Audubon Republican. [volume] (Audubon, Iowa) 1894-1925, 1905-10-05
NIISCEEIaANX
Soil Fertility In the Corn eelt.

ATllCleS nave recently appeared I
several agricultural journals suggest
ing that the total plant food content
of the soil is essentially permanent,
theory which is liable to mislead the
farmer and injure the farm. For en-
ample. take the following statements
quoted from Delaware station bulle-
tin:
An average of the results OF 40
analyses OF the typical soils of the
United States showed per acre for the
first eight inches of surface $500
pounds of nitrogen, 2,100 pounds Of
phosphorus, and 11,100 pounds of POI
tassium. The average yield of wheat
in the United States is IA bushels per
acre. Now If all the poten-
tial nitrogen, phosphorus, and potas-
SUM could be rendered available there
is present in such an average soil, in
the first eight inches, enough nitrogen
to last 80, enough phosphorus for 500.
and enough potassium for 1000
years."
Who wishes to raise only IA bush
els OF wheat to the acre? Let us plan
to raise 40 bushels and possibly we
shall then get 80 bushels. The aver
age yield of corn in Illinois is 33 bush
els. but those who prepare TO raise
100 succeed In getting rs bushels per
acre.
The average soil of the corn belt
does not contain 2,1O0 pounds Of phos
phorus per acre in the surface eight
inches, but only about 1900 pounds OF
total phosphorus to that depth. A
lOO-bushel crop of corn requires %
pounds of phosphorus; consequently
the total phosphorus content of this
surface soil, instead of being sufficient
for 10000 crops or for 500 crops, is
as matter of fact, sufficient for only
10 crops of corn of 100 bushels each
On the other hand the nitrogen con
tent OF the Illinois soil, instead Of be
ing only 1900 pounds, is about 5000
pounds per acre to a depth of eight
inches; and where clover or othef
legumes are being grown in rotation
or as catch cpops, the supply is being
to some extent at least renewed.
The total potassium content of an
acre OF Illinois prairie soil to depth
or eight inches is more than three
times 11,1O0 pounds. Thus, the com
monest type Of soil in the corn bell
contains, in the first eight inches
enough nitrogen for 60 years, enough
phosphorus for 80 years, and enough
potassium for 1000 years II 100-bushe;
crops of corn were the standard and II
the stalks were all returned to the
soil. If the entire CROP including both
grain and stalks, were removed from
the land and nothing returned, then
the nitrogen would last 40 years, the
phosphorus 70 years, and the potas.
SUM 500 years.
In 1904 the Illinois station harvest.
ed SO bushels of corn per acre from
field which had been rotated in corn,
oats and clover for 20 years. On an
other adjoining field which had been
in pasture for at least IS years pre-
vious to 1894 and in corn, oats and
clover since 1894, a crop of IA bushels
was produced without soil treatment;
but where lime and phosphorus had
been applied to part of the same field
SO bushels per acre were produced.
The value of the 20 bushels increase Is
not only double the annual cost of the
limestone and bone meal applied, but
the phosphorus applied is more than
would be removed in 100-bushel crop
of corn, so that this field is not only
growing larger crops but at the same
time it is being made richer and rich
er year by year, whereas the untreat-
ed land which produced "A bushels per
acre Is poorer by the II pounss of
phosphorus removed in the crop. The
II pounds are more than per cent.
of the total phosphorus in the first
eight inches.
If the phosphorus is continually sold
from the farm in grain or In the
bones of animals, 1t must also be
brought back, either in corn, or in coz
centrated feeds Gas bran or oil meaD,
or in bone meal Originally a farm
product), or in rock phosphate from
our great natural deposits, of which
more than million tons are now be.
ing shipped annually from the United
States to foreign countries
Briefly stated, with the use Of suf-
f1cient limestone to keep the soil
sweet and abundant, use of legume
crops and catch crops, and the addi-
ton to the soil of ton of ground rock
phosphate, or its equivalent, every six
or eight years, in connection with all
of the farm manure which can be
made, the ordinary lands of the Cen
trail West can be made to grow large
crops indefinitely"
Cyril G. HonkinS