and at the same time their growth
must fit into a scheme of crop production that can yield profit to the
farmer. Soils produce plants primarily for their own needs. It is a
provision of nature to maintain and increase their productive power.
The land's share of its products is that part which is necessary to
this purpose. Skill in farming provides for this demand of the soil
while permitting the removal of a large amount of animal food within
the crop-rotation. Lack of skill is responsible for the depleted
condition of soils on a majority of our farms. The land's share of the
vegetation it has produced has been taken from it in large measure, and
no other organic matter has been given it in return. Its mineral store
is left inert, and the moisture supply is left uncontrolled.
Helplessness results.

Drainage.--Productive soils are in a condition to admit air freely. The
presence of air in the soil is as necessary to the changes producing
availability of plant-food as it is to the changes essential to life in
the human body. A water-logged soil is a worthless one in respect to
the production of most valuable plants. The well-being of soil and
plants requires that the level of dead water be a considerable distance
below the surface.

When a soil has recently grown trees, the rotting stump roots leave
cavities in the subsoil that permit the removal of some surplus water,
and the rotted wood and leaves that give distinctive character to new
land are absorbents of such water. As land becomes older, losing
natural means of drainage and the excellent physical condition due to
vegetable matter in it, the need of drainage grows greater. The
tramping of horses in the bottoms of furrows made by breaking-plows
often makes matters worse. The prompt removal of excessive moisture by
drains, and preferably by underdrains, is essential to profitable
farming in the case of most wet lands. The only exception is the land
on which may be grown the grasses that thrive fairly well under moist
conditions.

Lime.--The stores of lime in the soil are not stable. The tendency of
lime in most of the states between the Missouri River and the Atlantic
seaboard is to get out of the soil. There is no evidence that lime is
not in sufficient quantity in most soils to feed crops adequately, but
within recent years we have learned that vast areas do not contain
enough lime in available form to keep the soil from becoming acid. Some
soils never were rich