is true of
those elements in manure which form vapor or water, when the
fertiliser decomposes in the ground.

Carbonic acid and nascent hydrogen evolved in rotting stable manure
are truly valuable food for plants, and perform important chemical
offices in the soil; but they are, nevertheless, not so indispensable
to the economical production of crops, as available nitrogen, potash,
silica, magnesia, sulphur, and phosphorus. These elements of plants
being less abundant in nature, and quite indispensable in forming
corn, cotton, and every other product of the soil, their artificial
supply in guano, night soil, and other highly concentrated
fertilisers, adds immensely to the harvest, through the aid of a small
weight of matter. In all sections where corn is worth 30 cents and
over a bushel, great benefits may be realised by the skilful
manufacture and use of poudrette. This article is an inodorous
compound of the most valuable constituents of human food and clothing.
It is the raw material of crops.

It is not necessary to restore to a cornfield all the matter removed
in the crop to maintain its fertility. A part of each seed, however,
ought to be carried back and replaced in the soil, to make good its
loss by the harvest.

In every barrel of meal or flour sent to market (196 pounds), there
are not far from 186 pounds of carbon (coal), and the elements of
water. When a bird eats wheat or corn, I have reason to believe, from
several experiments, that over 80 per cent, of the food escapes into
the air through its capacious lungs in the process of respiration; and
yet the 20 per cent, of guano left will re-produce as much wheat or
corn as was consumed. Imported guano, which has been exposed to the
weather for ages, often gives an increase in the crop of wheat equal
to three pounds of seed to one of fertiliser; while it has given a
gain of seven to one of corn, and fifty to one of green turnips.

Like other grains that have been long cultivated, Indian corn abounds
in varieties. In Spain they count no less than 130, and in the United
States the number is upwards of forty. The difference consists in
size, color, period of maturation, and hardness and weight of grain.
Of size there exists a considerable variety, from Zea Curagua of
Chili, and the Egyptian or chicken corn, both extremely diminutive, to
the large white flint, and ground seed corn of the United States. The
differences in color are the red, yellow, and white.