Atlanta tri-weekly journal. [volume] (Atlanta, Ga.) 1920-19??, 1921-11-12

in middle Georgia.
The plant food constituents deter
mined and reported are total nitro
gen, total phosphoric acid, total pot
ash, and total calcium oxide. There
are other essential elemtns of plant
4uod, but they are usually abundant
ly supplied in the soil and are, the e
fore, not considered in this article
The acidity of the soil was also de-
termined and is reported in terms OF
the limestone required for its cor
rection.
The principal upland soils of
Wilkes county are deficient in nitro.
gen and phosphoric acid. Most of
these soils, however, are we'll sup
piled with potash. In fact, some of
the samples of the Cecil types are
much higher in potash than the
average of the same types from 9TH
er sections.
1t has been estimated that a pro-
ductive soil of this section of the
state capable of giving good to
heavy yields with only light appli-
cations Of fertilizer, should contain
total plant food to the amount Of
1000 pounds of nitrogen, 5000
pounds of phosphoric acid and 10000
pounds of potash per acre to depth
Of 81 inches.
However, it must be remembered
that these figures are more or less
arbitrary and much depends on the
minerals present in the soil, the
amount of humus present, the farm
ing practices followed and other fac
tors. Thus it may happen that a
soil may contain a large total supply
of some plant food constituent, but
owing to poor physical condition OF
the soil or the inSoluble compounds
in which the plant food is combined,
may not give up enough available
plant food for the crop. This con-
dition is we'll illustrated in the case
Of potash, which though present IN
large quantities in some of the
types, seems to be needed in the fer
tilizer for at least some crops.
Where the total content of plant
food is low, it indicates that care
must be taken to conserve the
amount present and at the same
time shows that it is likely to be
needed in the fertilizer applied. On
the other hand, where it is present
in such large quantities as is potash
in some of these types, it indicates
that by good methods Of soil man.
agement more Of the supply can be
made available to plants.
When it is considered that only
very small percentage of the total
plant food in a soil becomes avail
able from year to year, and the rela-
lively large amount Of some OF these
constituents required by crops, the
significance of the chemical analy-
ses becomes apparent.
Comparing the plant food require
ments Of our common crops with the
average plant food content Of the
principal upland soil of Wilkes coun-
ty, it will be noticed that all these
crops require far more nitrogen than
they do any of the other elements,
yet nitrogen is the most deficient
of any of the plant food constitu-
ents Of the soil. In the case OF corn
and cotton, nitrogen requirement is
more than twice that of. phosphoric
acid or potash.
In other words, the soil is able to
furnish relatively less nitrogen, COM
pared to the amount needed for the
crop, than at can Of either phospho-
ric acid or potash. Consequently,
the yield will be limited in proper
ton to the available supply of nitro
gen, regardless of the abundance
of the other substances.
The nitrogen content of the soil
is dependent on the content of or
ganic matter; for decaying vegetable
matter is the principal source of
soil nitrogen. Clearly then, the first
step in soil building must be that Of
greatly increasing the present sup
ply of nitrogen through large addi-
tons of humus forming organic mat
ter. 1t would be a mistake to as
sumo that this deficiency Of nitro
gen could be met solely by the use
of commercial fertilizers, for the
value of fertilizers is largely depend.
ent upon the physical and mechani-
cal condition of the soil, which in
turn is influenced more by the con-
tent of organic matter than by any
other factor. This explains why the
productiveness of the soil cannot be
maintained solely by the use of min
eral fertilizers. AS the organic mat
ter becomes exhausted, increasingly
larger amounts of fertilizers must
be used to maintain yields, and the
margin Of profit becomes smaller.
until finally the fertilizer may be
used at a net loss, which is, in fact,
sometimes the case.
The methods to. be followed in
maintaining and increasing the or
ganic matter and nitrogen must nee
essarily depend somewhat upon the
type of farming being practiced.
There dairying and other live stock
farming have a prominent place, the
manure from the herds will go a
ong way toward maintaining the
lumus content of the soil, but would
hardly be sufficient. 1t should be
supplemented by winter cover crops
and other leguminous green manure
catch crops, such as coWpeas, soy
beans, velvet beans, ct cetera. These
legumes will not only increase the
humus content, but afford the only.
economical means of building up the
nitrogen supply. In ordinary farm
practice, where cotton and corn are
the chief crops, these green manure
crops offer the only means Of main
tanning organic matter and nitrogen.
They should be extensively grown in
general farming to prevent the soil
from becoming impoverished and un-
productive from continued cropping
The practice Of burning corn and
cotton stalks, and other crop resi-