The San Juan islander. [volume] (Friday Harbor, Wash.) 1898-1914, 1912-01-26
Farm AND l!!!I' ORCHARD
Nodns ANJqhua Colscs and Ex.es.s Sse.e
SOIL BACTERIA.

/ oOil BAL eHIA.
BY Professor T. D. Beckwith, Profes
sor OF Bacteriology at the O. A. c.
Oregon Agricultural College, Cor
wallis, Oregon Comparatively few
farmers understand the fact that the
soil is a great storehouse Of energy
particularly because it is the home OF
millions of germs per single ounce OF
soil. These germs are put there by
nature for purpose. If the soil
is so cultivated as to favor the &C.
tivities of certain of these germs,
which are called bacteria, the soil
becomes more fertile because of the
beneficial activities of certain of
these microscopic plants. If, how
ever, the farmer is careless in his
methods of tilling and does not
thereby produce conditions favorable
to the growth of the beneficial bac-
terra there also are certain germs
present which, like weeds, gain the
upper hand and produce conditions
which are less favorable to the fer
tility of the soil. It must be under
stood that the fertility of the soil de-
ponds upon the favorable activities
of all of these millions of germs
which are present in the soil. With
this understanding then the follow
ing few facts are presented concern
ing the activities of soil bacteria
and the conditions which influence
them particularly:
| One factor which controls the
growth of soil bacteria is that OF
light. Light in it's action is mega
tive, that is, it is unfavOrable. We
find bacteria then growing in places
where there is at least no direct sun
light, and better still, where dark
ness is almost complete. For this
reason the numbers found on the
surface of the soil are very small
and when one digs down for even
the fraction of an inch below the
| point of penetration of light the
numbers rise very rapidly indeed
Yet when material is thrown on soil
and decompOses we find that there
are sufficient bacteria present in the
immediate vicinity of this material
to start growth and thereby their
work of causing decomposition to
take place is uninterrupted. They
have a slight power of motion on a
moist surface and therefore have a
certain small radius of action.
| Bacteria likewise require certain
amount of food supply. This food
supply may be very diverse in its
composition. Some of the classes of
germs have the power to break down
highly organized material into sim
| pier compounds, such as nitrogen,
ammonia, carbon dioxide. hydrogen
bisulfide gas, ETC., while there are
other classes which have the faculty
of using simple compounds and build
! ing up very complex ones out of
them The moisture which is found
| in soil naturally dissolves out of the
soil certain constituents, making
thereby very weak solution and yet
the solution is entirely sufficient for
the varieties of bacteria found there
and they are able then to use it
for their food supply. Consequently
certain fertilizers in their applica-
ton have special function OF giving
extra food for and enriching the
growth of certain germs.
Another factor is that of the reac-
ton of soil. 1t is well known fact
that soil that is acid or sour is UNI
fertile. Such soil owes this unfav-
orable quality particularly to restric-
uon in the growth OF its microscopic
crop. Before such land may reach
it's highest point of efficiency It Is
necessary to neutralize this acid1ty.
This is done generally by using lime
or similar compound. Under these
conditions then we find the soil read
lily becomes rich and productive. An
especial example of the soil reaction
is found in germs which cause the
nodules on roots of such crops as
alfalfas, clovers, peas, beans, etc.,
plants which are generally called le-
guminous. The bacteria producing
these nOdules enrich the soil very
greatly by fixing the nitrogen In the
nodules and when finally the nodules
are broken up by following, cultiva-
ton and disintegration the nitrogen
which has been secreted there Is left
intact in the soil for use of future
crops In this way we have a lOgi-
cal reason for the popular belief that
the growth of. alfalfa enriches, the
soil And yet if the soil be acid
these bacteria will not grow; the
4 farmer will not get good catch be-
cause for one particular reason OF
the fact that the soil is not ready
for the growth of bacteria which
must necessarily accompany the al
falfa in the SOIL This is but one
example. There are many others
4 which might be cited Another con
J sideration is that of association Of
bacteria in SOIL There are certain
kinds which are injurious to the
growth of other more beneficial vari
cites. It is simple matter to dem
onstrate this under laboratory con
ditions, but a popular example Is
one which is, rather difficult to cite
However, the following may be
quoted: For years it has been the
|custom in certain parts OF France
where there are certain grape dis
eases, to treat the. soil with q very
Iill-smelling liquid called carbonbi
sulfide. It was found after such
treatment, when a proper time had
! been allowed for the liquid to evap
lorate out of the soil, that that soil
became very productive. and 1t was
suDnOsed that It was because OF the