Forest City press. (Forest City, Potter County, D.T. [S.D.]) 1883-19??, 1906-06-21

In addition to the nine elements all
ready mentioned. the growing plant re-
quires four other elements, as follows:
Hydrogen, which it secures from water
(water IS Il compound of hydrogen and
OXYGEN; oxygen, which 1t secures part
~ from water and partly from the air;
carbon, which is secured from carbonic-
acid gas in the air. and nitrogen.
Nitrogen is in many respects the most
important of all the plant food ele-
ments. 1t is not found in appreciable
quantities in the rock particles of the
soil. Ordinary plants depend for their
nitrogen entirely On %decaying organic
matter. AS decay proceeds n~itrates are
formed from the nitrogen contained in
organic matter. The nitrates are ex-
ceedingly soluble. and unless soon made
use of by growing crops they are wash
ed out of the soil. Nitrogen is there
fore usually the first element to be-
come exhausted in the soil.
Fortunately, there are certain species
OF bacteria that can use atmospheric
nitrogen, of which there is an mex
haustible supply. One family of plants
the legumes-has learned to exchange
work on these bacteria, and these
plants are hus easily supplied with an
abundance Of nitrogen in a form they
can use. When these nitrogen-fixing
bacteria are present in a soil on which
a legunlinous crop is growing. the bac-
terra invade the roots of the legume
and live there. Their presence is usual
ly mad manifest by swellings-the so
called tubercles-on the roots of thrifty
plants of clover. alfalfa, beans. peas.
and other legumes. Nitrogen from the
soil air filters into the roots, where the
bacteria appropriate it, manufacture an
abundance of nitrates, and give a por-
ton to the plant In exchange for starch.
The tissues of leguminous plants be-
come very rich in heterogeneous COM
pounds, and when they decay in the soil
they set free large amoun of nftrates
for the use of any crop which may
be growing at the time.
Soil Moisture and Humus.
The cultivation of l%eguminous crops
is one of the most important and
economical means of maintaining a
supply of heterogeneous plant food in the
soil. Nitrates may. of course, be sup
piled in commercial fertilizers; but fer
~tilizers containing nitrogen are very
expensive, and it usually pays better
to supply nitrogen by growing legumes
or by the application of stable manure.
which is rich in nitrogen when proper
ly handled. In good farm practice both
stable manure and leguminous crops
are used as sources of nitrogen.
In order to produce a ton of dry hay
on an acre of land 1t Is necessary that
NAAS - " R0AsI S's@S
acre approximately 500 tons of water.
In order to supply this enormous guam
tity of water, the soil must not Only be
in condition to absorb II hold water
we'll, but 1t must be porous enough to
permit water to flow freely from SOL
to soil grain. The presence OF large
quantities of decaying organic matter
(humus) adds enormously to the water
holding capacity of the soil. One ton of
humus will absorb two tons of water
and give 1t up readily to growing crops.
Not only that, but the shrinkage of the
particles of decaying organic matter
and the consequent loosening of soil
grains keep the soil open and porous.
Furthermore, humus of good quality
is exceedingly rich in both nitrogen r
mineral plant food. The maintenance
of fertility may almost be said to con-
sist in keeping the soil we'll supplied
with humus. The first step In renovat-
ing n soils is to give them an
abundant supply of humus of good
quality. Perhaps the best source of
hunus is stable n containing both
the liquid and the solid eNcrement, as
pecially when the stock is fed rich,
heterogeneous foods. Even a poor quality
of barllyard manure. which has had
much of the plant food cached out Of
il, has considerable ALL because OF
the humus it makes.
.AllObAiSi -
source of humus. but one which
must be used UNDERSTANDINGS. is
crops grown to turn unde as manure
HE lesumeS are especially valuable TOR
This purpose because of the nitrogen
they contain, but other crops. such as
rye, and even corn sown thick, may
sometimes be made to supply large
quantities of humus of fair quality.
! Crops thus used are called green man
uros.
Soil Air.
A proper circulation of air In the
soil is just as important as any other
factor of plant growth. Nearly half
of the volume of ordinary soils is oc-
| cupied by air spaces. The air spaces
IN the soil wind in and out between
| the soil particles, just as they do in
a pile of larger stones. If the layer
of water on the surface of the soil
grains becomes so thick as to stop the
air passages here and there the soil
is then too wet for most crops and
needs drainage. Plants have no special
breathing organs. the oXygen required
in their breathing finding entrance all
over the surface of the plant. Plant
roots must therefore be supplied with
air, and hence the soil must be porous
enough to permit of tree circulation Of
air. A good supply OF humus n prop
err tillage will accomplish this result
in clay soils. Sandy soils are usually
too porous. needing huInus to help them
retain water.
Another reason why air must cir
culate freely in the soil is that large
quantities of oxygen are required to
insure proper decay of organic matter
to supply plant food. Also, carbonic
acid gas is produced by the decay of
organic matter. and this must escape
easily to make room for the atmos-
plheric oxygen needed in the SOIL. The
movement of air in the soil Is fire.
quently shown by the bubbles which
appear at the surface of the soil Just
after a hard rain. AS the water soaks
into the soil it drives the air out. and
bubbles may be seen at the surface II
water enough is present to form them.
One of the most important objects
L ~ rlosuin0 ic 70 loocan IN fha coil a..l