The San Juan islander. [volume] (Friday Harbor, Wash.) 1898-1914, 1912-01-26

grape had been killed out of the soil
That Without doubt was one very
important result Of the treatment.
however. subsequent investigations
nave shown that 1t was due to the
Iact that the germ balance in that
SOL was broken up by the destruc-
ZION OF certain kinds of bacteria
winch are inimical to the growth of
those which produce the greatest de-
gree OF fertility, thus these other
forms had more favorable oppor-
unity for growth and the soil imme-
olately became more productive.
Such conditions held for some months,
until the other kinds. of germs had
nad opportunity to get back into the
SOIL again from the surrounding
areas. Such method of treatment,
however. is not at all economical for
general cultivation.
Moisture likewise is another import
ant factor. AS general law it is
stated that bacteria require 80 per
cent of water in their surrounding
medium in order to grow. Thirty per
cent of moisture in soil would be
very excessive, but we must remem.
49, ~AA0S SoAAOuo 0OAA POI C1OlO0 Oh Y
covered over with a very thin layer
OF water which is known as hygrO-
scopic moisture, and though this layer
OF liquid is so very thin it is quite
enough to sustain the germs. In
practice we find that where the
amount of moisture falls below this
point preservation itself fails, by
which we mean that growth of bac-
terra is stopped. Cereal grains are
preserved Indefinitely as long as they
are kept dry because there is not
enough moisture there for the growth
OF bacteria which would spoil the
grain; as soon as it gets wet and
soaks it changes rapidly and becomes
worthless because of the action of
certain bacteria, which are not de-
sired in that particular instance In
order to reduce the amount of mOis-
ture and also to increase the number
OF air spaces so that there may be
a greater supply of oxygen in the soil
a farmer then has to drain his soil
as the excess of water makes it heavy
and consequently unfertile.
Another condition which must be
looked out for in order that bacteria
may produce the most favorable re-
suits in soil is to keep the soil as
open as possible and yet so cultivated
as to retain the soil moisture An
open soil is one which contains a good
deal of air. Air is necessary to bac-
terial growth of the favorable kind in
soil because of the fact that it con-
tains one-fifth part of oxygen, and
bacteria thrive much better in the
presence of this element. The nitro
gen which is in the air and which
makes up four-fifths of the ordinary
atmosphere is in this condition mere
ly an inert diluting medium for the
oxygen in it's relation towards most of
the bacteria of the soil. Because of
the fact that air is necessary and
most favorable to bacterial growth it
is then easy to see why certain kinds
of beneficial soil bacteria are much
more active in sand than they are in
heavy clay. In certain parts of our
state we find that loose sands are
most exceedingly fertile and this is
due particularly to the fact that they,
because of their texture, have fur
thered, the growth of bacteria normal
~ present in them, and these bacteria
convert the insoluble plant foods into
a soluble condition so that they may
be used to better advantage by plants
The fact that free circulation of
air in the soil is interrupted by a
number Of factors in the lower depths
Of the soil, but particularly by friction
and by the water table, brings us to
an understanding of the well known
fact that the steadily lessening growth
of bacteria Is found In the upper
three feet. The most numerous life
lies from two to six inches below the
surface, and below this point there
is gradual diminution in the num-
bers present so that below three feet
the number is very small.