Checking the Waste | Page 7

alfalfa are the best
known, have the power of drawing large stores of nitrogen from the air,
and, by means of bacteria attached to their roots, restoring it to the
ground.
So farmers have learned that if they plant corn one year, it is wiser not
to plant corn in the same field the next year, but to sow wheat, which
requires less nitrogen, and the following year to sow clover, so that the
nitrogen which the corn and wheat have taken from the soil, may be put
back into it. If the land 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.