t 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 whi