Checking the Waste | Page 7

be naturally fertile, and has been well cared for, the soil is then ready to produce a good crop of corn again.
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