of value that should be sufficient in itself
to encourage the feeding of crops on the farm and the careful saving of
the manure. When one can market his crops to animals on the farm at
their cash value, and at the same time retain for his fields four
fifths of all the fertility, he is like a manufacturer who can use much
of his raw material over and over again. The value is in the manure,
and full appreciation is lacking only because a majority of farms do
not provide for careful saving of its valuable constituents.

Relative Values.--The plant-food content of manure is determined
chiefly by the feed. The animals add nothing: they subtract. The kind
of animals consuming the feed does not affect materially the value of
the manure made from it, if the animals are mature and not giving milk.
The manures from the various kinds of animals differ in value per ton
because the feeds differ in character and the manure varies in
percentage of water. On an average, however, the total annual product
of manure from farm animals, per 1000 pounds of live weight, does not
vary widely in value. The rich protein feeds given the cow, and the
heavy feeding, more than make amends for the fertility that goes into
the milk, and her annual product, per 1000 pounds of live weight, may
exceed in value that of the horse by 25 per cent. This is likewise true
of the pig, figured on the 1000-pound basis, while in the case of the
sheep the value, per 1000 pounds of live weight, is near that of the
horse.

[Illustration: In the fertile Miami Valley, Ohio.]

These variations are not wide enough to have great importance to the
livestock farmer. The manure represents to him four fifths of all the
fertility that was contained by the feed he gave the various animals.
They added no plant-food, and they took away only a fraction that was
not large. They converted the crops into a form of plant-food that
either is available or can become so quickly enough, and in addition to
the nitrogen, phosphoric acid, and potash that would have a high
valuation in a commercial fertilizer, there is a body of organic matter
that affects the physical condition of the soil favorably. The manure
also promotes the multiplication of friendly soil bacteria. Its
possibilities are so great that the inference of many farmers that no
successful agriculture can be maintained without it is very natural.

Amount of Manure.--Vivian states that the amount of manure that may be
made fr