all,
or for timothy and clover seeding in August, may use oats as a spring
cover crop. A large amount of humus-making material may be gained by
this means. The only danger lies in the effect upon soil moisture. The
oat crop uses up the water freely in its growth, and when permitted to
form heads before being plowed down, the mass of material in the bottom
of the furrow does not rot quickly enough to induce the rise of water
from the subsoil. The land should be plowed early enough to permit a
solid seed-bed to be made.

CHAPTER XII

STABLE MANURE

Livestock Farming.--The fertility of the soil is most safely guarded in
regions devoted to livestock farming. "Selling everything off the farm"
is a practice associated in the public mind with soil poverty. It is a
rule with few exceptions that the absence of livestock on the farm is
an index of gradual reduction in the productive power of the land.
Generally speaking, the farmers who feed the most of their crops on the
farm are maintaining fertility, and those who do not feed their crops
on the farm have been making drafts upon the soil's stores of available
plant-food that are evidenced in a reduction of yields. These
statements will have the assent of all careful observers. The inference
has been that the maintenance of fertility requires the return to the
land of all the manure that would result from feeding its crops on the
farm. We know that by such feeding we can return to the fields at least
four fifths of all the plant-food taken out by the crops, and we
loosely reason that such a scheme is demanded by nature. The
maintenance of fertility involves good arithmetic, and a plant must
have certain weights of mineral elements at command before it can grow,
but it is not true that the productive power of land is chiefly
dependent upon the return to it in manure of all the fertility removed
by its crops. If this were true, meat and other animal products would
be the sole food supply of the world's markets.

[Illustration: Texas calves on an Ohio farm.]

The Place for Cattle.--There are general trends in human practice that
cannot be changed by man. A change in human diet that makes the
percentage of meat lower will not come through propaganda, but there
are forces at work that will restrict the consumption of meat by the
individual. The increase in population makes heavier demand for food.
Armsby has shown that the fattening steer returns to man for food only
3