two to four times, and in Germany they are largely used to restore the fertility of the land, even if the sugar-beets themselves are sold at a loss.
It is most important that farmers should understand the principle of rotation of crops, because nothing is taken from the soil so quickly or in such large quantities as nitrogen, and nothing is so easily put back; while, if it is not so replaced, the land becomes worthless.
A comparison of the results of single cropping and the rotation of crops has been clearly shown at the Experiment Station of the Agricultural College of the State of Minnesota, where for ten years they have planted corn on one plot of ground. For the first five years it averaged a little more than twenty bushels per acre, and for the last five years, eleven bushels.
On another plot, where corn was planted in rotation, the average yield was more than forty-eight bushels, the difference in average in the two plots being thirty-two bushels, or twice the value of the entire average yield on the exhausted ground. The corn grown at the end of the ten years was only about three feet high, the ears were small, and the grains light in weight. But it cost just as much to cultivate the land that produced it as it did to cultivate the land that produced forty-eight bushels.
Of the other two elements, potassium is found abundantly in most soils. It is also found in a readily soluble form in various parts of the United States and is sold at a very low price. But even if these deposits were exhausted we could still use the rocks which are very rich in potassium, and are very abundant, in a pulverized form, or potash could be manufactured from them.
The only remaining element of the soil is phosphorus. This element was discovered in 1607, the year of the first English settlement at Jamestown and was first noticed because of its property of giving off light from itself. The name which was given it means light-bearer. It was at first thought to be the source of all power, to heal all diseases, and to turn the common minerals into gold. Although we have long ago learned that these ideas are absurd, yet we have also learned that its real value to man is far greater than was even dreamed of then.
It is the most important element in every living thing, for no cell, however small, in either animal or vegetable organisms can grow or even live without phosphorus. It is found in the green of the leaves, and helps to make the starch. It enters largely into the grain and seeds of plants, and is necessary for their germination, or sprouting, as well as their growth. Three-fourths of all the phosphorus in a crop of cereals is in the grains, giving them size and weight. It will thus be seen how necessary it is that the soil which feeds our plants, which in turn become the food of animals and of man, should contain a sufficient amount of phosphorus.
Phosphorus is taken from the soil in large quantities by every kind of crop. In parts of Wisconsin which have been farmed a little more than fifty years without fertilizing, it is found that about one-third of the phosphorus has been taken out of the soil, which would mean that in one hundred and fifty years, or a hundred years from now, the soil would be incapable of producing any living thing, and long before that time the crops would not pay for the labor of producing them. Almost every acre of land that has been farmed for ten years without fertilization is deficient in phosphorus, that is, so much has been used that the soil can no longer produce at its former rate.
It may be asked, if this be true, why the soil of America, which before it was cultivated had borne rich forests and fields of waving grass, has not become exhausted long ago. We must remember that nature always adjusts itself; that, in the wild state, all plants decay where they grow, and the same elements are returned again to the soil. But when the entire product of vast areas is removed year after year, the soil has nothing except the slow rock-decay with which to renew itself.
In tropical regions it is not necessary to feed domestic animals at any season of the year, but in those countries where the natural food can be found only during a part of the year, the need of artificial feeding is seen at once, and it becomes a part of the regular expense of farming.
It would be considered the height of folly for a man to allow his valuable animals to starve to death because of the expense of feeding them, but few people recognize the fact, which is also true, that it is equally bad business policy to allow the valuable crops of wheat, oats, and corn to starve for want of plant food.
The phosphates (that is, phosphorus) are the only large items of expense, and in a large measure this may be lessened by raising live stock, for which high prices can be obtained either as meat or dairy products, and returning the manure, which contains a large amount of phosphate, to the soil. If all the waste animal products could be returned to the land, Professor Van Hise says, three-fourths of the phosphorus would be replaced. All animal products are rich in phosphates. The packing houses manufacture large quantities from the bones and blood of animals.
The garbage of cities, when reduced to powder, yields large returns in phosphorus. It is said that if the sewage of cities, which in this country is often turned into rivers and streams, polluting them and causing disease, was reduced to commercial fertilizer, it would supply the equivalent of from six to nine pounds of rock phosphate per year for every acre of cultivated land in the United States. And this valuable product is now totally lost, and worse than lost, since it menaces the life and health of great numbers of our people.
There still remain to be considered the rock phosphates, the form in which phosphorus is found in separate deposits. The only large deposits that have been used are in Florida, South Carolina, and Tennessee, and from them about two and a quarter million tons were mined in 1907. Unfortunately, however, there is no law that prevents its export from this country, and almost half of this found its way to Europe, where it is eagerly sought at high prices.
Within a short time valuable phosphate beds, more extensive than any before known to exist in this country, have been discovered in Utah, Wyoming, and Idaho. Professor Van Hise, who is one of the highest authorities on the subject, says of these deposits that with the exception of our coal and iron lands, they are our most precious mineral possession; that every ounce should be saved for the time which is coming when the population will have outgrown the capacity of the land, and means of increasing its fertility in order to prevent famine will be sought from every possible source.
The other great waste of the soil is by erosion, or the wearing away of the soil by stream-flow. We can all see this in a small way by wandering along the shore of any swift-running stream and noticing how the banks are worn away, and what deep gullies and ravines are cut into them by the water running down from the fields above. Another way in which we can observe the effect of this waste is by noticing the muddy yellow color of streams during floods and after heavy rains, and comparing it with the clear blue of the same stream at ordinary times.
When we realize that this muddy color always means that the water is filled with soil, all that it will hold in