y
stated. The knowledge of bacteria and their work is recent and limited.
They are many in kind, and scientists are only in the midst of their
discoveries. The practical farmer does well to let bacteriologists
monopolize interest in the whole subject except in so far as he can
provide some conditions that have been demonstrated to be profitable.
The work of bacteria must come more and more into consideration by the
farmer because nature uses them to produce a vast amount of the change
that is going on around us.

In consideration of the value of legumes we must take into account the
bacteria which they have associated with them, and through which they
obtain the atmospheric nitrogen. This would be a negligible matter, it
may be, if all legumes made use of the same kind of bacteria. It is
true that the bacteria must have favorable soil conditions, but they
are the same favorable conditions that our plants require. A fact of
importance to the farmer is that the bacteria which thrive on the roots
of some legumes will not serve other legumes. This is a reason for many
failures of alfalfa, crimson clover, the soybean, the cowpea, hairy
vetch, and other legumes new to the region.

Soil Inoculation.--The belief that the right kind of bacteria may be
absent from the soil when a new legume is seeded, and that they should
be supplied directly to the soil, has failed in ready acceptance
because examples of success without such inoculation are not uncommon.
Even if the explanation of such success is not easy, the fact remains
that legumes new to a region usually fail to find and develop a supply
of bacteria adequate for a full yield, and some of these legumes, of
which alfalfa is an example, make a nearly total failure when seeded
for the first time without soil inoculation. Experiment stations and
thousands of practical farmers have learned by field tests that the
difference between success and failure under otherwise similar
conditions often has been due to the introduction of the right bacteria
into the soil before the seeding was made.

Explanations offered for any phenomenon may later become embarrassing
in the light of new knowledge. We do not really need to know why an
occasional soil is supplied with the bacteria of a legume new to it. We
have learned that the bacteria of sweet clover serve alfalfa, and this
accounts for the inoculation of some regions in the east. We believe
that some bacteria are carried in the dust on