ert to
repair the wastes and mistakes of man. We may gain fundamental truth
about soil fertility through observance of her methods in restoring
land to a fertile condition. Our best success comes only when we work
with her. When a soil has been robbed by man, and has been abandoned on
account of inability to produce a profitable crop, the first thing
nature does is to produce a growth of weeds, bushes, briers, or aught
else of which the soil chances to have the seeds. It is nature's effort
to restore some organic matter--some humus-making material--to the
nearly helpless land. Vegetable matter, rotting on and in the soil, is
the life-giving principle. It unlocks a bit of the great store of inert
mineral plant-food during its growth and its decay. It is a solvent.
The mulch it provides favors the holding of moisture in the soil, and
it promotes friendly bacterial action. The productive power of most
farming land is proportionate to the amount of organic matter in it.
The casual observer, passing by farms, notes the presence or absence of
humus-making material by the color and structure of the soil, and
safely infers corresponding fertility or poverty. Organic matter is the
life of the soil.

[Illustration: A good crop for a poor soil.]

A great percentage of the food consumed by Europe and the Americas
continues to come out of nature's own stores in the soil, organic and
inorganic, without any assistance by man except in respect to selection
of seeds, planting, and tillage. The percentage grows less as the store
of original supplies grows less and population increases. Our science
has broadened as the need has grown greater. We have relatively few
acres remaining in the United States that do not require intelligent
treatment to insure an adequate supply of available plant-food. The
total area that has fallen below the line of profitable productiveness
is large. Other areas that never were highly productive must supplement
the lands originally fertile in order that human needs may be met.

When soils have been robbed through the greed of man, nature is
handicapped in her effort to restore fertility by the absence of the
best seeds. Man's intelligent assistance is a necessity. Successful
farming involves such assistance of nature that the percentage of
vegetable matter in the soil shall be made high and kept high. There
must be such selection of plants for this purpose that the organic
matter will be rich in fertility,