The river press. [volume] (Fort Benton, Mont.) 1880-current, 1909-03-17
FIG. n1-THE GROWTH OF corn ROOTS.

CA0s 0uO"Aa Oc OOxN hOOlSs
building them up in still different ways
1t makes the hard wood Of the oak or
the delicate petals of a rose. Man,
with all his skill and machinery, has
never been able to make any products
half so wonderful as are being made
every day in every field on your farm.
If plants are to grow rapidly and
produce large yields, they must be we'll
fed. About half the dry weight of a
mature plant is made up Of carbon.
Practically all Of this m from the
carbon dioXide Of the air. Every acre
of wheat will use a ton of this gas or
all that is in a layer Of air three miles
deep over the acre. The constant mix
ing Of the air by the wind is always
bringing fresh supplies within reach of
the plant.
The farmer does not need to concern
himself with the supply of carbon di-
oxide, for every time he builds a ire
or even breathes he Is adding to the
store Of this material in the air.
The smooth upper surface Of a leaf
is both air and water tight. On the
underside, however, r many small
openings, which are really the mouths
of the plant. 1t is through these tiny
holes that carbon dioxide is taken into
the leaf to be used by the c%hlorophyll.
In making starch and other products
out Of carbon dioxide and water some
oxygen is given off. This passes out
through the openings in the leaves.
Th11S Won cnn fhaf r1ortc Iroo%1,o -,
much the same way as animals do,
only they give off oxygen, the product
which is used by animals, and take up
carbon dioxide, the gas which is
breathed out by animals. In this way
plants make animal life possible. Ami
mails give off carbon dioxide and
manure as waste products. Plants
tear these waste products to pieces
and by rebuilding them make them
once more into food for the animals.
Next to carbon hydrogen and oxy-
gen are the foods that the plant uses
In largest quantities. Since water is
composed of these elements, the sup
ply will be plentiful as long as there
is plenty Of water in the soil.
There is one element, nitrogen,
which forms a considerable part of
the plant, that is harder to get. While
three-fourths of the air is nitrogen.
the plant does not seem to be able to
use 1t in this form. The only kind Of
plants that can use the nitrogen in the
air at all are the legumes, such as
clover and alfalfa. Certain bacteria
that live on the roots Of these legumes
have the power Of changing the at
which the plant can use 1t. We shall
study more about this process later.
Nitrogen Is n Of the most impor-
tant plant foods, and it is one that Is
very often lacking. If the plant can
not get a sufficient supply Of nitrogen
it will be stunted. will stop growing
early, and the yield will be very much
reduced. Since all the crops. with the
exception of the legumes, must get
their nitrogen from the soil, the farm.
er must see to it that there is a plen-
tiful supply there If he wishes to OBJ
tain a large yield.
If you will drop a little rich black
soil on a hot shovel some Of It will
go up in smoke. The part that burns IS
humus and is made up Of vegetable and
animal matter which is partly de.
cayed. This humus contains large
amounts Of nitrogen, and from this
source the greater share of this ele-
ment used by the plant must come. If
your soil Is black, spongy and well
supplied with humus there is little
danger that the plant will go hungry
for nitrogen. One Of the best ways to
keep a field In this condition is to ap-
ply liberal quantities Of barnyard ma.
nure. Another way is to plow under
green crops, especially clover. Some
times It is necessary to buy nitrogen
for the plant in the form Of CONNER
cial fertilizers, but this is a very ex-
pensive way of obtaining 1t.
Even when the plant Is given all the
nitrogen it can use it sometimes fails