to $8.41 as an average for the last four years. Thus the profit was
from about 560 to 800 per cent on the investment, counting corn at
35 cents a bushel, oats at 30 cents, wheat at 70 cents, and hay at
$6 a ton. These figures represent the increase produced by
phosphorus over and above the value of the crops grown without
phosphorus fertilizer. In this case no farm manure was used on
either part of the field; but commercial nitrogen and potassium were
applied alike on both parts, and clover was grown in the rotation.

Acid phosphate was also used in direct comparison; and, in answer to
the question whether the general farmer should apply liberal amounts
of finely ground natural rock phosphate, or whether he should pay
four times as much for phosphorus after the fertilizer manufacturer
has mixed one part of the raw rock with one of sulfuric acid and
thus produced two parts of acid phosphate, these Pennsylvania
experiments tell us that the yearly average for the twelve years
gave a gain per year of $2.45 from the raw phosphate and 48 cents
from the acid phosphate, at the prices used by the Pennsylvania
Experiment Station. But we must not draw general conclusions from
this one experiment, even though it covers twelve years.

In 1895 the Maryland Experiment Station began field experiments with
different forms of phosphorus; and, as an average of six tests every
year for twelve years, $1.965 invested in ground raw rock phosphate
produced increases in corn, wheat and hay that were worth $22.11, at
35 cents a bushel for corn, 70 cents for wheat, $6 a ton for hay,
and 3 cents a pound for phosphorus in the ground natural phosphate.
How would you like 1000 per cent profit as the result of mixing
brain with brawn, in connection with the improvement of your own
business, thus keeping the investment under your own control?